Description: KNIGHTDALE BYPASS - WAKE COUNTY LOCATION: New section of US 64 just east of Raleigh.
ITEM(S) OF INTEREST:Project with numerous structures that include many items of interest such as very tall MSE walls, work bridges, long span (140'+) bulb-tee girders, and steel intermediate diaphragms on prestressed girder structures.
Observations and Points of Discussion:
Concrete Girder Bridge on Faison Road
2-span continuous modified bulb-tee girder bridge, with each span 140+ feet long.
The deck had been poured except for over the bent, where it had been formed up for the continuous for live load diaphragm and slab.
During the main deck pour the long girders deflected more than anticipated.
In the area over the bent, the reinforcing steel appeared to have more than the standard 2½" of concrete cover.
The deck slab was had a few visible cracks near the end bent.
It appeared that the structure will carry a future sidewalk, so there were no dowels cast into the deck slab.
Each span had a single line of steel diaphragms.
There were questions on the appropriate amount of tension applied to the diaphragm bolts?
Steel bridge over US 64
Noted various configurations for tall MSE walls:
Wall with reversed wing walls and a single row of piles (on Knightdale Bypass project by Design-Build team).
Wall with turn back, skewed wing walls and battered piles (on Wake Forest Bypass by in-house staff).
Wall that follows the end bent envelope and the cap is supported on a double row of vertical piles.
Potential for settlement of embankment should be examined during design of MSE wall.
MSE walls with reversed wing walls raises some drainage issues, and
NC DOT
NC DOH
NC GOV
