RAPID suburbanisation in the Bay Area of California during the second half of the 20th century required urban planners and politicians to commit to substantial investments in sustainable transport links. Roads were considered the answer in the early 1950s leading to the decline and eventual removal of the Key System, a 106km streetcar and bus network in the East Bay that reached San Francisco via the Bay Bridge.

However, as congestion grew, and car parks were filled, urban planners rethought these plans. The Bay Area Rapid Transit District was formed in 1957 as rail once again became the preferred means to transport people from their new dwellings in the East Bay to the bright lights of San Francisco.

Bart opened in 1972 and currently spans 167km across five lines carrying 357,000 weekday passengers. It operates in conjunction with Muni Metro light rail services, which serve 151,000 passengers per day on seven lines and 115km of track, and the Caltrain commuter service which reaches San Jose and Gilroy in the south.

Bay Area residents in specific counties have voted on various occasions to increase sales taxes to fund additional rail projects, the latest occasion being in 2008, a year after Bart officials unveiled ambitious plans for the next 50 years of the service.

Among the boldest suggestions is the addition of a second four-bore tunnel that will run from Oakland, through Alameda adjacent to the existing tunnel under San Francisco Bay, emerging at the Transbay Terminal. Two of the tunnels could also be used by future California high-speed trains, while Bart would take up the remaining bores which would be extended to Presidio or North Beach.

The Bay Area's population is expected to reach 10 million by 2030, and these plans would go some way to relieving this pressure. While funding is yet to be secured for the tunnel project, construction on several other schemes that will take Bart to new areas are well underway.

These include an 8.7km, $US 890m extension of the Richmond - Fremont line to Warm Springs which is divided into two packages. Work is 80% complete on the 1.6km underground section under Lake Elizabeth and conversion of a former Union Pacific (UP) freight line, and will be finished in early 2013. The second package to fit out the line is due to be completed by late 2015.

The Warm Springs extension will ultimately act as the feeder line from the existing Bart network into the proposed Bart Silicon Valley project. This 25.8km route will run initially along the UP line south of Warm Springs station, tunnelling for 8.2km underneath San Jose, and rising to street-level in Santa Clara.

Unlike the other Bart projects, Santa Clara Valley Transportation Authority (VTA) is managing the project and will own the infrastructure. On December 8 this scheme took a major step forward when VTA awarded a joint venture of Skanska, Shimmick, and Herzog the first design-build contract for the project's initial phase, the 16.1km section from Warm Springs to Berryessa.

The consortium's $US 772m bid was around $US 77m below estimates, with the majority of funding coming from revenues from a 30-year 0.5% sales tax increase passed by Santa Clara voters in 2000, which was increased to 0.8% in 2008. But with an overall pricetag of $US 2.3bn, the project is reliant on securing a $US 900m grant from the federal government's New Starts programme for construction to proceed on schedule this spring.

An announcement on allocation of the funds is set for February, and local officials, including Mr Carl Guardino, CEO of the Silicon Valley Leadership Group, an advocate of the extension, are confident that the cash will be secured. "I would be stunned to the point of needing smelling salts if that doesn't happen, and happen soon," Guardino told the San Francisco Chronicle.

Funding for the second 9.7km phase of the Silicon Valley project is yet to be secured.

Turnaround

The Silicon Valley project is a major turnaround for Bart in this region after Santa Clara County officials decided not to join the district when it was formed in 1957. One county that did join but is yet to benefit from a direct Bart service is Contra Costa. However, this is about to change with construction of the $US 462m East Contra Costa County extension project, known as eBart.

Work began in October 2010 and encompasses the construction of a 16km, two-station line from the existing Pittsburg Bay Point terminus to Hillcrest Avenue in Antioch along the median of California State Highway 4. The extension is being built in conjunction with widening the highway from four lanes to six, with both projects expected to be completed in 2015.

Unlike conventional Bart which uses third rail electrification, this extension will be served by two-car dmus rather than existing Bart trains due to the estimated 60% reduction in cost, with services designed to be connect with San Francisco-bound trains at Pittsburg Bay Point.

Capacity on the existing line to Pittsburg Bay Point has also been increased through the Central Contra Costa County crossover project.

A junction has been added on the double track line between Walnut Creek and Pleasant Hill allowing for an increase in peak time capacity. The project cost $US 38m to complete and was due to become operational as IRJ went to press.

A dmu service is also being considered for the proposed Livermore extension of the Dublin Pleasanton branch. An environmental feasibility study for this 18.2km project was approved in July 2010, and an agreement on a preferred alignment reached in April 2011.

The line will run in the median of Interstate 580 and then through a tunnel and an existing rail corridor into the centre of Livermore. It will serve stations that will be constructed adjacent to the existing Altamont Commuter Express stations at Livermore and Vasco Road, replacing the existing shuttle bus service from Dublin Pleasanton. Bart is currently considering funding options for the project, which is estimated to cost $US 3.2bn and will serve 32,000 passengers per day.

Another airport that will soon be connected to Bart is Oakland International. A groundbreaking ceremony for the new $US 492m, 5.1km automated cable-operated peoplemover that will intercept Bart at Coliseum station was held in October 2010.

The project is expected to be completed by 2014 the service will operate at 4.5-minute headways.

Significant attention is being placed on improving existing infrastructure including a 10-year, $US 1.2bn programme to retrofit the core system so that it complies with current earthquake construction standards. This involves upgrades that meet the latest seismic standards to guarantee that infrastructure can withstand high-magnitude earthquakes, including at all elevated structures, tunnels and stations.

An overhaul of Bart's rolling stock is another major element of these improvement plans. Under a $US 3.2bn project, Bart's oldest vehicles, which date from the opening of the first phase, will be replaced over the next 15 to 20 years with up to 1000 vehicles required.

A preferred supplier from a shortlist of Alstom, Bombardier, CAF, CSR, and Hyundai Rotem, will be selected in the next few months, with the federal government funding the procurement of the first 200 vehicles which will enter service in 2018. These will all have to be designed especially for Bart to meet its unusual 1676mm-gauge infrastructure.

The new trains will feature improved passenger information systems and larger doors, with proposals for greater storage areas for bicycles, luggage and wheelchairs under consideration. Indeed, by adopting the latest technologies, the new vehicles will be a prominent symbol of a new era for Bart. And as the network continues to reach more passengers in new regions of the Bay Area, the service is set to remain an example for other American cities to follow.