Why Bike Lanes With Lots of Bike Traffic Can Still Appear “Empty”

Wherever there is a bike lane, there is probably an angry driver complaining that it is always empty.

San Francisco’s Market Street bike counter. Photo: Streetsblog

That tends to be the case even when plenty of people do use the bike lane. And there are reasons for that, writes University of Minnesota professor David Levinson. Mathematical, geometrical reasons. Like the fact that free-flowing bike traffic will look much sparser than gridlocked car traffic, even when the number of cyclists using the bike lane is the same as the number of motorists in an adjacent car lane.

“The view from the dashboard, from the front window of the car, is going to be looking at the view of cars and the density is high,” Levinson told Streetsblog. “And you’re going to look at the other lane and see there’s no bicycles in it and you’re going to think nobody’s using it.”

So the view from the dashboard is, not surprisingly, skewed in a way that works against bike lanes. If you want to get a real read on how well a bike lane or a car lane is being utilized, you need to count how many people pass through each lane during a given period.

“The productivity of the system is measured by throughput,” Levinson said. Unfortunately, he added, few places do bike counts thorough enough to assess how many people are using bike lanes.

Which doesn’t mean that today’s bike lanes actually get more use than car lanes. After all, it takes a whole network of safe bike lanes to make most people feel comfortable biking for most trips, and almost all American bike networks are still pretty sparse. But Levinson’s observation highlights the fact that looks can be deceiving when it comes to bike lanes, and you can’t reach a firm conclusion based on a casual glance.

17 thoughts on Why Bike Lanes With Lots of Bike Traffic Can Still Appear “Empty”

  1. Yeah, how many bikes would it actually take to fill the streets like cars do? They’d have to outnumber the cars 10 to 1.

  2. If you look at that photo, all you see is bikes. I don’t see ANY cars. So can we conclude that car lanes are always empty as well?

  3. Someone at work said a complaint like that to me once, so I just pointed out that the roadway isn’t always being used either!

  4. I have tried to explain this to driving friends who are pro-bike who have said the same thing about “empty” bike lanes. And I have even thought about that of driving lanes sometimes. For example, look at Kent Avenue some periods during weekdays, seriously, sometimes it might be a minute or so before you see a car.

  5. Empty roadways: glorious freedom, because no traffic is the best possible outcome
    Empty bike lanes: waste of taxpayer dollars!

  6. Alta Planning + Design released a white paper last month about automated technology to collect bike/ped data. Check it out if you’re interested in anything from manual (i.e., volunteer collected) counts to automated data collection. We also cover low-cost and or easy-to-use devices:


    I don’t want to sound spammy! I just want to share the news with folks who could use this tech in their own city/town.

  7. TA did bike counts last Summer, it was remarkable what a small footprint bikes at 10% of roadway traffic made versus cars. At 10% one hardly noticed the of bikes. it was only when bikes became 20% of roadway traffic that perceptually they started to be noticed.

    Some new numbers:

    A typical Manhattan avebue signal cycle is 90 seconds, max motor vehicle flow is about 40 cars per light cycle. ( think 6th avenue at rush hour ) 10% of 40 is only 4 cyclists in a 90 second signal cycle.

    More typical super busy Avenue motir traffic is 30 or so cars per 90 second light cycle. 10% is a mere 3 bikes. 20% is still only 6 bikes per signal cycle.

    Bikes simply create a minuscule footprint

  8. I don’t think it’s possible to generate enough bike traffic for bikes to be end to end in a traffic jam like car traffic often is. Even when you look at places like Amsterdam, bikes aren’t that densely packed, plus they’re always in motion unless they’re waiting at a traffic signal. The problem here is people trying to apply what they see with cars to a mode which works completely different. I’ve often heard the same thing about rail. A typical railway, even a busy one, will look like it’s empty to a layperson. Even the NYC subway only has one train every two minutes or so. More than 90% of the time there’s nothing on the tracks.

  9. how many bikes needed to fill the roadway same density as cars ?

    photo attached

  10. gas is too cheap! if we think the buses should pay for themselves, what about the roads? Nope.

  11. providing DOT numbers which I know to be wrong, because I have counted myself, only further buttresses my belief that DOT traffic data woefully undercountd active transportation and significantly over counts motor traffic.

    30-40 motor counts per cycle was extreme crowded rush hour and abything over 40 was near gridlock. 20-30 was typical busy CBD traffic.Anyone can verify this, stand on a CBD for a few 90 second light cycles and count cars. It’s easy

    in Manhattan, the number of people moved in motor traffic is less than 1.0.,once one accounts for For hire drivers. Many times 1/2 of motor traffic consists of empty cabs/ubers with only the Driver aimlessly searching. The 1.6 number often cited is simply wrong when applied to CBD.

    Buses in their dedicated bus lanes don’t cojnt.

  12. I sometimes hear, from people who live in highly dense New York City neighborhoods, that clearly everybody drives, because it’s so hard to find parking around here on the street.

    So I ask them to estimate how many people live in that apartment building over there and then ask them to count the number of parking spaces in front of it.

    Same issue.

  13. Perhaps it would be useful to edit a video and replace every cyclist in the cycle lane with a car. That ought to show ’em!

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