[pgrouting-dev] Support for Time Constraints

[Jay Mahadeokar]

Hi,

Since we will be working on time-dependent shortest path problem, I was
wondering if time-dependent geographic data is freely available for research
purposes. [1] states that we witness an increasing number of navigation
service providers (such as Navteq and TeleAtlas) have started releasing
their time-dependent travel-time datasets for road networks at
high-resolution temporal granularity as fine as one sample for every five
minutes.

I guess that data is not freely available. Anyways, if you know such
data-source can you please direct me? Besides this project, I am also
working on some new heuristics for time-dependent shortest path as part of
my thesis and the data would be really helpful for my work.

Thanks.

[1] http://portal.acm.org/citation.cfm?id=1869865

On Thu, Mar 31, 2011 at 7:49 PM, Stephen Woodbridge <woodbri at swoodbridge.com
> wrote:

> On 3/30/2011 9:45 PM, Daniel Kastl wrote:
>
>
>>            float cost := getEdgeCost(time, vehicle_type, node_from,
>>        node_to);
>>
>>            or something like that. Where time could be NULL for some
>>        default
>>            behavior, or a value that would be used to figure out the cost.
>>            vehicle_type might be helpful if there are multiple costs to
>>            traverse a link based on say, car, carpool, bus, truck,
>> walking,
>>            taxi, etc. This could also be used to implement the rules
>>        for bus
>>            and train lines.
>>
>>
>> I think one of the difficulties with routing topic is that everyone
>> (also myself) immediately think about routing in terms of vehicle types.
>> It's the easiest example to explain pgRouting, but I think one premise
>> of pgRouting is that it should work for any kind of network. Let's say
>> your network would be the human nervous system. What is a vehicle there?
>> Well, probably changing "vehicle_type" to "speed" would make sense, right?
>>
>
> Sorry for using vehicle as the selector maybe "service_type" would be
> better, but the point is not the name, "speed" is equally misleading, the
> point is to be able to be able to pass a selector to the under lying
> function so that based on the selector we can compute an appropriate cost.
>
> For my vehicle routing example, I chose: car, carpool, bus, truck, walking,
> taxi, etc. because these might have different rules associated to them. The
> selector values would be appropriate to the model that you were working
> with.
>
> car vs carpool vs bus - many cities have HOV lanes that bus and carpool can
> use but not single occupancy cars. We might want to allocate a higher speed
> to those lanes vs the normal lanes during rush hours. Emergency vehicles
> many be allowed to make u-turns on highways that other vehicles can not
> make. Trucks might be banned from some streets so need to be costed
> appropriately, etc.
>
> If we had a live traffic feed information linked to segment ids in another
> table, The cost function could be implemented to check that table and if a
> record exists then use that information or return the standard information.
> By keeping this data in a separate table that is presumably much smaller and
> dynamic than the street records it would make it much easier and more cost
> effective to make dynmaic changes to that table and to hide (abstract away
> complexity) by using a cost function supplied to the underlying code.
>
> -Steve
>
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-- 
Regards,
-Jay Mahadeokar
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