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Traffic calming without the hump

December 1, 2003 12:00 AM
By Julia Samson in Challenge
A typical residential road, with wide carriageways and clear sightlines encouraging motorists to drive fast.

A typical residential road, with wide carriageways and clear sightlines encouraging motorists to drive fast.

Julia Samson examines alternatives to the speed hump

It is generally agreed amongst transport and road safety campaigners that there should be blanket 20mph speed limits on residential roads and around schools, preferably as a default limit in all urban areas. But the big question is how do we ensure that people do actually drive at 20mph or less?

Speed humps are the traditional and probably the most widespread form of speed control in residential areas and have proved effective in saving lives and injuries. A Department for Transport survey found that 80 per cent of people support the idea of 20 mph speed limits in residential roads and that 60 per cent welcomed speed humps to achieve this.

But speed humps have been criticised in some quarters because of noise, potential damage to vehicles, and increased pollution due to the tendency for drivers to speed up between the humps. So are speed humps the only option?

Speed cameras can be used in residential areas and could be used far more often. Cameras keep speeds low through enforcement, rather than through engineering. They do not involve a lot of street clutter and are cost-effective.

In-vehicle speed limiters are also a realistic possibility and trials are being conducted in Leeds. Ultimately, a sophisticated system of ISA would mean that speed limit enforcement would no longer need to happen as cars would physically be incapable of driving above the programmed limit, whatever the intention of the driver.

However, in the run up to an intelligent speed-restrained future, speed control in residential roads will lie in a mixture of measures, including speed humps.

Striplaan in Rijswjik, Netherlands, is a new housing development. The design of the streets has kept speeds very low. Narrow carriageways, short sight lines and shared surfacing all help to stop motorists driving too fast (Photo: Transport 2000)

Striplaan in Rijswjik, Netherlands, is a new housing development. The design of the streets has kept speeds very low. Narrow carriageways, short sight lines and shared surfacing all help to stop motorists driving too fast.

But maybe we should learn more from how other countries such as the Netherlands are looking at these issues. They have started to alter the way that residential roads are designed and engineered.

At the moment, residential roads are often straight and wide and simply encourage high speed driving. They have clear segregation between the pavement and the road, which gives the driver confidence to drive fast presuming that the pedestrians will stay in 'their' space.

Drivers 'read' the road and from that decide what speed is appropriate. If the road 'reads' 30mph then people will drive at 30mph, with little attention paid to the actual limit, which might be lower.

Most residential roads have not been designed to inform drivers that they are residential. Thus when residents on these road demand lower speeds, it is not enough to just reduce the limit on the signpost, because the message to the driver from the road design itself is still that you can drive at 30mph.

We need to challenge the assumption that residential roads should prioritise the needs of motorists above everything else and maybe we can do this through new design techniques.

The design principles used in the Netherlands include:

These techniques give us an alternative vision to the speed humps and bumps; one in which people are trusted to behave appropriately in the surroundings they find themselves in. The question remains: would it work in Britain?

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