Re:Humans Are Slamming into Driverless Cars and Exposing a K...
by ScottRAB on Monday December 21, 2015 @06:14PM
(#10774281)
All modern roundabouts have median islands separating incoming and outgoing auto traffic. Pedestrians don't have to find a gap in two directions of traffic, just one. This is safer for pedestrians, especially for younger or older ones, because they only have to concentrate on one direction of traffic at a time. This is what is meant by two-phase. Cross the first half, pause if you need to, then cross the second half. On multi-lane crossings pedestrian beacons or signals are often added if the auto (or pedestrian) traffic is too numerous. The signals can also be two phase, requiring the pedestrian to push a second button when they get to the median. The median can also have a Z path to reorient the pedestrian to view oncoming traffic. Also, the signals usually rest in off, so they are only activated if a pedestrian needs the help crossing. This way only motorists that need to stop are delayed.
Re:Humans Are Slamming into Driverless Cars and Exposing a K...
by dalke on Saturday December 19, 2015 @12:19PM
(#10764128)
"Significantly more than $1.7m to build a roundabout"
No. Look again. The quoted text says "$1.7 million to design and build the roundabouts". Plural. That was three roundabouts, not one, on "51st Ave S, Renton Ave S and S Roxbury ST". And some of the objections you just now raised have been addressed in links I gave earlier, including examples of SDOT proposals for roundabouts in urban Seattle.
I give up. You have decided on your answer and no real-world information will change your personal beliefs. You win.
Re:Humans Are Slamming into Driverless Cars and Exposing a K...
by WalterBright on Sunday December 20, 2015 @03:40AM
(#10766505)
It's still 10x the cost. Costs of the light system can be further reduced by instead of installing a computer at the light, have the computer centrally located to serve any number of lights. Since the cameras are already network connected, this is practical.
I've been in countries that are comfortable with roundabouts. They also still have traffic lights everywhere. Something is missing in your analysis that explains this choice.
* Adding roundabouts requires more land, which is in tight supply in a built-up city like Seattle. I don't think shaving the corners off of buildings is going to go over very well.
* As I've noted, the buildup of the cameras is very recent. The traffic light data you cited is over a year old. They're creeping into the side streets now.
* Nobody needs a study to see the obvious improvements possible in cases I cited.
* Given the desire of the government to install cameras everywhere on the roads, the cost of them is going to be there with or without roundabouts.
* Far friendlier to pedestrians? How is that possible when cars don't stop? I've crossed roundabouts in England as a pedestrian. It involves pushing a button and a traffic light turns red so you can cross. I.e. the traffic lights are still there!
* In Romania the roundabouts also had traffic lights for the pedestrians, as well as pedestrian tunnels under the intersection. That can't be inexpensive.
* I can see a roundabout as cost effective in a rural area where land is cheap and there are few pedestrians. In a builtup city, not so much, as they'd be massive and expensive construction projects. A $40,000 box can be installed instead with no disruption and immediate improvements. Sounds like a winner to me.