This post has been update with paving-expenditure numbers from SDOT.

Whenever a new on-road bike project is proposed, someone inevitably makes the argument that bicyclists don't truly have a right to the road. Their logic is that road construction is paid for by gas taxes, which are paid by drivers, not cyclists, who get a free ride. This is wrong for a number of reasons.

Most bicyclists also own cars (95 percent of Americans, in fact, are car owners). Moreover, 200 pounds of bike and rider have significantly less impact on roads (and safety, and the environment) than a 2000-pound car (a 12-ton bus has even more impact, of course, but it has capacity to transport significantly more people). But, most importantly, the claim that gas taxes pay for our roads simply isn't true.

The Seattle Department of Transportation's 2009 annual report breaks down the agency's $340.8 million budget by funding source. The gas tax accounts for $13.4 million, or 4 percent of that total. The full budget breakdown (in millions):

Grants & Other: $96.9 (29 percent)
Debt: $77.4 (23 percent)
Bridging the Gap (a property-tax levy passed by voters in 2007): $60.9 (18 percent)
General Fund: $42.3 (12 percent)
Reimbursables: $42 (12 percent)
Gas Tax: $13.4 (4 percent)
Cumulative Reserve Fund: $7.6 (2 percent)

Other than gas taxes, Seattleites contribute most directly to the voter-approved Bridging the Gap levy and the general fund. The voter-approved portion of Bridging the Gap is funded by property taxes (the rest comes from the commercial parking tax), and more than 75 percent of the general fund comes from property, business and occupation, and sales tax---revenue sources that  all city residents pay for in one way or another. The remaining general fund revenue comes from government and private grants, traffic fines, and other fees.

Obviously, SDOT's budget includes salaries and other spending in addition to road projects. But the budget breakdown nonetheless shows that bicyclists, transit riders, and drivers alike pay nearly equal shares of the city transportation budget (and bicyclists have a smaller impact on road maintenance costs), granting everyone their "right" to space on the road.

UPDATE

The SDOT budget office sent me their 2009 arterial and non-arterial paving expenditures. They spent $29,377,725 for arterial and $261,000 for non-arterial for a total of $29,638,725. The arterial revenue sources breakdown as follows:

Bonds: $14,748,947 (50.20 percent)
Bridging the Gap Property Tax: $9,693,410 (33 percent)
Bridging the Gap Commercial Parking Tax: $4,801,062 (16.34 percent)
Gas Tax: $129,981 (.44 percent)
Grants: $4,325 (.01 percent)

All of SDOT's non-arterial paving work was 100 percent funded by the gas tax, but non-arterial work only accounts for .9 percent of total paving expenditures for 2009.

The paving numbers reinforce what the budget numbers already showed: everyone is paying for Seattle's roads.