State Rep. Pam DeLissio announced last week that the planned detour around the Walnut Lane bridge later this year will last for six months.
The full rehabilitation of the bridge, which includes improvements to the roundabout, is expected to take 18 to 24 months.
The detour will take traffic over Henry Avenue, Midvale Avenue and Wissahickon Avenue and total 3.25 miles, according to DeLissio.
Pedestrian access to the bridge will not be restricted during construction.
The project is expected to begin in May.