Rapid Transit Series

**Power/Fuel** | Diesel, natural gas

The **Rapid Transit Series (RTS)** bus is a series of transit buses originally manufactured by General Motors and finally produced by Millennium Transit Services as the RTS Legend. The RTS is notable for its timeless styling featuring automobile-like curved body and window panels.

## History

In the 1960s, General Motors was developing a next generation transit bus. They produced the Rapid Transit Experimental (RTX) prototype in 1968. The bus had three axles and a lower floor than other buses at the time. It had 2+1 bucket seating and used a GT-309 gasoline turbine with toric-type continuously-variable transmission.

In 1971, the Urban Mass Transit Administration launched the Transbus research project with the goal to design a bus that would be lightweight, comfortable, and accessible to the elderly and disabled. General Motors proposed their RTS-3T (Rapid Transit Series 3-axle Transbus). It had a lowered floor, three axles, and resembled the RTX, but was 45 feet in length and had conventional transit seating. The RTS-3T used a Detroit-Diesel Allison GT-404 gasoline turbine with an Allison HT-540 transmission.

As the future of the Transbus project became uncertain by 1976, both General Motors and Rohr announced their intention to to produce so-called "Advanced Design Buses" (ADB) in the interim. General Motors incorporated features of the RTX and Transbus into what became the earliest RTS prototype in 1973. This bus had two axles and a higher floor. The Transbus designs never entered production, and General Motors focused their energies on the RTS which began production in 1977.

General Motors sold the RTS design and patent rights to Transportation Manufacturing Corporation (TMC) of Roswell, New Mexico in May 1987. The two companies did a joint order for the New York City MTA to prepare TMC for the production. TMC would sell the design and patents to Nova Bus in September 1994 in the midst of an order for the Massachusetts Bay Transportation Authority. Production under Nova Bus would continue until 2002 when Nova Bus left the US market and concentrated solely on producing it's LFS model for the Canadian market. Production was revived by Millennium Transit Services in 2003, although the status of the firm's viability and future is somewhat uncertain.

## Propulsion

The Detroit Diesel 8V71N engine was standard in the early models, but the 6V71N engine was made available beginning with the RTS-03. Both engines were later replaced by the 6V92TA. The Allison V730 transmission was standard until it was replaced with the V731. TMC continued with the Detroit Diesel and Allison powertrain, later offering the Detroit Diesel Series 50 and VR731. Powertrain options diversified beginning in 1989 with a CNG engine option. The 1990's saw the introduction of ZF Ecomat transmissions and Cummins engines. Nova Bus continued to offer Detroit Diesel and Cummins engines including CNG and LNG options with Allison and ZF transmissions.

The Demonstration of Universal Electric Transportation Subsystems (DUETS) project was launched in 1994 and sought to apply electric drivetrain systems, originally developed for defense, to civilian use. Nova Bus supplied the project with their RTS for the development of a electric hybrid transit bus. Kaman Electromagnetics supplied the electric generator and two-wheel traction motors. The generator was driven by a natural gas-fueled rotary combustion engine. Energy storage was provided by a 270 volt Saft Nickel-Cadmium battery with a 216 kilowatt-hour capacity. The vehicle management system was developed by Honeywell Technologies. A specialized suspension system that took into account the added weight of the components and incorporated compressible fluid technology to improve handling was developed by David Technologies International.. From 1997 to 2000, the bus was extensively tested.

Nova Bus partnered with the Federal Transit Administration and Georgetown University to produce an RTS bus that used a methanol reformer integrated phosphoric acid fuel cell. It was supplied by International Fuel Cells (later known as UTC) and worked with a Lockheed Martin HybriDrive electric drive system to propel the vehicle. Another fuel cell hybrid RTS bus was developed in 2001. It was equipped in a similar manner to the first bus, but used a proton-exchange membrane fuel cell supplied by Xcellsis (know known as Ballard Fuel Cell).

At the start of 1999, New York City Transit placed an order for five diesel-electric hybrid RTS buses to be used for trial and evaluation. They were equipped with the Lockheed Martin HybriDrive system and the Detroit Diesel Series 30 engine. The auxiliary systems including air conditioning would be electrically driven. Only two buses were ultimately built, with the first going into service for a few years.

Millennium introduced the option of the Caterpillar C9 engine coupled to a ZF Ecomat 2 transmission in a T-drive configuration. The Cummins ISL and John Deere engines were also advertised, but there are no known examples built with them. In complying with the EPA 2010 emissions, the Cummins ISL9 and Cummins Westport ISL G were made options when RTS production was revived in late 2011.

## References

1. ↑ Report 38: Guide Book for Evaluating, Selecting, and Implementing Fuel Choices for Transit Bus Operations. Transit Cooperative Research Program.
2. ↑ 2.0 2.1 *Hybrid Electric Vehicle Projects*. Federal Transit Administration, 2001
3. ↑ Weaver, Graham. *World Fuel Cells - An Industry Profile with Market Prospects to 2010*. Elsevier Advanced Technology: Kidlington, 2010. Online.
4. ↑ Lockheed Martin to deliver more diesel electric propulsion systems for New York City buses. Press release. 13 January 1999. Lockheed Martin Control Systems.
5. ↑ [http://onlinepubs.trb.org/onlinepubs/tcrp/tcrp\_rpt\_59.pdf TCRP Report 59- Hybrid-Electric Transit Buses:
Status, Issues, and Benefits]. Transit Cooperative Research Program.

## See also

* New Look - Previous 1960s generation GMC bus
* Classic - Updated version of the New Look, offered as an alternative to the RTS