[pgrouting-dev] Support for Time Constraints
Stephen Woodbridge
woodbri at swoodbridge.com
Wed Jun 22 16:06:18 EDT 2011
Hi Daniel, Jay,
Ok, sorry for my *rant* about OSM attributes!
So it looks like osm2po does the importing and classification via its
black box java .jar file and you can use the tables afterwards. Ok this
could work, but I'm not sure I like the idea of using someone's black
box to import the data. Long term it would be better to just use
osm2pgrouting and to understand the issues that I presented and a write
a stored procedure to do the classifications that are needed.
I have not been on the osm routing list, but I'm sure we can get
guidance from them to setup appropriate classifications. Or if someone
want to to try out osm2po we can review the resultant tables and look at
how they classified segments.
-Steve
On 6/22/2011 12:19 PM, Daniel Kastl wrote:
> Hi Jay,
>
> You could once import OSM data with http://osm2po.de/
> You can't configure the import of attributes as you do with
> osm2pgrouting, but the created tables have a good set of attributes.
> So you don't need to worry much about what Steve mentioned, that there
> are no clear rules for setting attributes.
>
> Daniel
>
>
> 2011/6/23 Stephen Woodbridge <woodbri at swoodbridge.com
> <mailto:woodbri at swoodbridge.com>>
>
> Hi Jay,
>
> For now just push forward with what you have for testing that should
> be fine.
>
> In general, the OSM data has lots of options for classification, but
> it does not have clear standards or descriptions on how segments
> SHOULD be classified, so it is easy for different people to
> interpret the classifications differently. Hence, you end up with a
> huge list of segment classes like on:
>
>
> http://workshop.pgrouting.org/ chapters/advanced.html
> <http://workshop.pgrouting.org/chapters/advanced.html>
>
> with only short 1-2 word descriptions. So for example what is the
> difference between motorway, motorway_link, motorway_junction or for
> that matter a lane, opposite, opposite_lane, track, byway,
> circleway, living_street, residential, road, secondary, tertiary,
> track, roundabout and grade* types and how should these be
> represented as classes or for average speeds?
>
> In the link above they are trying to deal with this same issue by
> assigning a cost to the classes table based on the type name. They
> then use that cost as a multiplier of the length which is weird, but
> kind of works. This assumes the a cost multiplier of 2.0 means that
> that class takes 2X as long to traverse that segment as a class with
> a cost multiplier of 1.0.
>
> UPDATE classes SET cost=2.0 WHERE name IN ('pedestrian','steps','
> footway');
>
> versus:
>
> UPDATE classes SET cost=0.3 WHERE name IN ('motorway','motorway_
> junction','motorway_link');
>
> and in these segments vehicle speed is faster to the cost is smaller.
>
> I take a more intuitive approach to this problem, by assigning an
> average speed for each class of segment, then length / average speed
> represents the average traversal time. So it is easy to make
> adjustments to the model and you can easily do shortest time or
> distance.
>
> -Steve
>
>
> On 6/22/2011 10:42 AM, Jay Mahadeokar wrote:
>
>
>
> On Wed, Jun 22, 2011 at 7:57 PM, Stephen Woodbridge
> <woodbri at swoodbridge.com <mailto:woodbri at swoodbridge.com>
> <mailto:woodbri at swoodbridge. com
> <mailto:woodbri at swoodbridge.com>>> wrote:
>
> Hi Jay,
>
> I am back from my trip and wading through emails.
>
> I am interested in what your rationale for looking a length as a
> classifier is. It would seem to me the length of a given
> segment has
> nothing to do with classifying a segment with respect to
> speed or
> road class. The length of a segment is typically a function
> of how
> often that route is intersected by other features. For
> example and a
> path through a city will have more intersections than a path
> through
> a rural country side. A mountain pass could be a very long
> segment
> but might be a very slow path because it is twisty and has a
> lot of
> elevation changes. A major road through a city might have
> intersections at every block hence have short segments but could
> still move a lot of traffic from one side of the city to
> another.
>
> For testing purposes, any random classification is fine, but
> I like
> to pick classifications the reasonably model real life so
> when I see
> the results they reflect some general cognitive expectations
> and I
> can understand then or detect anomalies which might indicat
> a bug in
> the algorithm.
>
>
> Maybe I am missing the point, anyway just trying to
> understand and
> not suggesting that you change anything at this point.
>
>
> Hi Steve,
>
> Well I was very confused regarding the classification too since
> I have
> zero experience with real world data, and so I just choose length as
> criteria. This data is just for test purpose. We can modify the
> model
> and criteria any time, since writing the plsql procedure to generate
> such does not take too much effort. Also, the data does not
> affect the
> internal working of the algorithm, so I think for now, I can
> work with
> the currently generated test data.
>
> Any other ideas/ criteria for classification are welcome, and I
> would
> write the scripts to generate corresponding data.
>
>
> -Steve
>
>
> On 6/17/2011 12:42 AM, Jay Mahadeokar wrote:
>
> Hi,
>
> Here is an interesting look into the data in ways table:
>
> pgrouting-workshop=# select round(avg(length)*10000) as avg,
> round(min(length)*10000) as min, round(max(length)*10000) as
> max,count(*) as count, class_id from ways group by class_id
> order by avg
> desc;
>
> avg | min | max | count | class_id
> ------+------+-------+-------+ ----------
> 5320 | 250 | 12163 | 21 | 101
> 2135 | 1885 | 2385 | 2 | 111
> 1970 | 396 | 5168 | 17 | 102
> 1343 | 10 | 27485 | 234 | 106
> 1115 | 33 | 7964 | 221 | 108
> 1037 | 14 | 20020 | 248 | 109
> 938 | 9 | 23142 | 2761 | 110
> 837 | 21 | 2212 | 43 | 100
> 626 | 8 | 3327 | 90 | 112
> 619 | 26 | 9089 | 252 | 119
> 486 | 123 | 1618 | 11 | 117
> 473 | 7 | 16582 | 1259 | 114
> 364 | 97 | 1578 | 45 | 122
> 260 | 4 | 718 | 109 | 401
> (14 rows)
>
> So, I am going by the average length figure and considering
> class_id =
> (1001,111,102) as Type I (major_highways), which will be
> affected most
> by the traffic.
>
> class_id = (106,108,109,110,100) as Type II (minor_highways)
> which be
> comparatively less populated.
>
> class_id = (112,119,117,114,122,401) as Type III
> (streets) which
> will
> have least traffic.
>
> We want to have model such that during traffic hours the
> shortest path
> should go through streets.
>
> So, I am dividing day into following intervals, hope it
> sounds
> reasonable. I will write the corresponding plsql
> function that will
> generate the data accordingly. Note that the speed is in
> percentage of
> average speed. Since, we want to deal with time, we can
> effectively
> increase the lengths of the edges by same factor and
> assume speed as
> constant.
>
>
> Time Interval Speed for Type I Speed for Type II
> Speed for Type III
>
>
>
>
> 10 PM – 6 AM 100 100 100
> 6 AM – 7 AM 95 90 100
> 7 AM – 8 AM 80 75 90
> 8 AM – 9 AM 50 45 85
> 9 AM – 10 AM 60 55 85
> 10 AM – 11 AM 90 85 95
> 11 AM – 5 PM 100 100 100
> 5 PM – 6 PM 90 85 95
> 6 PM – 7 PM 75 70 90
> 7 PM – 8 PM 50 45 85
> 8 PM – 9 PM 60 55 85
> 9 PM – 10 PM
> 95 90 95
>
>
>
> Any feedback is welcome.
>
> I am currently stuck with a bug in the core
> time-dependent function,
> there seems to be a problem with non-integer data. Will
> try and
> fix that
> soon.
>
>
> On Wed, Jun 15, 2011 at 7:26 AM, Jay Mahadeokar
> <jai.mahadeokar at gmail.com <mailto:jai.mahadeokar at gmail.com>
> <mailto:jai.mahadeokar at gmail. com <mailto:jai.mahadeokar at gmail.com>>
> <mailto:jai.mahadeokar at gmail <mailto:jai.mahadeokar at gmail>. com
> <mailto:jai.mahadeokar at gmail. com
> <mailto:jai.mahadeokar at gmail.com>>>> wrote:
>
>
>
> On Sun, Jun 12, 2011 at 8:00 PM, Stephen Woodbridge
> <woodbri at swoodbridge.com <mailto:woodbri at swoodbridge.com>
> <mailto:woodbri at swoodbridge. com <mailto:woodbri at swoodbridge.com>>
> <mailto:woodbri at swoodbridge <mailto:woodbri at swoodbridge>. com
>
> <mailto:woodbri at swoodbridge. com
> <mailto:woodbri at swoodbridge.com>>>> wrote:
>
> Jay,
>
> Try:
>
> select class_id, count(*) as cnt from ways group
> by class_id
> oder by classid;
>
> Typically you should a a distribution in real
> world data
> something like:
>
> 5% limited access major highways
> 15% major roads
> 75% minor roads
> 5% trails, pedestrian ways, etc
>
>
> Hi,
>
> We have got following data in the pgrouting-workshop
> ways table.
>
> pgrouting-workshop=# select distinct(count(class_id)) as
> no_of_entries,class_id from ways group by class_id
> order by
> no_of_entries;
> no_of_entries | class_id
> ---------------+----------
> 2 | 111
> 11 | 117
> 17 | 102
> 21 | 101
> 43 | 100
> 45 | 122
> 90 | 112
> 109 | 401
> 221 | 108
> 234 | 106
> 248 | 109
> 252 | 119
> 1259 | 114
> 2761 | 110
> (14 rows)
>
>
> The classes table in routing database gives more
> information
> on the
> class_id field. Also available here:
> http://workshop.pgrouting.org/ chapters/advanced.html
> <http://workshop.pgrouting. org/chapters/advanced.html
> <http://workshop.pgrouting.org/chapters/advanced.html>>
>
> So, we have:
>
> class_id name no_of_entries
>
> 110 track 2761
> 114 path 1259
> 119 steps 252
> 109 service 248
> 106 primary 234
> 108 living_street 221
> 401 roundabout 109
>
> These are the major class_types with more than 100
> entries
> in ways
> table.
>
> Steve had earlier suggested following idea for time
> dependent data
> generation:
>
>
> "If we think about "rush hour" around a major city, the highways
> (based on road class) flowing into the city in the
> morning
> would get
> reduced average speeds you could apply curve like
> average
> speed*percent based on 6am (90%), 7am(75%),
> 8am(45%), 9am(50%),
> 10am(85%) and do something similar in the evening
> rush. It
> might be
> too hard to figure on direction of flow in/out bound so
> apply the
> curve to all traffic. The assumption is that the
> highways are
> congested which will force traffic onto side
> streets. You
> might want
> to also reduce the lower class speeds by say a
> constant 80%
> during
> rush hour."
>
> So, what classes should I consider as highways, what
> classes as
> streets and so on? Or What should be the pattern of
> speed
> changes in
> various classes?
>
> The main focus would be, we should be routed through
> less
> congested
> areas during rush hours right?
>
> Once we finalise this model, I can write the plsql
> function to
> generate the corresponding data.
>
>
>
> Well in the US anyway. Also if this is OSM data
> then you
> might
> get a better clue on classes by looking to that ....
> OH!, look
> what I found in google :)
>
> http://workshop.pgrouting.org/ chapters/advanced.html
> <http://workshop.pgrouting. org/chapters/advanced.html
> <http://workshop.pgrouting.org/chapters/advanced.html>>
>
> Looks like first digit is type and the three
> digits are
> from the
> classes table.
>
> -Steve
>
>
> On 6/12/2011 4:33 AM, Jay Mahadeokar wrote:
>
>
>
> On Sun, Jun 12, 2011 at 1:32 PM, Anton Patrushev
> <anton.patrushev at georepublic. de
> <mailto:anton.patrushev@ georepublic.de
> <mailto:anton.patrushev at georepublic.de>>
> <mailto:anton.patrushev@ <mailto:anton.patrushev@>
> georepublic.de <http://georepublic.de>
> <mailto:anton.patrushev@ georepublic.de
> <mailto:anton.patrushev at georepublic.de>>>
> <mailto:anton.patrushev@ <mailto:anton.patrushev@>
> georepublic.de <http://georepublic.de>
> <mailto:anton.patrushev@ georepublic.de
> <mailto:anton.patrushev at georepublic.de>>
> <mailto:anton.patrushev@ <mailto:anton.patrushev@>
> georepublic.de <http://georepublic.de>
> <mailto:anton.patrushev@ georepublic.de
> <mailto:anton.patrushev at georepublic.de>>>>>
>
> wrote:
>
> Hi Jay,
>
> No, there was no specific meaning, just
> king of
> cyphering - first
> digit for road class and then two last
> digits
> for road type.
>
>
> Hi Anton,
>
> So, as you said last 2 digits are for road
> type. I
> can see
> they are
> mainly 00, 01, 02, 06, 08, 09, 10, 11, 12
> ,14, 17.
>
> Road class is just 1 or 4.
>
> Can I differentiate major highways, minor
> highways,
> streets
> etc using
> this info?
>
> Anton.
>
> On 6/12/11, Jay Mahadeokar
> <jai.mahadeokar at gmail.com <mailto:jai.mahadeokar at gmail.com>
> <mailto:jai.mahadeokar at gmail. com <mailto:jai.mahadeokar at gmail.com>>
> <mailto:jai.mahadeokar at gmail <mailto:jai.mahadeokar at gmail>. com
> <mailto:jai.mahadeokar at gmail. com
> <mailto:jai.mahadeokar at gmail.com>>>
> <mailto:jai.mahadeokar at gmail <mailto:jai.mahadeokar at gmail>. com
> <mailto:jai.mahadeokar at gmail. com <mailto:jai.mahadeokar at gmail.com>>
> <mailto:jai.mahadeokar at gmail <mailto:jai.mahadeokar at gmail>. com
> <mailto:jai.mahadeokar at gmail. com
> <mailto:jai.mahadeokar at gmail.com>>>>> wrote:
> >> Hi Jay,
> >>
> >> I think that instead of just random times, I would take
> a different
> >> approach to generate this data. If we think about "rush
> hour"
> around a
> >> major
> >> city, the highways (based on road class) flowing into
> the city
> in the
> >> morning would get reduced average speeds you could apply
> curve like
> >> average
> >> speed*percent based on 6am (90%), 7am(75%), 8am(45%),
> 9am(50%),
> 10am(85%)
> >> and do something similar in the evening rush. It might
> be too
> hard to
> >> figure
> >> on direction of flow in/out bound so apply the curve to all
> traffic. The
> >> assumption is that the highways are congested which will
> force
> traffic
> >> onto
> >> side streets. You might want to also reduce the lower class
> speeds by say
> >> a
> >> constant 80% during rush hour.
> >>
> >> If we can get OSM data then it should be easy to
> populate the
> table with
> >> that data.
> >>
> >> -Steve
> >>
> >
> > I am trying to write plpgsql query to generate
> time-dependent data
> > corresponding to the ways table in pgrouting workshop. As
> suggested by Steve
> > above, instead of generating random data, I will follow
> patterns
> (see above
> > message) so that the data is nearer to the real worlds
> scenario.
> >
> > So, now I need to make distinction between highways,
> streets etc.
> I saw the
> > attribute class_id in ways table. It has 14 distinct values:
> > class_id
> >
> > ----------
> >
> >
> > 102
> >
> >
> > 122
> >
> >
> > 106
> >
> >
> > 111
> >
> >
> > 108
> >
> >
> > 100
> >
> >
> > 109
> >
> >
> > 112
> >
> >
> > 101
> >
> >
> > 110
> >
> >
> > 401
> >
> >
> > 119
> >
> >
> > 117
> >
> > 114
> >
> > Any specific meaning attached to these values? I did not
> find any
> > information on the pgRouting-workshop website [1].
> >
> >
> > Thanks in advance.
> >
> > [1] http://workshop.pgrouting.org/ chapters/topology.html
> <http://workshop.pgrouting. org/chapters/topology.html
> <http://workshop.pgrouting.org/chapters/topology.html>>
> >
> > --
> > Regards,
> > -Jay Mahadeokar
> >
>
>
> --
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>
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>
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>
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>
>
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> Regards,
> -Jay Mahadeokar
>
>
>
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