No. We in our office have always applied the typical clearzone concept per the Roadside Design Guide. However, we cannot find any info on an urban curbed section. We are working on a DCR for stretch of roadway that is mostly rural now but expected to be urban in a few years. I am trying to set drop inlets and culverts so that the ends are safely outside of the clearzone.
My understanding is that clear zones and their slopes are for vehicle recovery from the main lane. A curb is meant to prevent a vehicle from going off the road for certain speeds, so a clear zone should not apply there.
I agree VOD, however, we are only dealing with a 6" reveal for this curb. Also there is no distinction on wether this type of curb is a barrier curb or is mountable.
If possible, the normal clear zone should be provided.
Clear zones will not redirect a vehicle, except for low speed, low angles impacts. The Greeen Book lists offsets for street furniture, luminaires, etc, but this is mostly so truck mirrors don't hit them, and people can open car doors.
Curbs should not be used on higher speed roads. Vehicles ten to vault at higher speeds.
------------------------------------------
"Come to think of it, there are already a million monkeys typing on a million typewriters, and the Usenet is NOTHING like Shakespeare.
Typically, we have been using the standard clear zone distances. It seems that the smart thing is to continue using the full distance. Thank you all for your input!
Even at lower speeds, a vehicle will climb a curb. As speeds increase, the curb can throw the car upwards. At 80 km/h and above, a vehicle can actually clear a guiderail.
It's a bit complicated to go into detail here - depends on curb type, guiderail type, distance between rail and curb, etc. See the AASHTO Roadside Design Guide or your state DOT/MOT's design manual for more info.
------------------------------------------
"Come to think of it, there are already a million monkeys typing on a million typewriters, and the Usenet is NOTHING like Shakespeare.
