A related design is the SD-400/SD-460 high-floor light rail vehicle, which was initially built by a Siemens–Duewag joint venture.

Production of the SD-100 was launched in 1992 when the Regional Transportation District, located in Denver, Colorado placed an order for 49 vehicles.

The first vehicles rolled off the production line at the Siemens facility in Florin, California in 1994, in time for the start of Light Rail service in Denver.

Along with some electronic improvements, they have been upgraded to be compatible with Calgary's newer SD-160s, which were previously incompatible due to software differences.

The refurbished fleet will eventually start to run with the newer units once the software has been adjusted to allow seamless operation.

[2] Currently, the Metropolitan Transportation System (MTS) of San Diego, California is in the process of donating its Siemens SD100 pairs to the Mendoza Transportation Society, which has an urban metro-tram service that connects four departments (Las Heras, Ciudad , Godoy Cruz and Maipú) of the Province of Mendoza, Argentine Republic.

Some SD-160 trains, such as those operated in Denver, are configured to reach higher speeds of 90 kilometres per hour (56 mph).

Each vehicle also features an onboard closed-circuit TV security camera system for increased passenger safety.