Preliminary work is beginning on a new bridge to replace an aging culvert under Coal Creek Parkway between Forest Drive Southeast and Southeast 60th Street.

Puget Sound Energy crews are on the site at night (to minimize impacts on travelers), 8 p.m. to 6 a.m., Sunday through Thursday, for about two weeks.

During that time, only one lane will be open in each direction on Coal Creek Parkway. All four lanes will be open during the day until bridge construction begins in May.

When the bridge contractor begins construction in late May, one lane will be closed in each direction 24 hours a day until the end of November, when the first phase of the project ends. Traffic delays and congestion are expected, especially during morning and evening commutes, and drivers are encouraged to use alternate routes.

One lane in each direction will be closed again during the second phase of the project, 24 hours a day, from mid-April through September 2014. Relocation of complex utilities, such as fiber optic cables, a natural gas main and high-pressure fuel pipe lines, requires the project to be done in two phases.

The existing 45-year-old Coal Creek culvert is deteriorating and needs to be replaced to keep the parkway safe for the nearly 28,000 commuters that use this route each day.

The project includes construction of a pedestrian pathway that will run underneath the bridge and connect the Coal Creek trail, giving pedestrians and hikers a safe way to cross the parkway. Replacing the culvert, a large corrugated pipe, with a bridge will also make it easier for salmon to migrate up the creek.

During construction, bicyclists will need to share lanes with cars for about 900 feet through the work area on Coal Creek Parkway.

In between Phase 1 and Phase 2, when the road is open to four lanes of traffic, interim bike lanes or widened lanes will be available for bikes through the 900-foot construction area. By the end of September 2014, all four lanes of traffic will be reopened, with bike lanes restored on both sides of the road.

The Coal Creek trailhead and parking lot will close in May and remain closed during construction of the bridge. A new trail accessing the park has been established nearby at 5199 Forest Drive. A more developed interim parking lot is planned to be completed at this location in spring/summer 2013.

The project will be completed by the end of November 2014.