Highway Off-Ramp Segment Question

[Spil]

If it is at a T-intersection, or if the crossroad is named the same on both sides of the split road, then there's no problem with naming the median segment the same as those segments.

However, if the crossroad has different road names or city names on each side of the split road (for example, N. Main St. above the split and S. Main St. below the split), then you must leave the median segment as "No Name", so that the turn instructions will pick up the appropriate segment name from the next segment automatically.

[rottielover]

mapcat bow tie?

I don't think that's going to be necessary here. Bow ties are used to stop u-turns on cross junctions, but on t-junctions, you can set up the turn restrictions in a way to stop the u-turns from happening, which is already being done here.

That is one benefit, but the other benefit is allowing you to connect split roads to singles using a single junction point. It's just a thought.

Edit, I took a 2nd look. The turn restrictions are such that you can make a U-Turn if you were heading South on Keele and came to this "T" segment. (example 1). From the aerial image it doesn't look like a u turn would be allowed there, but I have no familiarity with Canada, you'd have to tell me if you would be allowed a U-Turn there. *IF* not, then the bow tie method would allow you to suppress any U-turns, and bring all the segments to one junction. Again it's just a thought, and I have no idea about the U-Turns at that location.

[rottielover]

mapcat bow tie?

[PhantomSoul]

I agree that bow ties look weird in the client, particularly if you have it set to auto-zoom and you stop for a red light. So I try to avoid them unless improper u-turn instructions start to become repeat problems in a particular junction.

[ottonomy]

It seemed to me that the early consensus in this thread was that example 2 was better for routing purposes. Obviously, if U-turns are specifically allowed on the minor highway there at the intersection of the ramp, then a small two-way section would be needed there.

Since your question about the applicability of bow-ties is still up was the air, I thought I would take the time to confirm my own thoughts on that. I created some temporary example roads out in the sticks, so I could fiddle with turn restrictions and make useful screenshots without possibly messing up someone's hard work.

As andrewkjs said, a bow-tie is not necessary at a T-junction for controlling U-turns.

The off-ramp segments have permission to make their turns onto the highway:

Intersections12.jpg (40.03 KiB) Viewed 488 times

The southbound segment of the highway can have a left turn restriction to prevent it from using the short ramp segment to make a U-turn, but if it's not a T-junction, and another street is inline with the ramp, then the southbound highway segment needs permission to turn left onto that street. The median segment has to allow a lefthand turn going north, because that is one of the allowed turns from the off-ramp. So now you have potential U-turn routing from the map, and no way to prohibit it without also limiting a legal left turn:

Intersections34.jpg (40.56 KiB) Viewed 488 times

Enter the mapcat bow-tie. With it in place, you can give the off-ramp segment and the highway segments all the turn permissions they need, but specifically restrict U-turns where applicable:

Intersections56.jpg (40.59 KiB) Viewed 488 times

Does this make sense?

[jmp316]

I answered earlier, I would keep it as a ramp. It is an exit to a road, not a crossroad.

[jmp316]

Bow ties look terrible in the client IMO. I'd say option 2.

[hmarian]

Thanks for the explanation.
The concept of bow ties intersection is now clear to me.

My question regarding the two examples are related to the road type between the two parallel Northbound and Southbound. They are both a T junction to a parallel road segment, but I'm still not clear if it suppose to be a street type segment or a ramp type segment.

Please try to address my question in your answer.

Thanks,
Hagay.

[hmarian]

So what is the conclusion?
Using example 1 or example 2?

[hmarian]

Could someone explain the concept of bow ties and how is it related to the question asked?

Any other thoughts so we could reach conclusion on this?

Thanks,
Hagay.