Standard Responses #3: Response to "Cyclists cause congestion"

Periodically, someone will try to make the claim that cyclists, due to their slower speeds, cause traffic congestion.

Bikes ... slow traffic, which creates more pollution.

Or that the introduction of bike lanes causes significant congestion.

removing auto lanes or narrowing them to accommodate dedicated cycling infrastructure tends to have a traffic calming effect, which often significantly increases traffic congestion.

There is, of course, a large amount of evidence to the contrary.

In one study, "Research On Bicycle Conversion Factors,” bikes were calculated to cause as much congestion as 0.28 passenger cars (less on trails, more when turning left).

In an AASHTO study, it was calculated that the passenger car equivalent for a bicycle depended on the width of the lane, but can be as low as 0.

“Opposed” means that a bicycle encounters interference from other road users, such as when making a left turn.

A third study, by Heru Sutomo, places the PCE for bikes in developing urban areas at 0.19.

The Victoria Transport Policy Institute translated this into a per vehicle mile cost. They calculated the cost of bicycle-induced congestion as 0.2 cents per vehicle mile. Passenger cars are more than ten times as high at 3.5 cents per mile. Even taking into account the 1.6 passengers per car and assuming one passenger per bike (probably a little low)  they per passenger cost becomes 0.2 cents per passenger mile for bikes and 2.2 cents per mile for cars - 11 times larger.

As for bike lanes, even when they result in closing whole roads, they might - by themselves - reduce congestion. And at an 11 time improvement, you don't have to induce many people to bike to cut down on congestion. Bikes don't cause congestion, they reduce it.

Cars are another issue.

Comments

[Crickey7]

Wonder if this factors in the impact of cars looking for parking spaces at trip's end.

[Brendan]

Something that causes congestion would imply something that has uncongested traffic in front of it and congested traffic behind it.

I never experience that biking to work. I bike through congestion that exists in front of me already without any influence from me.

[freewheel]

In rush hour, I thread through the congestion as Brendan describes. Still, there are times when I know I'm slower than traffic, at least until we all meet again at the next red light. In these situations, I take the lane, the right lane, because I know motorists who think I'm holding them up will do something stupid and pass too closely. By taking the lane, I give drivers 2 choices in dealing with me: 1) pass me in the passing lane, 2) slow down and follow me. I know that's a pain, but it's the safe way of doing things.

[JeffB]

Cars parking, cars double parking, cars turning, cars illegally turning, cars blocking the box, cars ... cars ... cars are what cause congestion.

To paraphrase Pogo every motorist can say "We have met the congestion and it is us".

[Crickey7]

I'm going to do my part. No more left turns on my bike.

[guez]

I don't think that bikes are a major source of congestion, but I'm suspicious of these numbers. Congestion is a non-linear function: the first car on the road causes non congestion, the millionth a lot more. This makes it very hard to compare the effect of one bike to one car. Is it the 1st, 10th, 1000th, 10000th, 100000th, or 10000000 bike? What about the car? Even if we compare the 10000th car to the 10000th bike, we can't assume that the congestion effects of the two vehicles scale in the same way.

[Contrarian]

There are an awful lot of people who think that traffic is caused by slow driving -- that if everyone would just drive fast there would be no traffic. If that's what you think, then cyclists are the ultimate villian -- the driver who deliberately chooses the slowest possible vehicle. Makes perfect sense.

[Eric]

The introduction of bicycle lanes on roads where there was no bicycle lane before increases congestion.

Here in Adelaide Australia many roads in the city are having bicycle lanes installed by narrowing the carriage way available to cars. Narrower carriageways cause congestion. This has not been compensated for by the uptake in the use of bicycles. With many of these lanes seeing less than 2 bicycles per hour.

[washcycle]

Eric, despite your statement, I am unconvinced.

[oboe]

There are an awful lot of people who think that traffic is caused by slow driving -- that if everyone would just drive fast there would be no traffic.

Well, this is true isn't it? I mean, isn't that why, in case of a fire, we're instructed to run pell-mell as fast as we possibly can for the exits?