Remove left turns for less dangerous city traffic • Hacker News Board

Re: Remove left turns for less dangerous city traffic

#141

Post by AtlasBarfed » Sun, Jun 06, 2021, 8:41 PM UTC

PaulDavisThe1st wrote: post #130

gertlex wrote: post #58

Earlier quoted context omitted.

Sounds similar to a "Michigan Left"... which I've known of since I was a kid, though I haven't seen any new ones built that I know of (though, I no longer am in Michigan...) https://en.wikipedia.org/wiki/Michigan_left

Also common in several parts of NJ, notably driving up US1 between Phila and NYC.

New Jersey does jughandles where you do a right turn after the intersection and then a mini-cloverleaf.

Detroit/Michigan go through the intersection in the left lane, u-turn after the intersection, then turn right at the light.

Have lived substantial years in both states.

New Jersey has the driver drive through the same intersection twice.

Michigan has three intersections: the first one you drive through, the second for the u-turn and the third for the right turn, although the u-turn and right turn could often be done on a red light with low traffic, so it might be faster.

Both require more infrastructure (clover leaf lanes or the u-turn and the light for it)

Re: Remove left turns for less dangerous city traffic

#142

Post by bostonabrams » Sun, Jun 06, 2021, 8:46 PM UTC

nabilhat wrote: post #55

The photos in the article are irrelevant to both subject of the title - city streets, and turning left away from controlled intersections: The intersections are large, arterial-scale, rather than typical surface streets in a city. Both have medians to prevent left turns away from the signalled intersections. The first photo also provides an example of a left turn lane blocked by a t-bone crash of two drivers who appe…

Nothing evil about the motivation: this article is from The Conversation (my employer) and we distribute all of our articles widely under a Creative Commons license: https://theconversation.com/us/republishing-guidelines

Our motivation is to publish articles by experts sharing their knowledge and spark discussion, as has been done here on Hacker News: https://theconversation.com/us/who-we-are

Re: Remove left turns for less dangerous city traffic

#143

Post by awillen » Sun, Jun 06, 2021, 8:55 PM UTC

If you found this interesting, I highly recommend the book Street Fight by Janette Sadik-Khan. She was the Commissioner of the NYDOT, and she was able to make really meaningful improvements by looking at relatively easy, low-cost solutions that didn't require enormous political capital. Things like expanding the sidewalk at corners out into the lane where cars are parked, which reduces the length of crosswalks and lowers pedestrian injuries. It's not just an interesting book about transportation infrastructure, it also really has some great lessons for startups about finding ways to make change in large, hairy systems where many of the participants don't want change.

Re: Remove left turns for less dangerous city traffic

#144

Post by whatevertrevor » Sun, Jun 06, 2021, 9:01 PM UTC

Kim_Bruning wrote: post #134

raffraffraff wrote: post #132

Earlier quoted context omitted.

The problem with these roundabouts is that a car driver cannot simply "exit the roundabout". They have to watch front, side and rear for cyclists. IMHO a roundabout should only ever impede traffic on entry. Once you're in the roundabout your journey around and out should be entirely unimpeded. Following the basic principles, there should never be a situation where a vehicle is going around the outter circumference of…

Only the front in theory: the crossing with the bicycle path is fairly close to 90 degrees. Even so -in practice- you should be checking side and rear anytime you make any turn on any kind of intersection (you fail the dutch driving exam if you forget even just once). I agree that even ideally-er the journey out should be 100% unimpeded, but in practice this setup seems to work ok. See also video I posted for you, ab…

What if they moved the bike/pedestrian crossings to further along the lanes away from the roundabout? This would give more room for the cars to exit the roundabout without encountering immediate cross traffic, and more "collection space" on the exit itself so if a driver does have to stop to let a pedestrian/cyclist through they don't impede the roundabout traffic.

Re: Remove left turns for less dangerous city traffic

#145

Post by whatevertrevor » Sun, Jun 06, 2021, 9:06 PM UTC

kibwen wrote: post #116

burlesona wrote: post #51

One of the best ways to eliminate left turns is to replace four way intersections with roundabouts. This has the advantage of working even where there isn’t a grid to facilitate the “3 right turns” strategy. For a great description of why this is so effective, see the recent freakonomics podcast: https://freakonomics.com/podcast/roundabouts/

As a pedestrian and a cyclist, please, no. I don't trust crossing a lane of traffic unless traffic is fully stopped, and nobody expects to stop in a roundabout, so I don't even feel safe using the crosswalks and hoping that the traffic will yield. Let cars come to a complete stop.

I think this is a pertinent point to the way roundabouts are implemented and used in North America. Cars are almost always going too fast on their exit from the roundabout, which renders the "yield" sign on the exit side crosswalks defunct. Not to mention that if they do yield to a pedestrian there, the crosswalks are close enough to the roundabout that they might be impeding traffic in the roundabout itself.

The crosswalks in the roundabout need to be moved away from the circle itself significantly (10-15m at least) for roundabouts to be safe for cyclists and pedestrians. At least for the way they are used in North America IME.

Re: Remove left turns for less dangerous city traffic

#146

Post by drran » Sun, Jun 06, 2021, 9:09 PM UTC

phobosanomaly wrote: post #139

Lammy wrote: post #135

Earlier quoted context omitted.

Yeah, and anybody who can't afford to buy a home in the city should just stop coming here. Maybe they should all have to leave by sundown too :)

They can have multiple free-of-charge parking garages on the outskirts that are associated with a light rail system. So you park, hop on the metro, and head into the city without having to worry about the nightmare of parking or the stop-and-go traffic. I never, ever drive into LA. I use the free parking at an outlying metro station and ride the train in (20 min). You can even leave your vehicle overnight so you can…

Why not just extend a light rail system to suburbs? It will be much faster to have point-to-point rail than car + rail.

Re: Remove left turns for less dangerous city traffic

#147

Post by rrobukef » Sun, Jun 06, 2021, 9:27 PM UTC

Zababa wrote: post #88

burlesona wrote: post #51

One of the best ways to eliminate left turns is to replace four way intersections with roundabouts. This has the advantage of working even where there isn’t a grid to facilitate the “3 right turns” strategy. For a great description of why this is so effective, see the recent freakonomics podcast: https://freakonomics.com/podcast/roundabouts/

As a French, it's really surprising to see how other people from other countries aren't used to roundabouts. I really like how diverse roundabouts are here. Some are arranged like gardens, some have flowers, some have sculptures, some have decorations made by the local school. A funny anecdote: we used to go to Pontarlier from time to time because our grandparents had a house here. Every time we went, we saw that [1]…

You know, it's kinda cool. If that's the worst roundabout in France...

Re: Remove left turns for less dangerous city traffic

#148

Post by Kim_Bruning » Sun, Jun 06, 2021, 9:32 PM UTC

whatevertrevor wrote: post #144

Kim_Bruning wrote: post #134

Earlier quoted context omitted.

Only the front in theory: the crossing with the bicycle path is fairly close to 90 degrees. Even so -in practice- you should be checking side and rear anytime you make any turn on any kind of intersection (you fail the dutch driving exam if you forget even just once). I agree that even ideally-er the journey out should be 100% unimpeded, but in practice this setup seems to work ok. See also video I posted for you, ab…

What if they moved the bike/pedestrian crossings to further along the lanes away from the roundabout? This would give more room for the cars to exit the roundabout without encountering immediate cross traffic, and more "collection space" on the exit itself so if a driver does have to stop to let a pedestrian/cyclist through they don't impede the roundabout traffic.

Posted video link of this type of roundabout in action just above ( https://news.ycombinator.com/item?id=27415631 )

There's just sufficient space for 1 car to tuck in each time.

Note that the priority here is not necessarily to maximize car throughput at all costs; but to ensure safety for all modes of traffic; and to do so inside a given amount of space and cost.

Given a different set of parameters, a different intersection type might be chosen.

(+) That said, note in the video that there's a significant number of people using the bicycle lane and pedestrian path; I think they're carrying more people than the car lanes here. I'm not a traffic expert, but forcing the denser traffic to take a longer route in favor of the less dense traffic does not seem like the right choice here. ;-)

Re: Remove left turns for less dangerous city traffic

#149

Post by jethack » Sun, Jun 06, 2021, 9:41 PM UTC

rjsw wrote: post #104

Zababa wrote: post #88

Earlier quoted context omitted.

As a French, it's really surprising to see how other people from other countries aren't used to roundabouts. I really like how diverse roundabouts are here. Some are arranged like gardens, some have flowers, some have sculptures, some have decorations made by the local school. A funny anecdote: we used to go to Pontarlier from time to time because our grandparents had a house here. Every time we went, we saw that [1]…

The French are not very good at using roundabouts IME, they don't indicate which exit they intend to use.

Just making sure this isn't a misunderstanding: Roundabout signaling laws and conventions vary between countries, and in some countries you're supposed to signal your intent both entering and exiting the roundabout, while in some you only signal at the exit. I'm not sure about French conventions, but in some European countries (Germany, some Eastern European countries, probably others) indicating before the roundabout is actually illegal.

Re: Remove left turns for less dangerous city traffic

#150

Post by PaulDavisThe1st » Sun, Jun 06, 2021, 9:44 PM UTC

AtlasBarfed wrote: post #141

PaulDavisThe1st wrote: post #130

Earlier quoted context omitted.

Also common in several parts of NJ, notably driving up US1 between Phila and NYC.

New Jersey does jughandles where you do a right turn after the intersection and then a mini-cloverleaf. Detroit/Michigan go through the intersection in the left lane, u-turn after the intersection, then turn right at the light. Have lived substantial years in both states. New Jersey has the driver drive through the same intersection twice. Michigan has three intersections: the first one you drive through, the second…

Driving north on US1 between Phila and NYC, there are several turns where you turn/fork right before an intersection, and then make a left onto the minor road. Particularly true in the 20 miles on either side of Princeton.

Yes, I've seen the right-turn after the intersection too.