Sunday, December 20, 2009

Riverside Roundabouts

Roundabouts can be safe or dangerous; inclusive or exclusive of bikes and pedestrians. In Enschede, Netherlands, we experienced the gold standard in safe multimodal roundabouts, consisting of concentric lanes, inner for cars, outer for bikes/peds, separated by island arcs. Bikes/peds have right of way and are easy to spot by motorists looking to enter/exit the roundabout. Traffic moves efficiently and safely.

Riverside roundabouts should be carefully designed after studying innovative examples like these.

6 comments:

Peter said...

this is excellent!

everyone keeps saying that roundabouts are awesome, but i almost get killed every time i enter this one particular roundabout (the only one i know about) in sf. the cars 'turning' off the circle don't really need to turn at all -- they just go straight, right into me!

Nathan Phillips said...

Peter - see my next blog - I hear you - some can be incredibly dangerous.

Anonymous said...

It looks nice, but I haven't actually been through a roundabout that is safe for pedestrians. And if you think about kids crossing them, I'd much rather have the cars stopped. The plans I've seen about putting roundabouts at Centre and Beacon Streets in Newton Centre are scary in my opinion. Too many teens walk down there. At least I see them wait for the light. Talking to each other and trying to cross the street watching for cars that may not stop is just too dangerous.

Steve Runge said...

Anonymous: The thing about the safe roundabouts (and there are none that I know of currently in the boston area) is that they slow traffic to 20 mph or below, which means several things:

1. traffic is slow enough that pedestrians and drivers can make eye contact & communicate
2. traffic is slow enough that drivers have more time to react and stop, if need be and
3. traffic is slow enough that even if there's a collision, the chances of a serious injury are small. (1 in 40, vs. 1 in 5 at 30mph)

We're so used to thinking in terms of drivers ALL driving over 30mph (even in school zones, with lights flashing) that we base all of our sense of pedestrian danger on that speed. At lower speeds, the whole game changes

Anonymous said...

OK, but I have never seen a roundabout slow cars to 20MPH. I understand the theory, but the vast majority of people I see treat a roundabout as entrance ramps to highways. They are looking to the left and stepping on the gas when they think they have an opening. I'm not sure I see that changing here. They are NOT looking or expecting pedestrians to be in front of them, and certainly not making eye contact. And if you get a roundabout with enough traffic from one entrance, then they seem to disregard all the rules and think they have the right of way over the folks already in the roundabout. I would not agree to risk pedestrians being hurt on the theory that we're going to slow cars enough to provide eye contact or lessen their chances of being killed. 1 in 40 is not small enough, not when I haven't heard of anyone getting hurt with the existing stop lights. Build a pedestrian overpass, then I would talk about environmental savings.

probiscus said...

Hey I think you just need to make sure that properly designed Modern Roundabouts are installed. Check out this link for examples. Modern roundabouts are much smaller and slower moving than the rotaries and traffic circles common in Massachusetts.

Despite the slower speeds, both one and two lane modern roundabouts can handle just as high a volume of traffic with less stop and go pollution than lights.

Not only that, but single lane roundabouts are inherently bike friendly and two lane roundabouts can be easily made bike friendly with a bypass, as you mentioned.