For a successful technology, reality must take precedence over public relations, for nature cannot be fooled.Richard P. Feynman, physicist, 1918–1988
The choice of rapid transit technology will affect travel times, personal transport expenditures, and commuter comfort. The choice will also dramatically affect government finances and a city’s economic efficiency. Ultimately, the selection will shape a city’s urban form and the lifestyles of its inhabitants. But the choice should be guided first and foremost by what type of service is needed. Technology then becomes the tool to provide that service.
Choosing the appropriate rapid transit technology for a city requires balancing what citizens want and where they want it with more technical considerations such as costs and potential benefits. This chapter summarizes the technical differences among three main mass transit options: Bus Rapid Transit (BRT), Light-Rail Transit (LRT), and Heavy Rail Transit (HRT).
When deciding on the type of rapid transit most appropriate for a city, cost, performance, implementation speed, scalability, and local preferences all need to be taken into consideration. For most cities, the costs of different rapid transit alternatives, both capital and operating expenditures, should be preeminent decision-making factors. Even wealthier cities will benefit from cost-effective investments, offering greater benefits per dollar of investment. As the economic and social benefits of funds invested in rapid transit need to be weighed against other economic and social investments, an effort should be made to get the greatest social benefit per dollar of investment possible. The quality of the service, including the capacity, the speed, and the comfort of the service are also very important. People will willingly pay more for a higher speed and more comfortable service, and some corridors have more potential riders and require a higher capacity service.
The flexibility and scalability of the system also matters. Perhaps normal existing transit speeds are very fast in a city everywhere except in one area such as downtown. A high-speed congestion-free service may be needed in the congested area but not elsewhere. For different transit modes, there are different minimum operable lengths, which are the shortest segments that make sense to build and still bring benefits. The costs of the stations, vehicles, rights-of-way, and other factors will change this length for various modes. Some modes are easy to build in small segments, while other modes make financial sense in larger segments. There is also a benefit to expanding existing modes, as services and infrastructure can be connected more seamlessly.
As all public investments are ultimately political, they require some sort of mandate from the political leadership and the general public. Because politics and public opinion change rapidly, implementation speed is also very important. If a project can be implemented during a single term of political office, it stands a greater chance of being implemented, and its benefits can be realized more quickly.
Economic development impacts also matter. If one type of rapid transit is known to have a greater economic development impact, this would also affect investment decisions. Many cities are looking to rapid transit investments to help stimulate economic development in particular locations to guide urban growth to strategic locations. This chapter reviews how BRT, LRT, and HRT options vary with respect to each of these issues.