OT - Access/Turn Restrictions
I have the situation below where road C is pedestrianised except for buses between 0800 and 1800 and is accessible by everything at other times. I've currently got it covered by no_left_turn restrictions from A or E to C and no_straight_on from B or D to C but this doesn't fully describe the restrictions (these have hour_on/off parameters). My question is how would I fully describe this situation with turn or access restrictions? |A | | B------@-------C---------@---D--- | |E Cheers Paul
Hi Paul,
I have the situation below where road C is pedestrianised except for buses between 0800 and 1800 and is accessible by everything at other times. I've currently got it covered by no_left_turn restrictions from A or E to C and no_straight_on from B or D to C but this doesn't fully describe the restrictions (these have hour_on/off parameters). My question is how would I fully describe this situation with turn or access restrictions?
|A | | B------@-------C---------@---D--- | |E
I do not know if garmin supports restrictions that are only in force during certain hours. I have carried out web searches and found nothing so far on that subject. If we had an example map (unlocked) that contained an example of such a restriction we would have a chance to reverse engineer it. The restriction records in the map certainly have space for some more flags/info but all the examples I have seen so far look the same. Cheers, Mark
On Sat, 28 Feb 2009, Mark Burton wrote:
I do not know if garmin supports restrictions that are only in force during certain hours. I have carried out web searches and found nothing so far on that subject. If we had an example map (unlocked) that contained an example of such a restriction we would have a chance to reverse engineer it.
Well, there is an example: The Sierichstraße in Hamburg is a one-way street where the direction of traffic changes daily at 4:00 and 12:00. Garmin respects this with City Navigator as I have just tested. Swiss mountain passes might help as well to understand the mechanism as they are blocked in Winter and disallow routing. -Wolfgang
Hi Wolfgang, On Sun, 1 Mar 2009 12:32:39 +0100 "Wolfgang v. Hansen" <wvhansen@fom.fgan.de> wrote:
On Sat, 28 Feb 2009, Mark Burton wrote:
I do not know if garmin supports restrictions that are only in force during certain hours. I have carried out web searches and found nothing so far on that subject. If we had an example map (unlocked) that contained an example of such a restriction we would have a chance to reverse engineer it.
Well, there is an example: The Sierichstraße in Hamburg is a one-way street where the direction of traffic changes daily at 4:00 and 12:00. Garmin respects this with City Navigator as I have just tested.
That's very interesting. So we know it can be done. However, unless we can see the restriction record and learn the magic, it's going to be difficult to achieve.
Swiss mountain passes might help as well to understand the mechanism as they are blocked in Winter and disallow routing.
To me, that implies that the timing information is likely to be specified in additional fields being added rather than setting values within the existing record because there isn't a huge amount of space in the records that we don't understand the purpose of fully (3 bytes). That isn't enough space to be able to specify an active/inactive time that can be in a range of hours (probably minutes) to months. Hmm, we need an unlocked example. Another thing, mapsource doesn't seem to show the restrictions so you can't query them. Does mapsource show the timed restrictions you mention above? For that matter, does the gps show them in any way? Cheers, Mark
On Mar 1, 2009, at 19:19, Mark Burton wrote:
"Wolfgang v. Hansen" <wvhansen@fom.fgan.de> wrote:
On Sat, 28 Feb 2009, Mark Burton wrote:
I do not know if garmin supports restrictions that are only in force during certain hours. I have carried out web searches and found nothing so far on that subject. If we had an example map (unlocked) that contained an example of such a restriction we would have a chance to reverse engineer it.
Well, there is an example: The Sierichstraße in Hamburg is a one-way street where the direction of traffic changes daily at 4:00 and 12:00. Garmin respects this with City Navigator as I have just tested.
That's very interesting. So we know it can be done. However, unless we can see the restriction record and learn the magic, it's going to be difficult to achieve.
Swiss mountain passes might help as well to understand the mechanism as they are blocked in Winter and disallow routing.
To me, that implies that the timing information is likely to be specified in additional fields being added rather than setting values within the existing record because there isn't a huge amount of space in the records that we don't understand the purpose of fully (3 bytes). That isn't enough space to be able to specify an active/inactive time that can be in a range of hours (probably minutes) to months.
An hour in a week can go in a byte (7*24 < 256); day in year needs 9 bits. So it is possible (but unlikely) this goes within the three bytes. For those interested in experimenting, the relevant bytes are HEADER = 0x004005 in imgfmt/app/net/RouteRestriction.java. The other option is longer records in the restrictions table (Table C). Those are currently 11 bytes, but are not of fixed size. Cheers Robert
On Sun, 1 Mar 2009, Mark Burton wrote:
Another thing, mapsource doesn't seem to show the restrictions so you can't query them. Does mapsource show the timed restrictions you mention above?
No. The times I mentioned were taken from Wikipedia. I just tried the Sierichstraße in MapSource but I can't get a route at all. It seems to be completely blocked in MapSource.
For that matter, does the gps show them in any way?
No. You just get a detour around but don't know why. -Wolfgang
participants (4)
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Mark Burton -
Paul -
Robert Vollmert -
Wolfgang v. Hansen