AutoblogGreen

Recently, we reported on so-called eco-towns in the U.K. which have imposed 15 mile per hour speed limits in an effort to reduce pollution. We're pretty sure that their end-goal is to remove vehicles from the roads entirely, not simply forcing them to slow down. It seems that other towns are lowering speed limits for a completely different reason: safety. The city of Portsmouth has recently become the first city in Britain to impose a 20 mile per hour speed limit for nearly every residential street, 1,200 in total.

According to the Portsmouth City Council's official website, the goal is threefold:

• to boost the safety of pedestrians and cyclists - especially children and old people
• to encourage cycling and walking
• to make streets more useable for the people who live on them

We can see the benefit to removing cars completely from the transportation equation where possible, but there is a problem in forcing cars to drive this slowly without offering an alternative, and it centers on emissions. Most any newer car has been designed to run most efficiently at a higher speeds, and pollute more when driven too slowly. Electric vehicles are less likely to encounter this problem, but we doubt that many Portsmouth residents are driving through their city in electric vehicles.

[Source: Portsmouth City Council]