JOPLIN, Mo. — Work to upgrade the Range Line Road interchange on Interstate 44 — one of the busiest interchanges in Southwest Missouri — begins Monday night.

The $8 million project will replace the I-44 bridges over Range Line and convert the roadways underneath the interstate into a diverging-diamond interchange. The project, which will replace the four-leaf clover design built in the early 1960s when the interstate first opened, is to be completed by the end of 2013.

Highway officials began alerting businesses along Range Line about the project this week. Message boards also have been set up to alert motorists, and surveyors have placed wooden stakes in the ground to mark where new temporary ramps will be constructed.

“It is a very big project,’’ said Marvin Morris, project manager for the Missouri Department of Transportation. “The challenge will be to build it while maintaining traffic.

“Our goal is to build this thing and keep all lanes of traffic open between 7 a.m. and 7 p.m. That means we will do most of the major work at night,’’ he added. “We want to have as little impact on the flow of traffic as possible.’’

Average daily traffic count for Interstate 44 at the interchange is 28,030 vehicles.

“Let’s say we were to close the eastbound lanes of the interstate. With that many vehicles, traffic would back up into Oklahoma,’’ Morris said. “That’s what happens now when we have a bad accident on the interstate. We have to keep all lanes of traffic open.’’

One lane will be closed in one or both directions on Interstate 44 at various times at night. Lane closings on Range Line also will take place only at night.

Highway officials say the project is needed because the volume of traffic at the interchange has increased threefold since the early 1960s and safety has become an issue. Three fatality accidents and five other serious crashes have occurred at the interchange since 2006. All but one of those accidents was associated with merging traffic on the four-leaf clover.

In September 2009, the city of Joplin raised concerns about safety at the interchange and let the Missouri Highways and Transportation Commission know that it thought time was running out for the existing cloverleaf design. The cloverleaf ramps will be eliminated in favor of straight, directional ramps.

The project will replace the deteriorating eastbound and westbound bridges on Interstate 44 with a single bridge. At 14 feet 6 inches, the vertical clearance on the existing bridges is substandard for an interstate highway. The standard is 16 feet and the new bridge will be raised to 17 feet. To achieve that, the profile of Interstate 44 also will be raised.

In recent years, MoDOT has had to make costly repairs to the bridges after they have been struck by vehicles that were too tall to pass under them.

Range Line below those bridges will be converted into a diverging-diamond interchange, which will create special lanes so motorists can make so-called “free left and right turns” onto and from the interstate. The design changes are intended to decrease the likelihood that accidents will happen and will increase traffic flow.

FRENCH DESIGN

The first diverging-diamond interchange in the United States was constructed in recent years at Interstate 44 and Highway 13 in Springfield at a cost of approximately $3 million. It was based on a design first used in Versailles, France. It has since been used at five other interchanges in Missouri.

Joplin’s project costs more because the bridges that span Range Line will be replaced. No bridges were replaced in Springfield, but one was added. The Joplin project also is slightly more complex than the Springfield interchange, according to MoDOT.

With the diverging-diamond design, traffic in each direction will be shifted to the left-hand side of Range Line by traffic signals on each side of Interstate 44. This will enable drivers on Range Line to make left turns onto the interstate ramps without having to turn in front of oncoming traffic. Signs, pavement markings and concrete islands will guide drivers and help prevent wrong turns into the opposing lanes.

Through traffic on Range Line Road will return to the right-hand side of the road at new traffic signals after traveling underneath Interstate 44.

Also included in the project will be a sidewalk through the interchange between the concrete walls dividing the northbound and southbound lanes of Range Line.

Morris said one of the first objectives will be the narrowing of the lanes on Interstate 44 to a width of 10 feet. They will be shifted toward the median. The speed limit will be reduced to 60 mph in the work zone.

The speed limit on Range Line will be reduced to 35 mph. Lanes on Range Line will be narrowed to a width of 10 feet, and temporary traffic signals will be installed on Range Line.

The primary contractor is Emery Sapp and Sons, of Columbia.



Motorists beware

Speeding in the work zone when workers are present will add $250 to the total fine for drivers who are ticketed. Signs will be posted with that warning.