Q.: Why aren't concrete median safety barriers built higher so that there is no need to install steel glare screens? The screens get damaged by cars or trucks hitting the median barrier and they are expensive to fix. We are thinking about using concrete to build our existing barriers higher. Has this ever been done?

A.: A median barrier that is built about 5 feet high initially should do the job of blocking out headlight glare. The Georgia Department of Transportation upgraded median barriers on I-20, I-75 and I-285 in the Atlanta area by adding a layer of concrete on the top. They found that to completely screen out truck headlights they had to add a 27-inch-high layer on top of existing 30-inch barriers. The contractor used dowel bars epoxied into the top of the median barrier to tie the new concrete to the old. Then the concrete glare screen was made by slipforming along the top of the median barrier. Areas adjacent to light poles and bridge columns were hand formed, but this work amounted to less than 10 percent of the concrete work.