How can I build the topology in a multimodal network dataset to successfully find the shortest routes between OD pairs?

[ConnieSu]

Hello! I've built a multimodal network dataset with 4 groups (roads, railways, waterways, and sea routes).

The first group has the railways ("PNL2017_Ferrovias") and the edges connecting the railways and terminals ("PNL2017_Ferro_TermFerro", built using ArcGIS Pro tools “Near” and “Points to line”). The terminals are in the "PNL2017_TermFerro".

The second group has the waterways ("PNL2017_Hidro_Cabot") and the edges connecting the waterways and ports ("PNL2017_Hidro_Portos"). The ports are in the "PNL2017_Portos".

The third group has the sea routes ("PNL2017_Maritimo") and the edges connecting the sea routes and ports ("PNL2017_Marit_Portos") and the sea routes and international destinations ("PNL2017_Marit_OD"). 

The fourth group has the roads ("PNL2017_Rodovias_Completo") and the edges connecting the roads and railways terminals ("PNL2017_Rodovia_TermFerro_Completo"), the roads and ports ("PNL2017_Rodovia_Portos_Completo"), and the roads and the Origins and Destinations ("PNL2017_Rodovia_OD_Completo").

The network dataset was successfully built. However, the Route solver found only 2841 out of 2916 OD pairs. I used the Explore tool and at least some of the 75 OD pairs without a route seem to be connected. In addition, some of the created routes are not the shortest path for the OD. Like the example below. The shortest route should cross the country instead of going around it.

I've built a Topology to improve the Network Dataset. I've already fixed the errors for "Must not overlap", "Must not intersect", "Must not self-overlap", "Must not self-intersect", and "Must be single part".

My questions are:

- What other rules should I include in the Topology to fix my network dataset so I can successfully find the shortest route for all my OD pairs?

- If there are overlaps or intersections between lines in the same feature class or in different feature classes, is the Route solver able to find the shortest route?

- What other problems in the multimodal network dataset prevent the Route Solver to not reach the destination point? All the unsuccessful OD pairs have the status "5 (Not Reached)".

Thanks and regards!

[JaySandhu · Accepted solution]

There are probably some logical issues on how the various modes connect that you are not able to find the "shortest" path and are finding a longer path. If you can identify one of the OD pairs, use the start location in a Service Area layer and generate polygons and lines using multiple breaks. Perhaps the shape of the resulting polygons will show you where the problems are occurring. 

Jay Sandhu

[ConnieSu]

Hello Jay, thanks for your reply! I ran the Topology with "Must not intersect with" with all the lines feature classes and managed to find a route to all OD pairs. Then I ran the Service Area layer and found out that the shortest route problem was due to my freight equations.

Thanks and regards!