Re: [sumo-user] JTR router with fixed turning ratios

[Jakob Erdmann <namdre.sumo@xxxxxxxxx>]

Ansers inline...

JTR router

-       Does it make sense to define smaller interval sizes, but do not change the turning ratios in these intervals?

no.

-       What’s the effect of “route-steps”? Does it only affect the result when different turning ratios are specified for different interval sizes?

no effect on output at all (it only affects memory usage while processing input files) .

 

RouteSampler

When I apply the RouteSampler.py, I indeed get more uniformly distributed turning flows. As input, I take the routes previously computed by the JTR router. However, the overall desired accumulated counts are not correct. I confirmed this by applying the “generateTurnRatios.py”. For example, at a specific intersection (two unidirectional links crossing) the turning ratios should be 50% for each leg. In contrast, I got 47% and 53% after applying the routeSampler. I apply the “—optimize full” option, and the interval size does not seem to have a big impact.

Does routeSampler report on the mismatch (GEH > 0)? If so, the candidate routes did not allow satisfying all constraints even using optimization.

-       Does it make sense to reduce the counts for early intervals at intersections where it takes some time to load the network?

No. because routeSamper does not take into account the time it takes for vehicles to reach the intersection. It assumes that flows are stationary in each interval.

This may be a source of counting deviations looking at the simulation counts in smallish intervals.

-       Are there any other ways to reach the desired turning ratios?

First you need to figure out the source of the mismatch:

- constraint effects:routeSampler reports that it could not match all the counts

- temporal effects: only simulate a single interval and sum up counts over the whole simulation, if the counts fit then the effect is temporal

regards,

Jakob