I do. But Chris Edwards of the Cato Institute has done the work. Over at Downsizing the Federal Government, Edwards writes:

Most of the activities of the U.S. Department of Transportation are properly the responsibility of state and local governments and the private sector. There are few advantages in funding infrastructure such as highways and airports from Washington, but there are many disadvantages. Federal involvement results in political misallocation of resources, bureaucratic mismanagement, and costly one-size-fits-all regulations imposed on the states.

He suggests eliminating the Federal Highway Administration and the Federal Transit Administration, removing air-traffic control from the federal budget and setting it up as a stand-alone and self-funded agency or private company, privatizing Amtrak, and more. Total $85 billion.

More about the Department of Transportation here.