(10-28-2019, 03:44 PM)danbrotherston Wrote: I have mocked out a few different options (I just used preview on mac) to try and guess what you are saying.

[....]

But all of these lead to a really big point, what problem exactly are we trying to solve here? Why are we creating turns different from simple tight narrow turns?  The original reason for the ped island and slip ramps was to increase vehicle speeds in turns, I see this as an anti-goal, I don't really understand why we wouldn't just aim to go back to a traditional tighter corner with lower speeds all throughout.

(10-28-2019, 04:50 PM)jamincan Wrote: From a driver perspective, I hate slip lanes because unless they have space for a merging lane, they effectively put the traffic I'm supposed to merge with in my blind spot. A regular turn is safer for drivers and pedestrians/cyclists.

(10-29-2019, 10:00 AM)ijmorlan Wrote:

(10-28-2019, 04:50 PM)jamincan Wrote: From a driver perspective, I hate slip lanes because unless they have space for a merging lane, they effectively put the traffic I'm supposed to merge with in my blind spot. A regular turn is safer for drivers and pedestrians/cyclists.

Even ones like at Westmount and University? Where you actually turn onto the road, you’re basically just turning from one road onto another, except it’s a side road next to the road you were on rather than one big piece of pavement. I can see where you’re coming from if the separated lane is more like at University and Weber, where you’re almost facing in the direction you will be going by the time you reach the end of the turn lane.

(10-29-2019, 10:29 AM)jamincan Wrote:

(10-29-2019, 10:00 AM)ijmorlan Wrote: Even ones like at Westmount and University? Where you actually turn onto the road, you’re basically just turning from one road onto another, except it’s a side road next to the road you were on rather than one big piece of pavement. I can see where you’re coming from if the separated lane is more like at University and Weber, where you’re almost facing in the direction you will be going by the time you reach the end of the turn lane.

I haven't turned at that intersection, so I can't really comment well on how good or bad it is, but as soon as the oncoming traffic is over your shoulder, it's in your blind spot, and it looks to me like that would still be the case at Westmount & University.

(10-28-2019, 04:49 PM)ijmorlan Wrote:

(10-28-2019, 03:44 PM)danbrotherston Wrote: I have mocked out a few different options (I just used preview on mac) to try and guess what you are saying.

[....]

But all of these lead to a really big point, what problem exactly are we trying to solve here? Why are we creating turns different from simple tight narrow turns?  The original reason for the ped island and slip ramps was to increase vehicle speeds in turns, I see this as an anti-goal, I don't really understand why we wouldn't just aim to go back to a traditional tighter corner with lower speeds all throughout.

I just took a look on Google Maps. The 3 that exist at Westmount and University are pretty much I’m looking for, except I would probably try to go for a smaller radius where each lane ends and less forgiving curbs (keeping in mind that large trucks do still need to be able to make the turns).

https://goo.gl/maps/DrSjQDPGTX6PXG15A

The problem we are solving is making it better for everybody, especially pedestrians. I would much rather cross Westmount and University, even with the fairly broad radii currently in place, than a comparable intersection without separated turn lanes. Crossing a single lane of one-way traffic is almost always easy, even if it is moving fairly quickly. Then, with that out of the way, the radius at the main intersection is effectively zero, minimizing the crossing distance. And if I’m crossing both ways, I don’t interact with the right-turning traffic at all when I’m ending one crossing and beginning the other.

I don’t like the islands at Weber and University; they are too small, and the lanes are just smooth curves. Also traffic isn’t forced to choose where it’s going until rather close to the intersection so the ease of crossing what I called a single lane above is reduced — really I need to watch other lanes for people pulling late maneuvers. By contrast at Westmount the islands have lots of space and traffic pretty much has to choose where it’s going some distance back from the crossing.

Some numbers crossing Weber at University:

North side (islands): 18.1m
South side (no islands): 23.7m

I don’t like the existing islands there, but rebuild that intersection with the same islands as at Westmount and University and I’ll take them any day.

Of course another approach, which is, um, a little hard to retrofit into existing roads but would actually be perfectly practical if adopted as a design approach for an entire new area of a city, would be to put the sidewalks about 100m away from the roads. Then put a pedestrian refuge and pedestrian crossings where the sidewalk crosses the roads. No turning traffic or other complexities and only need to cross 2 lanes at a time no matter how many turn lanes there are at the intersection. Put parking lots immediately next to the road, and buildings either on both sides of the sidewalk or only on the non-road side, depending on how much parking is needed.

(10-29-2019, 11:04 AM)danbrotherston Wrote: I see.  So what you are describing are what the region refers to as something like "enhanced, delayed decision point slip lane" (because drivers must slow down and nearly stop at the corner instead of being able to turn at speed) and they are preferred by regional engineers in new construction.

Yes, they are not as bad as traditional turn islands. But I disagree that these are better for peds than no slip lanes, yes, they do reduce the crossing distance, but I still don't believe drivers are looking for peds while making turns, the main goal is still to benefit drivers, why not just have a tighter turn with no slip lane.  The value here is only that drivers can turn faster.  Large trucks can easily make these turns, even far tighter turns.  They're only "better" when prioritizing cars is the assumed condition.

(10-29-2019, 01:07 PM)ijmorlan Wrote:

(10-29-2019, 11:04 AM)danbrotherston Wrote: I see.  So what you are describing are what the region refers to as something like "enhanced, delayed decision point slip lane" (because drivers must slow down and nearly stop at the corner instead of being able to turn at speed) and they are preferred by regional engineers in new construction.

Yes, they are not as bad as traditional turn islands. But I disagree that these are better for peds than no slip lanes, yes, they do reduce the crossing distance, but I still don't believe drivers are looking for peds while making turns, the main goal is still to benefit drivers, why not just have a tighter turn with no slip lane.  The value here is only that drivers can turn faster.  Large trucks can easily make these turns, even far tighter turns.  They're only "better" when prioritizing cars is the assumed condition.

Well, this pedestrian would rather cross an intersection with carefully designed slip lanes. So you may want to consider that this isn’t entirely a motor vehicle enthusiast vs. pedestrian safety enthusiast issue.

Why are they called “delayed decision”? It seems to me the driver has to make a decision to use the slip lane earlier than they are forced to make that decision at a non-slip-lane intersection or at one like Weber and University which has small slip lanes.

I’m a bit confused by “The value here is only that drivers can turn faster”. With the slip lanes I favour, I don’t see how they can turn faster, because of the tight turn at the exit.

(10-28-2019, 01:19 PM)avernar Wrote:

(10-27-2019, 01:13 PM)danbrotherston Wrote: Also, right turn lanes are 100% unnecessary if they have pedestrian scrambles.

Unless they screw it up like Toronto did and allow pedestrians to also cross (like a normal intersection) when the cars had green.

(10-29-2019, 01:15 PM)danbrotherston Wrote: And yes, what I mean is that, instead of having any slip ramp, we could have a tighter turn radii---I believe this would be better for peds, but drivers would have to slow down more.  The slip ramps (of any kind) exist in order to allow turning traffic a few benefits, first being much wider corners without requiring to the signal poles to be moved too far back from the intersection, and second being a yield instead of a stop for drivers.

(10-30-2019, 04:33 PM)ijmorlan Wrote:

(10-29-2019, 01:15 PM)danbrotherston Wrote: And yes, what I mean is that, instead of having any slip ramp, we could have a tighter turn radii---I believe this would be better for peds, but drivers would have to slow down more.  The slip ramps (of any kind) exist in order to allow turning traffic a few benefits, first being much wider corners without requiring to the signal poles to be moved too far back from the intersection, and second being a yield instead of a stop for drivers.

Slip ramps could be built with any turn radius, and could turn back to parallel so they end at a right angle with the road, so I’m not really seeing how your point applies to hypothetical slip ramps that are designed differently from the ones we currently have in the city. And as I’ve said I believe that slip ramps of appropriate design are a benefit to pedestrians, not just motor vehicles. I have no idea who the traffic engineers believe benefit from slip lanes. Anybody who is opposed to all slip ramps on the basis that they’re bad for pedestrians is not speaking for all pedestrians. Of course, I may be a minority of 1 for all I know.

(10-30-2019, 09:00 PM)danbrotherston Wrote:

(10-30-2019, 04:33 PM)ijmorlan Wrote: Slip ramps could be built with any turn radius, and could turn back to parallel so they end at a right angle with the road, so I’m not really seeing how your point applies to hypothetical slip ramps that are designed differently from the ones we currently have in the city. And as I’ve said I believe that slip ramps of appropriate design are a benefit to pedestrians, not just motor vehicles. I have no idea who the traffic engineers believe benefit from slip lanes. Anybody who is opposed to all slip ramps on the basis that they’re bad for pedestrians is not speaking for all pedestrians. Of course, I may be a minority of 1 for all I know.

I can tell you the engineers use ramps to benefit drivers, that's the reason they do almost everything they do in the region, but also, they've told me outright. They aren't going to build a slip ramp that doesn't increase the turn radius on a corner, even if it is geometrically possible.

As for peds, there are objective measures of safety that trump our opinions.  If you can show data which shows islands make safer intersections than narrowing turn radii and shrinking intersections, I'll happily support them, but all the data I've seen contradicts that.

(11-04-2019, 09:28 AM)panamaniac Wrote: A question - in Ontario, if a school bus is stopped on a city street divided by a centre boulevard, is the oncoming traffic required to stop?