Abstract
Advantages and disadvantages of using blank-out arrows and matrix signs, drum type signs, and manual flip signs are briefly covered. Blank-out arrows and X's are used to indicate lane openings and closures, however, they are difficult to see under direct sunlight. Matrix signs can be utilized to convey an unlimited number of messages, but the new standards designed by the manual of uniform traffic control devices for street and highways may limit the effectiveness of these signs.