Variable Advisory Speeds at I-270/255 Begin Today

Interstate 270/255 is one of the most congested roads in St. Louis. In an effort to improve traffic flow and warn motorists of slowed traffic, variable advisory speeds will begin posting today. The digital speed signs will show an advisory speed varying between 55 mph-10 mph.

In addition, the standard black on white signs with the posted enforceable speed limit on I-270 will be 60 mph, except in work zones.

“Starting today, the digital speed signs will display flashing advisory speeds whenever traffic ahead is slowed to between 55 mph and 10 mph,” said MoDOT Assistant District Engineer Tom Blair in a statement. “The purpose is to advise drivers of congestion ahead. You need to slow down, pay attention and prepare to reduce speed.”

When average speeds on I-270 are at the posted speed limit of 60 mph, the digital boards will be blank. As conditions change, the I-270 variable advisory speeds will adjust showing the advised speed in increments of 5 mph starting at 55 down to 10 mph depending on the congestion on the road.

Advisory speed limits are not enforceable. MoDOT’s message signs also will include information regarding the congestion or lane closures ahead and increased travel times.

Variable advisory speeds are designed to pace the traffic leading up to recurring rush hour congestion or from congestion caused by closed lanes due to a crash or work zone. If drivers ignore the speeds and hurry to the point of the congestion, it actually creates more congestion and is slower to get through. If drivers obey the advisory speeds, the overall pace of traffic will get through the congested area more quickly.

A video explaining the changes and the theory behind variable advisory speeds is available on MoDOT’s You Tube account by clicking here. 

I-44 Exit Ramp to I-270 Closes For Weekend

Also in South St. Louis County starting at 8 p.m., the eastbound I-44 exit ramp to southbound I-270 will close until 10 a.m. Monday morning, weather permitting. The ramp closure is part of the start of bridge repairs on southbound I-270 between I-44 and Gravois Road. Only two lanes on southbound I-270 will be open this weekend, as crews begin restriping and shifting the southbound I-270 lanes to the left. Motorists can use Route 141 this weekend as an alternate route. All lanes will reopen Monday morning, but with reduced speed limits and narrowed lanes.

Oakville motorists may be affected by these ongoing closures:

•      I-55, St. Louis City, Delor Street across I-55 is closed for bridge replacement.
•      I-55, St. Louis City, Holly Hills across I-55 is closed for bridge replacement.

Please see the list of daily interstate lane closures, weather permitting:

Thursday, July 7, 2011

•      I-55, St. Louis City, 10 a.m. to 3 p.m., two lanes closed northbound and southbound at Holly Hills.
•      I-55, St. Louis City, one various lane closed northbound and southbound @ River Des Peres.
•      I-55, St. Louis City, 9 a.m. to 3 p.m., one various lane closed northbound and southbound at railroad bridge, north of River Des Peres.
•      I-55, St. Louis City, 10 a.m. to 2 p.m., one various lane closed northbound at 7th Street.
•      I-44, St. Louis County, 9 a.m. to 3 p.m., one lane closed westbound at Meramec River.
•      I-44, St. Louis County, 9 a.m. to 2 p.m., one right lane closed eastbound and westbound at Burlington Northern railroad.

Friday, July 8

•      I-55, St. Louis City, 10 a.m. to 3 p.m., two lanes closed northbound and southbound at Holly Hills.
•      I-55, St. Louis City, 10 a.m. to 2 p.m., one various lane closed northbound at 7th Street.
•      Poplar Street Bridge, St. Louis City, 11 p.m. to 12 a.m., ramps closed from eastbound I-70 and southbound Memorial Drive.

Saturday, July 9

•      Poplar Street Bridge, St. Louis City, 12 a.m. to 12 p.m., ramps closed from eastbound I-70 and southbound Memorial Drive.
•       I-270, St. Louis County, 8 p.m. Friday to  Monday, at 10 a.m., two to three lanes closed southbound from north of I-44 to south of Rott Road.

Sunday, July 10

•      I-270, St. Louis County, 8 p.m. Friday to Monday, at 10 a.m., three lanes closed southbound from north of I-44 to south of Rott Road. 

Monday, July 11

•      I-55, St. Louis County, 9 a.m. to 2 p.m., two northbound lanes closed at Bayless.

Tuesday, July 12

•      I-55, St. Louis City, 9 a.m., to 2 p.m., one lane closed northbound at 7th and Park. Gravois/12th  Street ramp is also closed.

Wednesday, July 13

•      I-55, St. Louis City, 9 a.m. to 2 p.m., two lanes closed northbound at Virginia.