Circling back to the traffic circles. I remember a experiment on Myth Busters that showed the circles had more throughput than stop signs for cars.
HOWEVER, they didn't look at some safety issues I experience as a driver.
Among the differences between a 4-way stop and a traffic circle
A. The crosswalk is 20 feet from the traffic circle. This is fine, unless traffic is backed up beyond the crosswalk. Then it basically becomes another intersection. All it takes is to be the 2nd car waiting to get into the circle.
B. The traffic circle situation is more like sitting at a stop sign wanting to cross a busy one-way street where the cross-traffic doesn't stop. And cross traffic wanting to turn right don't signal.
C. In congestion, a driver wanting to enter the circle can not tell when he can go until a car in the circle exits the circle to go the opposite direction as he is going. This doesn't leave much time to react to get into the circle before the next car comes around. That makes for rushed decisions.
Issues:
1. A pedestrian may enter into the crosswalk from the right when the driver is focused on the left.
I encountered this when traffic was congested entering the circle due to traffic leaving the parking lot across from Maples after a game. I'm headed southbound on Campus Drive at Jane Stanford/Serra. A car is stopped in front of me, waiting to enter the circle. I'm waiting behind him, with maybe my bumper into the crosswalk. No pedestrians in sight. I'm watching the traffic in the circle, watching for cars to peel out of the circle headed in the opposite direction I am headed. One does, and the car in front of me goes. I start to pull forward, but 120 degrees from where I've been looking, pedestrians enter the crosswalk from my right. Yes, the driver should reassess what used to be clear is still clear just like at a stop sign when you want to cross a one-way street; Yes, the pedestrian should be able to see the driver isn't looking in their way.
2. People (pedestrians, bicyclists, etc) in or approaching the crosswalk are backlight by the street lights, from the point of view of a driver approaching the traffic circle. In the evening, the pedestrians are not well lit from the point of view of the approaching drivers. But there are lots of moving lights to catch your attention elsewhere.
At the 3 circles on Campus Drive, for entering each from any of 4 directions, the street lights are above and behind the pedestrians on the driver's left and right. Why not set up lights so pedestrians are illuminated from the front as viewed by the driver approaching the crosswalk and circle?
3. A bicyclist coming down the pathway and then straight out into the walkway at 15 to 20mph can seem to appear out of nowhere. A bicyclist going 15 MPH is halfway across the street (to middle of the median) in about 2 seconds, just 1 second from running into you (or vice versa). Just 2 seconds before that, he was 100 feet away from the driver, on a pathway. Spotting the approaching bicyclist is aggravated by the lighting at night.
(What bicyclist on the path headed to the crosswalk would voluntarily turn 90 degrees to get onto the street parallel to his path, just so they could get into the traffic circle and cross with traffic? Nope, they'll go straight through the crosswalk with the pedestrians.)
I would suggest at least two remediations.
- The first would be to alter the sloped transition from sidewalk to street to be at 90 degrees to its current orientation so it doesn't present a raceway for bicyclists. I expect that can be done in an ADA-compliant way (but I'm not expert). (Alternately, have the pathway and the crosswalk be offset from each other. Having a turn both slows down a bicyclist and provides more time for drivers to see they are about to enter the crosswalk.)
- The second would be to move or add lighting so those in or approaching the crosswalk are illuminated primarily from the side facing the driver. Especially on the driver's right. A low (8' high?) light would be good.
Until traffic circles are common in the US, I expect a college campus will have a large percentage of drivers (students, parents, visiting opponents & their fans) that are not used to them, increasing the chance of accidents year after year. If these were traffic circles in residential Mountain View, most drivers would be used to them after the first year.
Traffic circles also have an obvious Denial of Service vulnerability. If I were a rival, I'd exploit that on game day. Campus security would need to be on hand to stop it.
