Many work zones require lane closures, and road users need to be notified of these closures through appropriate upstream signage. This literature review found several previous studies indicating insufficient comprehension of the U.S. standard lane closure sign (designated in the MUTCD as W4-2) and similar signs used internationally. The W4-2 sign is also unsuitable for signing interior lane closures on roadways with three or more lanes. Several alternative sign face designs have been developed by U.S. states and other countries. Among these, variants of the Vienna Convention G12a and G12b signs appear to be the most widely used. Some of these alternatives are potentially easier to understand than the W4-2, but additional research is required to determine which alternatives could be the most effective. It is anticipated that Americanized versions of some of these signs will be used in driver comprehension testing in future research.