Description: ATLANTIC AVE. & CRABTREE CREEK - WAKE COUNTY LOCATION: Bridge # 342 - Atlantic Ave. over Crabtree Creek
ITEM(S) OF INTEREST: Cored Slab built in 1972. ADT = 30,000
Observations and Points of Discussion:
Location now has a high ADT count.
Sidewalks on both sides of the bridge
There were no deck drains to rapidly remove water from the roadway surface.
There was some spalling on the under side of bridge starting with slab units 3 through 5 and in some areas 7.
Based on the observations asphalt overlays on box beams and cored slabs on high ADT/ADTT and high salt application locations may not be the best product.
It was suggested that the Department consider overlay systems that will better protect the superstructure.
It was noted that quality control for producing cored slabs has improved, e.g. more cover for strands on the bottom is now required.
In addition, the Materials and Tests Unit has refined the asphalt super-pave mixes. Mixes are not as coarse and therefore not as permeable as some of the earlier mixes.
It was noted that the Department usually details 4" f through-the-rail drains, which are generally not very efficient for rapid drainage and generally and allow salt to permeate and accumulate in the asphalt.
FHWA suggested that the Structure Design Unit develop criteria for use of concrete overlays with consideration for location and traffic counts.
In addition, the Structure Design and Construction Units will use 8" wide x 4" tall drainage slots on a trial basis.
It was also suggested that the Materials and Test Unit take asphalt cores from a variety of cored slab bridge overlays and test for chloride content to severity of chloride ingress.
The Hydraulics Unit noted that there were lots of trees leaning in to the creek, and therefore A-frame bents would not be recommended due to potential for debris accumulation.
NC DOT
NC DOH
NC GOV
