Do multiple lanes move more traffic?
Fri, September 9, 2011 
In Los Angeles a new bike lane has been installed along 7th Street. The story in the LA Times states:
"In a city known for traffic gridlock, deliberately eliminating an entire lane for cars could be politically dubious."
My question is this: Do multiple traffic lanes actually move more traffic, or do they simply hold more cars when they become a parking lot during rush hour? Even 6 and 8 lane freeways grind to a standstill at certain times of the day all over the Los Angeles area.
My point is this; there is always a bottle neck somewhere and a journey on an 8 lane freeway has to end on a narrow city street somewhere along the line.
I remember in 1994 I had left the bike business and moved to Corona, near Riverside. I drove 25 miles to work each day on the 91 Freeway to the City of Orange. The 6 lane freeway was a parking lot from the start of the journey to the end. Stop and go all the way moving sometimes at a walking pace.
The 25 mile trip took between an hour and a half, to two hours, each way. I could have ridden a bike to work quicker, except that the freeway was the only direct route, to ride a bike I would have had to take a wide detour on minor roads which would have made my trip 40 or 50 miles.
One evening I drove home in a torrential rain storm. The rain was so heavy I could barely see the next car ahead of me. Everyone drove at a steady speed, and no one changed lanes. That night I got home in less than one hour.
This experience convinced me of something that I had suspected for a long time; that traffic gridlock is mostly caused by people constantly switching lanes and trying to travel at different speeds.
This particular evening we all drove home almost like a procession, traveling at a reasonable speed. The main thing was we kept moving; rather than the usual stop and go.
On a multi-lane street or freeway there is always one lane moving faster than the next. Usually, it seems, it is the one you are not in. This encourages drivers to switch lanes. If everyone stayed in the same lane and drove at a reasonable speed there would be less hold ups.
In the case of this new bike lane on 7th, is it really going to slow traffic? There is now only a single lane for cars so no one can switch lanes, drivers will be obliged to follow the car ahead of them at the same speed as everyone else.
The bike lane will encourage more people to ride bikes, which will cut down on the number of cars on the street. I maintain in time, bold moves like this will improve traffic flow rather than impede it. What do you think?
Reader Comments (10)
Ski season.This not quite on the topic, But does reference the 'This particular evening' and what the Colorado Highway Patrol is proposing for the ski season. Because 1`70 west is the main highway to the ski resorts, Drivers are in a hurry to spend big bucks skiing, they change lanes zip in and out to get AHEAD causing accidents ALL to be first on the slopes. CHP is going to pace lead, groups of cars up 1-70. Now this is going to slow down the time it takes to get there, BUT get there you will and Safely? Maybe California HP or LAPD could do the same on the freeways around LA.? How many times have you had some ahole roar past you only to arrive right behind him in the end.
You have an excellent point here. I live and commute in a maze of congested speeds, and agree with you. Unfortunately, I think people will only realize it around here when the traffic gets much worse than it is now.
Cheers
Helton, from Porto Alegre, Brazil
They did something similar in Seattle last year, and throughput hasn't decreased, speed has slowed etc. etc.
http://publicola.com/2011/02/02/preliminary-data-show-nickerson-road-diet-is-working/
Seems like a positive move IMHO.
Thanks Ed, remove a lane and still move the same amount of traffic per day; that pretty much answers my question.
Dave
Perhaps someone ought to point out to the LA Times that traffic throughput is measured in people, not objects. Or, to put it another way, we are traffic.
One other thing that has been changed in the Denver area, RIGHT TURN ONLY lanes have been made turn and through lanes, This has ment that the right lane is open all the time, making a better flow for traffic. This in my mind has caused a problem with cars entering the flow of traffic from side streets. You have to be patient, a virtue some never possess.
The Braess Paradox puts some mathematical rigor behind the question:
http://en.wikipedia.org/wiki/Braess's_paradox
The same thing was done with a major artery road around here - the thing is, traffic moves more slowly now, but it keeps moving. It is also much much safer for people using forms of transportation other than cars (and for people in cars as well) because it is now impossible to weave in and out of traffic.
You have an excellent point here. I live and commute in a maze of congested speeds, and agree with you. Unfortunately, I think people will only realize it around here when the traffic gets much worse than it is now.
Cheers
Helton, from Porto Alegre, Brazil
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James
STR works best for everyone when it is promoted by design instead of just hope. Simply adding more lanes for cars just increases the size of the parking lot and increases the risks to all road users.