Item I1 BOARD OF COUNTY COMMISSIONERS
AGENDA ITEM SUMMARY
Meeting Date: September 17, 2013 Division: Public Works Division
Bulk Item: Yes _ No X Department: Engineering Services
Staff Contact Person/Phone #: Judy Clarke X4329
AGENDA ITEM WORDING: Presentation of condition assessment of the Old Seven Mile Bridge
from Knight's Key to Pigeon Key by HDR Engineering, Inc.
ITEM BACKGROUND: The Board of County Commissioners is considering partnering with
Florida Department of Transportation (FDOT) to fund repairs to the Old Seven Mile Bridge from
Knight's Key to Pigeon Key and to assume maintenance of the structure upon completion of repairs.
The BOCC directed staff to hire a consultant to review existing bridge reports and prepare a condition
assessment of the bridge as part of the evaluation process.
PREVIOUS RELEVANT BOCC ACTION: The BOCC approved Resolution 129-2011 that
requested that FDOT work with county staff to develop a cost effective alternative for bridge upgrades
that would allow the Old Seven Mile Bridge to remain open for public use and to participate in a
multi-agency partnership to save the Old Seven Mile Bridge in April 2011.
CONTRACT/AGREEMENT CHANGES: N/A
STAFF RECOMMENDATIONS: N/A
TOTAL COST: $0 INDIRECT COST: BUDGETED: Yes No
DIFFERENTIAL OF LOCAL PREFERENCE: N/A
COST TO COUNTY: -0- SOURCE OF FUNDS:
REVENUE PRODUCING: Yes No AMOUNT PER MONTH Year
APPROVED BY: County Atty OMB/Purchasing_ Risk Management
DOCUMENTATION: Included Not Required
DISPOSITION: AGENDA ITEM#
Revised 7/09
Draft Evaluation Repo
OLD SEVEN Mill E BRIDGE
ASSESSMENT PROJECT
Project Limits : Pigeon Key to Knight Key
Project Number:
® Prepared For:
Monroe County
Engineering Department
Prepared By:
HDR Engineering, Inc.
August 2013
"r ti
Draft Evaluation Report
OLD SEVEN MILE BRIDGE ASSESSMENT
PROJECT
Project Limits : Pigeon Key to Knight Key
Project Number:
Prepared For:
�o
Monroe County
Engineering Department
Prepared By:
HDR Engineering, Inc.
15450 New Barn Road
Miami, FL 33014
Nelson E. Canjura
P.E. No. 43235
HDR Engineering, Inc.
Monroe County Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
TABLE OF CONTENTS
Section Pe e
SECTION 1 EXECUTIVE SUMMARY................. .......... ...-.., ......... ......, ......... ......... .......... 1
SECTION2 INTRODUCTION....... ......... ......... ......... ................. .. ........ ......... ..I...... ........... 2
2.1 Purpose of Evaluation.. ......... ......... ................. . . ................... ............ .... .. ......... ............2
2.2 Need for Improvement........... .......... . ....... ............... .. .. .......... ,. , . ,..,...,... 2
2.3 Bridge History........................................... .... ........ .................. .......,....,,,,....---,......... .....,2
2.4 Document Request....... ........... ................ ..... ...... ....... .................... ......... ......... ............3
SECTION 3 EXISTING BRIDGE CHARACTERISTICS ...................................... ....... ...... ........ 4
3.1 Existing Bridge Characteristics...................... ............. ..... ......... ......... .............. 4
3.2 Vertical Clearance.................................................... .......... ....... ............ ......... ...... 6
3.3 Drainage................................................................... ......... ...... 6
3.4 Bathymetric Data ......... ............... . ............. .............. . ... ......... ......... ........... .. .................- 6
SECTION4 PROPOSED RETROFIT...............................................................................I.. ........... 7
4.1 Old Seven Mile Bridge Internal Estimate...................................... ................,,....,.............7
4.1.1 Summary....................................................... .. ..... ........ ...,..,.. ,.... .... ............ 7
4.1.2 Assumptions Used in Estimate .................. ........... .............................. ,.. ............8
4.1.3 Proposed Load Carrying Capability................................w,.,,..,,,.,...............,.,....,.,,..,........ 9
4.1.4 Cost Estimate............ .............,,.,.... ...........,,... .. .................,.,......,..,...,,..,,. , . .......... 12
4.1.5 Additional Comments................. .. ......... ..................---....... ........, ......... 12
SECTION 5 EXISTING BRIDGE EVALUATION.... ......... ......... ........ ......... ...............................14
5.1 Existing Conditions................................. ..... .-....,. .........,,. ...,... ....,.... ..........,.,... .............. 14
5.2 Substructure.................... ...... ................ ....... .. ..,....,,..,,................. 15
5.3 Superstructure ......................... ........ ...,...,...,,...,, ............... ................ 16
SECTION 6 FUTURE MAINTENANCE CONSIDERATIONS AND REPAIR REQUIREMENTS................21
6.1 Frequency of Inspections .... ......... .•,...... .,...,,,...,., . ....
21
6.2 Fracture Critical Bridges......... ............ ....... ....... . ,,. .. ...... ......... .....,..,. 21
6.4 Constructability& Construction Access...,... ................. ......... ... ,•.,......22
6.5 Painting/Coating Systems...... ............. . .... ......... ...............„..... ........, .,..,.,,. ..,........,..... ..22
6.6 Potential for Additional Costs........... ........... ....... ...... 23
6.6.1 Deck Repair versus Deck Replacement.......... ......... ...... 27
6.6.2 Superstructure Rehabilitation to Improve the Load Carrying Capacity........................ 28
6.6.3 Substructure Corrosion Evaluation........... ......... ___.............. ......... ......... .......29
6.7 Major Repair and Rehabilitation Costs........ .....,.,. ,..... 29
SECTION 7 OTHER CONSIDERATIONS ............ ........ ........ ..................,. ....,..., ........ .............31
7.1 Superstructure Replacement Costs.............. ......... ..................... ,........ .....31
i Revision 0
August 2013
A40mve Coloq), Old Seven Mile Bridge Assessmeni Pr qjec(
llrqjeci No. Evandalion Awpori
7.2.1 Constructa bi I ity�. ................... ......... ................ ...... ..................... 32
7.2.2 Cost Estimating... ....... ..... ........................ ...... 32
7,23 Environmental Considerations ...... ......... ............. ........ ..... ..........-...32
7.2.4 Funding.....-- ........ .............................. .......--.....-...-..........---...............................32
APPENDIX A FDOT OLD SEVEN MILE BRIDGE INTERNAL ESTIMATE,APRIL 14,2011.....................A-1
APPENDIX B POTENTIAL FUTURE COST SUMMARIES.................................................................. 8-1
APPENDIX C FDOT DOCUMENTS REQUESTED............................................................................ C-1
H
till August 2013
Monroe County Old Seven Mile Bridge Assessment Project
t
Project No. �� P
Evaluation Report
Section 1 Executive Summary
Due to its significance in the areas of transportation and engineering, the Old Seven Mile
Bridge/Knights Key Bridge was listed in the National Register of Historic Places (NRHP) in 1979.
The Old Seven Mile Bridge was built in 1912 as part of Flagler's FEC Railway, and was converted
(after the Labor Day Hurricane of 1935) to the Overseas Highway, via placement of a wider road on
top of the steel girder bridge.In 1982,when the New Seven Mile Bridge was built,the Old Seven Mile
Bridge was removed from the State Highway System. In March 2008 the bridge was closed to
vehicular traffic.
Today the bridge is showing signs of distress and needs a long term commitment to rehabilitate and
maintain the bridge in accordance to current guidelines. This report contains a general assessment of
potential additional repairs and associated costs (order of magnitude). These costs are substantial, but
so is the state of distress. The existing conditions are well documented in the Bridge Inspection
Reports. Per the 2012 November Report:
• The bridge is Structurally Deficient with the Substructure rating 4 (Poor), including
approximately 206 linear feet of the reinforced concrete pier walls exhibit advanced
deterioration. Corrosion of reinforcement and/or loss of concrete section of substructure is
sufficient to warrant review to ascertain the impact on the strength and/or serviceability of the
reinforced concrete pier walls.
• The steel substructure bracing system around the pier top section was noted to have severe
corrosion with associated minor section loss.
• The foundations were rated "high" for susceptibility of scour, however no report of current
scour conditions were provided.
• The Superstructure was rated 2 (Critical), approximately 20,960 linear feet of open steel girder
were noted to have section loss due to corrosion that is sufficient to warrant structural review
to determine the ultimate serviceability of the bridge elements.
• All top gusset plates have a general condition of 100%section loss.
• Approximately 44,055 linear feet of floor beams exhibit a general condition of severe
corrosion up to 100%section loss along the top and bottom flanges and web.
• Approximately 55%of the floor beams are not bearing over main girders due to section losses.
The connection welds between girders and floor beams overhang supports have a general
condition of 30%section loss.
• The increase of deficiencies for the steel floor beams between November of 2011 and May of
2012 was calculated to be 3.2%.
• The Deck component was rated 3 (Serious) and large sections of spalling concrete were noted
along the underside of the deck and curbs leaving portions of steel exposed to the elements.
The 2012 November Bridge Inspection Report recommended that the entire superstructure be replaced
and that the bridge be closed until retrofit or replacement is complete.
Based on our evaluation, the cost of the repair/rehabilitation that is required, in addition to the $18.2
million in repair work proposed by FDOT Internal Estimate is as follows:
Year 0 Year 1-5 Year 10 Year 20 Year 30
Replace Deck, Replace Floor Replace Floor
Deck Only Replacement&FDOT Steel Rehab Approach Alternative FDOT 239,758 SF Floor Beams& Beams& Beams&
Estimate Deck Repairs Substructure Substructure Substructure
Re air Re air Repair,,
ITEM SUMMARY Total over 30 yrs 1 $71,764,275 187,214,340 $5,560,688 1 $28,660,200 $14,379,970 $4,949,077
Figure 1—Potential Future Estimate of Costs
1 Revision 0
fill August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
Section 2 Introduction
2.1 PURPOSE OF EVALUATION
The purpose of this evaluation report is to document the costs of the repair work proposed by the
Florida Department of Transportation (FDOT) and estimate additional costs that may be expected
based on the existing conditions. The estimated cost of repairs to the bridge should allow use of the
bridge by pedestrians, cyclists and a light tram vehicle (carrying passengers to Pigeon Key) and
discuss the expected future maintenance costs based on a 30-year lifespan.
The report contains a general assessment of potential additional repairs and associated costs (order of
magnitude). A bridge inspection to include superstructure, substructure and piling is not part of this
work order. A detailed inspection may be required as a future assignment in order to (a) validate the
scope of the repair proposed by FDOT; (b) determine changes to the condition of the structure since
the last inspection; (c)determine extent of future repair costs.
2.2 NEED FOR IMPROVEMENT
In April 20, 2011, the Board of County Commissioner's approved Resolution No. 129-2011 to save
the Old Seven Mile Bridge. The resolution requested the FDOT to develop a cost effective design
alternative for bridge upgrades that will allow the Old Seven Mile Bridge to remain open for public
use.
The resolution also highlighted the significance of the bridge as follows:
• The Pigeon Key Historic District and the Old Seven Mile Bridge in Monroe County are each listed
in the National Register of Historic Places
• The Bridge provides the only land access between Knights Key and Pigeon Key in Monroe
County.
• The Bridge is considered a"linear park"for walkers,joggers, skaters and cyclist.
• Monroe County, in partnership with other state, federal and local agencies and nonprofit groups,
desires to repair the Bridge to restore safe access from Knights Key to Pigeon Key, and preserve
the Bridge and Pigeon Key as historic, recreational and cultural resources
2.3 BRIDGE HISTORY
The Old Seven Mile Bridge was built in 1912 as part of Flagler's FEC Railway, and was converted
(after the Labor Day Hurricane of 1935) to the Overseas Highway, via placement of a wider road on
top of the steel girder bridge. In 1982,when the New Seven Mile Bridge was built,the Old Seven Mile
Bridge was removed from the State Highway system. The FDOT retained title to the two-mile
segment of the Old Seven Mile Bridge(Bridge#900020)between Knights Key and Pigeon Key.
In March 2008 the bridge was closed to vehicular traffic associated with Pigeon Key and in June 2008
it was closed to fishing as well. The FDOT has continued conducting annual bridge inspections which
reveal the structure has continued to deteriorate at an accelerated rate.
2 Revision 0
IER August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. P
Evaluation Report
2.4 DOCUMENT REQUEST
FDOT provided a Draft Proposed Retrofit option for review by Monroe County. This proposed retrofit
was provided with the title"Old Seven Mile Bridge Internal Estimate,April 12, 2011"and is provided
in Appendix A.
In preparation for this evaluation,HDR requested the following list of documents from FDOT:
Item 1 Bridge Inspection Reports (2006-2012)
Item 2 Existing Bridge Plans
Item 3 1974 Repair Plans and Any more recent Bridge Repair/Rehabilitation Plans
Item 4 Bridge Load Rating Calculations for Vehicular Traffic and Pedestrian Loads
Item 5 Report of Findings, Old Seven Mile Bridge Internal Estimate,April 14,2011 —Monroe
County received from FDOT the three-page summary outlining an approximate cost for
Option 1 Rehabilitation.We are asking for the full report.
Item 6 Corrosion Evaluation and Associated Damage on the Piers Report,May 2004 by
CONCORRFlorida or more recent
Item 7 Bridge Rehabilitation Reports that include Bridge Repair Costs Estimates
Item 8 Essential Fish Habitat Assessment,August 2004
Of the requested documents,the following items listed above were/were not provided:
• Item 4: The Load Rating for vehicular traffic dated 2002 was provided. The Load Rating for
Pedestrian loads referenced in the April 14, 2011 Internal Estimate was not provided.In
addition,the Inspection Reports mention a September 19, 2008 Load Rating Analysis
which was also not provided.
• Item 5: The full estimate and the basis for the April 14, 2011 estimate was not provided, including
the 2010 Deficiency List table referenced in the document.
• Item 7: No additional Bridge Repair Estimates and basis for the estimates were provided.
• Item 8:Not provided.
3 Revision 0
IER August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. fa��"
� Evaluation Report
Section 3 Existing Bridge Characteristics
3.1 EXISTING BRIDGE CHARACTERISTICS
The Old Seven Mile Bridge from Knight Key at the southern tip of Marathon to Pigeon Key was
removed from the State Highway System in 1982. The bridge now acts as a minor road serving only
Pigeon Key.
The Old Seven Mile Bridge contains:
• Spans 1 thru 16: Sixteen(16) 60'-0" spans
• Spans 17 thru 135: One hundred nineteen(119) 80'-0"spans
• Total length of 10,480 feet
• Bridge width is 22'-10", with two 9'-11"lanes and 1'-6"curbs
The superstructure is comprised of the following:
• Two main girders per span,fracture critical due to the lack of redundancy
• Main girders are simply supported,riveted steel plate girders with transverse stiffeners
• Main girders are 8 feet deep for 80'-0"spans and 6 feet deep for 60'-0" spans
• Main girders have diagonal and lateral bracing between girders
• Needle beams(floor beams), 8"deep and perpendicular to the main girders, are placed on top of
the main girders to support the concrete deck
• Spans 1 thru 16: Thirtcen(13)floor beams per span
• Spans 17 thru 135: Seventeen(17) floor beams per span
• Existing traffic railing is steel post and railing system
The substructure is comprised of the following:
• Solid concrete piers founded on timber piles
• Type types of piers,rounded shaped and rectangular shaped
• Only east and west faces are reinforced
4 Revision 0
laq August 2013
Monroe County Old Seven Mile Bridge Assessment Project
�i
Project No. Evaluation Report
4
U � r^!'ASPHALT �..,. .._...i.
WOO
Grr ,. .• ., .._ _ ..� �r _ _, _.e.e
r r *
�� �•��, sxahry
� \—T£E 01 0 IJ>S.
TEE 4X4 o U.5� t L 5%x xJ%7 9'/d ti
y ,
of
II
,9 8
AT END SPAN AT CENTER SPAN
TYPICAL SECTIONS
Figure 2—Typical Section for 80'-0"Spans
�•.6• d"i•p" I'-6
ASPHALT
2I'.
O�x
m
L ex+x'y L 6x4xyr
'^-iEE AXI a 13.5o
L ShxJ%a T/,w f d
TEE 04 a 4.5• r
b Y
a
AT END SPAN AT CENTER SPAN
TYPICAL SECTIONS
Seo@:,'-J'
Figure 3—Typical Section for 60'-0"Spans
$ Revision 0
lul August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
3.2 VERTICAL CLEARANCE
The vertical alignment of the existing bridge is flat. The vertical clearance is about 16 feet above
MHW for the 8 foot deep beams, 18 feet above MHW for the 6 foot deep beams. Over Pigeon Key,
the vertical clearance is about 15.5 feet above the existing ground to the 6 foot deep beams.
3.3 DRAINAGE
The existing bridge currently discharges to the ocean via deck runoff.
3.4 BATHYMETRIC DATA
Bathymetric(depth)readings are as follows:
• Piers 1 to 11 —water depths 7 to 12 feet deep
• Piers 11 to 19—water depths 2 to 3 feet deep
• Piers 19 to 30—water depths 8 feet deep
• Piers 30 to 51 —water depths 3 to 4 feet deep
• Piers 51 to 135—water depths 7 to 12 feet deep
• Pier 135 and Knight Key—water depths 2 to 5 feet deep
The channel is approximately between Piers 19 to 30.
6 Revision 0
fill August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
Section 4 Proposed Retrofit
4.1 OLD SEVEN MILE BRIDGE INTERNAL ESTIMATE
An internal FDOT estimate was provided to Monroe County and is shown in Appendix A. The total
estimate at the bottom of the third page stated a value of $18,214,832 dollars. This section will
evaluate the work proposed by this FDOT estimate.
4.1.1 Summary
A 2010 Deficiency List table is referenced that was created based on the 2008 Load Rating report. The
2008 Bridge Inspection Report was provided as part of our document request, however, the Detailed
Deficiency List referenced in the Inspection Report and in the Internal Estimate was not provided for
our review. However, an evaluation of the information that was provided is still feasible.
The internal estimate was based on the following:
• Estimate to repair ONLY a five foot section of each main steel girder top flange on Spans 13, 15,
50, 73, 83 and 135. This represents 6 spans out of 135 spans,or—4.5% of all spans.
• Evaluated the floor beams at numerous locations, and proposed to retrofit 810 floor beams. This
represents 810 out of 2231 floor beams,or 36% of all floor beams.
.I
t' II
r
i f
f rj I f � �, � 1✓�� i%
Figure 4—View of Deck,Short and Long Floor Beams,Main Girder,and Floor Beam Strut Angles
• Bearing stiffener angles were being retrofitted for each bearing area within Spans 13, 15, 50, 73,
83 and 135. This represents 24 bearings out of 540 total,or^4.5% of all spans.
• Estimate includes removal of deteriorated paint and repainting main girders and all fracture critical
elements, estimated at $3.5 million dollars.
7 Revision 0
tal August 2013
Monroe("'ouqv p Old Seven Mile Bridge Assessment Project
Project No, Evaluation Report
k"I"
"ZI-0/1
IY
Figure 5—View of Main Girder Bearings,Bearing Stiffeners and Strut Angle
4.1.2 Assumptions Used in Estimate
The internal estimate specifies the following findings or assumptions:
1. Each original main girder has three plates at mid-span for the top and bottom flanges. The repair
estimate will allow 100% section loss of the top plate, 50% section loss of the middle plate and
20% section loss of the flange angle. This means that our of the original 1-1/2" of plate thickness,
approximately 7/8"in thickness can be considered lost and only 5/8"in thickness remaining to be
able to carry the pedestrian loading.
2. The webs have had extensive loss in section; however the remaining section is still adequate for
the intended pedestrian loading.
ICE PI ;a -0
7 se,0' C
s
M. �-o I -A,-
, A
av
*:�-7 4
7
4,
...........
Figure 6—At the Center of the Span,the Top and Bottom Flanges Have
Two Cover Plates in the Original Design
Revision 0
Axqust 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. j r Evaluation Report
Web
Anyle
2 12'x%'
Plate
..... .. .. . ..
lhrilncss = i%f /h,ilne,s = X'
Section Loss = (7' Sr•r:ron Loss '/"
Section Loss
ORIGINAL SECTION LOSS ALLOWED
Figure 7-Assumption of Section Loss in FDOT's Internal Estimate
4.1.3 Proposed Load Carrying Capability
According to the Bridge Inspection Report of May 2013, it states that a Load Rating analysis was
submitted on September 19, 2008 and based on this load rating, the condition of the existing bridge
does not allow vehicular loads and pedestrian loads shall not exceed 58 pounds per square foot(psf).
FDOT in their internal estimate are targeting a capacity of 65 psf at the Inventory rating level. It is also
mentioned that this will allow a rating of 85 psf at the Operating rating level. In layman terms, a
simple explanation of Inventory and Operating ratings are the following:
3. Inventory rating is the capacity rating for the vehicle type used in the rating, or the pedestrian
loading in this case, that will result in a load level which can safely utilize an existing structure for
an indefinite period of time. Inventory load level approximates the design load level for normal
service conditions.
4. Operating rating will result in the absolute maximum permissible load level to which the structure
may be subjected for the vehicle type used in the rating. This rating determines the capacity of the
bridge for occasional use. Allowing unlimited numbers of vehicles to subject the bridge to the
operating level will compromise the bridge life. This value is typically used when evaluating
overweight permit vehicle moves.
5. Vehicles, such as maintenance vehicles, or even the light tram may be too heavy to be safely
carried on the bridge and needs to be evaluated.
The LRFD Guide Specification for the Design of Pedestrian Bridges (December 2009 Edition)
specifies that pedestrian bridges should be designed for a uniform pedestrian load of 90 psf. In the
Commentary to Section 3.1 of the Specification, it states that previous editions of the Guide
Specifications allowed a reduction to 65 psf but typically designed for 85 psf. What this means is that
a pedestrian bridge designed in 2013 would be designed for 90 psf while the Old Seven Mile Bridge is
targeting a capacity of 65 psf.
9 Revision 0
fal August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. M Evaluation Report
tr
y,ei ;: I rif, 9
Figure C3.1-1—I.Ive Load of 50 psf
i
l��y��i jglq��9ff � TBA
V
Figure C3.1-2—Live Load of 100 psf
Iwo fail ll�� ��
0
y
m
ilia �
Figure C3.1-3—Live Load of im psf
Figure 8—Visual of Pedestrian Loading
To visualize the above, a new pedestrian bridge designed to 90 psf will have an Operating level load
of about 150 psf as shown in the Figure. The Old Seven Mile bridge can safely carry 65 psf loads but
will have a maximum capacity of an Operating level load of 85 psf. The density of the people on the
bridge will be between the 50 psf and 100 psf visuals. However, this is NOT the load that can be
10 Revision 0
I-alAugust2013
Monroe County DR Old Seven Mile Bridge Assessment Project
Project No Evaluation Report
carried indefinitely without compromising the life and safety of the structure; it is an occasional
maximum load. The safe indefinite load will be a density closer to the 50 psf shown in the Figure.
The internal estimate does not mention any vehicles that will be able to be safely carried for an
indefinite period or an occasional vehicle. Since the last time the bridge was load rated, it had a
maximum capacity of 58 psf for pedestrian loading, and the proposed retrofit improvement is targeting
65 psf, it can be assumed that the capacity to carry any type of vehicle will be the same as what is in
the current load rating.Based on the May 2013 Report, a two axle truck has a posting limit of 4 Tons.
fable 3.2-1—Design Vehicle
Clear Deck Width Dcsi n Vchicic
7 to 10 11 H5
Over 10 fi 1110
14 ft 0 in.
........
. .. 0 kips 16 0 k� `.
ps .....�
H'10 +�. �'
H 5 2.0 kips 8.0 kips
NI 14ft0n.
c W-Tolal Weghl of Tnitk and Load o
I I
Figure 9—Single Truck Loading Without Any Concurrent Pedestrian Loading
Based on the figure, an 1110 vehicle weighs 10 Tons and an H5 vehicle weighs 5 Tons (e.g. a van type
ambulance), which exceeds the 4 Ton posting. Based on this evaluation, a light tram could be
acceptable if under a 4 Ton total weight with passengers and golf cart traffic.
-„��y�,
mow.
i
1 .
Figure 10—Tram with 23 Passenger Capacity at 6 Tons Will NOT be Acceptable
11 Revision 0
August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. Uri Evaluation Report
J
Figure 11—Electric Light Tram with 14 Passenger Capacity at 3 Tons May be Acceptable
4.1.4 Cost Estimate
The estimate for the repairs is provided and summarized in the figure below.
CITY 7$S10,800,160
ost
Description Unit Unit Price (Option 1) (Option1)
Struct Steel
Rehab, Carbon LB $10 1,080,016
Rivets- High Strength Bolts,
Replacement EA $100 26,493 $2,649,348
Coating Existing Structural
Steel,Touch up ONLY SF $10 8,000 $80,000
Remove Existing Railing LF $3 23,232 $69,696
Install AASHTO Compliant
Raiing LF $48 23,232 $1,115,136
Remove deteriorated paint and
repaint main girders and fracture
critical components LS $3,500,000
TOTAL: $18,214,340
Figure 12—FDOT Internal Estimate for Repairs
4.1.5 Additional Comments
In my opinion, this estimate is the minimum cost in a range that can vary significantly. If Monroe
County is sharing the cost of the repairs, then there is definitely a valid concern that the costs of the
repairs can escalate based on field conditions. Otherwise, FDOT will provide a structure that meets the
loading requirements of 65 psf and it will be up to Monroe County to determine the future repair
needs.
The Friends of Old Seven, Inc., a non-profit group whose mission is to save, restore, enhance and
maintain the bridge had the following subsequent slides in one of their presentations. The FDOT
Restoration Proposal is accurate, and the cost of the restoration matches the Cost Estimate.
12 Revision 0
fill August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
FDOT Restoration Proposal
Retrofit Bridge To Increase Structural Capacity:
Maintain Pedestrian and Bicycle traffic and ��� � /„ '�''°` �� Xi«� „
occasional golf-cart traffic
Place Two (2) new floor beams, one on each
side of the long floor beams to be retrofitted. '`"�f
4
Install new steel plates in areas with
deteriorated top flange cover plates.
� Replace rivets with high strength bolts.
Replacement of railings with new (AASHTO) f��
pedestrian railings and paint steel girders
Estimated Restoration Construction Cost: Million
iwuuuuuuuuuuu�mmmuuummmmmo�mmrmm��m�mmrc�mmm�mmmmrcmr�w
9 Million
F't twtT to contribute, 50%. �W�wwwww wwWWWWWWWWWWW wwwwwwwwwwwwwwwwwmWWWW
Figure 13—Friends of Old Seven FDOT Restoration Proposal Slide
Annual Mainte nance Costs
)1 L , w (as per FDOT estimates)
'i 0 --15 - then c .r
costs .�� 3.8 million
�wwwwwwwwww�� wwwwwwwwwwwwwwwwwwww �
(realistic estimates)
Figure 14—Friends of Old Seven Annual Maintenance Cost Slide
However, the similarity ends when looking at the estimated Annual Maintenance Costs. These costs
will be discussed and evaluated in Section 6.
13 Revision 0
laq August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. °� Evaluation Report
Section 5 Existing Bridge Evaluation
5.1 EXISTING CONDITIONS
The 2012 November Bridge Inspection Report show a bridge structure that has a posted weight
restriction of 4 tons. There is a statement toward the end of the Inspection Report that reads:
Based on the load Rating Analysis submitted on September 19, 2008 the condition of the existing structure does not allow vehicular
loads and pedestrian loads shall not exceed 58 pounds per square foot
I speculate that the steel main girder spans (Spans 13, 15, 50, 73, 83 and 135) chosen to be repaired in
the FDOT Internal Estimate were spans that lowered the load carrying capacity of the bridge from the
65 psi'target to the 58 psi'stated in the 2012 Inspection Report. However, without having performed
an on-site detailed inspection of the bridge components, the exact condition of the bridge is
speculative and based on the information in the Inspection Reports.
Ont'lont Flanq
i%o
i uiu
14
I,
Figure 15—Bottom Flange with 100%Section Loss near Wall Pier 51(Possibly Span 50)
As of November 2012, the existing bridge had a structural Sufficiency Rating of 15.0 and a Health
Index of 6.76. Typically, bridges are rehabilitated based on Federal Highway Administration(FHWA)
guidelines when the bridges have a Sufficiency Rating in the range of 50 to 80. Under 50, the bridges
in Florida are generally replaced since it would qualify for Federal Funding.
The bridge is also Structurally Deficient. A deficient bridge, when left open to traffic, typically
requires significant maintenance and repair to remain in service and eventual rehabilitation or
replacement to address deficiencies. To remain in service, structurally deficient bridges often have
weight limits that restrict the gross weight of vehicles using the bridges to less than the maximum
weight typically allowed by statute.
14 Revision 0
faq August 2013
Monroe County Old Seven Mile Bridge Assessment Project
p
Project No. �f" < Evaluation Report
5.2 SUBSTRUCTURE
Per the 2012 FDOT November Bridge Inspection Report, the bridge Substructure has a rating of 4
(Poor), including approximately 206 linear feet (7%) of the reinforced concrete pier walls with
exposed reinforcing with up to 100% section loss exhibiting advanced deterioration.
i
All
r �
i
iii of uuumu. Y II i�"
P�1%
Figure 16—Concrete Pier Walls with Advanced Deterioration
This is a concern because the piers were reinforced only in the east-west faces to protect the pier
columns against thermal cracks. Due to the deterioration of the reinforcing, the concrete will tend to
further crack due to the (a) corrosion of the reinforcing and (b) temperature shrinkage and expansion
affects. This is a significant concern for future maintenance costs due to the following factors:
• 24%of the total pier column lengths exhibit spalls and honeycombs and efflorescence
• 29%of the total pier column lengths exhibit exposed reinforcing
• 7% of the total pier column lengths exhibit exposed reinforcing with up to 100% section loss
The progression for spalls and the potential for repairs will increase with time as the efflorescence and
cracks cause more exposed reinforcing to exhibit more and more section loss. While the foundation
columns are over-designed for the pedestrian loads, left unattended, the cracking can lead to structural
concerns.
Severe section loss is also documented for the bracing system that was placed on the piers around
1988. The initial work to place post-tensioning bars and collar bands around 22 piers was
approximately $205,000 dollars. If the pier collars need replacement, the lifespan of these collars has
been approximately 15 to 20 years. There is significant potential that additional piers will need collars
installed due to the efflorescence and spalling noted in the inspection reports.
15 Revision 0
EUR August 2013
Monroe County" 1 Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
Of//IF
r,
r
//O/i/ /
011
Figure 17—Concrete Pier Walls with Advanced Deterioration
The footings are also an area of current concern. The 2012 November Inspection Report states that
there are cracks up to 1/8"wide, delaminations and major spalls with exposed rebar or corrosion stains
in about 74 pier footings. Cracks up to 1/16" wide, delaminations and major spalls with no exposed
rebar or corrosion stains were present in about 54 pier footings. In addition, there are voids along the
seal/footing interface. The voids caused by the seal and footing separating may not be a structural
concern since the seal is used during construction as a surface that the structural concrete(footing) can
be cast against. The seal has no structural value. However, by having voids, water can now reach the
bottom of the footings and begin to cause corrosion of the bottom. Corrosion of the bottom reinforcing
will impact the structural capacity of the footings,therefore it is a concern.
The foundations were also rated "high" for susceptibility of scour; however no report of current scour
conditions were provided. It is assumed that a hydraulic analysis showing the wave that can be
generated by a hurricane or the flow velocities around the footings causing scour has not been
performed. In addition, the piling tips or embedment is an unknown since there are no pile driving
records.
5.3 SUPERSTRUCTURE
In 2008, the deck was rated 4 (Poor). Cracks up to '/" wide were reported in 50% of the total deck
area. In 2012, the Deck was rated 3 (Serious) and large sections of spalling concrete were noted along
the underside of the deck and curbs leaving portions of steel exposed to the elements. Cracks up to %"
wide were reported in 95% of the total deck area. Spall with and without exposed steel increase
slightly by less than 1%between 2008 and 2012.
16 Revision 0
laq August 2013
Monroe County "31Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
The structural integrity of the deck slab needs to be evaluated. The slab may have adequate capacity to
sustain a 65 psf pedestrian load, but it may not have additional capacity for any more load. Most
important, if additional spalls and corrosion occur, the slab may not have any capacity for loads when
analyzed by current guidelines and codes. In the FDOT's Internal Estimate, replacement or repair of
the deck slab was not included. Under the assumption that the deck slab is to remain, it will require
significant maintenance to keep the capacity at 65 psf.
VI
i
r
a
ull
1
Figure 18—Concrete Deck Slab and Railing
Some maintenance has been performed. The 2012 November Inspection Report shows the expansion
joints pourable seal repaired at thirty (30) locations. However, a potential major issue with the deck
slab is if there are no plans available that show the reinforcing at the overhangs and in between girders.
Without the reinforcing being known, we don't really know the capacity. A load rating will check the
capacity of the main girders but the assumption is that the deck can transfer the loads to the girders
since it has adequate strength. The approach taken when this situation arises is to replace the
components without adding any additional loads. If the railing is being replaced, it will be replaced
with a railing that is not heavier but potentially lighter.
The 2012 November Bridge Inspection Report recommended that the entire superstructure be replaced
and that the bridge be closed until retrofit or replacement is complete. However, there are
complications to increasing the scope of the work if the deck is removed. By removing the deck and
exposing the existing steel, such as the floor beams and main girders, it could cause more section loss
damage to these members by the concrete removal operations,thus creating a wider repair scope.
17 Revision 0
lal August2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. l�
✓ Evaluation Report
k jo
At
WIN
fire �/ i
Figure 19—Floor Beam and Main Girder Corrosion
In addition, the Superstructure was rated 2 (Critical), in the 2012 November Inspection Report. The
superstructure comprises of the Floor Beams and Main Girders. There are plenty of photos in the
various inspection reports of corrosion to these elements throughout the bridge. In 2007, the
Superstructure was rated 4(Poor). Ili 2008, the Superstructure was rated 2 (Critical).
NUT.UNIT 0$ ,P&SATRUCTURE
ELEMENT/ENV:10714 Paint Stl Opn Girder 20960 If. ELEM CATEGORY:Superstructure
CONDITION
STATE(5) DESCRIPTION QUANTITY
Surface corrosion is�. Y... _....., _ ..,, ........ �.
3 prevalent.There may be exposed 82941f.
metal but there is no active corrosion which is causing
loss of section.
4 Corrosion may be present but any section loss due to 105591f.
active corrosion does not yet warrant structural review of
either the element or the bridge.
5 Corrosion has caused section loss and is sufficient to 21071f.
warrant structural review to ascertain the impact on the
ultimate strength and/or serviceability of either the
element or the bridge
ELEMENT INSPECTION NOTES:
NOTE: For deficiency details refer to the Bridge Report Addendum.
ELEMENT/ENV:15214 Paint Stl Floor Beam 44055 If, ELEM CATEGORY:Superstructure
CONDITION
STATE(5) DESCRIPTION QUANTITY
_.... ......... .....Surface corrosion is rev... ......... _. ..._.. .
3 prevalent,There may be exposed 12551f
metal but there is no active corrosion which is causing
loss of section,
4 Corrosion may be present but any section loss due to 36161 If
active corrosion does not yet warrant structural review of
either the element or the bridge.
Figure 20—2008 Inspection Report Evaluation of Main Girders and Floor Beams
18 Revision 0
August 2013
Monroe County , Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
UNIT:UNIT 0 SUPERSTRUCTURE
ELEMENT/ENV:107/4 Paint Sti Opn Girder 20960 If. ELEM CATEGORY:Superstructure
CONDITION
STATE(5) DESCRIPTION QUANTITY
........ ........... kw ....w
warrant structural review to ascertain he impact
c t o
5 sufficient to 20960If,
pact on the
ultimate strength and/or serviceability of either the
element or the bridge.
ELEMENT INSPECTION NOTES:
CS 5:
-There is a general condition of paint distress with associated severe corrosion and section loss up
to 100%throughout all spans with the exception of the girder webs between supports which exhibit
up to 75%section loss.Rivets missing along he top and bottom flanges and severe section losses
at all cross bracings elements was observed to be typical.The abandoned 18"water main supports
attached to the Ocean side of girder 2 were found to have a general condition up to 100%section
loss with several locations not providing any support at all.
SEE ADDENDUM FOR DETAILED DEFICIENCY LIST AND TYPICAL PHOTOS
ELEMENTIENV:152/4 Paint Stl Floor Beam 44055 If. ELEM CATEGORY:Superstructure
CONDITION
STATE(5) DESCRIPTION QUANTITY
.....
5 Corrosion has caused section loss and is sufficient to 4405511'.
warrant structural review to ascertain the impact on the
ultimate strength and/or serviceability of either the
element or the bridge.
ELEMENT INSPECTION NOTES:
CS 5:
Floor beams exhibits a general condition of paint system failure with associated severe corrosion
and up to 100%section loss along the entire length of the flanges and webs.There is also a general
condition of 100%loss of bearing of most floor beams over the main girders.(See photos 22 and 23)
Figure 21—2012 November Inspection Report Evaluation of Main Girders and Floor Beams
As can be determined by the Inspection Report, both the floor beams and main girders had severe
corrosion and section loss up to 100%. In 2008, the bridge was flagged as needing to have an
evaluation of structural strength. If all these locations are not repaired,the status of whether the bridge
is closed or open will depend on the severity or increase in corrosion of all the elements to remain and
determined at every inspection cycle.
The FDOT Internal Estimate shows the strengthening of 810 floor beams by adding small beams
adjacent to the existing beams to remain. The 810 quantity represents only 36% of the total floor
beams on the bridge. Leaving these floor beams in place will necessitate an inspection that inventories
the extent of corrosion and sets a threshold such that if exceeded, those floor beams will also need to
be strengthened or replaced.
The main girders show top flange section loss at locations where the floor beams cross the main
girders and bottom slab flange section loss at end bearing locations. Without a visual inspection of the
bridge, it is difficult to determine the extent of the damage and the extent of the repairs. For a simple
span bridge, the critical areas for carrying the loads are the ends of the girders and in the middle of the
span. Corrosion in the top flange of the main girder needs to be repaired because it carries the deck
slab. The bottom flange at mid-span and approximately one-third of the total length in each direction
from mid-span is critical and is needed to carry the loading. Since all this loading needs to go the
piers, the ends of the beams are critical to transfer the loading that is in the webs to the bearings and
19 Revision 0
1DR August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. �� Evaluation Report
onto the pier. The need for a design level detailed inspection cannot be over emphasized. The
inspection reports will show photos of areas that are a concern and will minimize the photos of areas
that are sound. The figure below shows a span of the bridge with sound material, however, it is not
known what the other side of the flanges look like and what is the overall condition of the floor beams
and deck.
i
➢w
Iu
V '
4� G
e
n
Figure 22 View of Main Girders Bottom Flanges
The extent of corrosion can be summarized as follows:
• Approximately 20,960 linear feet of open steel girder were noted to have section loss due to
corrosion that is sufficient to warrant structural review to ascertain the impact on the ultimate
strength and/or serviceability of the element of the bridge.
• All top gusset plates have a general condition of 100% section loss area of 8" x 9".
• Approximately 44,055 linear feet of floor beams exhibit a general condition of severe corrosion up
to 100% section loss along the top and bottom flanges and web.
• Approximately 55%of the floor beams are not bearing over main girders due to section losses.
• The connection welds between girders and floor beams overhang supports have a general
condition of 30% section loss.
• The increase of deficiencies for the steel floor beams between November of 2011 and May of
2012 was calculated to be 3.2%.
The 2012 November Bridge Inspection Report had the following work order recommendation that
reads:
GENERAL BRIDGE RECOMMENDATION: Based on the visual inspection results and the advance section loss
found in the structural steel elements it is recommended to properly retrofit or replace the entire superstructure of
the bridge, A structural analysis performed during the previous cycle demonstrated that the bridge floor beams
are extremely deteriorated and cannot withstand loading It is recommended to close the bridge until the
superstructure is properly retrofitted or replaced.
20 Revision 0
FER August 2013
Monroe County Old Seven Mile Bridge Assessment Project
1
Project No. Evaluation Report
Section 6 Future Maintenance Considerations and Repair
Requirements
6.1 FREQUENCY OF INSPECTIONS
The classification of a bridge as structurally deficient does not imply that it is likely to collapse or that
it is unsafe. By conducting properly scheduled inspections, unsafe conditions may be identified; if the
bridge is determined to be unsafe the structure must be closed. A deficient bridge, when left open to
traffic, typically requires significant maintenance and repair to remain in service and eventual
rehabilitation or replacement to address deficiencies. FDOT typically schedules bridge inspections on
a 2-year cycle. Since 2006, the bridge has been inspected on an annual basis and in 2012 there were
two bridge inspections, one in May 2012 and the other in November 2012.
6.2 FRACTURE CRITICAL BRIDGES
The Old Seven Mile Bridge is fracture critical. A"fracture critical"bridge is defined by the FHWA as
a steel member in tension, or with a tension element, whose failure would probably cause a portion of
or the entire bridge to collapse. Fracture critical bridges lack redundancy, which means that in the
event of a steel member's failure there is no path for the transfer of the weight being supported by that
member to hold up the bridge. Therefore, failure occurs quickly, as we saw with the collapse of the I-
35W Bridge in Minnesota.
The FHWA National Bridge Inspection Program mandates routine inspections at least once every two
years of bridges that were a part of the federal-aid highway system. Federal standards for inspections
of bridges call for regular observations and measurements that capture the physical and functional
state of a bridge. Inspections are largely close-up visual examinations which include examination of a
bridge's major components: the bridge deck, superstructure, and substructure. A comprehensive study
performed in 2001 by the FHWA highlighted the fact that visual-only inspections were largely
unreliable. In addition to being subjected to regular conditions inspections, all bridges are analyzed
for their capacity to carry vehicular loads. Bridges that cannot safely carry heavy vehicles, such as
tractor-trailers, are posted with weight limits. Based upon inspection and load capacity analysis, gny
bridge deemed unsafe is to be closed.
Each state, under federal mandate, is required to perform an annual fracture critical inspection on each
bridge in its state inventory. (Fracture critical bridge designs were discontinued in the late 1970s.)
Recognizing that fracture critical bridges are inherently lacking the structural capacity to prevent
failure if even one structural element fails,the annual fracture critical inspection is intended to identify
which of these bridges is increasing its "risk profile" if needed maintenance is not forthcoming. Thus,
those fracture critical bridges that have, from continued lack of maintenance to maintain their
structural integrity, been rated by state transportation agencies as "structurally deficient," i.e., "poor"
as a reflection of its condition rating, are at the highest level of risk since a failure of any element of
such a bridge will trigger a failure mode and potential catastrophe for all located on or near such a
bridge.
While the Old Seven Mile Bridge will become a pedestrian bridge, it can still be deemed unsafe and
will need to be closed upon routine inspection findings. The bridge will continue to erode and the cost
of maintenance will continue to increase in frequency and costs. The costs of the inspections will
increase since more detailed inspections, including non-destructive testing may be required. While the
Old Seven Mile bridge may be considered more like a pier than a bridge, the requirements to inspect,
maintain and repair will be the responsibility of the maintaining agency,Monroe County.
21 Revision 0
fal August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. 01!11; ,
J � Evaluation Report
6.3 HISTORICAL SIGNIFICANCE
Due to its significance in the areas of transportation and engineering, the Old Seven Mile
Bridge/Knights Key Bridge was listed in the National Register of Historic Places (NRHP) in 1979. In
the 2012 November Bridge Inspection Reports, the bridge is incorrectly coded as "Bridge is possibly
eligible for the National Register of Historic Places (requires further investigation before
determination can be made)or bridge is on a State or local historic register.
According to the Master Site File in the Florida Division of Historical Resources, the Old Seven Mile
Bridge has two distinct portions. The eastern portion exhibits steel plate girder construction and the
western portion is a concrete arch spandrel bridge. The features to preserve on this bridge are the
Spandrel Arch and Steel Girder Floor beam Bridge. The complete bridge contained 546 concrete
foundation piers,the most of any bridge in the world.
It seems that the significant features to preserve are the Steel Girder Floor beam system of the bridge
and the substructure from Knights Key to Pigeon Key. Pending further investigation, it would seem
that replacing the deck slab, railing and replacing the rivets with bolted connections will not impact
the significant features of the bridge. However, repair schemes that would involve a complete
superstructure replacement not matching the existing framing system would need to be evaluated to
see if the historical significance of the structure is maintained.
6.4 CONSTRUCTABILITY& CONSTRUCTION ACCESS
The existing substructure consists of 134 piers founded on timber piles and one wing wall structure
(Pier 51). The existing vertical clearance above Mean High Water (MHW)under the 60-foot spans is
approximately 18 feet and under the 80-foot spans is 16 feet. The areas of water depths less than or
equal to 4-feet MLW are present between Pier numbers 11-19, 30-51 and 135-Knights Key, or
approximately 23% of the bridge length. Deeper water depths (greater than 4-feet MLW) are present
at Pier numbers 19-30 and 51-135, or 77%of the bridge length.
In the shallow waters (depths less than 4-feet), use of barges would be difficult to use and permit.
Barges that would be required for material access and demolition of bridge components typically have
a 4-ft draft. Shallow draft (sectional)barges that will need to be considered but with water depths of 2
to 4 feet, impacts to the fish habitat is a concern for permitting.
In the deeper waters (depths more than 4-ft), more conventional barge sizes are available. The
concern with these barges is that they are typically anchored to the ocean floor by spudding. The spud
is typically a 2-foot diameter pipe pile and two per barge would be required to hold the barge in place.
It is estimated that at least two barges will be required at one location, one to hold the construction
equipment and the other to carry materials and construction crews.
The location of the bridge sea floor is comprised of algae communities; sea grass communities and
corals (patch reef communities). Spudding into these sea floor communities and barge tow damage
will be a concern during the permitting process and also creates an access and constructability issue.
In summary, the construction costs will be greater for any work done in these areas due to the
limitation of marine construction equipment.
6.5 PAINTING/COATING SYSTEMS
Until the mid to late 1970s, all steel bridges were protected from corrosion by paint coatings
containing lead and chromate. Over the past several years, "overcoating" has become the common
term used to describe bridge maintenance painting operations which only partially remove existing
paint and apply new coatings over the existing paint. Cost is the most common driver for the selection
of overcoating versus full removal and replacement of existing paint systems. Due to the dramatic
22 Revision 0
lul August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
increase in costs for full maintenance painting operations spurred by environmental and worker safety
regulations, overcoating has become increasingly popular. Present costs for overcoating are in the
range of$1 to $3 per square foot while full removal and replacement of paint systems is $5 to $20 per
square foot.
It is assumed that the rust and flaking will not be completely removed to the bare metal since
significant section loss will occur, causing the member to be replaced or repaired. Therefore,the paint
will be applied to a surface that is not totally free of contamination and corrosion and adherence is
dependent on the existing coating. It is assumed that painting will be required every 10 to 15 year
period.
Year 0
Unit FDOT
Item Unit Price QTY Estimate Year 1-5 Year 10 Year 20 Year 30
Remove deteriorated paint and
repa i nt mai n gi rders a nd LS --• $3,500,000
fracture critical cam onents
Future Full Paintin Cost SF $10 1 3521281 $3521.280
Future0ver-Paintin Cost 5F 1.50 352128 $528192 528192_ .. SS28192_
IT fiA4 SUMMARY ... -, ---- 3 500 000 528 192 528 192 3 521 280 528 192
Bri dge Length=119(80-ft s pans)+16(60-ft spa ns)=10480-ft
FI a nge a rea s=2 gi rders x 4 fl a nge I i nes/gi rder x(12"wi de x 10480 ft)a rea/ft a nge I i ne=83,840 SF
Web a rea=6-ft webs x 10480 ft x 4 webl i nes=251,520 SF
QTY to Pa i nt=FI ange a reas+W eb a real=335,360 SF+5%for FI oor Bea ms=352,128 SF
Assume touch up paintingfor Years 1-5,Year 10 and Year 30 assumes as 25%of full painting cost
Assume full painting at20 years
Figure 23—Painting Cost Summary
6.6 POTENTIAL FOR ADDITIONAL COSTS
Unfortunately,there is a significant amount of potential for additional costs as summarized in Tables 2
through 4 below. To answer the question"What does $18.2 million in repair work accomplishes?",
the Tables below provide a summary of what is being repaired and what remains to be repaired.
23 Revision 0
EDRAugust 2013
....................
O M
E Z a cd a
la
cu
Ol
p U 1i
J CCD
N a
b b
O N yyO yO
N H H
Mq Tj
O c� cl
ell ,� G� c�C 7U•�
LL U y A In
o , O U
c
00 U !�
ON
Q \ O N Q C
f0
s (l d
C I
c
m
7
tn
V
3
� o
i bA O y
00 ti
W b 01) 00 W
y O T y c""Illl]i q'i
N
P
%i, •r a f �����i��/I� ° is
....................
o
13411
0
jA 14
0 00
............... ...............
>
Eg
04 j
ti
C4
0
.................. _..._.
CLO V)
00
0 cd 'A
to 0 y bq bo 0 cd
0 g — 0 00 0 -5 00
40-
,!
4) 4C,
0 4�
3 0
41 Z ri 0
:3 �O 0
C� 0 Cl 4.,4 O 0 0
0 C) 'a •-
CD
.2
�py
CL
(A
to
t
0 0 CD
0
.0 440-1
0
0 j3
bad Grj�.9 �a 0 0 00
0
55
ON
bD u 0 0 C)
1A
Ifl,
4a,
41 MV,
m n oo ° a U in o
Cj
m
N
y
'mod b b
z z z
a
0
o In
r 4 O V1 rU+ N U U
OU O O O
` y Z 40, W
N M
300 r1lon0
LL
+°
c
U
,Yr
N m U Ull
r �
n °
a�
° a o `� b10.0 ^
a� ❑� Q 0 U
,.iCc U 2 W 0 -1 N 'r� 1p r3 OO
r. �+
N N cd 5 O .9 O
Q O — O
[V I 4-a .U00 10,
.� � w
00 � a3 y uT
rO°- o s�
rU} p t� 00 N O
• • • emu,
r
e
� o "wo MI,
ti m r n
I Ili �
Monroe County Old Seven Mile Bridge Assessment Project
Project No. P
Evaluation Report
6.6.1 Deck Repair versus Deck Replacement
The following assumptions are made with respect to the deck slab:
• Based on Inspection Report,the deck slab is in"Serious" condition. A deck replacement or a
deck repair is needed as soon as possible.
• Deck slab is repaired and will need to be replaced within the next 5 to 10 years.
• The proposed repair by FDOT to install two beams for each Floor Beam will give additional
support to the deck slab to allow a major repair to be scheduled within the next 5 to 10 years.
• A deck slab repair,utilizing the quantities shown in the 2012 November Inspection Report,
seems more expensive than a deck slab replacement.
• A deck slab replacement will"throw-away"the pedestrian railing installed by FDOT.
• A deck slab replacement will damage some of the Floor Beams embedded into the deck slab.
It is assumed that'/2 of the total Floor Beams will need to be replaced(1116 total).
• It is assumed that for every Floor Beam to be replaced,the top flange of the girder,a 5'-0"
section,will need to be repaired similar to the FDOT estimate.
Unit
Item Unit Price QTY Year 0 Year 1-5 Year 10 Year 20 Year 30
Deck Repair OR Replacement FDOT 239758 SF 48000 SF 48000 SF 48000 SF
Alternative Estimate Deck Re airs Deck Re air Deck Re air Deck Re air
Deck Slab Repair Cost SF $20 239758 $4,795,160 $960,000 $960,,000 $960,000
Deck Slab Re Iacement Cost CY $600 6277 �, $3,— 6.104
Reinforcin Sted Su erstruct LB $1.25 1286752 $1608,440
Deck Repair Quantity for Year 10,20 and 30 estimated at 20%of 2012 QTY
Unit
Item Unit Price QTY Year 0 Year 1-5 Year 10 Year 20 Year 30
Deck Repairs/Replace& FDOT 239758 SF Replace Deck& Replace 30%of Replace 30%of
Replace 50%FloorBm Estimate Deck Repairs 50%FBs RemainingFB's RemainingFB's
Alternative
Deck Slab Re air Cost SF $20 239758 $4,795,160
DeckSlab Re IacementCost CY $600 6277 $3,766J04
Re!nforcin Steel Su erstruct LB $1.25 1286752 $1608440 --
RemovalofExistingCost SF $15 239290 $3,589,348
Estimated atS15,sf
Pedestrian Railing Cost LF $48 20960 $1,115,136 - $1,006,080
Estimated at$ASl'1f
Floor Beams LB $10 940367 $10,770,000 $9,403,665 $940,367 $940,367
say replace 50%of FB=1116
Girder Top Flanges LB $10 341908 $18,382 $3,419,083 $341,908 $341,908
5'section at each FB
Rivets-High Strength Bolts, EA $100 73656 $2,650,000 --- $7,365,600 $736,560 $736,560
Re lacement
ITEM SUMMARY - $14,553,518 $4,795,160 $30,158,320 $2,018,835 $2,018,835
Deck Slab QTY=10480-ft bridge length x 22.83-ft bridge width x 8.5"thickness=6277 CY
Removal QTY=10480-ft bridge length x 22.83-ft bridge width=239,290 SF
Rai I i ng QTY=2 x 10480-bridge 1 ength=20,960 ft
Fl oor Bea m QTY=843 avg I b/FB connection.1116 FB=940,367
Gi rder Top FI a nge(5-ft sect!on)QTY=306.4 1 b/FB x 1116 FB=341,908
Rivets-HSB QTY=66 ea/FB x 1116 FB=73,656
Floor Beam/Girder Top Flange/Rivets Quantityfor Year 20 and 30 estimated at10%of Year 10
Figure 24—Deck Repair OR Replacement Alternative
These tabulated results show that replacing the deck slab will cause additional costs in addressing
corrosion issues and section loss with the Floor Beams and Main Girder Top Flange plates. We also
considered the option that removing the deck slab will not damage the Floor Beams and the amount of
rehabilitation that is required will be the same quantity (810 Floor Beams) as FDOT proposed in the
initial estimate. This assumption is reasonable since 1393 Floor Beams or 27,855 LF of Floor Beams
will remain with corrosion damage after FDOT finishes up their repairs.
27 Revision 0
lal August 2013
Monroe County ) Odd Seven Mile Bridge Assessment Project
Project No. Evaluation Report
Unit QTY
Item Unit price —!Mon 1) Year 0 Year 1-5 Year 10 Year 20 Year 30
Deck Repairs/Replace&FDOT
Steel Rehab Approach µ _.. FDOT 239758 SIF Replace Deck& Replace 612 FB Replace 10%of
Alternative Estimate Deck Repairs 820 FBs Total FB
Deck Slab Repair Cost SF $20 239758 $4,795,160
Deck Slab Re IacementCost CY $600 6277 3766104
Reinforcin. Steel Su erstruct LB 1,25 1286752 16ti84g0
Removal of Existing Cost SF _ $15 239290 $3,589,348
Estimated at 15 sf
Girder Top Flanges(1-5'
section er bea.m LB 1838
Girder 1Bearin Areas LB _ - 1 471
........
Floor Beams LB 1 076 707
Struct Steel
Rehab Carbon LB $10 1080016 $10,800,160 $10,800,160 $8,160,121 $2,976,044
Rivets-High Strength Bolts, $2,649,348
Re lacement EA $100 26493 $2,649,348 $2,001,730 $729,388
Coating Existing Structural
Steel Touch up ONLY SF $10 8000 $80,000 $80,000 $80,000 $80,000
RemoveExistin Railin LF $3 23232 —69696
Install AASHTO Compliant LF $48 23232 $1,115,136
•-p $1,115,136
Railn ._ ...........
.......
ITEM SUMMARY I --- »-- ---- $14,724,340 $4,795,160 $23.608.537 $10,241,851 $3,785,433
FBs:YR 0=810, YR 10=810,YR 20=612 for a total of 2232„YR 30=10%of 2232
Figure 25—Deck Repairs/Replace&FDOT Steel Rehabilitation Approach Alternative
This evaluation shows that at Year 10,there will need to be an additional investment in rehabilitation
in the range of$23.6M to $30.2M dollars.This is not considering costs due to rehabilitation of the
bottom flange,bearings and substructure.
6.6.2 Superstructure Rehabilitation to Improve the Load Carrying Capacity
The only way to increase the load capacity of the bridge is to restore some of the section loss to the
bottom flange as shown in Figure 26 — Assumption of Section Loss in FDOT's Internal Estimate.
The quantity in the inspection report is 20969 LF of main girder bottom flange to repair. If this repair
is made, the deck slab should be considered for replacement as well since the overall load capacity of
the bridge will definitely be increased. Deck slab replacement without rehabilitating the main girders
will not be cost effective since the loading on the deck will be limited by the capacity of the main
girders. If the deck and girders are not rehabilitated, at some point a complete superstructure
replacement should be considered.
For purposes of this evaluation,the following repair will be assumed:
• Bottom flange double angles 7"x7"xl/2"will be added in a 10-ft section at each girder end, or
40-ft section per span.
• One bottom flange plate, 12"x'/z",will be added to the bottom flange for additional capacity.
• 20%increase will be added to the weight for bolts
• Repair work will be performed in Year 10 when the deck is replaced
28 Revision 0
tal August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
Year 0
Unit QTY FDOT
Rem Unit Price O tlon 1 Estimate Year 1-5 Year 10 Year 20 Year 30
Bottom Fl a nge a n gl e,40-ft per
span LB -_• 142 560
12"xl/2"Coverpl ate,full
Ien h LB 213,792
bolts 20% LB 71270 ®® _w
Struct Steel LB $10 427622 $4,276,224 $427,622 $427,622
Rehab Carbon
ITEM SUMMARY 0 0 4 276 224 $427,622 427 622
Bottom Flange QTY=26.4 plf x 40-ft/s pa n x 135 spans=142,560 LB
Cover plate QTY=20.4 plf x 10840 LF=213,792 LB
Bolts=20%x(Bottom Flange and Cover plate QTY)
Assurnere iairsaredoneinYear1.0,whendeckisreplatedandYear20andYear30areon[y10%of YearlOcosts
Figure 27—Bottom Flange Repair/Rehabilitation to Increase Capacity
6.6.3 Substructure Corrosion Evaluation
A corrosion evaluation (Draft) was conducted by CONCORRFlorida, Inc. in May 19, 2004. The
evaluation was titled "Corrosion Evaluation and Associated Damage Projections on the Piers of the
Old Seven Mile Bridge between Knight's Key and Pigeon Key, Florida". The purpose was to develop
a quantitative estimate of the concrete damage and develop a projection of corrosion damage to the
piers. A conclusion of the report stated that "presently 32 percent of the area on battered walls and
caps do not exhibit significant corrosion induced cracks and almost 70 percent is void of
delamination. After 50 years, however, these percentages are projected to decrease to 22 and 52
percent,respectively".
The conclusion of the corrosion evaluation means that the corrosion induced cracks will grow by 10%
within 50 years. This means that the growth can be estimate to be 2% for every 10 years. The existing
pier collars are to be replaced and new piers are expected to need collars due to the cracking that has
already occurred.
Year 0
Unit QTY FDOT
Rem Unit Price O tion 1 Estimate Year 1-5 Year 30 Year 20 Year 30
Substructure Crack Re airl LF 132 1798 8237,336 $4,747 $4,747 $4,747
Re Iace20PierCollars LS 5205,000 1 $205000
Add 20 Pier Collars LS 5205=0 1 ... 205 000 $205 000
Footin Cracks EA $300 125 37500 5750 S750
ITEM SUMMARY 0 237 336 247,247 210 497 $210 497
Pier Collar Unit Price used was original price
Assume Substructure Crack Repair done in Year 1-5 and crack growth is 2%every 10 years
Assume footing repairs are done in Year 10,when deck is replaced and Year 20 and Year 30 are only 2%of Year 10 costs
Figure 28—Substructure Repairs
6.7 MAJOR REPAIR AND REHABILITATION COSTS
It is difficult to estimate a repair and rehabilitation cost without having done an in-depth inspection.
However, the Tables summaries provided in this section, show significant work that will be required
to maintain the structure and repair/rehabilitate additional items. The repair work proposed by FDOT
is shown as work done in Year 0. Unfortunately, their scope of work does not address all the issues
listed in the Bridge Inspection Reports; therefore these items are listed as "Potential Additional Future
Work"and cost itemized and summarized as follows:
29 Revision 0
fal August 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. .,DIE Evaluation Report
Unit QTY
Item Unit Price (Option 1 Year 0 Year 1-5 Year 10 Year 20 Year 30
Deck Only Replacement& Replace Deck, Replace 30%of
Y P FDOT 239758 SF 810 FBs& Replace uct reFI3 Total FB&
FDOT Steel Rehab Approach ... --• --• &Substructure
Alternative Estimate Deck Repairs Substructure Repair Substructure
Re air Re air
Deck Slab Repair Cost SF $20 239758 $4,795,160
Deck 51abLe IacementCost CY 600 6277 --- 3766104
Reinforcing Steel Su erstruct LB $1.25 1286752 91,608,440
Removal of Existing Cost SF 1.5 239290 3 589 348
GirderTop Flanges(1-5`
section Per beam LB -- 1 838
Girder Bea rin Areas LB --•- 1471
Floor Beams U3 1 076 707
St , LB $10 1080016 10,800,160 10,800,160 8,160,121 2,973,377
arb RehaabbC Carbon
Rivets-High Strength Bolts, EA $100 26493 2,649,348�- - 2,649,348 2,001,730 729,388
Re lacement
Bottom Flange angle,40-ft per
s an LB 142,560
12"x1/2"Coverplate,full
IX h LB 213,792
bolts... 20% LB 71,270
Struct Steel
Rehab Carbon LB $10 427622 -• $4,276,224 $427 622 $427,622
,
Coating Existing Structural - SF
Steel Touch u ONLY $10 8000 80,000 80,000 80,000 80,000
RemoveExistln Ra111n LF 3 - 23232 69.696 _ " ...
Install AASHTO Compliant LF $48 23232 1,115,136
Raiing 1,115,136
_
Remove deteriorated pa i nt a nd
repaint main girders and LS -•- 3,500,000 --- 3,500,000
fracturecritical tom onents _
Future Over-Pai Ming Cost SF $1,50 352128 S281.92 528,192, 528192
Substructure Crack Repair LF 132 1 798 $237,336 $4 747 4 747 4 747
Re lace 20 Pier Collars LS 205 000 1 205 000 --- ---
�Add 20 Pier Collars LS 205 000 1 --. 5205,000 2.05000
Foogn Cracks EA $300 125 $37500 $7SQ $750
ITEM of WORK SUMMARY -- - $18 214 340 5 560 688 28 660 20p 14 379 970 4 949 p77
Mobilization LS 10% - 1821434 55 28 6069 66020 14 37 997 $494.908
Project Unknowns LS 15% d,2 732 151 834 103 $4 �,99 030 $2 156.995 l42 362
Construction over Water LS 3% 546,430 166821 859806 '431399 $148,472
t -
CONSTRUCTION --" 23 314 56 $7 117 681 36 685 p56 $18 406 362 6334819
Desi n Services �-2.
1865 148 569 414 2 934 804 51.472 509 506 785
Construction Ins 2 797 723 854 122_ 4402,207 2 208 763 760 178
TOTAL $27,977,227 $8,541,217 1 $44,022,067 $22,087,634 $7,601,782
Figure 29—Deck Only Replacement&FDOT Steel Rehabilitation Approach Alternative
Note that the Year 0 value of$18,214,340 matches exactly to the FDOT Internal Estimate value before
adding contingencies and design/inspection services. This analysis shows the potential of a significant
<1niount o!" worl( that may be required iri order to maintain the bride operation 1. '1""11ere are other
factors that were not itemized, but for purposes of this evaluation,the potential future investments will
be as substantial. Referring to the Figure 13 in Section 4, we can summarize as follows:
Maintenance Costs
• $250,000/year Annual Maintenance Cost
• Year 0 -Initial FDOT Repair/Rehabilitation: $18.2 million
• Year 5 -Deck Repairs: $5.6 million
• Year 10 -Deck Replacement and Steel Repair/Rehabilitation: $28.7 million
• Year 20 - Steel Repair/Rehabilitation(similar to FDOT): $14.4 million
• Year 30 - Steel Repair/Rehabilitation(similar to FDOT): $4.9 million
30 Revision 0
I-alAugust 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No.
1 Evaluation Report
Section 7 Other Considerations
7.1 SUPERSTRUCTURE REPLACEMENT COSTS
For comparisons,we estimated the cost of a complete superstructure replacement. This cost will occur
at Year 10 and will be a complete replacement of steel bearings,main girders, floor beams and cross
bracing, as well as a replacement of the deck slab and pedestrian railing. The proposed superstructure
will be structural steel plate girders in the same framing as the original structure, except it will have
bolted connections for the floor beams and main girder connections. The floor beams can be rolled
shapes and the main girders will be welded plate girders.
Unit QTY
Item Unit Price (Option 11 Year 0 Year 1-5 Year 30 Year 20 Year 30
Superstructure
Superstructure Replacement FDOT 239758 SF Replacement& Substructure Substructure
Alternative Estimate Deck Repairs Substructure Repair Repair
Repair
Deck Slab Repair Cost SF $20 239758 $4,795,160
Deck Slab Re IacementCost CY $600 6277 •-• 3766104 -_
Reinforcin Steel Su erstruct LB 1.25 1286752 $1608 440
Removal of Existin Cost SF 30 239290 $7178 695 -"
GirderTop Flanges(1-5'm •_
section er bea LB 1 838
Gi rder Bea ri ngAreas LB 1471 -• ""'
Floor Beams LB _.• 1,076707
Struct Steel LB $10 1080016 10,800,160
_.
Rehab Carbon
Rivets-High Strength Bolts, EA $100 26493 2,649,348
Re lacement _.
Beams-Steel PI ate Girder LB $1.5 13707500 20561250
Com osite Neo rene Pads CF •$900 151 -135 900
CoatingExistingStructural SF $10 8000 80,000
Steel.Touchu ONLY
Remove Existing Railing LF 3 23232 69696 -
Install AASHTO Compliant LF $48 23232 1,115,136 1,115,136
Railn
Remove deteriorated paint and
repaint main girders and LS =-- --- 3,500,000
fracture critical com onents
FutureOvef•Paino n. Cost SF 1.50 352128 528192 528192
Substructure i:rack I$e air LF $132 1 798 9237 336 $4 747 $4,747 1 $4 747
Re ace 20 Pier Collars LS 122S 000 1 205,000 -
Add 20 Pier Collars LS $205 000 1 205 000 S205=0
F'ootd tin Cracks EA 300 125 37 500 $750 750
ITEM of WORK SUMMARY 18 214 340 5 560 688 34 612 773 210 497 738 669
Mobilization LS 10% -- 1821434 556069 3461277 $21050 73869
Pro'ect Unknowns LS 15% 2 732 151 �834 S 19�33
�315 �011Construction over Water LS 3% $546 430 1 03 CONSTRUCTON 23 314 356 44 36
Desi n Services LS 8% 1 86S 148 1 $569 414 1, $3,544 348 1 $21 555 1 $75 642
Construction Ins ection LS 12% S2,797,723 1 $854 122 5 316 522 32 332 1.1.3 463
TOTAL tl,217J $53,165,219 $323,323 $1,134,626
Figure 30—Superstructure Replacement Alternative
31 Revision 0
I-alAugust 2013
Monroe County Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
7.2 NEXT STEPS
In order to provide detailed cost estimates the following"Next Steps" should be considered. These
steps will help to develop a more defined scope and will allow a better understanding of the scope of
work to rehabilitate or replace the superstructure.
7.2.1 Constructability
• A design level detailed field inspection will be needed to quantify the extent of distress of the
existing superstructure and develop design strategies to address deficiencies.
• A new Corrosion Evaluation should be performed to assess the scope of work required for the
repairs of the substructure since the prior corrosion evaluation was performed in 2004.
• The design life and desired capacity loading must be defined.
• The methods and costs for repair/rchab construction in shallow water iirust be evaluated.
• Any proposed repair or rehabilitation has to be coordinated with both FHWA and SHPO
where Section 106 of the National Historic Preservation Act of 1966 process must be
completed.Initiation of Section 106 consultation is a good faith consultation process with
SHPO, FHWA, other state or federal agencies, and locally affected parties. This will mean
looking at all possible options for maintaining or altering the bridge, including a full
rehabilitation or a partial adaptive reuse of the bridge.
7.2.2 Cost Estimating
• Substructure repair costs need to be further evaluated based on the extent of distress,
• Estimates for the necessary steel repair or replacement must be verified.
• Costs associated with work methods in shallow waters must be determined.
7.2.3 Environmental Considerations
• Permits would potentially be required from State Historic Preservation Officer(SHPO),U.S.
Army Corps of Engineers, South Florida Water Management District(SFWMD),U.S.Fish
and Wildlife Service,National Marine Fisheries Service, and U.S. Coast Guard. An important
consideration in the permitting process would be any restrictions to construction equipment in
the shallow waters that may pose a threat to the marine environment.
7.2.4 Funding
The Old Seven Mile Bridge is deteriorating and needs an investment to repair,rehabilitate or replace
the bridge. As shown in the comparison below, the investment need to rehabilitate is more substantial
than a partial replacement. A decision needs to be made and funded to assure the bridge continues to
serve the communities of the Florida Keys,Florida and the many tourists that visit the area each year.
Year 0 Year 1-5 Year 10 Year 20 Year 30
Replace Deck, Replace Floor Replace Floor
Deck Only Replacement&FDOT Steel Rehabilitation Approach FDOT 239758 SF Floor Beams& Beams& Beams&
Alternative Estimate Deck Repairs Substructure Substructure Substructure
Re air Repair Re air
ITEM of WORK SUMMARY Total over 30 yrs 71 764 275_ $18 2.14 340 5 560 688 28 660 200 14 379 970 4 949 077
Superstructure
Superstructure Replacement Alternative FDOT 239758 SF Replacement& Substructure Substructure
Estimate Deck Repairs Substructure Repair Repair
Lair
ITEM of WORK SUMMARY Total over 30 yrs 59 36 987 1$214 340 $5 560 688 $34,612,773 $210 497 738 6$9
Figure 31—Rehabilitation versus Replacement Alternatives Cost
32 Revision 0
tal August 2013
Monroe Cosrnly Old Seven file B'ridp ,Isse,earrrva Project
P'r.rpjeo Na �.
Eyr'rlarc^rtar"urr Re,rrrrr•t
Appendix A
FDOT Old Seven Mile Bride Internal Estimate, April 14, 2011
A-1 fieevr"s ion 0
al Barr rrsr 201
Monroe County Old Seven Mile Bridge Assessment Project
Project No. Evaluation Report
FT
Report of Findings
Review of 2010 Deficiency List
Old Seven Mile Bridge
Structure Id No.90020
Monroe County,FL
Summary:
The following report was prepared to address the following items at Old Seven Mile
Bridge,Structure ID No.900020,Monroe County,FL.
a. Review of the condition shown in the 2010 Deficiency List table of the critical
elements identified in the 2008 Load Rating report for possible reduction in
rating. The following components were reviewed:
i. Girders: Spans 13,15,50,73,83 and 135
ii. Floorbeams: At numerous locations,the section loss exhibited is
significant and the dead load stress exceeds the allowable capacity of the
beam. Additional locations may fall under this category at this time.
b. Preparation of preliminary retrofit details for controlling girder and
floorbeams to increase load carrying capacity to desired level.
C. Preparation of preliminary cost estimate for proposed repair.
a. Findings:
I. Girders in Flexure:The original load rating is based on 100%loss of one
cover plate and 50%loss of the second cover plate on the girder with up to
20%loss in the flange angle outstanding legs at the location of maximum
stress. The 2010 findings do not indicate further section loss at these
critical locations other than increase in length. Further deterioration along
the length of the girder does not affect the rating of the member at this
location but will require additional steel to replace the deteriorated steel.
2. Girders in Shear: Despite extensive loss of web above the bearing,the
load rating for shear is adequate. However,because the bearing stiffeners
are also deteriorated,the load path from the bearing to girder web may
lead to localize yielding of flange angles and/or portion of causing the
girder to displace downward or cause loading on the end diaphragm for
which it was not designed.
3. Floorbeams: Additional areas exhibit 100%section loss and loss in
carrying capacity.
Page 1
A-2 Revision 0
August2013
Monroe County ➢ Old Seven Mile Bridge Assessment Project
Project No. a"� Evaluation Report
F"r
b. Proposed Retrofits to Increase Structural Capacity:
The following retrofit schemes are proposed to address the deficiencies noted in
the Findings section above:
I. Girder top Flanges: It is recommended that the girders rating less than 65
psf in Inventory be retrofitted to this level which will allow them to have a
rating of 85 psf in Operating rating.However,this rating must be
acceptable to the entity responsible for maintenance of this facility.Install
repair plates in the areas with deteriorated top flange cover plate and
flange angles. If there is not adequate space to develop the repair plate
beyond the limit of deterioration before reaching a floorbeam,remove
intermediate stiffeners,place splice plates under the outstanding leg(o.s.l.)
of the top flange angle,cut the intermediate stiff to clear splice plate and
reinstall. Work of installing splice plates must be done on one side of
girder web at a time only.. See attached Sketch 1.
2. Girder Bearing Areas: Fit and Install retrofit plates be at the lower
portions of the bearing stiffeners to ensure that load transfer from the
bearing to the girder webs follows the path intended by AASHTO. The
plates can either be welded or bolted to the portion of the outstanding leg
of the bearing stiff-'eners that exhibit only minor section loss for the length
necessary to develop the capacity of the plate. See attached Sketch 2.
1 Floorbeams: One option is to neglect the deteriorated floorbeams and see
if the slab has the necessary carrying capacity for the increase span length.
However,based on a review of the as-built drawings,the deck slab
appears to be simply supported between the long floorbeams. Based on
calculations,it appears that the existing slab can span the approximately
10' between long cantilevers with a live load of 85 psf. Retrofit options
include the following two:
i. Place two new floorbeams,one on either side of the long
floorbeam to be retrofitted. See attached Sketch 3.
ii. Stitch two channels onto the existing floorbeam similarly to retrofit
performed in 1974. This is not feasible at locations where the
existing floorbeam exhibits extensive deterioration and for which
load transfer from the deck slab to the new channels through the
deteriorated floorbeam will be suspect.
C. Cost Estimate:
Retrofit work will be comprised of the following work items:
Page 2
A-3 Revision 0
August 2013
Uonroe ON Seven Mile Briekw Avvesvnenf Prqjeet
Pro "t No,
04 Evaluation Repon
Appendix B
Potential Future Cost Summaries
B-I ReviWfm 0
/hagusl 013
fill
Old Seven Mile Bridge Assesunent Prxrjetl
/'Irojec(No Evahwaon Report
Appendix C
FDOT Documents Requested
C-1 Revision 0
fal August 2013
Monroe County l Old Seven Mile Bridge Assessment Project
i
Project No. b v Evaluation Report
Title
C-1 Revision 0
fal August2013