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Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 3 Jan 2019, 6:18pm
by The utility cyclist
I was just looking through the documents from the DfT regarding historical casualty rates for cyclists, both fatalities and injured, and thought the graph seemed to indicate a very low number of miles (in billions) travelled in the 70s and 80s, it certainly seems at odds with what I experienced in those decades as a child/teen/young adult though Kingston upon Hull and surrounds certainly had a higher % than national average.

Also when I was visiting my home city and saw this table from a 1989 newspaper, it got me thinking that either the article (which isn't attached to the data table) referred to an earlier period of time or there's some serious discrepancy in the governments data re miles travelled and thus from that historical injury rates per miles travelled.
Of course bike use for work isn't all cycling miles but surely that would be a reasonable indicator, the low miles travelled (as below) just doesn't seem to match up with my impression of the time and certainly not given the table of cycling in my 'local' area? :?

I'm going to see if I can get hold of the original paper from the history centre in Hull to see if there's more information about the table that was printed in that days Hull Daily Mail, fortunately saved myself some time as I've just asked on FB and apparently the central library microfiche archives were transferred 8 years ago.

What do others think regarding the official government stats re miles travelled?

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 3 Jan 2019, 6:25pm
by brynpoeth
Impossible to know, very unreliable, maybe the figures are a bit more accurate now but they seem to have fluctuated a lot in the past
Sort of wish I had started cycling in 1949 :wink:

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 3 Jan 2019, 6:32pm
by Airsporter1st
If you think about it, there's no logical way those figures could have been produced other than by extrapolation, the accuracy of which depends to a great extent on the original sample size(s) along with numerous other factors. I would certainly take them with a large pinch of salt.

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 3 Jan 2019, 7:21pm
by mjr
I think you should tell us which documents you are looking at and then we might find the source and be able to point you at past criticism of DfT counts, the National Travel Survey, Active People Survey, Census questions or whatever it is.

Similarly on casualty data, RRCGB is an underestimate because cyclists aren't required to report, some don't want to and motorists often don't despite being required. HES is an overestimate because injuries get recorded as cycling casualties when it was incidental.

So, most of the sources are flawed but they're slightly better than nothing and comparing a source with itself over time is sometimes useful.

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 8:53am
by atlas_shrugged
I reckon the OP has a legitimate concern regarding accuracy of miles travelled by cycles in the UK.

I was looking at the traffic sample points for Cranebridge which reports the highest levels of cycling in the UK. Looking at the map of the city where the sample points are made got me very curious. If I wanted to catch bike traffic then the sample points are in all the wrong places. For example I would want to know the traffic travelling down Mill Road. This was a very busy artery for cycle commuters. Now the road is jammed packed with parked vans (which may discourage cyclists). However there appears to be no sample point on this road and instead only on a side road.

Here is an example of an obscure sample point on a side road in Cranebridge:
https://roadtraffic.dft.gov.uk/manualcountpoints/941061

In addition Cranebridge has the misguided busway and the Greenway beside this has been a spectacular success in transporting cyclists/pedestrians/scooters/skaters etc etc. Other Greenways are also being improved or built. However none of this traffic is going past a samplepoint. So is the DfT missing statistics or do they have a cunning plan?

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 9:44am
by mjr
atlas_shrugged wrote:So is the DfT missing statistics or do they have a cunning plan?

They're missing and we have no evidence that Grayling's DfT has any plan to correct this - or indeed any cunning.

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 11:02am
by thirdcrank
I'd take some convincing that there's any benefit to cyclists or cycling from stats about casualty rates, although accuracy is always to be preferred.

The most obvious outcome is that air travel is somehow best and cycling the worst. All that tells is what we know already ie that cyclists are vulnerable in comparison with the occupants of motor vehicles. If it were to be possible to collect and compare data measuring distances ridden on, say, ordinary roads, cycle lanes, cycle tracks (ie segregated provision) that still wouldn't factor in the crap provision as compared with the decent stuff.

The case for cycling is already pretty obvious in terms of things like the health benefits and sustainability. It's also pretty obvious that motor vehicles can travel faster and so go further in a given time. The big problem is that policies which acknowledge this are politically unacceptable here.

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 1:04pm
by mjr
thirdcrank wrote:I'd take some convincing that there's any benefit to cyclists or cycling from stats about casualty rates, although accuracy is always to be preferred.

The most obvious outcome is that air travel is somehow best and cycling the worst. All that tells is what we know already ie that cyclists are vulnerable in comparison with the occupants of motor vehicles. If it were to be possible to collect and compare data measuring distances ridden on, say, ordinary roads, cycle lanes, cycle tracks (ie segregated provision) that still wouldn't factor in the crap provision as compared with the decent stuff.

I'd agree with most of that, especially that comparisons between transport modes are fraught with problems.

However, it can sometimes tell us interesting things and focus the minds of the decision-makers on changes that might actually do some good. There was a recent statistic that 75% of Norfolk car-cycle collisions occur at junctions which seems to be helping us to get some attention on changing junctions to reduce risks of left hooks and all the other bad things too familiar to us, instead of the bad old habits of protected cycling infrastucture ending as soon as designing a junction gets difficult. Of course, we could just have copied what London's doing (or Denmark or the Netherlands), as more often than not.

thirdcrank wrote:The case for cycling is already pretty obvious in terms of things like the health benefits and sustainability. It's also pretty obvious that motor vehicles can travel faster and so go further in a given time. The big problem is that policies which acknowledge this are politically unacceptable here.

In general, I agree, but I think some parts of that are more politically unacceptable than others...

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 1:13pm
by thirdcrank
... focus the minds of the decision-makers on changes that might actually do some good. ...


I fear that so long as casualties are being counted and the aim is to reduce them, then it seems inevitable that discouraging cycling, whether intentionally or as the result of sheer incompetence, will be recorded as success. ie Less cycling = fewer casualties, no cycling = no cycling-related casualties at all.

There are differing ideas of what amounts to good.

PS I'm not suggesting that casualties don't matter, just that counting and comparing them is unhelpful to cyclists and cycling.

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 2:02pm
by Vorpal
No matter what is, or isn't presented, it will cause problems. It is in our nature to argue about stuff :lol:

I don't think it is unreasonable to present statistics. The problem is that statistics such as crash rates are presented as if they were risk, when in reality they are only a part of it, and the mental and physical health benefits, reduced pollution, and other things all contribute to the overal risk associated with cycling.

If risk were to be presented, including things like crash rates, people would pick it apart and argue about it. When crash rates are presented, people pick them apart and argue about it.

It is not reasonable to compare air travel to cycling because they serve different purposes. One can hardly take a commercial airliner to pick up milk, eggs, and the daily paper.

As for the historic data, the National Travel Survey began in the 1970s, so data collected before 1973(?) would have been collected by a different means, and may not be comparable. They also made some changes in the weighting methods in 1995. Details are available from the National Travel Survey Technical Reports.

That said, I doubt that it is very much worse in terms of quality, and I would look for other reasons for the low numbers. For example, was cycle modal share similar to now, but people just travelled that much less? People did not travel as far for work, school or shopping.

This report shows differences between 2005 and 2015, and there are significant differences for all modes. One of the things that I thought was most interesting was that the number of trips per person went down for all modes except cycling. At the same time, The distance per person went up for all modes except driving.

You also have to remember that active travel will be much more common in cities and towns, than across the population as a whole. There have also been significant shifts in where people live since the 70s. Populations have become more urban and less rural.

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 2:23pm
by mjr
thirdcrank wrote:I fear that so long as casualties are being counted and the aim is to reduce them, then it seems inevitable that discouraging cycling, whether intentionally or as the result of sheer incompetence, will be recorded as success. ie Less cycling = fewer casualties, no cycling = no cycling-related casualties at all.

There are differing ideas of what amounts to good.

PS I'm not suggesting that casualties don't matter, just that counting and comparing them is unhelpful to cyclists and cycling.

Locally, the focus is on reducing casualty rates, not just numbers of casualties, because of the above obvious flaw - it's led by the Public Health Directorate and their statisticians seem very aware of this danger. Of course, the weaknesses in the various "miles travelled" stats are a pain, but comparing (for example) RRCGB cycling casualties per NTS cycling mile to itself from year to year can be helpful to figure out whether changes have made things better or worse.

A big difficulty is that the RRCGB stats updates come out much more frequently than any of the official activity statistics. I think it's monthly casualty report summaries published within about a month compared to at-best twice-annual activity surveys published within about four months - local automatic cycle counters have all been decommissioned to save money, robbing us of possibly the most up-to-date activity change data.

So there's now a big delay before the raw casualty numbers can be scaled into rates and it seems difficult to persuade government to either keep faith with current policies until the official activity data appears (and so we have a better idea whether casualty rates went up or down) or to use more recent community estimates of cycling activity changes (volunteers standing by the now-dead automatic counters for periods of time and reporting the numbers back on our website and our sibling groups').

I don't see anyone getting away with discouraging cycling as a way to improve safety or health locally any more. The arguments against cycling lately tend to focus on the equally-mistaken idea that more motoring means economic prosperity, instead of probably being a blight.

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 2:28pm
by irc
The stats may well be accurate. I'd suggest there would be a vast decrease in cycling miles from the 50s to the 70s as cars became affordable to most people rather than just the better off.

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 2:32pm
by thirdcrank
... it's led by the Public Health Directorate ...


That's good to hear and I hope the highwaymen listen. The vast bundle of evidence I once received when I represented the CTC at a local enquiry included a statement which began along the lines "I am the Medical Officer for Health for the City of Leeds and I am surprised that I am not consulted ...."

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 3:13pm
by mjr
thirdcrank wrote:
... it's led by the Public Health Directorate ...


That's good to hear and I hope the highwaymen listen. The vast bundle of evidence I once received when I represented the CTC at a local enquiry included a statement which began along the lines "I am the Medical Officer for Health for the City of Leeds and I am surprised that I am not consulted ...."

Sadly, the highwaymen are still rather hit and miss. I'm told they've adopted various great policies - the "Safer Systems Approach" which they say is like Vision Zero but I've not checked that yet - but on the ground I'm seeing some nonsense from external consultants about particular projects and while the Public Health Directorate is consulted, they're still far too trusting in such nonsense and agreeing to obviously dangerous stuff like allowing HGVs to use part of a cycleway for routine access to premises instead of the current turning off an adjacent former A road. So, small steps forwards, not yet in utopia or cycletopia!

Re: Accuracy of historical bicycle miles travelled and cyclist casualty rates.

Posted: 4 Jan 2019, 11:56pm
by The utility cyclist
mjr wrote:I think you should tell us which documents you are looking at and then we might find the source and be able to point you at past criticism of DfT counts, the National Travel Survey, Active People Survey, Census questions or whatever it is.

Similarly on casualty data, RRCGB is an underestimate because cyclists aren't required to report, some don't want to and motorists often don't despite being required. HES is an overestimate because injuries get recorded as cycling casualties when it was incidental.

So, most of the sources are flawed but they're slightly better than nothing and comparing a source with itself over time is sometimes useful.

The governments DfT document TRA0401 shows the cycling miles