BAY BRIDGE

MTC Bay Bridge Rail Feasibilty Study

EXECUTIVE SUMMARY

For more than sixty years, the San Francisco-Oakland Bay Bridge has been one of the landmarks most identified with the Bay Area. During that time, the bridge has undergone several modifications. Originally designed with five lanes of auto traffic on the top deck, and commercial vehicles and "Key System" rail on the lower deck, the bridge was converted to ten lanes of auto operations (five in each direction) in 1959.

Although the bridge is thought of as a unit, structurally it is actually two distinct bridges that meet at the Yerba Buena Island (YBI) tunnels. The West spans include the graceful suspension sections connecting YBI to the San Francisco anchorage. The East spans connect YBI to Oakland, utilizing a cantilever system.

Following the 1989 Loma Prieta earthquake, which resulted in a failure of the upper deck and a month-long closure of the bridge, Caltrans conducted an extensive assessment of the options for seismic strengthening of the Bridge. Their studies concluded that it was possible and cost effective to strengthen the West spans, while the East spans required full replacement. Strengthening of the West spans is already underway. East span design is progressing and the entire seismic strengthening project will be completed over the next decade.

In 1998, voters in four cities - Oakland, Berkeley, Emeryville and San Francisco - passed a non-binding declaration of policy stating that rail service should be restored to the Bay Bridge. The ballot measure that was placed on the four city ballots did not define what type of rail service would be offered, where it would go, or what it would cost to complete. The Metropolitan Transportation Commission (MTC) sponsored this feasibility study as a first step towards narrowing the question of how or whether to implement rail on the bridge. The study is designed to answer three key questions:

• What are the possible options for rail service on the Bay Bridge? This includes defining technology options and alignment possibilities for rail service, both over the bridge span, and within the west and east bay areas.
• What are the impacts of each type of rail service on the structure of the Bay Bridge? This requires an understanding of where the rails might be located, whether they would change the lane configuration on the bridge, and how the east and West span systems will be joined by rail.
• How much will the structural changes and the rail infrastructure cost to implement? While this feasibility level study is done without any engineering or design work, it does provide an order of magnitude estimate of costs, both for structural improvements and for the rail infrastructure itself. It should be noted that not all costs need to be incurred at the same time - for example, it is possible to add the rails to the bridge before adding the rail infrastructure for a long term implementation.

For the purposes of this study, the seismically retrofitted West spans and the proposed replaced East spans were considered.

RAIL OPTIONS
Four rail options were identified, each providing service to a different but significant share of the travel market:

• Transbay Light Rail Service
• BART Transbay Bridge Service
• Basic Bridge Railroad Service - combining commuter rail and high speed rail
• Aggressive Bridge Railroad Service - combining commuter rail and high speed rail

Figures describing these alternatives are attached at the end of this Executive Summary.

Transbay Light Rail Service
This would be a modern version of the Key System, characterized by operation from the Transbay Terminal, where space would be shared with transbay buses on the bus deck, over the Bridge to the East Bay where service would divide into three routes, providing frequent all-day service. The three routes assumed in this study included an Oakland-Foothill Blvd. - Airport route; a MacArthur-Hegenberger route; and a Berkeley-Telegraph-University route.

BART Transbay Bridge Service
Significant additional transbay BART service could be offered by taking one of the four present transbay lines out of the Transbay tube and placing it on the Bridge. For purposes of this study, it was assumed that the Richmond-San Francisco line would run over the bridge. New aerial structure would be required to connect the bridge line to the MacArthur station. Service on this line would be improved and service to the remaining tube lines would also be improved to take advantage of the capacity that would become available in the tube.

Basic Railroad Service
This alternative would add both FRA compliant commuter rail and high speed trains over the Bay Bridge. Trains would be operated up the Peninsula, through Downtown San Francisco¹s Transbay Terminal and over the Bay Bridge. All transbay trains would stop at a new Oakland Harbor Station. From there, half of the trains would head north, stopping at Emeryville, West Berkeley and on to Richmond. From Richmond, some trains could be extended as part of the Capitol Corridor, by connecting to diesel powered Sacramento-Oakland-San Jose trains. The remaining trains would turn south and run along a new track, stopping at 16th Street, running along Third street to Broadway and Oak where they will terminate. Commuter service would be supplemented by high speed rail operating as far as the Oakland Harbor Station.

Although high speed service is assumed to travel over the bridge, none of the rail services would be traveling at high speeds over the bridge, particularly over the West spans. The probable alignments and grades entering and exiting the Transbay Terminal will require operating speeds appropriately below the speeds along unencumbered portions of the alignment. Due to vertical and horizontal geometric restrictions, the operating speeds are assumed to be roughly 50 miles per hour.

Aggressive Rail Service
A more aggressive rail option would extend the commuter and high speed services beyond the area described under the basic scenario, and would also improve frequency of service. Trains turning north would continue to Martinez, with half of the trains continuing further to Suisun-Fairfield. Some trains would be extended to Sacramento. High speed trains would operate over the bridge every 30 minutes, with every other train going on to Sacramento. The southern commuter rail line would be extended to San Jose.

IMPACTS OF RAIL SERVICE ON THE BAY BRIDGE
Each of these rail options has a different impact on the bridge structure. Figure ES-1 shows the rail system weight and clearance requirements for each option.

FIGURE ES-1: RAIL SYSTEM WEIGHT AND CLEARANCE DATA

Rail System	Loaded Rail Car Weight in lbs. per linear foot of track	Rough Rail Envelope Size (height by width)
		Single Track	Double Track
BART	1,170	14' by 16'	14' by 32'
Light Rail	1,390	18' by 16'	18' by 29'
SEPTA	1,720	26' by 17'	26' by 34'
Amtrak — Acela (high speed)	1,800	26' by 17'	26' by 34'
Caltrain — Current System*	1,900	26' by 17'	26' by 34'
*Included as a basis of comparison.

Summary of West Span Impacts
Adding rail to the West spans can be achieved in any of three configurations: either below the existing deck, alongside the upper deck, or alongside the lower deck. Under any of these options either rail operations or auto lanes can be placed outside of the current bridge envelope, providing the widest range of alternative locations for rail. Each of these options has advantages and constraints. From a rail operations perspective, rail suspended below the current lower deck of the bridge has the advantage of working best with the concept for an underground Transbay Rail Terminal. Rail placed alongside either of the existing spans, outside of the envelope of the current structure is not compatible with an underground terminal. Placing rail below the current lower deck has a potential flaw however, in that it will reduce the vertical clearance of the maritime channel, requiring Coast Guard approval. Another possible alternative, replacing auto lanes with rail service was not considered, as increasing demand for Transbay travel will necessitate expanding capacity for all modes. Total travel in the Transbay corridor is expected to increase by 22% over the next 20 years from 518,000 person trips in 2000 to 633,400 daily person trips in2020.

While each of the alternatives for rail implementation is highly complex, none is considered infeasible. The added weight from either the side-by-side or below deck schemes would require improvements to the foundations, strengthening of the existing truss and towers, and possibly the replacement of the current concrete roadway decks with a much lighter system. Even with the implementation of a lighter decking system, strengthening of the main cable is anticipated. The main cable system would need to be strengthened by adding two new main suspension cables above or beside the existing cables or by adding new tower legs at the existing pier locations and suspending cables from these. This amounts to essentially building a new bridge on the outside of the existing bridge.

Adding weight for rails and for the structural improvements required will impact seismic behavior. Seismic improvements beyond those envisioned for the current retrofit would be necessary and would likely include foundation strengthening as well as pier, truss and tower strengthening.

Summary of East Span Impacts
A review of the current design of the replacement span suggests that the bridge is designed for five traffic lanes in each direction with the potential to add one lane of rail and carry four traffic lanes in each direction. While there is sufficient width for five lanes of traffic and rail in each direction, the design lacks the structural strength to carry this load.

The current design places rail on the insides of the two parallel decks. This alignment does not provide the greatest flexibility for crossing YBI and connecting to the West spans. Moving rails to the outside of the decks would provide the needed flexibility, allowing for new tunnel bores to be constructed without impacting current traffic operations.

To accommodate any of the proposed rail options on the East spans, the design team currently completing this work would need to be redirected to fully incorporate the needs of rail into the design. While this would add to the cost of the East span, and could introduce some additional delay in the project, it would be less costly to make these changes during design and initial construction, rather than waiting until after the bridge is built.

Summary of Yerba Buena Island Impacts
The feasibility study showed that reconstruction of the existing YBI tunnel is not feasible without closing the bridge for sustained periods. Reconstruction would be necessary unless new bores are created, because of headroom and load carrying constraints. Therefore, construction of new tunnel bores is considered the preferred alternative for crossing the island.

COSTS
Costs were determined by the study team working closely with a peer panel, using national and international examples of recent costs. Unit costs for any project on the Bay Bridge would be higher than most projects because of the unique environment, working on an older structure, and the need for continual traffic operations. Figure ES-2 summarizes the costs for Bay Bridge structural improvements only. It should be noted that these are feasibility level costs only, and will be considerably refined with more study. The structural costs for Bay Bridge improvements are estimated at about $3 Billion, regardless of the technology selected.

FIGURE ES-2: STRUCTURAL COST SUMMARY

	Options
	Below	Side by Side
San Francisco Approaches	$193	$436
West Spans	$1,334	$1,447
Yerba Buena Island	$317	$198
East Spans*	$546	$546
Oakland Mole	$60	$40
Subtotal	$2,450	$2,667
25% Contingency	$612	$667
Total	$3,062	$3,333
Costs are in Millions
* East span costs are based on revisions to the design prior to awarding the construction contract. Costs to implement heavy commuter rail would be higher if widening and strengthening were performed after construction.

The costs estimated in Figure ES-2 provide a "rail ready bridge". The true cost of implementing rail service includes the cost of rail infrastructure and rolling stock as well as the costs of bridge modifications. Figure ES-3 summarizes the costs of each of the four alternatives considered, exclusive of the bridge costs. Costs range from about $1 Billion to as much as over $4 Billion. It should be noted that any rail option could be completed in stages, avoiding the need to spend the full costs at once.

FIGURE ES-3: ALTERNATIVE COST SUMMARY

Alternative	Infrastructure*	Rolling Stock	Total
A. Transbay Light Rail Service	$1.4 billion	$210 - $315 million	$1.6 - 1.8 billion
B. BART Transbay Bridge Service	$1.8 billion	$144 million	$1.94 billion
C. Basic Bridge Railroad Service	$774 million	$144 million	$918 million
D. Aggressive Bridge Railroad Service	$4.3 billion	$461 million	$4.77 billion
*Infrastructure includes all estimated project contingency (40%) and engineering (30%), including that applied to rolling stock.

The total capital costs for Transbay rail service using the Bay Bridge would range from about $5 Billion to as much as $9 Billion. Costs to operate rail service would be in addition to capital costs and would require substantial annual operating subsidies.

NEXT STEPS
While implementing Transbay Rail service is feasible, it represents an enormous investment. Still, the ultimate benefits of such an investment can not be known at this time. The costs and benefits of this option must also be compared to other potential investments.

To better understand the relative value of this investment, a more inclusive corridor study is required. This study would complete similar feasibility level analyses of various options including implementing a busway, adding an additional bridge (either as a rail bridge, or as a traffic reliever, making it possible to displace traffic with rail on the existing bridge), or adding a new transbay rail tube. Only when this option can be put into context with other alternatives will the benefits of Bay Bridge rail service be known. Following that study, much more detailed work is required to refine the cost estimates and alignments proposed in this feasibility study.

MTC has initiated the process for a Bay Crossing study that will expand on the conclusions of this preliminary study. The Bay Crossing study will consider:

• improvements to existing bridges with or without rail service
• adding a new rail tube for commuter and high speed rail services
• adding a second BART tube for increased Transbay service
• expanded ferry options
• bus service and busway options
• other operational enhancements to improve Transbay capacity