1967, with two decks tracks – the upper intended to provide local service. Major cost overruns in the BART project forced the state legislature to rescue the project in 1969: curtailing local service in San Francisco and converting the partially constructed stations into the basis of a new light-rail subway called the Muni Metro to connect the downtown stations to the Twin Peaks Tunnel and continuing along reserved tracks to St. Francis Circle. Construction on the metro began in 1970, but the project suffered from further cuts and design changes throughout the 1970s. The Muni Metro finally opened in February 1980, for one line (N-Judah), with other lines following later in 1980, but the many design compromises and piecemeal planning led to long-term operational challenges and inefficiencies. In 1970, Muni also suffered a severe diesel bus crisis. Muni experienced a diesel bus availability crisis in 1981–1982 when most of their diesel buses, 401 GMC and Flxible "New Looks" purchases in 1969, reached the end of their 12-year design life and funds for their replacement were not available. Most of the rest of the fleet were undersized 36-foot AM Generals purchased for neighborhood routes, and their use on heavier lines exacerbated conditions. The trolley bus fleet was in good order and had excess capacity at the time so Muni improvised a few temporary services with them to help out. One such service was a trolley 14-Limited that used the abandoned trolley overhead on South Van Ness. The diesel 82-Chinatown was replaced with short runs of the 30-Stockton. But the trolleys could only go where their wires went. Muni adopted some policies to alleviate future service issues due to an aged fleet. They would stagger bus purchases so not as large a portion of the fleet would hit retirement age at once. They would arrange for mid-life rebuilds to keep the buses more serviceable in their final years. And they would work to reduce the role of diesels in the total operation. Three trunk diesel lines were converted to trolley bus service in the next twelve years. But these efforts have not been as successful as hoped. Out of necessity most of the fleet, 330 standard bus equivalents out of 506, were replaced in just two years in 1985–1986. (Standard bus equivalents factor the 30-foot and 60-foot into their equivalent capacity in 40-foot buses). And seven years passed without any new buses