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just like now, the car does cross the bus lane. in some places, the bus lane is used by cars as a right turn lane, or if there's a dedicated right turn lane, th

just like now, the car does cross the bus lane. in some places, the bus lane is used by cars as a right turn lane, or if there's a dedicated right turn lane, the bike lane is routed around it, and the cars still merge into it across the bus lane, while yielding to bikes (and buses) as need be.

u801e 5y ago
The problem is that the system you're proposing introduces an extra step before turning. That is, yield to a bus, then to a cyclist, then to pedestrians. The more steps there are, the more likely one will make a mistake and fail to yield because they failed to account for one of the steps necessary to successfully make a turn. The traditional system where a right turning vehicle moves as far right as practical in advance of making a right turn reduces the number of step necessary to complete the turn. That is, they only need to account for yielding to pedestrians instead of 3 streams of traffic (bus, then cyclist, then pedestrian). That's why I asked about having separate traffic light phases for each lane. That would ensure that only a single lane is allowed to enter the intersection and complete their turn without having to yield to any other traffic stream. But, doing that would reduce instersection throughput by a significant amount.
- clairity 5y ago
  that's actually a traffic calming technique, to make car drivers more attentive and more purposeful/communicative, rather than driving on (human or machine) auto-pilot all the time. more obvious collision dangers make car drivers more mindful, but to drivers, pedestrians by themselves are clearly not enough 'danger' in a car-centric city to demand appropriate attentiveness. cars create some of the highest congestion/vehicle, as they demand more street area/time per person than other forms of transportation. so by displacing cars, viable mixed-mode transportation reduces congestion extralinearly, which in turn mitigates the extra right-turn burden for cars despite needing to navigate a more diverse traffic stream.
  - u801e 5y ago
    >> The problem is that the system you're proposing introduces an extra step before turning. That is, yield to a bus, then to a cyclist, then to pedestrians. >> The more steps there are, the more likely one will make a mistake and fail to yield because they failed to account for one of the steps necessary to successfully make a turn. > that's actually a traffic calming technique, to make car drivers more attentive and more purposeful/communicative, rather than driving on (human or machine) auto-pilot all the time. more obvious collision dangers make car drivers more mindful I don't really know if this assumption holds. Collisions are more common complex intersections versus simple ones. For example, one is more likely to get into a collision when making a left turn from a side road because they have to check for pedestrians approaching from the left, pedestrians approaching from the right traffic approaching from the left, traffic approaching from the right, and possibly traffic entering the roadway directly across from them. If you contrast that with a roundabout, when entering, one has to check for pedestrians approaching from the left, pedestrians approaching from the right, and traffic approaching from the left. Because there are fewer things to check for, the chance of getting into a collision is reduced. The other part of it is when exiting the intersection. After one has started turning, one needs to check for any pedestrians who may be crossing before completing their turn, so that's another step that the left turning driver has to account for. With a roundabout, that check is postponed and actually can be thought of as a separate check once they get to the exit of the roundabout (checking for pedestrians). You could get a similar spacing between checks if, instead of making a left turn, make a right turn and then a u-turn. In the case of the right turn crossing muliple lanes of traffic, the driver not only has to check for more things, but they don't have the time spacing to re-orient themselves to get ready for the next check. That increases the probability that the driver may fail to check before proceeding.

u801e 5y ago

The problem is that the system you're proposing introduces an extra step before turning. That is, yield to a bus, then to a cyclist, then to pedestrians. The more steps there are, the more likely one will make a mistake and fail to yield because they failed to account for one of the steps necessary to successfully make a turn. The traditional system where a right turning vehicle moves as far right as practical in advance of making a right turn reduces the number of step necessary to complete the turn. That is, they only need to account for yielding to pedestrians instead of 3 streams of traffic (bus, then cyclist, then pedestrian). That's why I asked about having separate traffic light phases for each lane. That would ensure that only a single lane is allowed to enter the intersection and complete their turn without having to yield to any other traffic stream. But, doing that would reduce instersection throughput by a significant amount.

clairity 5y ago
that's actually a traffic calming technique, to make car drivers more attentive and more purposeful/communicative, rather than driving on (human or machine) auto-pilot all the time. more obvious collision dangers make car drivers more mindful, but to drivers, pedestrians by themselves are clearly not enough 'danger' in a car-centric city to demand appropriate attentiveness. cars create some of the highest congestion/vehicle, as they demand more street area/time per person than other forms of transportation. so by displacing cars, viable mixed-mode transportation reduces congestion extralinearly, which in turn mitigates the extra right-turn burden for cars despite needing to navigate a more diverse traffic stream.
- u801e 5y ago
  >> The problem is that the system you're proposing introduces an extra step before turning. That is, yield to a bus, then to a cyclist, then to pedestrians. >> The more steps there are, the more likely one will make a mistake and fail to yield because they failed to account for one of the steps necessary to successfully make a turn. > that's actually a traffic calming technique, to make car drivers more attentive and more purposeful/communicative, rather than driving on (human or machine) auto-pilot all the time. more obvious collision dangers make car drivers more mindful I don't really know if this assumption holds. Collisions are more common complex intersections versus simple ones. For example, one is more likely to get into a collision when making a left turn from a side road because they have to check for pedestrians approaching from the left, pedestrians approaching from the right traffic approaching from the left, traffic approaching from the right, and possibly traffic entering the roadway directly across from them. If you contrast that with a roundabout, when entering, one has to check for pedestrians approaching from the left, pedestrians approaching from the right, and traffic approaching from the left. Because there are fewer things to check for, the chance of getting into a collision is reduced. The other part of it is when exiting the intersection. After one has started turning, one needs to check for any pedestrians who may be crossing before completing their turn, so that's another step that the left turning driver has to account for. With a roundabout, that check is postponed and actually can be thought of as a separate check once they get to the exit of the roundabout (checking for pedestrians). You could get a similar spacing between checks if, instead of making a left turn, make a right turn and then a u-turn. In the case of the right turn crossing muliple lanes of traffic, the driver not only has to check for more things, but they don't have the time spacing to re-orient themselves to get ready for the next check. That increases the probability that the driver may fail to check before proceeding.