Barricades line Robert Grissom Parkway in the days leading up to the Myrtle Beach Marathon and Half Marathon May 1.

MYRTLE BEACH – Road closures will impact much of Myrtle Beach on March 1 as runners churn through the city for the 28th annual Myrtle Beach Marathon .

There will be 4,000 runners and about the same number of barricades marking the routes.

The closures will span from the south end at The Market Common to the north at Grande Dunes Boulevard. They will also affect areas east from Ocean Boulevard to Robert M. Grissom Parkway and the Frontage Road between 65th and 62nd avenues north.

U.S. Highway 17 Bypass will remain open.

Robert M. Grissom Parkway from 29th Avenue to Mr. Joe White Avenue will close at 4 a.m. as runners gather for the staggered starts by the Pelicans Ballpark parking lot entrance between 21st Avenue North and Mr. Joe White Avenue.

The marathon and half marathon start around 6:30 a.m. with the 5K beginning at 7:30 a.m.

The winners of the 5K will be announced around 8:30 a.m. with the winners of the half marathon announced around 9 a.m. The half marathon course will close at 10, meaning the roads impacted by the half marathon will reopen. The marathon winners will be announced around 10 a.m. with the course closure at 1:15 p.m.

The Myrtle Beach Marathon is a qualifier for the Boston Marathon scheduled for April 21.

The ballpark serves as the start and finish line for all the races on Saturday. The routes for each race differ and dictate the various road closures.

Starting at the ballpark , the 5K route turns off 21st Avenue North to Mr. Joe White Avenue, left on Chester Street and left on 9th Avenue North to Ocean Boulevard. The route takes the runners back to Mr. Joe White Avenue and a return to the ballpark off 21st Avenue North.

The half and full marathon route begins at the ballpark, left on Mr. Joe White Avenue and then right on Kings Highway. The pack will continue to The Market Common as the route folds back on itself along Farrow Parkway just after the lake in The Grand Park. Runners will exit The Market Common from Farrow Parkway and head north on Ocean Boulevard.

At the parking lot of the 2nd Avenue Pier, the route heads north on the Myrtle Beach Boardwalk to 8th Avenue North and returns to Ocean Boulevard.

The half marathon route goes a few blocks north to Mr. Joe White Avenue, back to 21st Avenue North and the ballpark for the finish line.

The full marathon runners continue north on Ocean Boulevard after splitting from the half marathon runners at Mr. Joe White Avenue.

Near mile 17, the runners turn left on to Grande Dunes Boulevard where the route loops back on itself once again emptying out on Kings Highway.

Runners will be directed south on Kings Highway hitting the 20-mile wall in front of Crave Italian Oven & Bar at 74th Avenue North.

Continuing south on Kings Highway, the route turns right on to 65th Avenue North until Frontage Road near the bypass. The Frontage Road section crosses 62nd Avenue North where the runners start on the Perrins Path walking and biking trail section of the route. Perrins Path empties on Grissom Parkway at 48th Avenue North.

The route loops back on itself for a final time as runners are directed down Burroughs and Chapin Boulevard across from Broadway at the Beach.

After clearing the jaunt on Burroughs and Chapin Boulevard, the runners are on the homestretch down Grissom Parkway to the Pelicans Ballpark for the finish line.

The Myrtle Beach Parks Division put up more than 3,000 barricades from Grissom Parkway and Kings Highway to mark the course and block roads.

There will be a traffic diversion in The Market Common so people can drive in and out of the area.

Myrtle Beach Police officers will be at various places throughout out the routes to direct vehicle traffic across when there is a gap in the runners.