Is there a way to fly an UAV over a roadway?
For certain operations the FAA does grant waivers to 14 CFR § 91.119(b) and/or (c). These waivers are generally granted for the purpose of allowing pipeline or powerline patrol, aerial survey, or for other operations that are in the public interest. The waivers are also generally granted to the operators of certified or restricted category aircraft, not UAS.

If you represent an operation for which a waiver would be in the public's interest and can demonstrate that the operation would be conducted safely, you might qualify for a waiver.

However, even for that waiver, you have to demonstrate strong evidence to gain a minimum distance of less than 500 feet:


  3-185 A. Unless it is necessary to
  safeguard human life or it can be determined to be in the public interest and contributing to the public health, welfare, and safety, the 500-foot minimum separation distance from persons on the surface shall not be waived.


Note that 14 CFR § 91.119(a) and (d) are never to be waived.

See this document for more information on the above discussed waiver.



Now, all that being said, I don't know if the above example of a waiver apples directly to your question or not; perhaps 91.119 is not the regulation that you were concerned about. Regardless, that waiver is an example of what can be worked out.

The current UAS issue is uncharted water for the FAA; there may or may not be precedent for an operation or exemption. Bottom line, if you have a really good reason to do the operation you want to do, you might be able to work it out with the FAA. Otherwise, you will have to stick to the rules as they are.