Streets.MN recently published a thorough and intelligent article about user fees and roads. It's titled, "Yes, Bicycle Riders Should Pay Their Fair Share," and it's well worth a read. The author, Walker Angell, writes the piece in response to a recent op-ed in his local paper suggesting the bicyclists do not pay their fair share for use of the road. Angell begins:

I’m a strong believer in personal responsibility and that we should each pay for what we use. This makes for better decision making and creates much more efficient use of scarce resources than when the costs of using these resources are not tied to our choices.

Historically we paid for our roads with taxes on gasoline. In theory the amount of gas you used was roughly equivalent to the wear and tear you placed on the road system. In reality it was extremely rough but it sort of worked. As the costs to build and maintain our roads and bridges have increased, gas tax revenue has not. This largely due to increased fuel economy and the tax being a fixed amount per gallon instead of tied to inflation. Politicians were afraid to increase the gas tax appropriately, so either maintenance was foregone or the gap was filled with easier to vote on general funds.

Today, less than half of the costs to build, maintain, and operate our road system are paid for from such user fees, with the bulk coming from general tax revenue — mostly property taxes.