What’s that? It wasn’t really that bad? Oh, I guess you’re right, but you wouldn’t have known that from reading this blog – dead since the original shutdown began in January of 2008. The original predictions of mayhem (including some of my own) thankfully didn’t come true. Yet, as the highway plans to re-open, I thought it would be a good time to embarrass myself some more by issuing some final predictions.

Highway 40 traffic will flow more smoothly

There are a lot of good improvements accompanying the Highway 40 reconstruction, most notably on the mainline highway itself. The ramp from eastbound 40 to northbound I-170 has been a welcome relief for West Country drivers headed to Clayton or Washington University. Fewer — yet longer — on-ramps will eliminate congestion. Back in 2007, I predicted better traffic for Highway 40, and today’s Post-Dispatch article confirms it. I look forward to seeing it.

So, the mainline highway design is the winner, but what about the crossing arterials?

Brentwood and Hanley intersections will suffer

A big reason for the anticipated improved traffic flow at Highway 40 and I-170 is the merging of the Brentwood and Hanley exits into one. From either direction, there’s just one off-ramp and one on-ramp for both Brentwood and Hanley combined.

This is great for flow on Highway 40, but it also increases the amount of traffic going through the lights at Brentwood and Hanley. Exiting eastbound 40 for Hanley? You’ll have to stop first at Brentwood. On Hanley wanting to get to westbound 40? Again, plan on a stop at Brentwood. Same story if you flip eastbound/westbound and Hanley/Brentwood.

See the plans in all their details on MoDOT’s site.

Fortunately, Brentwood will have less traffic due to the ramp from eastbound 40 to northbound I-170. Yet, all told, I think you’ll see more traffic and probably more congestion at the Brentwood and Hanley intersections. Keep an eye here over the next few weeks — first to witness all the confusion and complaints over the merged exits, and then to see if traffic flows well at these intersections.

Lindbergh intersection at risk for gridlock

You might think that the Lindbergh intersection is old news. After all, it’s been open nearly a year without any significant issues. However, traffic exiting Highway 40 to Lindbergh has been lower than it will be after the re-opening, and I’m a little worried.

As you know, the new interchange at Lindbergh introduced a new stoplight for the Single Point Urban Interchange (SPUI). This light is awfully close to the Lindbergh-Clayton intersection (see image), and — prior to construction — southbound Lindbergh traffic would routinely back up under the Highway 40 overpass. If that were to happen with the new interchange, it could block traffic from getting through the interchange at all, causing gridlock. Additionally, those drivers going from eastbound Highway 40 to southbound Lindbergh have no merge lane, just a yield sign. Backed up traffic on Lindbergh will block these drivers from getting off the highway.

Careful timing of these lights will go a long way toward avoiding gridlock, but I wonder if these close intersections can handle it.

So Long

Well, that’s all my predictions for now, and likely my last post for this blog. I’ll leave the site up for another couple months, but I suspect by February, the Highway 40/I-64 closure will be a distant memory.

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

What’s the implication of this? Well, Eager Road (highlighted in red), already a nightmare during rush hour with the current construction, will only get worse. Drivers going between Brentwood and Hanley/Highway 40 will add to the already heavy traffic going to the multiple big box stores along Eager. Don’t count on returning those Christmas gifts to Best Buy or Target after January 2nd.

What about the Galleria? St. Louisans need their shopping fix, so the map above highlights a couple of alternate routes. The one in blue exits at Hanley Road, then Clayton Road to the Galleria. Although the shortest, I anticipate the Hanley exit will be extremely congested. In that case, take the scenic route, going north on I-170 (there will be two lanes to northbound I-170 from Highway 40). Then take your first exit, Forest Park Parkway. Exit at Brentwood Blvd going south to the Galleria. Then enjoy having most of the mall to yourself, since everyone else will be scared away from this area.

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

The official detour routes are shown above, westbound in blue and eastbound in green. Also highlighted are every road and overpass closure.

Motorists taking the westbound official detour will be routed north on Skinker then west on Forest Park Parkway, and finally south on I-170 to Highway 40. If the lights are timed appropriately and intersections controlled, this route has the potential to flow fairly well. The major areas for potential trouble are:

• Cars trying to access Demun
• Forest Park Parkway at Skinker and Big Bend
• Merging traffic to one lane for the I-170 South ramp — If traffic is seriously backed up here, exit the Parkway at Shaw Park Drive and take Brentwood south to Highway 40
• Double yellow line on I-170 — use caution!

The official eastbound route has motorists exiting Highway 40 at Hanley, continuing north to Clayton road, then east on Clayton to Highway 40. Officials have worked hard to minimize side street disruption particularly on Clayton between Hanley and Big Bend, yet there remain some serious potential trouble spots:

• Hanley exit — this is a congested intersection already. Even with better timed lights or police control I cannot imagine that this intersection will be able to handle the detoured traffic volume. Look for major backups onto 40 and potential gridlock on Hanley road by Dale.
• Clayton between Big Bend in Skinker — Although some side streets are closed here, this stretch of road is home to a large shopping center and hospital complex, causing potential jams.

Now that we’ve looked at the official detours, let’s discuss alternate routes. Unlike previous posts, I’m not mapping specific alternate routes, but will suggest some strategies for getting around backups:

• Avoid Highway 40 — If you live near or west of I-270 and are headed to Forest Park or further east, don’t go near Highway 40. Take I-44 of I-70 to get to your destination. Same suggestion applies in reverse.
• Exit early — The major pinch points will be the exits for the official detours. Be proactive and exit the highway earlier. If eastbound, you’ll be able to see any major backups before Brentwood Blvd, where you can exit and find alternates such as Manchester. For westbound traffic, consider bailing out at Kingshighway or south on Hampton. (Please don’t go north on Hampton and turn Forest Park into a giant parking lot).
• Use the opposite detour — If westbound, you might consider taking Clayton road to Brentwood to Highway 40 if Skinker is too congested. If eastbound, exit at Brentwood, find your way to I-170 north and take Forest Park Parkway to your destination.

Feel free to share you suggestions for alternate routes in the comments area. Also, if you drive near Highway 40 this weekend, please share your experiences. This weekend will be the best training we have for the 2008 shutdown, so now’s the time to learn our lessons.

Update:

As you can imagine, there are several news stories covering the pending shutdown. Most interesting is KMOV’s coverage, which includes video of them driving the detour routes (a mind-numbing 20 minutes long) as well as helicopter coverage of the detour routes. Ah, to have the resources of a local news station at your disposal…

KMOV
Fox 2
STLToday

Gateway Constructors, the contractor for the Highway 40 rebuilding project, has recommended a detour route exiting Highway 40 to north on Big Bend to west on Forest Park Parkway to I-170. That route is shown in blue in the map below:

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

I’ve highlighted two other alternate routes that you might consider:

• Red route — If the official detour exit at Big Bend looks too crowded, exit Highway 40 at Hanley Road. Go north on Hanley Road, then turn left onto Forest Park Parkway, then join I-170
• Green route — Exit Highway 40 at Brentwood. Go north on Brentwood, turn right on Galleria Parkway, then left onto Northbound I-170.

It’s good to see the official detour route recommend Forest Park Parkway, since the Parkway is the closest divided roadway in the area. However, I think the green route is the most obvious and potentially the quickest. The green route passes through 5 stoplights, one fewer than the official route, and spends less time off the highway. In the end, the best of these routes will probably be the one less traveled.

Upcoming, I’ll take a look at alternate routes for the complete Highway 40 shutdown planned in a couple weeks. What routes will you use this weekend? Leave a comment and share with others.

Update 8/3:

The Post-Dispatch ran a story on just this topic today, mentioning all three of the above options.

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.