[OSM-talk] Lane turn restrictions

Yann Coupin yann at coupin.net
Wed Aug 19 13:50:51 BST 2009


I admit that I ended up with a large and complex proposal. Since then  
it appeared that some aspects have already been covered. But not all  
of the lane part AFAIK. What you suggest whould probably be an  
independant proposal, at least for clarity reason, but has value  
nonetheless although I would prefer the "allowed" vs. "restriction"  
version because it's far more common if we interpret "allowed" as  
"suggested". On highways for instance, it's usually not so much  
prohibited as it'd be impractical, as it would require a sharp turn  
right before the exit/bifurcation.

What's left to be clarified is how lanes are numbered.


Yann

Le 19 août 09 à 10:55, Steve Hill a écrit :

> On Wed, 19 Aug 2009, Yann Coupin wrote:
>
>> I once started a proposition to do just that but it didn't get much  
>> traction, feel free to discuss it.
>>
>> http://wiki.openstreetmap.org/wiki/Proposed_features/Relation:type%3Droute_instruction
>
> I've not read the discussion page yet, but some initial thoughts:
>
> Your first examples aren't topologically identical - the first is a  
> 2 lane road with a short 3 lane section followed by a right hand  
> turn whilst the second is a 3 lane road with a right hand turn  
> immediately followed by dropping down to 2 lanes.  Of course, this  
> doesn't give you enough detail to know what lane you've got to be in  
> (although you could make some educated guesses).
>
> I also don't see the need for phonetics to be tagged (in fact, it  
> seems harmful because it breaks multi-language support).  We don't  
> know what kind of display device is going to be used (whether it be  
> on-screen instructions, text to speech, etc.) and it should be up to  
> the software to decide how to present it to the user rather than  
> being explicitly tagged like that.
>
> Overall, the proposal seems a bit too complex - I had envisaged a  
> simpler system whereby you could set a relation similar to a turn  
> restriction, such as:
> 	TAGs:
> 		type: lane_restriction
> 		lanes: 1,2
> 	Members:
> 		from: <way the user is driving along>
> 		to: <way the user wants to turn onto>
> 		via: <junction node>
> Whereby that marks a restriction that lanes 1 and 2 (the left two  
> lanes, in the case of the UK) cannot be used in a route using the  
> <from>, <to> and <via> members.
>
> It would actually be nicer to be able to tag which lanes are allowed  
> rather than which are disallowed, but that would be inconsistent  
> with the existing turn restrictions (maybe that isn't a problem?   
> comments?)





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