- In a parking lot with barrels
- Single lane approaches at four legged intersection
- Show driver which way to go (left, through, right) as they pull up to the intersection
- Test for two 15 minute periods and present average
- Test all way stop, uncontrolled with “traffic cop”, and roundabout (let drivers warm up in roundabout for a half an hour since we’re Americans, arguably not used to roundabouts)
- Looked like about forty cars were circulating, enough to keep queues on all four legs
- Count the total number of cars that goes through the intersection during 15 minute period
Roundabouts win with 460 vehicles going through the intersection during the 15 minutes. All way stop signs had 385 vehicles go through in the 15 minutes and the traffic cop had 289 vehicles go through. Roundabouts also have a safety advantage with less severe crashes.
Of course stop signs are a lot cheaper than a roundabout, so there are plenty of intersections that don’t warrant the extra cost of a roundabout but are just busy enough to need all way stop signs.
Takeaway question – should we ever use traffic cops or just go to all way stop control?
Need to calculate roundabout capacity? Check out our roundabout capacity analysis spreadsheet. An easy-to-use spreadsheet that can easily be adjusted for standard defaults, such as lane utilization, critical headway or follow-up headway, according to local factors.