Came across this press release from the Pennsylvania Turnpike Commission regarding pending overhead sign support installations on the Northeast Extension:
http://www.paturnpike.com/Press/2014/20140724090727.htm
What caught my attention was the fact the PTC proposes to completely close the southbound roadway for six hours to install three new sign supports. MassDOT practice for new sign structures is to have the contractor do most of the installation with lane closures, and then only do a full roadway closure, for a maximum of twenty minutes per closure, when actually placing the horizontal span and securing it in place.
So I'm curious. How does your favorite DOT or toll road agency stage new sign support installations to minimize impacts to traffic?
The only time I've seen one of these put up was in Oklahoma. This was a monotube gantry and the installation took place at 11:00pm on a weekend night. (You'd think that a weeknight would be better, but...) The road was reduced to one lane, backing traffic up pretty far (there may have been an intermittent closure I didn't see), but we were still allowed to pass by while the installation was in progress. Pretty surreal driving beneath an empty gantry being held up by a crane.
NJDOT/NJ Turnpike Authority keeps the highway open, and will stop traffic for about 15 minutes or so at a time.
DelDOT closes the highway all night long for their sign installations.
Florida uses a rolling roadblock. They have the highway patrol travel at 10 mph from a great distance away so that the road is clear for x amount of time. The ramps in between are closed completely during those time though.
The only time I've seen this done in Nevada was down in Las Vegas for a sign structure that completely spanned US 95 NB, near the Lake Mead Blvd exit. It was between midnight and 2am, don't recall the day. Traffic was already down to one lane for another reason (possibly lane striping), and it was in an established construction zone as they were wrapping a construction project. Highway Patrol blocked the road about 100 feet ahead of the sign bridge. I recall this lasting about 5-10 minutes, although that could just have been the time I was personally stopped and not the entire duration.
I believe NDOT would typically try to have contractors do full-width sign bridge installation at another time when the road would be closed or traffic diverted for other reasons, to avoid closures.
DDOT has done full closures on U.S. 50, I-395, I-695, I-295 and D.C. 295 fairly recently to hang new overhead signs.
The last sign replacement project I remember was in Kentucky while I-471 was being repaved. KYTC only replaced a few signs, and I believe only 1-2 lanes were blocked at a time at each spot, not full closures.