To build the new Interstate 55 interchange for Jackson and Cape Girardeau, the Missouri Department of Transportation is going to have to dig a hole through the highway.

While that construction is underway, four lanes of traffic will narrowed to two and funneled on to the portions of the new interchange that will evenutally be the on and off ramps to LaSalle Avenue on the Cape Girardeau side of the highway. And with the congestion sure to accompany that narrowing, MoDOT has a plan to route traffic around any accidents that occur, project engineer Andrew Meyer told the Cape Girardeau County Commission.

If an incident causing delays is expected to last less than a half-hour, Meyer told the commission, motorists on the highway will wait for it to clear. But if the incident lasts longer, traffic will be rerouted onto Highway 61 through Jackson, and, for longer blockages, the highway on-ramps leading into the construction zone will be blocked.

When MoDOT decides to use the detour, word will go out quickly, he said. "If an incident occurs, we will notify everybody as soon as possible," Meyer said.

Meyer made the same presentation Monday evening to the Jackson Board of Aldermen. The alternate route will be marked with signs, he said, and is primarily designed to keep through traffic moving.

Drivers from the area are likely to know routes that will help them avoid both the congested interstate and Highway 61, he said.

"The locals will find a way," Meyer said. "They will spread out on the letter routes. This is basically for the long-distance traffic, the truckers and people on vacation, who don't know their way through."

The traffic diversions to the ramps on the east side of the interstate should begin June 18, Meyer said. MoDOT hopes to have a public meeting on June 14 for anyone interested in detailed explanations of the diversion or alternate route during accidents.

MoDOT hopes to have the southbound interstate lanes re-opened by November, he said.

During an accident, as traffic backs up, MoDOT will make an escalating response, Meyer said. No traffic that would travel through the work zone will be allowed onto the interstate during backups.

That means traffic could be diverted off I-55 and southbound on-ramps closed at Fruitland -- exit 105 -- or as far north as Oak Ridge -- exit 111. Northbound traffic could be blocked from entering the interstate at Center Junction -- exit 99 -- or at Route K -- exit 96 -- in Cape Girardeau.

In an extreme case, northbound traffic could be diverted onto Highway 61 as far south as exit 93, Meyer said.

"I am sure that the first time something happens, we will look like the Keystone Kops," Meyer said. "But at least we are planning for it, not just waiting for it to happen."

Police will be stationed at strategic intersections, such as Main and Hope streets in Jackson and at Center Junction, to keep traffic moving, Meyer said. In addition, barricades will be pre-stationed at I-55 on-ramps to close them quickly.

On-ramps that lead away from the work zone, such as southbound ramps at Center Junction, will be allowed to function normally, Meyer said.

rkeller@semissourian.com

335-6611, extension 126