Question When traveling more slowly than 40 miles per hour on a limited-access highway, you should: Answers Drive on the shoulder. Use your high beams. Sound your horn to warn others. Use your four-way flashers. Explanation If you must drive below 40 mph on a limited-access highway, you should use your hazard (four-way) flashers to warn the drivers behind you. Take a FREE Practice Test Now This questions appears in the following tests: Pennsylvania Practice Test