(Updated at 12:35 p.m.) The West Glebe Road bridge over Four Mile Run will be completely closed to vehicles in two weeks, and will remain closed for nearly a year.

The circa-1956 bridge, which connects Arlington and Alexandria near the I-395/S. Glebe Road interchange, has been deemed “structurally deficient” since 2018. A $10 million project to replace its deck and beams was approved by the Arlington County Board last April and was slated to start this year, but in the meantime engineers have found “continued degradation of the bridge beams.”

As a result, the bridge is closing to drivers on Monday, May 9, the county announced today. That’s after southbound bridge traffic was detoured for the same reason in March.

New detours will be put into place that will divert vehicular traffic either over the Mount Vernon Avenue bridge to the east or Shirlington Circle to the west. Both of those bridges, coincidentally, are also aging and set for repairs over the next couple of years; the former received funding from the recent federal infrastructure bill.

The county expects two vehicle lanes on the West Glebe Road bridge to reopen in early 2023, while it’s still under construction. Work is expected to start shortly after the May closure and last until the summer of 2023.

Pedestrians and cyclists will still be able to use the bridge for a few more months. A temporary pedestrian path across Four Mile Run is expected to open in July. Four Mile Run Trail users, meanwhile, will re-routed to a parallel path, as the portion of trail under the bridge will be closed.

More from a county press release, below.

Because of continued degradation of the bridge beams, engineers will close the West Glebe Road Bridge to all motor vehicle traffic beginning on Monday, May 9, 2022, for construction of a planned replacement superstructure (road deck and beams). Two motor vehicle lanes on the renovated bridge are expected to reopen in early 2023 along with one of two widened sidewalks.

The current structure connecting Arlington and Alexandria over Four Mile Run was built in 1956. Elements have experienced noted deterioration in recent years.

In 2018, a 5-ton weight restriction was placed on all user vehicles. In March 2022, all southbound traffic was detoured away from the bridge amid signs of continued structural beam degradation.

Allowing continued motor vehicle traffic with the additional stress of construction has now been ruled out. Pedestrians and bicyclists will be able to use the bridge through June, after which they will be directed to a temporary crossing, independent of the superstructure, to be built along the bridge, expected to open in July.

The Mount Vernon Avenue Bridge further east over Four Mile Run will continue to handle vehicular traffic detouring from the West Glebe bridge.

The bridge’s original piers are stable and will be used to support the new superstructure, reducing project costs, construction time, and impact on the watershed.

The project is set for completion by summer 2023.

Arlington County and the City of Alexandria continue continue to coordinate closely on the bridge replacement project. Crews will mobilize for the job later this month.