Construction on a new Kansas River bridge on Interstate 70 is moving along. Once all Kansas Turnpike traffic is switched onto this new bridge — a move expected by Thanksgiving — contractors will start preparing the old bridges for demolition beginning in December.

Much of the 9 million pounds of steel that’s been supporting hundreds of thousands of vehicles crossing the Kansas River for more than 50 years soon will be coming down.

In a matter of seconds.

Officials behind a $130 million project to replace the Kansas Turnpike’s two river bridges and related upgrades are planning for a deployment of targeted explosive charges at the work site that runs through the northern edge of Lawrence.

And by Christmas, Patrick Carney, the president of Chicago Explosive Services, will press a single button to drop the first of two bridges that stand as high as 50 feet above the river below.

Upon detonation, Carney’s four directional charges — encased in copper tubing, held in place by industrial-sized rubber bands, backed with heavy-duty cloth and surrounded by double-plywood boxes — will focus blasts so strong that they’ll shear load-bearing sections of the bridge’s massive steel trusses.

Just like cutting through a frozen stick of butter with a white-hot knife.

“It shoots the copper jacket through the steel member,” Carney said of the RDX explosives that deliver force faster than traditional TNT. “It literally happens so fast: it shoots through before the rubber band even breaks.”

The strategic placement of charges — following preparatory cuts by Carney’s crew, and removal of all concrete deck and barriers on top by others — will allow the first bridge to fall into the river in three pieces, ready to be dragged out with assistance from heavy-duty cranes.

No Wile E. Coyote here

Anyone who shows up to watch likely will be disappointed, Carney said.

That’s because onlookers will be kept at least 1,000 feet away, he said, and the blast will be expected to occur overnight, in the dark — likely about 2 a.m. some day in December.

“It’s going to be so hard to see this thing,” Carney said.

Besides, once the three sections start their descent, Carney said, they should hit the water in little more than a second. Sound from the blasts won’t even reach spectators until after the steel has started falling.

“It’s not the Wile E. Coyote thing you think of,” Carney said. “It’s just ‘boom!’ and it’s down. That’s it.”

That’s just what Mike Jeffries, vice president for United Contractors Inc., plans to be paying for.

As the project’s subcontractor for both building the new bridges and removing the old ones, Jeffries is counting on Chicago Explosive Services to do its work without a hitch.

With the bridge coming down in sections, workers said, cleanup is easier.

Meanwhile, there’s plenty to coordinate: permits from various agencies; traffic-control plans with turnpike and law-enforcement personnel; and crowd control with on-site security teams, who will be tasked with keeping onlookers out of harm’s way.

“We’ve done several of these around the country, and you always have somebody who knows more than you and tries to get too close,” Jeffries said. “It always seems people want to be daredevils. We don’t want to get anybody hurt.”

That’s why planning is under way now.

‘Smooth’ blasts sought

The first step is to finish construction of the first new bridge. That’s so that all turnpike traffic can be routed onto the new span — two lanes in each direction — by Thanksgiving, giving crews enough time to take off the old bridge’s concrete deck and concrete barriers.

Then it’s up to Carney’s crew to set the charges, arrange for brief “rolling closures” of lanes on the turnpike and, with a press of a button, send the steel into the water.

Next up will be preparing the other old bridge — the one that’s about three feet south of the new one — for blasting a few weeks later, following the same process.

“I don’t think there’ll be all that much to it,” Jeffries said. “Everybody thinks there will be concrete flying, but it’s an anticlimactic deal.”

That’s the plan, anyway.

“It’ll be kind of a letdown once it’s over,” Jeffries said, “as long as everything goes smooth.”