SFMTA's board of directors is expected to approve the contract today and the San Francisco Board of Supervisors is expected to give its own approval in September.
The first prototype vehicle will be delivered in December 2016 and a further 23 units are due to arrive by 2018.
The initial order for 24 vehicles is funded from federal, state, and local sources via the budget for the Central Subway project, which will extend the T-Third line under Stockton and Fourth Streets from the Caltrain station to Chinatown. The extension, which includes new underground stations at Moscone Center and Union Square, is due to open in 2019.
A further 151 vehicles will be delivered between 2021 and 2027 to replace existing trams. SFMTA says funding for this batch of vehicles is in place.
Following the completion of a travel demand study, SFMTA estimates it will need a further 40 vehicles between 2018 and 2021, and 45 more in 2027-2030 which would take the total order to 260 vehicles. The authority is currently identifying funding sources for the initial option for 40 vehicles.
SFMTA says the price offered by Siemens was 20% lower than anticipated, which will allow it to order 215 LRVs with the budget allocation for 175 vehicles.