And this doesn't even consider the savings due to less car repair, tires, accidents, insurance, etc. The density along the proposed light-rail route is anywhere from a half to a fifth of the density that is generally required to support a rail system. One of the primary goals of light rail is to motivate smart residential and commercial growth along the entire rail line corridor. This counteracts the otherwise naturally occurring phenomenon of clustered and creeping downtown development that leads to loss of middle-class neighborhoods. The success that Dallas has had with DART has demonstrated this desired effect, with hundreds of millions of dollars invested in new residential development within previously low-density and undesirable neighborhoods.
Property values increase near the light-rail line.
With regard to economic impact, light-rail construction has minimal negative impact, typically removing one house per new mile of rail. Turnstile counts and ticket sales indicate 45,000 people travel DART daily. If all of those are roundtrips that means 22,500 people a day are not in cars. Even if you assume that only half of the light rail riders were previously driving their cars, there are still 11,250 cars off the road. Because Austin does not have its own roadway approval authority, it could take a decade just to approve, and then take decades to complete.