In a somewhat counterintuitive finding, an American study out of John Hopkins Bloomberg School of Public Health late last year has concluded that narrow lanes save lives and also improve the environmental impacts of transport.

The authors concluded that:

• Narrower lanes do not increase the risk of collision. When comparing 9- and 11-foot lanes, we found no evidence of increased car crashes. Yet, increasing to 12-foot lanes did increase the risk of crashes, most likely due to drivers increasing their speed and driving more carelessly when they have room to make mistakes.
• Speed limit plays a key role in travel width safety. In lanes at 20-25 mph speeds, lane width did not affect safety. However, in lanes at 30-35 mph speeds, wider lanes resulted in significantly higher number of crashes than 9-foot lanes.
• Narrower lanes help address critical environmental issues. They accommodate more users in less space, use less asphalt pavement, with less land consumption and smaller impervious surface areas.
• Narrowing travel lanes could positively impact the economy. This includes raising property values, boosting business operation along streets and developing new design projects.

You can read the full report here.