The proper debate is over how to manage the growth in demand for transportation capacity. It's cheaper to buy a Lexus or Mercedes for each person who would ride light rail than it is to build the train. It will cost about seven cents per passenger-mile for insurance and eight cents for gasoline at just over a dollar a gallon. Almost every study and survey provides data showing buses and trains attract different sets of riders. Bus passengers tend to be from low to middle income groups.
Buses are as efficient as light-rail, without the cost of expensive rail construction.
Cities that have chosen bus-only approaches spend more money moving their passengers. Double decking is the most expensive form of highway building. And virtually all of the light rail construction in the past decade has come in on time and on budget. Unless Austin is going to wall itself off and not allow anyone else to move here, we are going to see continued increases in the number of cars in the area. Therefore, attempting to reduce pollution through traffic reduction is a broken approach because new cars are coming in faster than it is possible to redirect or remove them.