Cycling UK Forum

boris wrote:when I got knocked off last year i heard the driver say that I had appeared to lose control unaccountably and fall off.

The second vehicle to hit me simply wrote that he did not see me until ........

exactly my experiences. drivers lie & police can't be buttocked. gladly, so far (and in all likeliness the rest of my natural) it's been minor soft tissue damage and/or the destruction of metal - mine and theirs.

I think the 2010 stats are excellent. There are over 300 people alive today who would have been dead if the fatals had been at 2009 levels. Even the cyclists fatals are the lowest ever recorded other than 2009 (as far as I know and at least from 1979).

I agree with irc that the stats are good news overall. Cycling casualties are on a downward trend, eg the fatal rate is 50% of what it was in 1992.

Cycling mileages second thoughts: these are more likely to have come from the DfT National Road traffic Survey (http://www2.dft.gov.uk/pgr/statistics/d ... index.html).

I've re-done some maths. For all roads, cycling is 2.64 times as fatal per hour as cars. For non-motorways, cycling is 2.49 times as fatal. The all-severity ratios are very similar.

Here comes the maths. Feel free to check it.

In 2010, the average car speed across all roads was 45.14 mph. Across all non-motorway roads, it was 41.79 mph.

(Traffic volumes from http://www2.dft.gov.uk/pgr/statistics/d ... index.html tra0104.xls; traffic speeds from http://www2.dft.gov.uk/pgr/statistics/d ... index.html spe0101.xls and spe0102.xls)

These speeds are 5.6425 (all roads) and 5.22375 (non-motorway) times a bike's speed.

The car driver fatality rate per billion miles is 2.35 on all roads, 2.69 on non-motorway roads.

Cycling fatality rate is 35 per billion miles. So the ratios per billion miles are 14.89 (all roads) and 13.01 (non-motorway).

So the ratio of fatalities per hour is 2.64 (=14.89/5.6425) and 2.49 (=13.01/5.22375).

For all-severity casualties per billion miles, car drivers suffer 367.47 (all roads) and 423.11 (non-motorway). Cyclists suffer 5,488. So the ratios per billion miles are 14.93 (all roads) and 12.97 (non-motorway). So the ratio of all-severities per hour is 2.65 (=14.93/5.6425) and 2.48 (=12.97/5.22375).

This assumes a bike's average speed as being 8mph. This seems very low to me.. Not least because those doing high bike mileages probably have a higher average. I'm always very sceptical as to the accuracy of bike mileage stats & trying to add in average speeds makes it even worse.

snibgo wrote:I've re-done some maths. For all roads, cycling is 2.64 times as fatal per hour as cars. For non-motorways, cycling is 2.49 times as fatal. The all-severity ratios are very similar.

Here comes the maths. Feel free to check it.

In 2010, the average car speed across all roads was 45.14 mph. Across all non-motorway roads, it was 41.79 mph.

(Traffic volumes from http://www2.dft.gov.uk/pgr/statistics/d ... index.html tra0104.xls; traffic speeds from http://www2.dft.gov.uk/pgr/statistics/d ... index.html spe0101.xls and spe0102.xls).

I think the flaw might be that free flow vehicle speeds are not average speeds.

"These statistics provide insight into the speeds at which drivers choose to travel and their compliance with speed limits, but should not be taken as estimates of actual average speed across the road network. Speeds have been monitored at about 100 sites using Automatic Traffic Counters (ATC), deliberately located where external factors which might restrict driver behaviour (including junctions, hills, sharp bends and speed enforcement cameras) are not present."

http://assets.dft.gov.uk/statistics/rel ... -notes.pdf

I would guess that free flow speeds might be close to an average for motorways where there are few restrictions other than congestion but they will be much higher than average for other roads where bends, hill, and junctions reduce speed.

The free-flow car speeds are certainly a problem, and the bike speeds may be also. If anyone has more accurate data, I'd love to hear it.

Digging deeper at that cycling speed: each rider averages 119.41 minutes per week, 15.87 miles per week (nts0314.xls). Thus 7.97 mph. These are the surveyed people who made at least one cycling trip in the week for which they recorded their travel (n=943).

From different tables: Average distance cycled, across all people, per year: 42.40 miles (nts0305.xls). Average time cycled: 5.38 hours (nts0310.xls). Thus 7.88 mph.

These different tables also give driving statistics. Average distance as car/van driver: 3415.77 miles (nts0305.xls). Total time spent driving: 140.49 hours (nts0310.xls). Hence speed 24.3 mph, which is about half the all-road figure I used earlier.

Using these numbers, the ratio of speeds is 3.08 (=24.3/7.88). So the ratio of fatalities per hour across all roads is 3.65 (=14.89/4.08). A bike is nearly 4 times as likely to be fatal as driving a car.

This is nearly twice as bad for bikes than I had thought. Is that reasonable, or have I got it the wrong way round? If the casualty rate per mile for car drivers is accurate but they travel at half the speed I thought, then their casualty rate per hour also halves. Bikes are pretty much the same, so bikes are twice as bad as I had thought.

As always, feel free to show me where I am wrong.

Would be interesting to know the difference between the south east and the rest of the country in terms of the likelihood of getting squished on my bike.

Fuel consumption is down 10-20% since 2008 according to the latest data, and a significant increase in cycling in the south east (although this data is not released yet). I wonder if the whole critical mass thing is actually happening, as the ratio of drivers to cyclists changes with that data ^.

snibgo

Having doffed my hat once for your work preparing and presenting your OP, it's back off again (and with a low bow) for your mathematics. I'd still suggest that the concentration on detail misses the point. We know that in a collision a cyclist or pedestrian will be more likely to be a casualty than the occupants of a motor vehicle ** and as a casualty will tend to suffer much greater injury. IMO the big issue is how we, as a society, deal with this. At the moment, I see little sign of anything other than displacing cyclists and pedestrians from the road network.

** NB do your calculations include passengers as well as drivers?

thirdcrank wrote:I'd still suggest that the concentration on detail misses the point.

I agree. Detail matters because facts are important, but opinion always counts for more. And what we do about the facts and opinions are even more important.

thirdcrank wrote:NB do your calculations include passengers as well as drivers?

No; I've considered the situation for drivers only. I suppose the risk for front-seat passengers is about the same as for drivers.

snibgo wrote:Using these numbers, the ratio of speeds is 3.08 (=24.3/7.88). So the ratio of fatalities per hour across all roads is 3.65 (=14.89/4.08). A bike is nearly 4 times as likely to be fatal as driving a car.

This is nearly twice as bad for bikes than I had thought. Is that reasonable, or have I got it the wrong way round?

Given that cyclists are sharing the same road system as cars but are not protected by metal cages, seat belts, and air bags, and are unlike car drivers at risk from overtaking vehicles all the time. and can be crushed by left turning HGVs I think a risk 4 times as high could be correct.

But of course even so cycling is very safe.

Nutsey wrote:Would be interesting to know the difference between the south east and the rest of the country in terms of the likelihood of getting squished on my bike.

That's an interesting question. I have the regional cycling casualty numbers (http://www2.dft.gov.uk/pgr/statistics/d ... index.html cas0009.xls), but for the regional cycling mileages, the closest I can find is "other private" mileages. These are National Travel Survey (nts9904.xls) figures for cycling plus motorcycle plus private bus hire. Cycling and motorcycling numbers are generally roughly equal, and private bus hire is roughly zero. So "other private" is roughly double the actual cycling mileage.

Multiplying the "other private" mileages per person by the population (from ONS http://www.ons.gov.uk/ons/rel/pop-estim ... --2010.pdf) and dividing by the casualty numbers gives a relative casualty risk. (EDIT: I meant, dividing the casualty numbers by the miles/year.) See my table below.

Note that I've pulled these numbers from various different years, so they shouldn't really be used together. Treat them only as a bodged rough guide to the relative risk in different regions.

The numbers suggest that Wales is the safest place to cycle; London is the worst. In England, the SW is the safest; the East (where I live) is twice as dangerous as the SW, but twice as safe as London.

snibgo wrote:

Nutsey wrote:Would be interesting to know the difference between the south east and the rest of the country in terms of the likelihood of getting squished on my bike.

That's an interesting question. I have the regional cycling casualty numbers (http://www2.dft.gov.uk/pgr/statistics/d ... index.html cas0009.xls), but for the regional cycling mileages, the closest I can find is "other private" mileages. These are National Travel Survey (nts9904.xls) figures for cycling plus motorcycle plus private bus hire. Cycling and motorcycling numbers are generally roughly equal, and private bus hire is roughly zero. So "other private" is roughly double the actual cycling mileage.

Multiplying the "other private" mileages per person by the population (from ONS http://www.ons.gov.uk/ons/rel/pop-estim ... --2010.pdf) and dividing by the casualty numbers gives a relative casualty risk. See my table below.

Note that I've pulled these numbers from various different years, so they shouldn't really be used together. Treat them only as a bodged rough guide to the relative risk in different regions.

The numbers suggest that Wales is the safest place to cycle; London is the worst. In England, the SW is the safest; the East (where I live) is twice as dangerous as the SW, but twice as safe as London.

Interesting. Thanks for this. I get why London is most dangerous, but its the change in recent years (esp post Boris Bikes) that would really shed light on this. Is it now less dangerous?

I'm still excited by the ongoing talk about Oxford Road (Manchester) being pedestrianised. Can't get safer than that

London casualties (absolute numbers, not necessarily casualties per miles) have risen about 20% in the last couple of years, against a general decline elsewhere. Dunno if these are Boris Bikes. Doubtless those stats are available somewhere.