Monday, 12 September 2011

In 2010 did more people cycle over Blackfriars than TfL predicts for 2012? Is TfL trying to hide increase in cycling from London's politicians?

TfL data - share of people using Blackfriars junction %
According to Transport for London, once the new station at Blackfriars opens, there will be plenty more pedestrians using the junction at the northern end of the bridge.

One of the justifications they have used for the design of the junction is that a vast increase in the number of pedestrians means they need to make it a better place for walking. I absolutely agree with that.

What I totally disagree with is the way that Transport for London continues to try and justify the way it marginalises people on cycles at this junction. As The Campaign for Better Transport says about Blackfriars "is right to improve facilities for pedestrians at an enlarged and improved station but there is no objectivity in the balance between the needs of all modes. The ‘balance’ is driven by policy choices." Those policy choices are in favour of motor vehicles, over the majority of people using this junction.

TfL recently released a copy of the report that it presented to London Assembly Members to justify its road design. I first commented on the report a couple of weeks ago here.

One feature of the report to the London Assembly's politician's is TfL's claim that a massive jump in the number of pedestrians means that the number of people on a cycle will drop from 9% of all users of the junction to 6% - a one third drop which compares with a two-thirds drop in the number of cars and light goods vehicles.

In a separate freedom of information request statement, TfL has told the London Cycling Campaign that "Both the April and May 2011 proposal were designed to accommodate an estimated six per cent of people travelling through the junction by bicycle."

I am trying to find out how TfL works out that 6%. Somehow it doesn't quite feel right. I'm hoping to see what raw data they have based their assumptions on but in the meantime, here are my very rough calculations that explain why I think TfL is under-estimating the number of people who cycle here.

TfL states that "an essential new road layout on Blackfriars Bridge ...will be capable of handling the 40,000 passengers expected to leave the upgraded Blackfriars station every day".

The eastern side of Blackfriars. No priority for
pedestrians here, only for motor racing
So, let's assume all 40,000 of those passengers both leave Blackfriars and then come back again. And let's assume one-third of them leave via the new south bank exit. Let's also assume a further 10,000 people use the junction on foot but not the station each day. And we have 70,000 pedestrians in total.

TfL uses 2008 as its base year in the chart above. In 2008, only 4,000 people crossed Blackfriars Bridge on a cycle each day. But by 2010, that had jumped to over 6,300 people using Blackfriars Bridge on cycles. That excludes people crossing the junction from east to west so let's assume 7,000 cycles in total. Plus a further 33,000 motor vehicles, according to TfL. If you add 70,000 pedestrians (2012 forecast), 7,000 cycles (2010 actual numbers) and 33,000 motor vehicles (2010 actual numbers), you get 110,000 'people' moving through the junction a day and cycles equivalent to 6.3% of that total.


So, when TfL claims cycles will make up only 6% of the total number of people using the junction in 2012, I reckon that if TfL had modelled the number of cycles in 2012 using 2010 data as its starting point, rather than 2008 data, then it would probably show the percentage of people cycling was already more than it predicts for 2012.

In other words, by using 2008 as a starting point, TfL is telling London Assembly Members that there are thousands fewer people cycling on this bridge than there are in reality.

I realise my numbers are fairly sketchy. But they hint that TfL may be underestimating the percentage of people who cycle over the bridge. It is certainly choosing not to show the extent to which cycling has increased here in the last couple of years.

In a broader context, this suggests is that TfL is justifying not creating proper cycle infrastructure by claiming there are fewer people cycling here than there actually are. And it perpetuates that claim by showing forecasts that may be lower than figures recorded last year. 

In that context, it's not all that surprising therefore to see TfL's response to one part of the London Cycling Campaign's freedom of information request:

"Question: Cyclist modelling report for the Blackfriars junction used in preparing the initial and revised plans for the Blackfriars junction.

TfL answer: TfL does not undertake separate modelling studies for the different traffic modes.  Cycling was incorporated into the wider traffic modelling for the scheme as illustrated within our traffic models previously requested and provided to you."

Kind of says it all really. 

7 comments:

  1. You might want to double-check your figures as in the Blackfriars presentation TfL is counting *people* in the *junction* (for the first time I recall) but all the previous counts I've seen have counted *vehicles* *crossing the bridge* - so not only does the pedestrian count show up from nowhere but also the new question "how many people per vehicle" - especially interesting with buses and taxis - pops up.

    Also note that TfL presentation figures are for AM peak (sum of 6am-10am to my knowledge) rather than total 24h - of course traffic pattern at 6am is likely very different from 10am or 11am or when counted as sum over extended periods. Oh well.

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  2. Yes, I've tried running all sorts of figures and in none of my models can I work out how TfL get to the sorts of numbers they get to. So all I've done for now is hint at inconsistencies. Agree with you that all these numbers are very variable and that's kind of my point. For the same reason that TfL randomly lumps private motor cars and white vans together in to a new category which makes it look like there are more of them than there are cycles, even though they never normally present these two categories together...

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  3. 'There are three kinds of lies: lies, damned lies, and statistics" (Mark Twain - attributing to Benjamin Disraeli)

    I suppose I expect people in public office to mislead and misdirect, and I don't suppose any of the figures TfL have used are specifically wrong or false, but TfL do seem to be more than usually adept at, and more than usually unscrupulous about, manipulating statistics.

    Two other recent examples illustrate this, both from their consultation document on the Network Operating Strategy (or make more room for cars, as it should have been called).

    They report the results of a pilot of 1,000 signalised junctions/pedestrian crossings where the traffic lights phasing was changed, to reduce pedestrian phases/increase traffic within a substantially unchanged cycle. While there is a marked improvement in percentages of vehicles waiting at lights to get through in the first following green, there is also a tiny (statistically insignificant) improvement in the same for pedestrians (a small fraction of a % on a base of high 90s) and certainly no decline. However, the comparison is meaningless - pedestrians at a crossing, utilising road space up to 40-50 times as efficiently (persons/sq m) as vehicles, almost always get through the first green BUT they now have to wait a lot longer for that green to come.

    On the trial for motorbikes in bus lanes, the document reports that "51% of cyclists and car and van drivers who were aware of the trial" approved of the trial. About as meaningful as "8 out of 10 cats (who expressed a preference) preferred Whiskas". But how else could they give the impression that a majority of cyclists (and therefore a majority of every class of road user) would approve that trial? Car and Van drivers who disapproved could only do so from jealousy - why should bikes use bus lanes when cars can't?

    What it needs is someone with the time and the temperament for close parsing of the statistics reported or shown graphically in TfL documents.

    Any volunteers?

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  4. it really doesn't matter how tfl cooks the numbers (though it is idiotic of them..)

    all that really matters is that thousands of cyclists pass through the junction every day, and that the design is clearly dangerous.

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  5. Whether TfL used 2008 figures or 2010 figures, they are still looking backwards, and not forwards.

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  6. I too tried to make sense of the TfL figures. It is great that they are for the first time talking about numbers of people and not vehicles but the numbers are guesses based on 2008 data. If you compare the share allocated to cyclists compared to other vehicles it seems that they have given us a relative increase of about a third to 2012. That is way less than the increase already measured on City of London streets for a shorter period.

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  7. It also seems motor vehicles of all types will also reduce dramatically. So why are they giving more space to them?

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