One of the Kansas Turnpike Authority’s 100 or so invited guests will get a chance to blast a 250-ton section of steel with the push of a button.

The “mystery blaster” will be identified through a raffle-style drawing Thursday at Kansas Athletics Inc.’s boathouse in Burcham Park, where officials will gather for a reception.

The person chosen to push the button will leave the park with KTA officials about 9:45 a.m. and head to the over side of the river, where a line will be set to detonate 6 pounds of directional explosives on a 251-foot-long section of original Kansas River bridge.

The 55-year-old bridge is expected to fall about 10 a.m. Thursday, upon the command of a professional blaster but actually triggered by the chosen-at-random bystander.

“I won’t be too far away,” said Pat Carney, owner of Chicago Explosive Services, the firm hired to blast the original turnpike bridges. “It’ll be fine.”

Attending the reception at the boathouse will be officials from the Kansas Turnpike Authority, Kansas Department of Transportation, city of Lawrence, Douglas County and other agencies and organizations who have helped the turnpike during its ongoing $130 million reconstruction project at the northern edge of town.

The first section of original bridge went down Sunday afternoon, as more than 100 onlookers watched in the rain from Burcham Park. Turnpike spokeswoman Rachel Bell had triggered that blast herself, from behind a concrete bridge support alongside the river.

She’s looking forward to someone else getting a chance to blast.

“Plant your feet and hit it hard,” Bell said. “That’s my best advice.”

Anyone looking to watch the bridge blast in person is encouraged to gather in the park, which is accessible from Second and Indiana streets. Spectators are prohibited from getting within 1,000 feet of the bridge as blast time approaches.

The Kansas Highway Patrol plans to conduct “rolling roadblocks” to keep traffic off the turnpike’s new Kansas River bridge as the blast approaches and is triggered.