You may want to consider hiring a private company to perform road cleanups instead of relying solely on volunteer groups. Below is information about one private company doing cleanups.
Adopt-A-Highway Litter Removal Service of America is a company that offers a litter pickup service for roadways.
Their main program is to obtain sponsorships from businesses that pay to have their business name advertised on signs on highways. The business pays a monthly fee and the 1-mile (one side only) section of roadway is cleaned twice a month by a scheduled crew. Adopt-A-Highway is fully insured and, although they are based in California, they have several crews working on major roadways and highways in the tri-state area.
In addition, they have been hired by two New Jersey Counties to perform road cleanups on roads deemed not appropriate for cleanup by volunteer groups.