Network data model for public transport

Question

Hi,
I've been playing with Gis for the last 10 years and now I am enrolled in a project to find best way to go from one point to another in Barcelona (Spain) locations, using the public transport network.
The goal is to get a route, from one address to another (both given as inputs), formed by:
-     a 1st piece of path walking to the bus stop
-     a 2nd piece of path involving the bus used to go from one bus stop to another
-     optional 3rd piece of path with a second bus
-     the last piece of path to walk from the destination bus stop to the destination address.
This is a nice problem to resolve with a quite good looking software like the Oracle NDM. I know the big problem will be to put all the data in the right format.
But the question I’d like to share with you would be to approve or improve the algorithm I am thinking to resolve this:
STRUCTURE
Network Data Model NDM_1: creation of a SDO spatial network with all the streets and cross-roads to walk through
Other NDM_2 to store the bus stops with the bus-route-linking information.
     The reason to put them separately is for easily maintenance (a priori).
     [A second approach perhaps would be to put the bus stops as nodes of NDM_1 also]
ALGORITHM
1. Look for bus-stops near the geolocated origin address. (say listing BS_ORIG_list)
2. Look for bus-stops near the geolocated destination address. (say listing BS_DEST_list)
3. Search through NDM_2 for possible correspondences between BS_ORIG_list and BS_DEST_list through single bus line or by two different bus lines applying a network constraint.
(if not correspondence found or if more than 2 bus lines needed, abort by app requirement)
4. Find the walking paths needed to complete the various routes found in step 3 to get from address origin to destination
5. Order the results by time spent or by meters to walk.
Sure there might be improvements to this solution and also other ways to face such a common problem.
Thanks in advance,
David Foix

Answer 1

Hi Andrejus,
Thanks for answering.
I read through your thread already...
I understand and agree it would be a multimodal network. But what would that mean in the time of storing the data and asking for the route?
But I am still doubting the way to query for the resulting route. Having two adresses to join, would there be a nice function or procedure to ask for the route giving preference to walk the minimum meters and use preferently the bus network?
Or should I rely on the first algorithm I proposed? I thought there would be a nicer solution.
In your case, "road transport, railway transport, naval transport and air transport" I understand it would be a case to use different networks as they don't share spatial geometry, only some nodes..isn't it? Did you have the need to join all of them to find route solution giving preference to one of them?
Regards,
David