I-270 Widening between Manchester Road (Route 100) and I-44
What is the problem?
The stretch of Interstate 270 between Interstate 44 and I-64 is one of the most heavily traveled sections of interstate in the St. Louis greater metropolitan area. On average, between 175,000 and 185,000 vehicles travel the section of interstate each day. During morning and evening rush periods, the heavy levels of traffic cause significant backup. In the morning, traffic on northbound I-270 backs up from about Big Bend to Gravois (Route 30). In the evening, it is not unusual to have traffic backups on southbound I-270 from Dougherty Ferry to Olive Boulevard (Route 340) or Page Avenue (Route 364). A significant amount of merging traffic from I-44, railroad bridges with columns just off the roadway and the rock bluffs on the east side of the roadway all contribute to overall congestion on the interstate.
During a typical weekday morning commute, traffic slows to 35 miles an hour in this stretch of northbound I-270. It takes about 10 minutes more to drive this stretch of roadway than when the roadway isn’t congested.
What options were looked at?
This particular stretch of northbound I-270 has a lot of areas which provide design concerns – among them, traffic ramps from Watson Road, eastbound and westbound I-44 and Big Bend; the rock bluffs on the east side of the interstate and a narrow railway bridge south of Dougherty Ferry. Southbound also has the narrow railroad bridge, the ramp to Big Bend, as well as ramps to eastbound and westbound I-44 and Watson Road.
What is the solution?
There is no easy solution to all of the problems, since there is so much traffic moving between so many different places. A portion of the solution involves increasing the merge lanes from Watson and eastbound and westbound I-44 onto northbound I-270 and adding one more through lane onto northbound I-270 between I-44 and Manchester Road. MoDOT is also adding an additional through lane on southbound I-270 between Dougherty Ferry and I-44. Because of the restrictions on the roadway, MoDOT will be widening the roadway somewhat, but will have to permanently narrow all lanes on northbound and southbound I-270 to 11 feet (the same width as I-44 during the I-64 reconstruction in 2009 and 2010). As much as possible, MoDOT will maintain full shoulders along the roadway.
MoDOT will narrow and shift the existing four lanes from Manchester to I-44 in the two year project, so motorists will have no shoulders in some locations as crews widen the road. There should be some lane closures at night as part of this work. When construction is completed, travel times through this corridor should decrease during peak hours and reduce traffic delays.
What will this solution require?
This work will require about two years of construction on I-270, to include widening work, roadway construction and work in the rock bluffs. We will narrow and shift the existing four lanes in that area early in the two year project, so drivers will have no shoulders in some locations as we widen the road. There should be minimal lane closures as a part of this work.
Construction overview northside of project (7.8 Mb)
Construction overview southside of project (8 Mb)
What will happen to the rock bluffs just north of I-44?
Some of the rock bluff will need to be removed as part of the widening project. The way that will be completed has not yet been determined.
Will sound walls be included?
MoDOT has conducted a sound study for the corridor and made some preliminary determination of which areas may qualify for a sound wall. Six sections of the roadway have qualified to this point for sound walls; however, construction of soundwalls is not guaranteed until after the construction contract has been awarded. At that time, the department will know if the final criterion of average cost per benefitted resident has been met. The department has held several meetings with the affected residents to discuss the sound study and why they may or may not qualify for a sound wall. For more information on sound walls and sound wall criteria, please surf to this web page.
Potential sound wall locations (8.3 Mb)
What is the timeline for work?
Construction for this entire project on I-270 will occur for approximately two years, which includes widening work, roadway construction, work in the rock bluffs and installing soundwalls. Construction of northbound widening work is scheduled to occur this year starting in mid-April. The southbound work begins in 2013.
For more information, contact:
