Showing posts with label speed. Show all posts
Showing posts with label speed. Show all posts

Monday, June 11, 2007

Sunday dollars+sense: speed versus life

Drivers beware, cyclists breathe easier. The ACT is getting more speed cameras. Yes, I know it will slow drivers down. It'll probably take you slightly longer to get where you are going. On the other hand, cyclists like me are more likely to live.

How do you weigh the cost of the change (extra travelling time for some) against the benefits (fewer people such as myself killed or injured)?

NSW and Victoria do it differently.

NSW is intentionally lax in its enforcement of speed rules. It is thought to allow a margin of 10 per cent over the speed limit before issuing a fine. Victoria is strict. As little as 3 km/h over the speed limit and you're gone.

The free-and-easy approach of NSW appears to come with a cost... We can't be sure that road rules are the reason, but it has a higher rate of road deaths than Victoria. It gets a benefit of saved travelling time but at a cost: extra lives lost.

Using the hourly wage rate it ought to be possible to put a dollar value on the benefit it gets from each life lost, in other words to work out the value that NSW places on human life.

As far as I know, no-one has done the calculation. But it has been done in the United States, in circumstances that were more clearcut. As a fuel- saving measure during the energy crisis of 1974, the Nixon administration imposed a low nationwide speed limit of just 55 miles an hour (88km/h). Road deaths plummeted.

After 1987, each state again became free to lift the limit on its rural interstate roads. Most boosted their limit to 65mph (104km/h). But seven left it unchanged at 55mph (88km/h).

Princeton economist Orley Ashenfelter and Chicago economist Michael Greenstone examined what happened in the states that boosted the limit. Their findings are chilling.

First, the actual increase in speed in the states that boosted the limit was low, averaging just 2mph (3km/h) on the roads affected. That's because a lot of the drivers on those roads were already speeding.

Second, that small increase in speed pushed up deaths by an astounding 36 per cent.

The states that boosted the limit appeared to have valued each life it destroyed at around $2million. I think I am worth more than that. I want more cameras.


Orley Ashenfelter and Michael Greenstone, Using Mandated Speed Limits to Measure the Value of a Statistical Life. Princeton University, Department of Economics, Working Paper number 463, April 2002.
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Wednesday, January 14, 2004

Life's cheaper in the faster state

This year's holiday road toll was the worst in eight years. But it's not because we drive badly. When asked, more than three-quarters of us say our driving is better than average.

It is true NSW recorded more deaths than Victoria over Christmas (25 compared with 17), but that needn't mean we are bad drivers, either. In the reassuring words of the pro-free market Centre for Independent Studies: "Victoria has always enjoyed slightly safer roads per kilometre travelled compared with NSW."

Most of us are very easily reassured that the deaths on our roads are not our fault. Six out of 10 of us admit to speeding (which is presumably OK because we are better than average drivers); six out of 10 of us oppose attempts to make the road rules tougher.

Late last year the CIS offered encouragement to speeders. On the front page of its magazine it asked: "Speed Traps: Saving Lives or Raising Revenue?" Inside it argued that speed had little to do with road deaths and that those of us who speed moderately "tend to be the safest drivers".

Since then the CIS appears to have softened its stand. The latest edition of its magazine devotes equal space to both sides of the debate.

So in that spirit I would like to take a look at what is actually happening in Victoria and whether it has any lessons for us here in NSW...

It is beyond doubt that there are far fewer road deaths south of the Murray: 334 last year compared with 553 in NSW. Victoria's population is lower, but not low enough to account for the difference.

It is also beyond doubt that Victoria enforces its speed rules more rigidly. In that state you will be booked if you are caught driving just 3kmh over the speed limit. In NSW we expect to be allowed to drive up to 10 per cent over the limit.

And in Victoria the speed cameras are hidden. Nineteen per cent of Victorian drivers say they have been booked in the last two years. In NSW the proportion is only 12 per cent. (The tough approach has become a political issue in Victoria. The Opposition has promised to reset the cameras to catch fewer speeders.)

The CIS is right to say that these facts do not necessarily mean that Victoria's approach has brought about the lower rate of deaths. There could be something else at work. To conclusively determine whether getting tough on speed saves lives you would need to run a controlled experiment in perhaps as many as 50 states which were free to vary their road rules over a period of years.

Fortunately the United States has conducted just such an experiment.

During the energy crisis of 1974 the Carter administration succeeded in enforcing a low nationwide US speed limit of just 55 miles per hour (88kmh). Road deaths slid 15 per cent.

From 1987 each state again became free to choose to lift the limit on its rural interstate roads. Within a year most states had lifted their limit to 65mph. But seven left the limit unchanged.

In a paper soon to be published in the Journal of Political Economy, the economists Orley Ashenfelter from Princeton University and Michael Greenstone from the University of Chicago examine what happened in those states that lifted their limits. Their findings are surprising.

First, the actual increase in speed in those states was quite low, an average of only 2mph (3.2kmh) on the roads affected. The professors say that is because a lot of drivers on those roads were already speeding.

Second, the small increase appears to have pushed up deaths per mile on those roads by an astounding 36 per cent.

So the professors asked a question only economists would ask: what benefit had the drivers in those states gained in exchange for each of the extra deaths?

The answer was reduced travel time - about 125,000 hours were saved for each extra life lost, which valued at the average wage rate, worked out at a benefit to drivers of about $US1.5 million ($1.9 million) per life lost.

Did the states that pushed up their speed limits value life too cheaply?

Perhaps not. That value of $US1.5 million per life is curiously close to the average $US1.8 million per life which is to be paid out in compensation to families of victims of the September 11 terrorist attacks.

Those US states that chose not to lift their speed limits valued lives more highly.

If speeding rules are indeed linked to deaths in the way that the US data suggests, then right now Victoria is valuing human life more highly than is NSW.

Those of us who enjoy the more relaxed approach to speeding law enforcement in this state are perhaps fortunate that no one has done the calculation for Australia.
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