Flashing Yellow Arrows Work Better

Even as early as kindergarten, I remember reciting the basic traffic rules mantra – “Red means ‘stop,’ green means ‘go.’ Now, although many people, myself included, often believe that yellow means step on the gas, I do still remember the often unmentioned addendum to the mantra – “Yellow means ‘proceed with caution.’

However, paying attention to that mantra was why traffic engineers are starting to embrace the use of the flashing yellow turn signal arrows to let drivers know they can make a yielding left turn. Until recently, most intersections that allowed drivers to turn left in the spaces between on-coming traffic used a round green ball signal with a sign that told drivers to turn left on the green ball. That rule made sense, but it didn’t keep the signals consistent. When the signal was green, you couldn’t “go,” you were supposed to “proceed with caution.”

So as St. Louis started to test these signals (three of them on Olive Boulevard in 2006) and now is installing them in locations around the area (currently, there are a number on Route K in St. Charles county, five more on Olive Boulevard, and a number on Lindbergh Boulevard), the concept made sense to me.

I have seen some comments from local drivers during the introduction of the flashing yellow arrows. They seemed to fall into two categories. 1) people seem to be confused by these signals, and 2) the change is simply because someone wanted to justify their continued existence and adjusted these signals just for the sake of change.

The first part may be somewhat true – as you introduce a new element to the driver, some of them can potentially misinterpret what the flashing yellow arrow means. The second is flat-out wrong. The Federal Highway Administration sponsored a study that showed that the signals were safer, and that more people understood what the flashing yellow arrow meant.
Basically it breaks down this way – the green ball signal with the yield sign is equal to the flashing yellow arrow. The flashing arrow is more intuitive, is safer, and is more consistent with what we teach our youth about traffic signals.

You can find out more information on the flashing yellow arrows at our website. You can also access the Federal Study from that site. We also have a video showing how to drive through a flashing yellow arrow on YouTube.

Andrew Gates
MoDOT Community Relations

Missouri's largest ARRA project starts

Yesterday, MoDOT and local politicians got together to launch the last section of a project that has been in the works for about 40 years -- the final section of Route 141.

Route 141, between Ladue and Olive Boulevard is still a three lane road (one lane in each direction with a turn lane). Often, during the spring or heavy rainfall, the section of Route 141 there has to be closed due to flooding. Also, anyone who has driven through the area during morning or evening rush hours can expect to be backed up for some time at Parkway Central or as Route 141 goes from a four lane divided highway to a three lane road.

This $44.5 million project is paid for by American Recovery and Reinvestment Act money will pull Route 141 above the flood plain and improve the traffic flow on the route. Not only that, but by relocating the new route to the east, a great deal of through traffic from Route 141 (people accessing the Maryland Heights Expressway and Route 364 to St. Charles County) will be removed from a roadway that services two schools, a school bus depot and a number of businesses and subdivisions.

This project will make the roadway safer and move traffic more efficently. Work on the project starts this month and work should be completed by summer 2010.

2008-2013 Transportation Improvement Plan adds three regional projects

The Missouri Highway and Transportation Commission approved the latest Statewide Transportation Improvement Plan on July 1, which included more than $300 million in new construction projects.

Money for these projects came from lengthened bond terms and lower interest rates on Amendment 3 money, as well as savings from practical design efforts and matching funds from local municipalities. This money will be spent across Missouri, constructing new roads, improving interchanges and purchasing needed right of way for future projects.

In St. Louis, three projects were added to the plan:

• Purchasing right of way for Route 141 between I-64 and Olive Blvd. in St. Louis County


• Completing another section of Route 364, Phase II in St. Charles County


• Interchange improvements at I-55 and Route M in Jefferson County

The five-year STIP includes nearly $5.8 billion in transportation improvements across Missouri, including about $4.3 billion for 730 highway and bridge projects, $810 million for other transportation modes, and $640 for local transportation programs.

Review the entire STIP here.