|Years of manufacture||
|Power||Direct current, Alternating current (only built as demonstrators)|
The Siemens–Düwag U2 is a six-axle, bi-directional, articulated light rail vehicle. They may be coupled together to form longer trains. The cars were constructed by consortium of Siemens, Wegmann & Co. and Düwag in West Germany.
The U2 was originally designed for Frankfurt's light rail transit system. Based on prototypes known as the U1, a total of 97 U2 cars were built for Frankfurt beginning in 1968. Düwag later successfully bid their U2 design for the city of Edmonton's new light rail system. Edmonton took delivery of their first 14 vehicles in 1977, eventually purchasing a total of 37 vehicles. Further orders for the U2 were placed by the cities of Calgary and San Diego.
From 2010 to 2012, an agency in Argentina acquired 18 U2 cars secondhand from San Diego. They are used to operate a new light rail system between the cities of Mendoza and Maipú.
Models and Variants
The U1 was the prototype of the U2. Two cars were built in 1965; both were withdrawn by 1980 due to their incompatibility with the U2 and U3 class cars. These cars were stored for many years, and eventually scrapped.
A copy of this car, numbered 1001, is now on display at the Frankfurt Transport Museum. It was built using parts salvaged from the unrestorable original cars before their scrapping.
The standard U2, running on direct current.
Top speed of 80 km/h. 295 built between 1968 and 1990, operated in Calgary, Edmonton, Frankfurt, Mendoza, and San Diego.
Runs on alternating current (with the help of an inverter), only built as demonstrators.
Top speed of 88 km/h. 2 built in 1988, operated between 1988 and 1990 in Edmonton, then brought to Calgary where they were eventually adopted into the permanent fleet.
Street accessible model of the U2. Similar styling to the SD-100 and SD-400, but the mechanics are identical to that of a U2-DC.
Top speed of 80 km/h.
26 built between 1985 and 1991 for the Sacramento Regional Transit System LRT.
Codename for the refurbished Frankfurt U2h cars, 3 units made before program was cancelled.
Lower floor height used on the Frankfurt system.
- Metrotranvía Mendoza - Mendoza, Argentina (18 U2-DC)
- Calgary Transit - Calgary, AB (83 U2-DC plus 2 U2-AC)
- Edmonton Transit Service - Edmonton, AB (37 U2-DC, briefly operated 2 U2-AC demonstrators)
- Government of Alberta (owned the U2-AC demonstrators until 1999) - Province of Alberta
- Frankfurt U-Bahn - Frankfurt, Germany (2 U1 prototypes, 104 U2h, 3 U2e)
- Memphis Area Transit Authority - Memphis, TN (1 U2-DC) 
- Sacramento Regional Transit District - Sacramento, CA (36 U2a)
- San Diego Metropolitan Transit System (MTS) - San Diego, CA (71 U2-DC)
- ↑ De Leuw, C. &. C. (1976). Light rail transit : State of the art review. United States:
- ↑ https://www.localmemphis.com/article/news/community/memphis-trolley-cars-different/522-50793080-58d8-44ec-9cc1-9608bc90fa3c?fbclid=IwAR0s1AO_xSZHHWN_qIYwvgzi2fn9IBKyv4jQHIDfJJ1XEt05HvDWwLpTOtU
- ↑ https://https://www.cbc.ca/news/canada/calgary/ctrain-car-art-1.5513891 Decommissioned CTrain car a dream canvas for Calgary artist. Published and retrieved on March 29, 2020.