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Junction style guide: ramp restriction inconsistency

Post by MisterMooCow
We've been discussing the need for straight-through prohibition for off-to-on ramps at intersections over here.

The junction style guide page mentions that there is a ramp transition penalty.

The limited access interchange style guide page says that there is a need to put a straight-through prohibition on to "prevent the routing server from trying to route someone off the freeway just to get back on it".

Is there really ever a case that the routing goes off and back on without something else causing it (slow average speed on the freeway vs. ramp, client "prefer shorter distance over time", hidden/latent restrictions, etc.)? If there's a penalty, then (all other things considered), why would it ever route straight through?

At the very least, there needs to be some consistency between these two pages.
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Re: Junction style guide: ramp restriction inconsistency

Post by jasonh300
skbun wrote:
kentsmith9 wrote:
skbun wrote:I see it go back and forth and back again in Washington and California at the very least, and if what you're saying is true, every instance of it going back and forth represents 'a different street' that the routing engine needs to check against.
I have been fixing it on all the major CA highways/freeways as I go through editing/updated the Exit numbers on each route. I have not attacked I-5 thinking it had so many people travel that road that it must have already been done. That is what I get for assuming. :oops:
Understandable, I think. In fact, we now know from this thread: that we've never come to agreement on which is right, and some believed we need the 'space in the name' format to work around a now-fixed bug. So I guess we come full circle.

Interstates, no space after the "I", then?
The official way is to remove the space. The standard was changed back in January or February. However, it doesn't mean you have to go and change every interstate segment in the U.S. It just means that if you build a new interstate, it should conform to the standard. And a good editor should be updating it while cleaning up existing interstates, unless you're hellbent on not losing your shields for a few months (indefinitely).
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Re: Junction style guide: ramp restriction inconsistency

Post by kentsmith9
CBenson wrote:I don't see the conflict. My understanding is that conditions like the slow speed on the freeway is what causes off/on routing over ramps. Many consider this to be bad routing even if faster, thus the straight-through prohibition.
I agree.
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Re: Junction style guide: ramp restriction inconsistency

Post by kentsmith9
skbun wrote:I see it go back and forth and back again in Washington and California at the very least, and if what you're saying is true, every instance of it going back and forth represents 'a different street' that the routing engine needs to check against.
I have been fixing it on all the major CA highways/freeways as I go through editing/updated the Exit numbers on each route. I have not attacked I-5 thinking it had so many people travel that road that it must have already been done. That is what I get for assuming. :oops:
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Re: Junction style guide: ramp restriction inconsistency

Post by kentsmith9
jasonh300 wrote:And a good editor should be updating it while cleaning up existing interstates, unless you're hellbent on not losing your shields for a few months (indefinitely).
This has been my technique (as I edit for other reasons), but frankly with my eyes the shields are harder to read than the text they replace on the client. :|

I realize I am not editing for only my eyes, but I was not so worried about temporarily breaking the shields since the driver will still see a name of the route in some form.
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Re: Junction style guide: ramp restriction inconsistency

Post by Kuhlkatz
Even though through routing can be done safely on most ramps, road markings almost always indicates that a straight through drive is not an option.
Even with no other signage explicitly prohibiting a straight through drive, my guess would be that this is illegal in most places.
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Re: Junction style guide: ramp restriction inconsistency

Post by MisterMooCow
jasonh300 wrote:To answer BlazeTool's question, yes, it may generate a problem report if someone actually goes straight, but no more than frequently violated illegal turns.

When the road crossing the freeway is split, I do the crossed exits trick, which prevents off-and-on routing and eliminates the need to restrict any turns.

https://www.waze.com/editor/?zoom=7&lat ... TTTFTTTTFT
Ugh, that's hard on the eyes (though I thought the same thing about bow-tie intersections when I first saw them, so maybe the crossed-exits trick will grow on me). Ignoring that, I'm still at a loss as to why there would be routing through that intersection (vs. the freeway). The average speeds seem to favor the freeway. Were there lots of complaints at this intersection or was it by chance a one-off wayward GPS that confused the routing server into thinking that the driver was actually going down the ramp?
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Re: Junction style guide: ramp restriction inconsistency

Post by MisterMooCow
So, just to bring this full circle-- I think the "be sure to restrict" paragraph in the wiki page is too strongly worded. Perhaps something like "Until the routing engine is refined, you may find it necessary to restrict..." with indications of the pathological cases that might make it necessary. Maybe even throw in the "Jason method" of crossed-exits as an alternative.
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Re: Junction style guide: ramp restriction inconsistency

Post by MisterMooCow
BlazeTool wrote:Just an FYI for anyone following along. Discussion of routing off and back on via ramps has also popped up over here, referring to this interchange. For the record, the path via ramps is 1082 meters, via the freeway is 1100 meters.
I just got around to reading this, where there is a post that says:
jasonh300 wrote: There's coding to prevent that type of routing if the city name is the same on all segment before, during and after the ramps. However, city names often change at those junctions, so the simple solution is to remove the city name and therefore remove all doubt.
So I'm having trouble seeing how the "put turn restrictions on straight-through to prevent ramp-routing" directive isn't further qualified for pathological cases. What am I missing?
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Re: Junction style guide: ramp restriction inconsistency

Post by MisterMooCow
So, should I take the silence here as being consensus on toning down the "Be sure to restrict the straight through" on the wiki page?

Perhaps to something like
In some cases, editors have found it necessary to restrict straight-through motion. If you are encountering inappropriate routing that seems inexplicable, please post details of it on the forums so that other editors can help identify what might be causing the problem -- and get support form waze developers if needed.
I don't want to make any gung-ho edits...
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