Honking to Reduce Traffic Jams

In order to find ways to help St. Louis drivers negotiate the Highway 40 construction project, I have been scouring academic research reports regarding traffic flow issues. The study I found today, reported by The Onion, seems to be the optimal solution. I’ll be submitting this idea to MoDOT for their inclusion in traffic planning for the upcoming Highway 40 shutdown.

Tired Of Traffic? A New DOT Report Urges Drivers: ‘Honk’


Prediction: WB Highway 40 will not jam at I-170

As mentioned in the introductory post for this blog, I will have regular posts that predict how traffic will flow after the Highway 40 construction is complete. Not that I have any credentials to do such predictions, but, honestly, it’s fun, and if I’m wrong, well people will have forgotten about it by December 31, 2009 anyway.

I thought I’d start with an easy prediction: Westbound 40 will flow more smoothly at I-170 and not jam as regularly as it did pre-construction. Let’s at least hope so! If we’re spending $535 million to improve the highway, one might expect to it flow a little more smoothly.

In order to back up this prediction with some analysis, let’s look at what was causing the regular westbound 40 jams pre-construction. The key is to look at where the jam clears up, not where traffic begins to slow down. For westbound 40 during the evening rush, the slowdown might start as far back as the Science Center, but it would always open briefly right between Hanley and I-170 before another (sometimes brief) slowdown just west of Brentwood. So, we need to focus on the Hanely/I-170/Brentwood area.

The map above shows the key chokepoints on Highway 40 pre-construction. Traffic from Hanley road onto westbound 40 was forced to merge quickly and criss-cross with traffic that was destined for northbound I-170. All of this lane changing in a short time slows down traffic, and the backup just propagated further back as the evening rush volume increased. Once all the cars had completed their lane changes, traffic would open back up again just past these two chokepoints, until traffic from southbound I-170 and Brentwood tried to squeeze into the three lanes of already-near-capacity traffic on westbound 40. This caused the final chokepoint in the daily commuter’s trek along westbound 40.

The design for the new Highway 40 eliminates these chokepoints, which will lead to a much smoother flow of traffic through the I-170 interchange. The video below, courtesy of Gateway Constructors, shows how westbound 40 will look after the construction.

Video from http://thenewi64.org courtesy Gateway Constructors (Problems viewing? View directly and fast-forward to the one minute mark.)

To view the designs up close, take a look at the Brentwood/Hanley/I-170 plans from thenewi64.org. If you zoom in, you will notice two key points:

  • No direct merges from Hanley to westbound 40 — this eliminates the first two chokepoints, since Hanley traffic won’t merge until after traffic bound for I-170 has already exited. (A future prediction will look at what this means for Hanley and Brentwood)
  • Additional lanes to support merging westbound traffic — Plans had always talked about an extra lane west of I-170, but in fact there will be two extra lanes between Brentwood and McKnight, giving plenty of space to absorb traffic joining westbound 40 from I-170, Brentwood, and Hanley.

Interestingly, construction crews have already eliminated the Hanley access points to westbound 40. If it weren’t for the large lane shift at I-170, I suspect you’d already see fewer backups on westbound 40, due to the elimination of those short merges and criss-crosses.

Overall, this is a very positive new design that should make for more pleasant evening commutes at this complicated interchange.


Update: Lane Shift Standards

Lane Shift guidelines In a previous post, I documented drivers’ behavior at the lane shift at Highway 40 and Tamm Avenue, which many of you agreed was dangerous. In looking for ways to make this area safer, I noted that the lane shift at I-270 and Dougherty Ferry used solid white lines for lane markers instead of dashed lines like at Tamm. It was much easier to stay in the lane with these bright solid lines. These two construction projects are handled by different contractors, so I asked MoDOT what standards they specify. I received a quick and professional response from MoDOT:

At the core of the issue, Federal Highway’s Manual on Uniform Traffic Control Devices dictates the guidelines we use for lane shifts. If you have a dramatic lane shift, or one that requires a quick traffic movement, the manual dictates using solid lanes. If the lane shift is a little more gradual, it is acceptable to use the dashed lines. Often times, the determination on the traffic impact of a lane shift is made by the person designing that particular traffic movement. So, though MoDOT doesn’t provide guidelines per se (since we use Federal mandated guidelines), we will adhere to, and ensure contractors adhere to, those guidelines. As with every guideline, though, there is some area for interpretation.

If you’d like to read the guidelines on lane shifts for yourself, here are links to the notes and the details . The guidelines seem to lean toward using solid lines as lane markers, but does leave it open to some interpretation.

At MoDOT’s recommendation, I will submit a comment form to the Highway 40 project team, asking them to look at the video I shot to see if solid white lines might be an improvement in this area. I’ll keep you up-to-date on their response.

Update 6/22:

I received the following response from the I-64 Community Relations team. They are not considering use of solid lane lines at Tamm, for reasons they describe below. So the best advice for now is to stay vigilant when driving through these lane shifts.

EB I-64 at Tamm, the traffic shift is fairly minor, and the use of solid lines is not recommended. WB I-64 at Tamm the lane shift is more noticeable on the inside lanes and very minor on the outside lane. This is caused by the lanes narrowing from 12′ to 11′ in the work zone, with the outside lane experiencing the smallest shift.

At this time, the use of solid lane lines between each lane is not being considered. One of the main reasons for this is that the transition points for the stripes use curves opposed to hard angle points and taper-style lane shifts. The taper lane shift is shown on the MUTCD excerpt on your blog; meaning, there are hard angle points where the stripes force traffic to turn abruptly to remain in their proper lane. The Tamm workzone lane lines use curves allowing for smooth transitions around the work zone. Plus, the striped curves are designed to handle 55 mph interstate traffic, so no speed reduction signs are necessary. By designing the traffic shift to current speed limit, the need for solid lane lines between lanes is also reduced.


Alternate Routes: Open Highway 40 to Bicycles in 2008 (Updated)

The impending closure of Highway 40 from Brentwood Blvd to Ballas in 2008 has led planners to look for any way to squeeze more cars onto the nearby side streets. From the $1 million in West County road improvements to opening more of Forest Park to car traffic, the conventional wisdom has been to find more room for cars at all costs. This fear of coming gridlock even led to rumors that bicyclists would be banned from Clayton Road during construction. I say rather than discouraging bicycles, we should promote bicycle commuting as an alternate route during construction. And what better way to encourage it than to open Highway 40 to bicycles during construction.


[Zoom and pan the map as needed; Click on markers for more information]

If you look closely at the planned construction in 2008, you’ll see there are actually long stretches of road with no major interchanges. The plan shown in the map above uses these open areas to provide the perfect alternate route for bike commuters. There are two key points to this plan:

  • Two route options – The route I’ve laid out includes two different routes: a northern route and a southern route, each leveraging frontage roads where available. Each route would be a paved two-way bicycle path, giving MoDOT the flexibility to close either route as necessary for construction.
  • Route around overpasses — The main reason for closing the highway altogether is to allow construction crews to completely tear down the overpasses and rebuild them without having to route traffic over a portion of the bridge (like is currently being done at Olive and I-170). The proposed bike routes would exit the highway at both Lindbergh and Clayton/Warson and use surface streets until it can rejoin the highway.

Certainly, there will be detractors of this plan who say it will be too costly and interfere with construction plans. Regarding costs, the price tag for this bike path would likely be a rounding error for the overall budget, and MoDOT could use some of the money they are spending on alternate car routes. As for interfering with construction plans, I’m optimistic that given a little creativity, construction crews can find a way to keep a 10-foot wide strip of asphalt open during construction.

Now just imagine zipping along Highway 40 on your bike to work, while your auto-bound friends sit in the jam along Clayton Road. . .

Update 6/22:

The I-64 Community Relations team responded to my suggestion here to add a bike path along the construction route. It looks like the entire road will be torn up, and they don’t see any way to support a bike path. It’s disappointing, but I understand that many design decisions have already been made. I will continue to seek ways that bike commuters can be supported through the construction project.

Regarding your suggestion that we allow bikes to use the closed portion of I-64 during the reconstruction:
All of the highway is being reconstructed, including all the pavement between the intersections, and reaching down to the subgrade with drainage structures. All of the pavement will be broken up and processed and/or hauled away. The work will include frequent traffic with large construction equipment, concrete trucks and large hauling trucks filled with a variety of materials. Unfortunately, there would be no safe path available for cyclists.


Lane Shifts and the Loss of Common Sense

You can’t drive far on St. Louis highways today without encountering a lane shift due to construction. On Highway 40 alone, there are 3 lane shifts from Kingshighway to I-170. As I drive through these lane shifts, I can’t help but notice just how challenging it is for many motorists to stay in their lane. I suspected that if you were to watch traffic at one of these lane shifts, you would see many dangerous situations in a short time. Little did I know how true that would be. See the video below. . .

It seems that drivers are just not paying attention. They’re zipping down the road, following the car ahead of them, unaware of the signs for the upcoming lane shift. The next thing they know, they’re across the dotted line. We tend to assume that the lanes follow the seams in the concrete and asphalt — which typically do line up with the painted lines — but can we not pay a little closer attention?

What are your thoughts? Can anything be done to make these seemingly simple lane shifts safer? Share your ideas by leaving a comment.


Welcome to Highway 40 Insight!

Welcome to Highway 40 Insight, a web site devoted to St. Louisians’ favorite road construction project!

Kingshighway Intersection

This site provides you with an independent viewpoint on the Highway 40 project and an opportunity for you to discuss the road work — or vent if you so choose. I hope to provide you interesting articles outside of the standard traffic reports and lane closure updates, touching on topics we all think about while driving on Highway 40. I mean, don’t you ever wonder why can’t people stay in their lane when the lane shifts?

I also plan on analyzing both the current construction and designs for the new highway. Special features on this site include:

  • Predictions — Using my total lack of traffic engineering knowledge, I will stake my highly honed reputation on bold predictions of just how well traffic will flow post-construction. Will backups on Highway 40 really disappear when the project is complete? What about all those new bridges and on-ramps — how well will they work?
  • Intersection Analysis — Relying on the mantra of air traffic controllers — “safe, orderly, efficient” — I will provide a scorecard of each new intersection along the construction route, rating it on those three criteria. Is it really safe? Will traffic flow orderly or will it be chaos? And, most important to many drivers, will it be more efficient than the old design?
  • Alternate Routes – This feature will give you an opportunity to weigh in on your favorite way to bypass the construction. In addition to looking at just how to get from Clayton to Town-and-Country, “Alternate Routes” will examine topics just a little off the beaten path.

Just to be clear, Highway 40 Insight is not: another traffic reporting site, a listing of lane closures, or MoDOT-sponsored. There’s plenty of sites to get official traffic and construction information, but only one site with a unique perspective that allows you to contribute to the conversation.

So, again, welcome, and I’ll see you on the road.


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