Bike volumes on Dunsmuir: the city is hiding something

The City of Vancouver has been kind enough to release bike volume data for the downtown separated bike lanes. Many people dispute these numbers. Here’s a perfect example:

First, the transportation department appears to be providing incorrect information about bike lane usage. We have our own 24-hour cameras that monitor Dunsmuir Street, and our results show that the city is wildly overstating the actual usage. Either our extremely expensive digital cameras are wrong, or someone at City Hall is fudging the facts.

I certainly hope no one would make this accusation without some factual basis, but I seriously doubt that anyone watched 24 hours of video, manually counting cyclists. According to the engineer in charge, staff regularly check the accuracy of their hose and wire counts and welcome anyone to come forward with evidence that the numbers don’t add up.

Canadianveggie’s detailed analysis points toward an upward trend in bike usage. My own analysis has been limited to eyeballing the numbers, but that was enough to see that the city is indeed hiding something. Look at the data on a block-by-block basis for September 22, 2010:

  • 1,376
  • 1,419
  • 19
  • 2,154
  • 1,818

One of these things is not like the others. More specifically, Richards to Homer. There’s no way that’s accurate. Cyclists coming down Dunsmuir would never take a detour for just one block. I’m quite confident it wasn’t construction because I bike Dunsmuir every day and have never been diverted (well, not since the lane was officially opened). The same thing happened on October 7, shortly after Council approved Hornby. And again on the Granville to Seymour block from January 7-9.

So there you have it: the city is fudging the numbers. Down.

Ok, not exactly fudging. More likely it was vandalism or a defective counter. I’ve heard that some of the pneumatic hose counters have been found cut and had to be replaced by city staff. If anything, the inclusion of these low counts speaks to the accuracy of the data. That said, I think the city should annotate the published data with such incidents, as it does impact the numbers. Likewise for the handful of blank cells in the data — what does that mean? Perhaps the city doesn’t want to acknowledge instances of vandalism in case doing so motivates more.

In case you share my curiousity, Hamilton to Cambie is the busiest of the Dunsmuir bike lane segments with an average of ~1,400 trips per day. I’m guessing the extra traffic is from the Beatty bike lane. Richards to Homer and the Viaduct are roughly the same (~1,100/day), with Hornby to Howe and Granville to Seymour being the least traveled (~800 each). These averages include both weekdays and weekends.

Oh, and I tried looking for any influence from Critical Mass, but didn’t notice anything significant on the last Friday of each month. I suppose taking the bike lanes would be contrary to the whole “we are traffic” philosophy.

Besides the city annotating such data glitches, my other request would be for more granular data. It might reveal, for example, whether some cyclists are skewing the numbers (as some folk claim) by repeatedly biking over the same counter. I seriously doubt that’s the case, but even if it were, the overall numbers wouldn’t be impacted that much. The discrepancies I mentioned above result in a difference of over 4,000 trips, but in the grand scheme of things, that’s almost negligible.

Best of all would be live digital counters à la Copenhagen. (How about repurposing the Olympic countdown clock?) Sadly, even with such transparency, I’m sure bike lane critics would still dispute the numbers.

Advertisements

5 thoughts on “Bike volumes on Dunsmuir: the city is hiding something

  1. I noticed those anomalies too, and also attributed it to vandalized or malfunctioning sensors. I would have addressed it in my post, but the data for the Dunsmuir Viaduct looked clean.

    If you search through the Bike Vancouver Facebook page you can correlate some of the low numbers with reported incidents of broken counters:
    October 7, 2010 – vandalized counter on Dunsmuir. The city’s data reports 28 trips at Richards to Homer.
    January 17-18, 2011 damaged counter on Hornby. Data file missing two values for Georgia to Dunsmuir.

    Because the city is measuring bike volumes at several points along Hornby and Dunsmuir, it makes it easy to determine individual readings which are anomalous. The multiple sensors also protect the data from fudging. Some of the doubters have suggested bike-lane advocates are boosting numbers by jumping on hoses or repeatedly biking over the same sensor. That might sound plausible until you consider there are 8 sensors spread over 3.3 km.

    I agree, that by leaving these anomalies in the data (instead of trying to interpolate what the value should have been – which would be quiet easy given the data from adjacent sensors), it lends credibility to the authenticity of the city’s data.

  2. Pingback: Dunsmuir Bike Lane – By The Numbers | Canadian Veggie

  3. Craigslister

    It isnt reasonable to believe the city is fudging the numbers, it isnt as your information indicates. People just THINK Vision is fudging because they havent given the numbers any real thought and because the so called ‘trial’ of bike lanes has not been assigned a level of useage that would make the trial a failure. ie.. there is NO useage level which will cause Vision Vancouver to call the trial a failure no matter how low. Put another way, the trial isnt a trial at all but a snow job.
    You have to add to that, the fact that Councillor Meggs has said he is ‘happy’ with the numbers. Again, since there is no lane useage level assigned that could make him ‘unhappy’, people realize they are being scammed and dont trust the numbers. Also, depending on where you go on the city website, you may be looking at weekly totals rather than the daily stats you have used and people may not notice that. But the numbers are correct except where you have noted although a slightly different conclusion can be drawn from them with just a little more thinking about it.
    David, you state that the busiest intersection averages 1400 ‘trips’ per day. That is one way trips, by the way, but consider that most are in daylight and there are on the average 12 hours or 720 minutes of daylight. These numbers then show what people intuitively know by repeated observation and why, without thinking, they say the numbers are fudged. You have on the average 1400 trips divided by 720 minutes or roughly 2 bikes a minute. A good 30 full seconds between bikes. As you see, the numbers do actually correlate with observation. Conclusion: The busiest bike lane, on the average, is pretty much empty.

    1. Thanks for taking the time to comment, Craigslister. I’m glad you agree it’s not reasonable to think the city is falsifying data.

      I understand your frustration about the open-ended nature of the separated bike lane trial, but I disagree that there’s no way that city council would call it a failure. If you look at information on the city’s website, I think it’s clear that the city is hoping to reduce congestion and increase sustainable commuting like cycling, especially among those who don’t feel safe with just painted bike lanes. So if congestion skyrocketed or cycling plummeted, the trial would certainly be deemed a failure. Likewise if the number of car-cyclist accidents shot up… safety is always a concern.

      So while the number of trips is important, that’s not the whole picture. And it’s not about reaching a certain level of bike lane usage, but about overall growth. While the numbers so far look promising, there isn’t yet enough data to know for sure either way; we’ll have to wait until summer to compare cyclist volumes year-over-year.

      Regarding the average of ~30 seconds between bike: what’s wrong with that? There are lots of streets downtown that don’t get nearly that much car traffic. And anyway engineers have to design for peak periods like the evening rush hour, during which I often see cyclists queued up… and that’s during the winter. I’m tired of hearing people say “I drove by the bike lane and it was empty” as if that means no one is using it. Even the Cambie Bridge — all 6 lanes — is empty at some times of the day.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s