How Wide is Your Street?

I still remember taking a class at Clemson in asphalt design and spending an afternoon lab mixing sample batches. Believe it or not, it was a fun class. However, it still bugs me when I see wasted applied asphalt. I know you have seen such an area – an extra-wide street, a huge parking lot that never fills up even near Christmas, or that huge cul-de-sac that you could launch a Titan rocket from the center.

Impervious cover can cause the potential for:

  • Higher peak discharge rates and increased flooding in streams
  • Greater streambank erosion
  • Greater loads of stormwater pollutants

I live in an older development where the street width is actually 22 feet. This seems to be enough space for us. So what is the perfect residential street width that balances safety while reducing the impervious area that could benefit our water resources?

ASCE and AASHTO, engineering organizations, both recommend 22 foot wide streets if the streets serve less than 400 daily trips or 50 homes. However a study by Swift and Associates, found the safest street was 24′ wide based on 20,000 accident reports over an eight year period. You can see in the graph below the 24′ sweet spot with accidents climbing as the streets get wider.

Read More:

The Narrow Street Database,
Center for Watershed Protection