Crossing from one lane to another on St Giles
At the moment, the decision to introduce 20mph speed limits for residential areas rests with local councils. Currently, Oxford is debating the decision. If a 20mph speed limit is enforced it will have a noticeable impact on road safety and the road environment. These are the arguments for and against.
Benefits of 20mph Speed Limits
- Lower speeds reduce number of accidents
- At lower speeds crashes are far less likely to be fatal. At 20mph, only 10% of crashes are fatal compare to 50% at 30mph
- 20 mph zones have reduced injury collisions of all severities by 60% and those involving child deaths and serious injuries by 70%. 20mph zones in London have reduced all casualties by 42% and deaths and serious injuries by 53%. In Hull’s 20mph zones, serious and fatal casualties have fallen by 90%.
- Lower traffic speeds will encourage more people to cycle, walk. (Transport select committee on Transport Report at CTC)
- 9 out of 10 pedestrian and cyclist fatalities occur in built up urban areas
- Lower traffic speeds makes cycling manoeuvres easier. For example, turning right can be difficult when you have to cross a lane of fast moving traffic. If the traffic speed is reduced to 20mph it becomes much easier.
Costs of 20mph Speed Limits
- Driving will take longer. As a motorist, I currently drive at 30mph in residential areas, having a speed limit of 20mph would require a change of habit and take a bit longer to drive. However, it’s not a huge imposition, as you have to keep stopping anyway.
- Problem of enforcement. I dislike schemes which reduce the width of the road and make it uncomfortable for a car and cyclist to squeeze by. Speed Camera are not popular. But, I quite like them. They would raise money to finance the road safety improvements. Average speed cameras would be best.
Enforcement
It’s one thing to have a 20mph speed limit, it’s another to enforce it. Since 20mph speed limits were introduced in Oxford (2010) they are rarely enforced. Motorists tend not to look at speed limits but what speed they can do. Thus speed humps, and thoughtful road design may be necessary to keep speeds down.
Overall,
Overall, I feel the benefits of 20mph outweigh the costs. It is true, driving will take a bit longer, but compared to the benefits of lower road fatalities and a safer road environment it appears a minimal cost. It would definitely be a boon to cycling and walking.
For a long time, society has kind of accepted the fact 3,000 road fatalities as just one of those things. But, maybe that is changing. Maybe people will feel that reducing road fatalities should be a much higher priority, even if it requires unpopular measures.
Look at how much inconvenience people put up with, on the very minor possibility of terrorists using water to blow up planes. We will do anything to reduce the risk of a potential attack on a plane. But, when it comes to easy measures to actually have an impact in saving lives on the road, society seems far more willing to drag its heals.
@Dan.H no it doesnt trust me.
Lol, poor cars, I was looking for speed limits for cyclists in town. Dunno if I could stick to a 20mph on my bike let alone a car
I hit a car while i was going about 30mph+ down a big hill today and left a big dent in it. The cheeky driver is claiming he has whiplash!!!!
People need to learn the difference between a 20 mph speed limit and a 20 mph zone before using one to support the other.
A 20 mph zone is basically an area wide traffic calmed area with speed reduction features (humps etc) at a maximum every 100 metres.
A 20 mph speed limit just has signs with no speed reduction features necessary.
The results for zones are due to the presence of traffic calming features reducing the speed of vehicles not the 20 mph signs.
There is no evidence that 20 mph speed limits on their own reduce speeds or accidents and most past research is that there is no significant reduction.
Surely a lot will depend on exactly how the authorities define “residential area” and whether it will be standardised across the UK or vary from one county to another?
Good point Dan!
Another advantage: the road space taken up by a vehicle increases linearly with its speed (because its stopping distance increases as the square of the speed, but the time spent on the road is inversely proportional to the speed). Thus, reducing speed from 30 to 20mph means you can get one and a half times the throughput on the same road space (when vehicles are moving at the limit rather than queueing), even before you take into account that such measures encourage cycling and walking.
Whilst approving of 20 limits entirely I do wonder whether emissions might increase because we’d have to drive in a lower gear. However the benefits far outweigh that disadvantage. Also, because driving would be less convenient might encourage less of it and cause drivers to look more closely at the alternatives.
I sure hope so.
I approve of 20mph speed limits entriely!