RALEIGH — Drivers in northern Wake County will see a slight increase in the speed limit on the Interstate 540 Outer Loop starting later this month.

The state Department of Transportation will post new signs bumping the legal limit up to 70 mph, from the current 65 mph, on a 21-mile stretch of the loop from U.S. 70 near Brier Creek to the U.S. 64/264 interchange near Knightdale.

DOT engineers concluded the faster speeds were justified after checking current speeds, crash data and road conditions on the 540 loop.

The Regional Transportation Alliance, a nonprofit business group that lobbies for road and transit improvements, had asked DOT to allow the higher speed on 540 and other Triangle-area freeways.

DOT approved faster speeds last year on Wade Avenue Extension in West Raleigh (60 mph) and on U.S. 1 from Apex through Sanford (70 mph).