Relative risk of walking and cycling

[srw]

I know we've touched on this one recently, but as I crossed a very busy road in London last week something occurred to me that I hadn't considered before. The statistics (for instance http://understandinguncertainty.org/node/243) tell us that per kilometre walking and cycling are about as risky as each other. I've pointed out several times that the statistics for kilometres travelled for cycling and walking are really quite flaky. What I hadn't considered is that "kilometres travelled" isn't necessarily the best definition of the risk exposure (Exposed to Risk in the jargon).

My best guess is that most walking is done in towns and cities. Which means that most walking is done on the pavement, largely insulated from the risk posed by the motorised traffic. The Exposed to Risk should really be measured relative to the relatively short distances walked as pedestrians on the road - mostly in crossing the road. By contrast, a large chunk of cycling is done directly on the road and directly exposed to the risk posed by the motorised traffic.

Following this train of thought through, it would suggest that once you make this adjustment, walking becomes rather more dangerous than cycling per kilometre, and so cycling is relatively even safer. It also starts squishing the arguments that are made about cycle segregation, and makes the argument "in favour of" head protection for pedestrians rather more urgent.

I realise that more adjustment needs to be made for age, and for incidents that don't involve motorised traffic. Does anyone happen to know if this sort of analysis has been done?

 

[Flying Dodo]

Last year, I'd been searching for some data, but all I could find was the latest DfT data, which as you say, is looking at fatalities per kilometre travelled. I've used that to justify telling people that cycling's safer than walking!

They say 61% of all accidents occur on rural roads, so clearly they do record the occurrence of all incidents and road type. They do have this index but I can't see anything giving the specific analysis you'd like.

 

[Banjo]

Most accidents occur in the home so get out on your bike as much as possible.

 

[Davidc]

Just about all activities involve some risk of injury. Does that mean we should all go round wearing full body armour all the time?

When the risk of death or serious injury is very low there's no justification in using &/or wearing protective kit to make that risk move from very low to even lower. I'll accept the sense in using lap belts in a 'plane at takeoff and landing and in serious turbulence, in part because it isn't intrusive. Same in a car. That doesn't apply to helmet wearing for pedestrians or during normal cycling.

Making children wear Thudguards is IMO both obscene and a form of child abuse. They deprive children of the experiences they need to be able to learn how to assess and avoid hazards.

Wearing a hard hat on a construction site or in some industrial environments makes sense. The risk of injury is high enough. For a journalist covering a war to wear a bullet resistant jacket is justified in the same way. I'm not suggesting that protection shouldn't be used when appropriate. Just that for very low risk activities such as cycling or walking only minimally intrusive measures are appropriate. (The higher risk issues such as eye and hand protection on a bike do justify goggles and gloves though)

 

[DaveReading]

What I hadn't considered is that "kilometres travelled" isn't necessarily the best definition of the risk exposure

For several reasons, not just the one that you mentioned.

When comparing modes of transport that differ significantly speed-wise, you will get completely different comparison results depending on whether you measure risk per distance travelled or risk per unit time.

 

[ufkacbln]

It was "proven" that cyclists kill or injure more pedestrians than HGVs!

Basically calculate the total mileage covered by HGVs and divide the deaths by that mileage

Then repeat for cyclists, and the number of pedestrians killed or injured per mile is actually higher!

 

[Nigel-YZ1]

 

[steveindenmark]

I think if you need to justify to people that cycling is safer than walking, you need to get out of the asylum.

Steve

 

[srw]

For several reasons, not just the one that you mentioned.

When comparing modes of transport that differ significantly speed-wise, you will get completely different comparison results depending on whether you measure risk per distance travelled or risk per unit time.

Of course. And the usual argument from someone who hasn't thought about risk a great deal is that walking is "of course" much safer than cycling because you spend longer doing the same distance. I'm challenging the "of course" and trying to find out if anyone's done the sums. Since it seems that no-one has I might be on to a do-it-myself exercise - if I'm bored enough one day.

 

[theclaud]

Exactly how bored would that be?

About this bored?

 

[deptfordmarmoset]

About this bored?

That thread is approaching the threshold of self-harming.

 

[StuartG]

This reminds me of the statistics that suggest its safer flying between airports than getting to and from the airport. This is because planes fly long distances so deaths per km is always going to be incredibly low.

However nearly all crashes occur on take-off or on final approach. So it doesn't really matter how far you fly, the risk is nearly the same. Most people are more concerned with just arriving alive. Hence deaths per journey is a better comparison. As srw indicated walking risk is probably more correlated to the number of times you cross a road rather than distance.

Most people use different travel modes for different distances. Another more useful way of comparing risk per journey is on time. That relates how many of these journeys you can fit in per day. I can relate better to risk per hour of my time even if the real risk per journey is compressed into only a small part of it.

So I did a club ride round Surrey today. I didn't die but 6 hours was the same as LHR-JFK. The kms ratio was around 100:1 which is the factor you should divide the plane risk deather per km by to compare with the cycle trip.