Bay Area Rapid Transit, widely known by the acronym BART, is the main rail transportation system for the San Francisco Bay Area. It was envisioned as early as 1946 but the construction of the original system began in the 1960s.

Origins and planning

The idea of an electric rail tube under San Francisco Bay was first proposed in the early 1900s by Francis "Borax" Smith – the San Francisco Chronicle ran a front-page editorial in 1900 suggesting an electrified subway. There were also plans for a third-rail powered subway line (Twin Peaks Tunnel) under Market Street in the 1910s. A 1915 study prepared for the cities of Oakland and Berkeley called a rapid transit link between the two cities "imperative," suggesting new street railway lines or an elevated railway between the two cities. Much of BART's current coverage area was once served by the electrified streetcar and interurban train network called the Key System. This early twentieth century system once had regular transbay traffic across the lower deck of the San Francisco–Oakland Bay Bridge. The final passenger run occurred on April 20, 1958 and the entire system was soon dismantled in favor of automobiles and buses and the explosive growth of highway construction.

Proposals for the modern rapid transit system now in service began in 1946 by Bay Area business leaders concerned with increased post-war migration and growing congestion in the region. An Army-Navy task force concluded that an additional trans-bay crossing would soon be needed and recommended a tunnel; however, actual planning for a rapid transit system did not begin until the 1950s. In 1951, California's legislature created the San Francisco Bay Area Rapid Transit Commission to study the Bay Area's long-term transportation needs. A New York-based firm, sponsored by the commission, submitted plans for an expansive rapid transit system in 1956. The commission's 1957 final report concluded the most cost-effective solution for the Bay Area's traffic woes would be to form a transit district charged with the construction and operation of a high-speed rapid rail system linking the cities and suburbs. Nine Bay Area counties were included in the initial planning commission.

The San Francisco Bay Area Rapid Transit District was formed by the state legislature in 1957, comprising the counties of Alameda, Contra Costa, Marin, San Francisco, and San Mateo. Because Santa Clara County opted instead to first concentrate on its Expressway System, that county was not included in the original BART District. In 1959 a bill was passed in the state legislature that provided for the entire cost of construction of the tube to be paid for with surplus toll revenues from the San Francisco–Oakland Bay Bridge. This represented a significant portion of the total cost of the system.

By 1961 a plan for the new system was sent to the boards of supervisors of each of the five counties. These plans called for three branches in the East Bay and four branches in San Francisco, meeting in a subway under Market Street and a tube under the San Francisco Bay. The East Bay branches would connect Concord in the east, Richmond in the northeast and Fremont in the southeast. On the San Francisco side, the system would branch to the south along the Peninsula to Palo Alto, to the southwest along Mission Street to Balboa Park, to Daly City in the west using the existing Twin Peaks Tunnel, and a new Geary Subway leading to the Golden Gate Bridge connecting San Francisco to Novato in the northwest.

However, on April 12, 1962, San Mateo County opted out of the district, citing high costs for the plan, existing service provided by Southern Pacific commuter trains (today's Caltrain), and concerns over shoppers leaving their county for stores in San Francisco. Marin County left the district soon thereafter in May, being forced out due to engineering objections from Golden Gate Bridge operators and fear that Marin voters would not approve the bonds, which had to win more than 60% approval.

The withdrawal led to the cancellation of the Peninsula branch and the Geary Subway. The remaining lines in San Francisco were also changed in the 1962 "Composite Report": the Market Street and Mission Street tunnels would be built and operated by BART and would be extended to Daly City, while the San Francisco Municipal Railway would operate the Twin Peaks route with streetcars remaining in the existing tunnel, and being fed into an upper level of the Market Street subway. The plan was approved by the voters of the three remaining participating counties in July 1962.

Berkeley initially approved a combination of underground and elevated lines on their portion of the system, as outlined in the 1961 and 1962 plans. Downtown Berkeley station would be located underground, while both Ashby and North Berkeley were to be constructed on elevated segments. Residents eventually came to oppose this scheme in favor of one where the line would be run in a tunnel for its length. After several hearings, the city voted to tax themselves for the funds necessary to fully underground the line, to the amount of $20 million ($ adjusted for inflation). BART estimates that the issue added $18 million ($ adjusted for inflation) to construction costs and delayed completion of the system.

New rail technologies As one of the first entirely new rapid transit systems built from scratch in the 20th century, the architects of what would become BART intended to take advantage of space age and jet age technologies to design a rail system that could be marketed to other cities and regions. This led to several unconventional design choices for the system.

The cars were to be made from aluminum, which would make them extremely lightweight, about per foot. To keep the lightweight cars stable while exposed to high wind conditions on superelevated curves, the joint venture of Parsons Brinckerhoff-Tudor-Bechtel, general engineering consultants to the District, recommended a broad gauge. The consultants report in 1964 recommended a gauge of , unusual in the United States, which they said would improve stability and comfort without an exponential increase in construction costs.

Also, tracks were designed to utilize flat-edge rails and wheels. The railway utilizes an electrical system powered at an unusual 1,000 volts of direct current using third rail. Historically, streetcars operated at 600 V DC overhead lines and older subway systems tended to adopt this voltage using third rail, while new systems contemporary to BART and since usually use 750 V power from third rail or 1500 V power from overhead lines. Standards BS EN 50163 and IEC 60850 only specify these as well as 1,500 V power.

The combination of unique loading gauges and unusual rail technologies has complicated maintenance and increased cost of the system, as rolling stock requires custom wheelsets, brake systems, and power systems.

The initial system (1964–76) Construction

BART construction officially began on June 19, 1964, with President Lyndon Johnson presiding over the ground-breaking ceremonies at the Diablo Test Track between Concord and Walnut Creek in Contra Costa County, where Parsons Brinckerhoff-Tudor-Bechtel would test out the system's new technologies and unconventional design choices.

The system was scheduled to be completed in 1971.

Meanwhile construction would also begin on some of the other major projects on the system. The enormous tasks to be undertaken were daunting, including the Transbay Tube, the two-level Market Street subway in San Francisco, the complex underground Oakland Wye junction, the Berkeley Hills Tunnel, more than a dozen underground stations in Berkeley, Oakland and San Francisco, along with new maintenance facilities throughout the system.

The centerpiece of the system, the -long Transbay Tube, connected Oakland and San Francisco beneath the San Francisco Bay. Restoring transbay passenger rail service for the first time since Key System service was discontinued across the Bay Bridge, the tube was the world's longest and deepest immersed tunnel when it was completed in August 1969 at a cost of $180 million ($ adjusted for inflation). It was constructed in 57 sections, each positioned and installed individually by sinking them into a dredged trough across the bay (that was later filled in).

The -long Berkeley Hills Tunnel was constructed through active faults between Berkeley and Orinda in order to avoid further use of the Caldecott Tunnel.

BART constructed right-of-ways utilizing several rail and freeway corridors. For the initial system, these included: the Sacramento Northern Railway right-of-way in Concord, Contra Costa Center and Walnut Creek; State Route 24 and Interstate 980 from the Berkeley Hills Tunnel to Oakland; Western Pacific Railroad from Fruitvale to Niles Canyon; Atchison, Topeka and Santa Fe Railway and Key System right-of-ways between Richmond and Berkeley (which also became the Ohlone Greenway and Richmond Greenway); and the San Francisco and San Mateo Electric Railway and original Southern Pacific Ocean View Branch right-of-ways to Daly City.

The final ceremonial spike for the original system was placed in 1971.

Opening

Service began on September 11, 1972, reporting more than 100,000 passengers in its first five days. The Market Street subway opened on November 3, 1973A Full BART Chronology (269k .pdf) and the Transbay Tube finally opened on September 16, 1974, linking the four branches to Daly City, Concord, Richmond, and Fremont. Service then was still 14 hours per day, and for five years BART operated weekday-only: Saturday trains began November 1977 and Sunday in July 1978. Until November 1975, fare was $1.20 ($ adjusted for inflation) from Concord or $1.25 ($ in adjusted for inflation) from Fremont to any station west of the bay; Richmond to Fremont was $1.10 ($ in adjusted for inflation).

BART diverted 44,000 trips made by private cars by 1976, well short of the anticipated 157,000. One possible cause of this was that riders had difficulty reaching stations, especially on foot, which was not properly accounted for in ridership models.

BART's cost in 1976 was pegged at $1.586 billion, which included both the initial system, rolling stock and the Transbay Tube. (Adjusted for inflation, equivalent to $ in .) Critics have said BART took four decades to develop at a high cost.

The original construction included space for a third track through downtown Oakland, but that track remained unopened until March 1986.San Francisco Chronicle 18 March 1986 p7, Oakland Tribune 18 March 1986 page A-12

Infill Station

Service at Embarcadero began on May 27, 1976, three years after the other San Francisco stations. The station was not part of the original plans. Due to increasing development in the lower Market Street area, the basic structure of the station was added into the construction of the Market Street subway, anticipating a later opening.

Automation BART was one of the first U.S. systems of any size to have substantial automated operations. As a first-generation installation, the automation system was plagued with operational problems during its first years. Shortly after revenue service began, a failure in the train control system caused a two-car train to run off the end of the elevated track at the Fremont station and into a parking lot. There were no serious injuries.