VC and ChrisL bring up an important aspect of traffic waste.
There is a lot of call these days for more use of rail service in the USA.
However, notice how much traffic gets tied up as those rusty old trains creep through town. Worse yet, in the USA, trains are often miles long which further ties up traffic in every city they groan into.
I bet that if you did the math from a national standpoint, it would be proven that the fuel wasted by traffic stopped at train crossings equals or outweighs any savings in fuel that rail transport might promise.