MoDOT Reveals Plans for Interchange Reconstruction at I-70 and Mid Rivers Mall

A plan two years in the making to alleviate congestion at Mid Rivers Mall Drive and Interstate 70 should begin work as soon as next month. 

Thursday afternoon the Missouri Department of Transportation hosted an open house at St. Peters City Hall to introduce the public to plans to reconfigured the heavily-trafficked interchange. Plans for a new diverging diamond interchange were unveiled and explained to the public in attendance.

"This is just another old interchange that needed to be updated to handle the volume of traffic it's trying to handle," said Russ Batzel, the public works service manager for St. Peters. 

Along with rebuilding the interchange, an additional lane will be added on westbound I-70. The estimated price tag for the whole project is currently set at $13 million with MoDOT, the city of St. Peters and St. Charles County covering the costs. 

"The cost-share agreement between the three groups was reached about two years ago," Transportation Project Manager Tim Schroeder said. "St. Charles County received a grant for the purpose of constructing the interchange. We've been working for approximately two years to arrive at this point."

Batzel said a study was done in 2010 on the interchange. In 2012, MoDOT began designing the project and now construction is ready to begin soon. 

"We're right on schedule with the original proposal," Batzel said. 

Bidding for the project was completed earlier this year, and construction is slated to begin in mid March of this year.

If everything goes according to plan, MoDOT said the targeted completion date is November 1, 2013—a date important to nearby Mid Rivers Mall.

"Because Mid Rivers Mall is a key stakeholder in the area, we wanted to try and get in and get out as quickly as we can to minimize the amount of time we're inconveniencing the traveling public," Schroeder said. "Most importantly we don't want to impact the next Christmas shopping season."

MoDOT describes the diverging diamond interchange as a new type of interchange traffic solution, but it's not entirely new to the St. Louis area. The Mid Rivers diverging diamond will be the second of its kind in area after MoDOT rebuilt the interchange at Dorsett Road and Interstate 270. Prior to that project, MoDOT has done several diverging diamonds throughout the state.

"We've had great success everywhere we've done it so far," Schroeder said. 

Batzel said the diverging diamond plan is good for the city—not just because it's unique. 

"It's one thing to be excited about it because it's new, it's another to be excited about it because it actually works," Batzel said. 

MoDOT said a big advantages of the diverging diamond is that it allows drivers to make left turns without crossing opposing traffic. Another advantage is improvements in signal timing because the reduction in the number of traffic movements for each cycle. MoDOT also said there will be increased efficiency and capacity of traffic at entrance and exit ramps of the interstate. 

Basically, MoDOT said the design allows for a safer interchange that will move traffic faster.

"We looked at a number of different interchange options," Schroeder said. "The diverging diamond has been proven very effective because it allows free left-turn movement ... much the way a conventional interchange allows for free right movements. This interchange fits very well and allows the best, most efficient use for traffic handling."