Whats with crossing gates on onramps?
In Southern states near the Gulf of Mexico or the Atlantic Ocean, these are employed to keep traffic from entering when the road in in contraflow mode, or when one direction of traffic is using both roadways, in the case of evacuations, especially due to a hurricane landfall. (For examples of details including signage, see http://www.gomdot.com/cetrp/ .) In Upper Midwestern states, these are employed when the highway is closed, usually due to blowing snow or high snowdrifts. These are also used at the entrances to reversible roadways (see Question 12.8.1 ).
