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STRUCTURAL ASSESSMENT OF RAIL ON THE BAY BRIDGESUMMARY REPORT

REPORT PURPOSE AND SCOPE

This Working Paper provides an analysis of the structural capacity and needed structuralimprovements, including costs, to establish rail options on the San Francisco-OaklandBay Bridge (Bay Bridge). The analysis is examining the retrofitted west spans, the

proposed new east spans currently being designed and the Yerba Buena Island tunnel.The limits of the assessment includes the Toll Plaza to the east to Harrison Street indowntown San Francisco to the west. This assessment only defines the requirements andcost estimates for structural improvements to the bridge spans. This structuralassessment does not include analysis and cost estimates for placing or operating rail onthe bridge (e.g. tracks, overhead or at grade electrification, etc.) and does not include

analysis or cost estimates of the structures required for the rail service distribution

system and approaches to the Bay Bridge from the east or from beyond Harrison Streeton the San Francisco side of the Bridge. Additionally, the analysis does not account for

potential bicycle lanes on the west spans of the Bridge.

A subsequent task of this study will define the alignments for the various rail options inthe East Bay and to the Transbay Terminal in San Francisco and include patronageestimates and capital and operating cost estimates for those services. It is expected thatthe full analysis will be completed in December, 1999.

POTENTIAL RAIL SYSTEMS..1

• Four rail options have been defined to provide potential rail services on the BayBridge for this study: Light Rail, BART, Commuter Rail (SEPTA) and High SpeedRail (Acela), as follows:

Weight in lbs. Per linear Rail Envelope SizeRail Option foot of track (Double Track)

(feet)Light Rail 1,390 ·' 18 by 29BART 1,170

'

14 by 32

Commuter Rail (SEPTA) 1,720 · 26 by 34

High Speed Rail (Acela) 1,800 ' 26 by 34Caltrain (diesel) 1,900

,26 by 34

Note: The Caltrain service as presently operated is shown in the Table above for

comparison purposes. It is not recommended and may not be feasible for diesellocomotives to be operated into the Transbay Terminal and on the Bay Bridge.

1

STRUCTURAL ASSESSMENT FINDINGS

The structural assessment examines the retrofitted west spans, the proposed new eastspans currently being designed and the Yerba Buena Island tunnel. It should be noted atthe outset that rail services could not be returned to the decks of the bridge spans as they

were operated in the past without significant structural and seismic strengthening, safetyconsiderations and operational impacts (loss of vehicular traffic lanes). Therefore, this

analysis considers restoring rail on the bridge decks and other potential alignments forplacing rail on the Bay Bridge and assesses the impacts and requirements for each of these

alignments. The major findings of the structural assessment for the west spans, east spans

and Yerba Buena Island tunnel are provided below.

West Spans

• Caltrans is currently conducting a seismic retrofit of the west spans of the BayBridge. As a result of the seismic project, the West spans will be retrofitted towithstand the design earthquake as defined by Caltrans.

• Six options were examined for placing rail on the west spans: 1) Rail on the BridgeDeck; 2) Vehicle Lanes Outside of the Truss; 3) Vehicle Lanes or Rail above the

Truss; 4) Rail Suspended Below the Lower Deck; 5) Rail Cantilevered from LowerDeck; 6) Rail Cantilevered from Upper Deck.

• Based on the analysis, it is recommended that three of the options (Rail on the BridgeDeck, Vehicle Lanes Outside of the Truss, and Vehicle Lanes or Rail above the Truss)be eliminated from further consideration. This analysis shows that each of these three

options have major construction or operational impacts which are considered as fatal

flaws, as follows:

Eliminated Alignment Options Fatal ImpactsReplacing vehicle lanes with rail • eliminates two existing traffic lanes per

rail track, which would significantlyimpact traffic operations.

Vehicle lanes outside of the truss • complete re-working of all SanFrancisco on and off ramps would berequired.

Vehicle lanes or rail above the truss • construction above existing upper deckwould require closure of the upper deckduring construction and result insignificant safety issues and aesthetic

impacts.

2

• The remaining three options have advantages and disadvantages and a number ofmajor issues and considerations. Some of the major issues and considerations for these

options are as follows:

Alignment Options Pursued Major Considerations/IssuesRail Suspended Below the Lower • will reduce the shipping clearance byDeck approximately 32 feet, which may not be allowed

by the Coast Guard. (Note: The Coast Guard has

been requested to make a determination ifreducing the shipping clearances would beallowable). ·

• rail tracks below the lower deck wouldsubstantially impact the aesthetics of the currentwest spans:

• will allow rail in the basement of the transbayterminal.

Rail Cantilevered from Lower • will reduce the shipping clearance byDeck approximately 4 feet.

• will impact a planned building north of the S.F.anchorage, requiring the purchase of air rights

• will require:reworking some of the Yerba BuenaIsland off-ramps.

• will require a flyover west of the San Francisco

Anchorages. to carry one track over the Freewayand through to the Transbay Terminal.

• will eliminate the opportunity to bring rail intothe basement of a new Transbay Terminal.

Rail Cantilevered from Upper • will impact a planned building north of the S.F.Deck anchorage, requiring the purchase of air rights.

• will require reworking some of the Yerba BuenaIsland off-ramps.

• will require a flyover west of the San FranciscoAnchorages.to carry one track over the Freewayand through· to the Transbay Terminal.

• will eliminate the opportunity to bring rail intothe basement of a new Transbay Terminal.

• Adding any of the proposed rail options would exceed loading requirements for thewest spans of the Bay Bridge and require significant additional seismic retrofitting

3

/,

measures to meet current codes. Therefore, significant strengthening will be requiredto accommodate adding rail to the structure. The extent and costs of the required

improvements are considerable because even after the current retrofit of the westspans there will not be significant reserve capacity in the structure. The addition of

rail to the structure will increase the dead loads and live loads and change the seismicbehavior of the spans, which requires substantial modifications and strengthening.Given that the improvements are being made to an existing structure, implementationofthe needed improvements (e.g. foundations) are complex and costly.

• In summary, the structural improvements required to accommodate rail on the west

spans include:

• Seismic retrofitting of the Bridge foundations, which would include addingcaissons and expanding the piers at each tower and the anchorages;

• Strengthening of the truss and towers and the addition parallel main cables;and

• Demolition of the existing decks and replacement of the decks with lightermaterial (e.g. Orthotropic Steel).

(Note: The estimated costs of these improvements are provided in Table 1 below).

4

New East Spans

• Caltrans has completed approximately sixty-five percent design of a replacement eastspan project. The current design includes side by side bridge decks with each carryingfive lanes of traffic and shoulders in each direction. The current design accommodateson deck rail on the inside lanes of each of the spans reducing the vehicle lanes to fourlanes on each deck without shoulders. According to Caltrans, additional strengtheningwould be required for the east spans to accommodate light rail on the inside lanes ofthe spans and maintain five lanes of auto traffic without shoulders, at an additionalcost of $50 to 100 million.

• Based on this analysis, the heavy rail options could not be operated on the inside ofthe bridge decks because there are inadequate clearances between the east and westbound roadways as they stack entering the east side of the Yerba Buena Island.

• This analysis finds that the most feasible method to transition rail services from theeast spans through Yerba Buena Island is to place the rail on the outside of each of theeast span decks. This would allow splitting the rail tracks off of the main decks

permitting alignments through new tunnels in Yerba Buena Island.

• Based on the analysis, except for BART or a similar low clearance rail options, rail onthe outside of the decks and provision of standard vehicle lane widths would requirewidening each of the east spans from its current design by 3 to 5' to provide adequateclearance for the suspension cable system. (The estimated costs for strengthening andwidening the east spans are included in the costs estimates below).

Yerba Buena Island

• Based on this analysis, the introduction of rail services on the Bridge should avoid

impacting the existing Yerba Buena Island tunnel. Rail on the upper deck of the bridgethrough the tunnel would significantly compromise the floor beams of the upper deck,which would be costly and operationaly difficult to remedy. Separate bores toaccommodate rail services through the Island are possible and preferred. Thisalignment requires separate rail structures with support columns on both the northand south sides of the new east span transition structures on Yerba Buena Island.

ESTIMATED PROJECT COSTS

• The total estimated cost (Table 1) of the structural requirements and improvements

for placing rail services on the bridge spans and through Yerba Buena Island range

. ,

5

from approximately $3.06 billion (rail below the lower deck of the west spans) to

$3.33 billion (rail cantilevered on west spans).

• The project cost estimates include the costs of strengthening and modifications to theeast and west spans of the Bridge to accommodate the rail services, tunneling throughYerba Buena Island and tunneling or building structure to Harrison Street in SanFrancisco. The costs do not include structure to carry rail beyond the Toll Plaza onthe East Bay side of the Bridge, structure or tunnel to the Transbay Terminal in SanFrancisco and do not include the costs of the rail tracks or other infrastructure to

operate the rail options.

• Please note that the costs presented are order-of-magnitude cost estimates. Theseestimates are based on costs gathered on bridge retrofit and construction projects that

are planned or underway in the Bay Area. Significant further analysis will be requiredto determine the actual costs. In general, the costs presented are appropriate for all of

the potential rail options.

ADDITIONAL ANALYSIS REQUIRED

• As scoped, the analysis performed is a "first cut" feasibility analysis of the structural

requirements for placing rail on the Bay Bridge. To further determine the structuralrequirements and costs, it is recommended that the next steps necessary to completethe analysis are as follows:

a) Develop a three dimensional computer model of the bridge in sufficient detail to

perform service load and seismic load analysis.

b) Perform both service and seismic analyses using the structural configuration andsection properties of the retrofitted west spans.

c) Using the preferred alternative, construct the rail corridor in the computer modeland determine the demand impacts on the structure.

d) Produce standard strengthening details;

e) Cost each major increment of work in the systematic construction of thecorridor.

SUMMARY CONCLUSIONS

Without a defined design, construction, and operation budget established, feasibility canonly be assessed in limited terms of structural feasibility. There are several hurdles that

6

must be crossed prior to deeming the whole of rail on the Bay Bridge feasible. Namely,the non-structural issues of operations, routing, systems costs, ridership, navigational

impacts, right-of-way acquisitions and environmental clearances must be resolved. In thecontext of structural feasibility only, rail on the Bay Bridge is possible.

However, restoring rail to the Bay Bridge is very costly based on this 'first-cut' study.More accurate cost estimates can be made after the design has been progressed. Note thatfurther design and greater accuracy could translate into cost decreases or increases.

Further analysis is required to better define the structural and operational modificationsneeded for rail.

It should also be noted that adding rail to a structure (west spans) that is more than 60

years old complicates the project and reduces the ultimate life of the entire project.Therefore, alternate means of crossing the Bay with rail should be evaluated and

compared with adding rail to the Bay Bridge.

7

STRUCTURAL ASSESSMENT OF RAIL ON THE BAY BRmGE

SUMMARY REPORT

October, 1999

8

Box 5, Folder 1

Item 8

*

ACCNO_000322