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Three lanes bad, two lanes better?
NCDOT says its traffic engineers will launch an experiment, starting Sunday, to see if they can make westbound I-40 run more smoothly at rush hour by slimming it from three lanes to two lanes near the U.S. 70 Clayton Bypass. What do you think? [9/14 update: see today's story.]
Westbound I-40 swells from two to three lanes as it approaches the U.S. 70 interchange (Exit 309) in southeastern Wake County. During the morning rush, lots of drivers move into that new outside lane and speed ahead. But this third lane disappears after about two miles, causing a regular rush-hour bottleneck when drivers struggle to merge back into the original two lanes.
So the question to be tested is: Would the morning traffic flow more smoothly without that temporary third lane?
To find out, DOT crews will use paint stripes and orange barrels to shift both lanes of westbound I-40 traffic one lane to the right. This means moving I-40 drivers into that new outside lane for two miles -- and forcing them out of the inside lane for the same stretch -- so I-40 stays just two lanes wide the whole way.
I-40 commuters, what do you think about this idea? I'd like to hear from you by phone (919-829-4527) or email. Don't forget to include your name and daytime phone number.
About 4,100 cars and trucks pass through that stretch of I-40 during the weekday morning rush, with another 1,000 vehicles using the Clayton Bypass ramp at the same time.
DOT engineers will monitor traffic patterns for a few weeks to see whether the change improves the heavy rush-hour flow. Then they'll decide whether to make the change permanent.
I-40 continues at two lanes wide for another three miles to the U.S. 70 Business interchange (Exit 306), and there it widens permanently to three lanes. DOT planners are working on a project to widen I-40 starting before the Clayton Bypass (Exit 306), but that construction is years in the future.
Bruce Siceloff reports on traffic and transportation. A News & Observer reporter, editor and blogger since 1976, he took over the
Comments
Congestion at Exit 309?
Mon, 10/03/2011 - 14:30 — LoneEagleMaybe finishing I540 outer beltline between 40 and 64 bypass may take some of that traffic out of the mix? Let's start something we can't afford to finish. Hmmm, sounds about par for the course for them.
I guess DOT's logic is "if we move the bottleneck, this bottleneck will no longer exist". Hmmm, sounds about par for the course for them.
So who's in Charge of DOT? Is it the Governor of NC? I'd love to hear her comment about this... anybody care to guess?
Same travel time either way
Tue, 09/13/2011 - 19:24 — jsymonA saturated highway delivers approximately 1 car per second per lane (depends on the average tailgating factor). To handle more traffic the speed slows down and it acts like a sponge but it still delivers 1 car/sec/lane.
If you temporarily expand a saturated two lane highway to three lanes then re-constrict it, the throughput will remain the same and in fact the travel time remains the same. It will feel worse because although you will speed up temporarily entering the three lane section, towards the end of the three lane section you will slow down to less than the speed you were traveling on the two lane section.
You notice the slow down (grrr) more than the speedup (what I deserve). The travel time and throughput are the same either way but eliminating the three lane section will probably reduce the cumulative road rage. The widening serves no traffic handling function (unless there is separate, extra traffic entering and exiting along that section).
where does the stupid end?
Tue, 09/13/2011 - 17:59 — outhousecatLet's cut it down to a gravel path. Maybe that would help. Couldn't hurt, anyway.
I certainly hope whoever designed that nasty little corridor has been fired. It's one wreck after another, and nothing but traffic jams in the morning and at night. Our DOT - no matter how many "studies" they pay for, they still suck.
stupid in three ways
Tue, 09/13/2011 - 17:44 — cb2003Hello, NCDOT?
1. With the construction of the Clayton Bypass moving the exit (and traffic) for US 70 down the road for a few miles, I-40 should have been widened to three lanes the whole way.
2. Since this didn't happen, three lanes should never have been opened for that 2 mile stretch - it doesn't make any sense at all.
3. The "experiment" also doesn't make any sense. Why close the left lane? The left 2 lanes are the through lanes and the right lane is the lane that doesn't go through and should be closed. This "experiment" will only show that the traffic is slowed even more at that the geniuses at NCDOT were right all along.
p.s. If Bruce (ha) or anyone at NCDOT (double ha ha) are reading this, I have another idotic lane striping for you. The exit off I-85 to US 15-501 in Durham is two lanes, but then another left lane is added on the flyover ramp while the right lane must exit to Hillsborough Rd. Drivers cut across a painted island to get to the additional lane through to 15-501. If both exit lanes went through to 15-501 and the right exit for Hillsborough Rd. was the lane added on the flyover ramp, the entire configuration would be much safer and much more logical.
I-85 ..
Wed, 09/14/2011 - 06:55 — BruceSiceloff (author)Thanks cb2003 I think the I-85 remodel in Durham is mostly terrific but I have trouble with the 15-501 exit too
Agreed about most of I-85 in
Wed, 09/14/2011 - 13:21 — cb2003Agreed about most of I-85 in Durham. Who would I talk to about this concern?
Great. I wrote DOT after
Tue, 09/13/2011 - 17:33 — geoherbGreat. I wrote DOT after coming back from the beach on Labor Day about this problem. I received a response promising to try a lane shift this fall in the westbound I-40 lanes to keep this portion from becoming a clogged bottleneck of traffic.
RE: THE MERGE OF THE LANES ON I-40/ CLAYTON BYPASS
Tue, 09/13/2011 - 14:03 — beachbum3Why was this not done prior to their ever having had the money spent at great expense to this state taxpayers? an definetly pprior to the actual nuilding of this additional lane if it is not an does not effect the traffice flow in this particular area of this streach of i-40 just another typical ncdot boondoogle if you ask me . the states trasportation system was way better off an had better roadways at considerably less cost to the taxpayers prior to othese so called p.e. engineers were ever made a part of the ncdot. can anyone out there say I-795 or I-40 or I-540 or US-17 or US 258 BOONDOGGLES when is enough enough thank you
Need more lanes
Tue, 09/13/2011 - 13:11 — arthurb3The third lane should be extended all the way to 440!