23 USC 102 - Program efficiencies

(a) Access of Motorcycles.— 
No State or political subdivision of a State may enact or enforce a law that applies only to motorcycles and the principal purpose of which is to restrict the access of motorcycles to any highway or portion of a highway for which Federal-aid highway funds have been utilized for planning, design, construction, or maintenance. Nothing in this subsection shall affect the authority of a State or political subdivision of a State to regulate motorcycles for safety.
(b) Engineering Cost Reimbursement.— 
If on-site construction of, or acquisition of right-of-way for, a highway project is not commenced within 10 years (or such longer period as the State requests and the Secretary determines to be reasonable) after the date on which Federal funds are first made available, out of the Highway Trust Fund (other than Mass Transit Account), for preliminary engineering of such project, the State shall pay an amount equal to the amount of Federal funds made available for such engineering. The Secretary shall deposit in such Fund all amounts paid to the Secretary under this section.