MARQUETTE — Thousands of drivers usually cross the Mackinac Bridge during the annual bridge walk, and the Mackinac Bridge Authority, Michigan Department of Transportation and other state agencies have been working for months to make sure every one of them knows they won’t be able to this year.

Typically, about 9,500 vehicles cross the bridge the morning of Labor Day, and MBA staff believe at least half of those are vehicles shuttling friends and family across the bridge to participate in the walk, according to an MBA release.

Participants this year will need to use the official shuttle buses, and the MBA and other agencies are trying to reach the remaining travelers in time for them to modify their travel plans.

“We’re reaching out through social media, posters in Michigan State Parks, commercials on the Michigan Secretary of State’s Motor Vehicle Network in all branch offices, flyers distributed at our toll booths, and posting messages on MDOT’s network of dynamic message signs,” MBA Executive Secretary Bob Sweeney said in the release. “We don’t want anyone to find themselves unexpectedly stopped in traffic Labor Day morning.”

Updates have been posted to the Mackinac Bridge Authority website, www.mackinacbridge.org; MDOT’s website, www.michigan.gov/mdot; and Mi Drive, MDOT’s travel information site, www.michigan.gov/drive.

The Michigan Department of Natural Resources will send emails regarding the closure to state park campground reservation holders, and the MBA will send updates to people who have signed up for email alerts. Other state agencies are also posting updates on their Facebook and Twitter accounts.

“Our goal is to reach as many of our customers as possible before the annual bridge walk, and we’re grateful to the state departments for their assistance,” Sweeney said. “For anyone we can’t reach, we’re planning to help minimize the inconvenience of the closure.”

Portable bathrooms will be placed along U.S. 2 for several miles west of the bridge, while water and snack stations will be on U.S. 2 and I-75 north and south of the bridge. Two MBA mechanics will patrol on both sides of the bridge as well to assist motorists with vehicle problems.

Michigan State Police will have additional troopers in the area during the bridge walk to regulate traffic, and MDOT is providing traffic control equipment.

Unlike previous years, only buses used to transport walkers to the starting point for the walk and emergency services vehicles will be allowed on the bridge during the event. All other vehicle traffic will be stopped from 6:30 a.m. Eastern time to noon while event participants are on the bridge. The authority made the decision during a special board meeting May 16, citing safety and security recommendations by the MSP and U.S. Department of Homeland Security.

Every year, 30,000 to 60,000 people from several states and countries come to the Mackinac Bridge for the annual walk, which has taken place since 1958, the year after the bridge opened to traffic.

The event will begin at 6:40 a.m. Eastern time with the start of the Governor’s Council on Physical Fitness Jog, followed by a greeting from Gov. Rick Snyder at 6:55 a.m. Walkers will begin across the bridge at 7 a.m.

For more information, go to the MBA website at www.mackinacbridge.org.