The Virginia Department of Transportation is posting a weight restriction on the Gwynn’s Island bridge on Friday because of rusting steel stringers under the deck of the swing span.

The 72-year-old bridge, which connects Cricket Hill Road on the mainland with Old Ferry Road on the island, provides the only land-based ingress and egress for island residents.

The weight restriction will be 10 tons for single-unit vehicles such as cars, trucks and buses and 15 tons for tractor-trailers. VDOT notified Mathews County about the restriction last week so that the schools, fire department, and rescue squad could adjust their procedures as necessary. The school system is now sending two buses to transport students off the island instead of one.

Water vessels traveling below the drawbridge aren’t expected to be impacted by the restrictions.

The bridge’s deteriorating stringers—the steel beams that support the grid deck—were found during a scheduled annual ...