Quia.com and QuizGoGo.com both offer good road sign practice tests. These road sign practice tests provide questions on general road signs used in all 50 states. The tests are available free online.
At Quia.com, the test taker finds 30 multiple-choice questions on common road signs. Test takers must answer all the questions before seeing their scores.
QuizGoGo.com offers five separate tests of road sign knowledge. Two of the tests provide 20 questions, while the other three offer 10 questions. On the random road sign test, new questions generate each time the test begins, making it advantageous to take the test multiple times.