Commuter railroads operate over existing freight rail lines, and commuter trains are typically quieter than freight trains. Light rail lines are usually built on the surface and use rail cars that are basically modern versions of old-time trolleys. Light rail vehicles are powered by overhead electric lines and usually operate as single cars or in short trains of 2 to 4 cars. Rochester is in the same population and density range as Sacramento, Portland and Calgary, which have all built successful light rail lines. Light rail is ideal for applications in smaller cities.
Light rail is built mainly on ground-level.
The cost of building a line on the surface is far lower than building the subway and elevated structures associated with heavy rail. A light rail line does not have to be completely grade separated. That is, light rail can cross over streets at street level, although busy streets are usually crossed by a bridge or underpass. Reducing the number of bridges and underpasses decreases the cost of building a line. The line in Buffalo was many times more expensive than any line proposed for Rochester.