It is essential that the track designer, the vehicle designer, and the designers of systems such as signals, catenary, etc., coordinate and cooperate to achieve compatibility between the LRT system components under all operating conditions. These interactions can be facilitated by generating a comprehensive design criteria manual for any new LRT system and keeping it updated with ”as-built” information as the project is developed, constructed, and operated.
It is generally inadvisable to design a new light rail line around the characteristics of only one make and model of light rail vehicle since doing so may limit choices for subsequent vehicle procurements as the system expands and matures. A transit system guideway may remain unchanged for a century or more, during which time it would not be unusual for three or more cycles of vehicle procurements to occur. Instead, it is recommended to consider a universe of candidate LRVs from several manufacturers and develop a fictitious “composite” LRV that incorporates the most restrictive characteristics of several cars, e.g., the longest, the widest, the one with the largest minimum radius capability, etc.
In this fashion, the transit agency will not be forever restricted to using only one particular make and model of LRV. It also minimizes situations where parts of the track alignment are at the absolute minimum or maximum capabilities of the vehicle, a condition that is highly discouraged in any event.
When new vehicles are procured for an existing transit line, the vehicle must be specified to operate on the existing track unless a concurrent rehabilitation and upgrading of the old guideway is proposed. When an existing transit line is extended, the track standards for the extension must accommodate both the old rolling stock and any new vehicles that might be procured.
