MultiTT DIMA and time-based road restrictions

[Howard]

Hello,

how does the MultiTravelTime DIMA handles time-based road restrictions?
My understanding is that the DIMA uses one specific route and then calculates the travel time for the different time segments. (The travel distance will stay the same in all segemnts, just the travel time will change.)
That could be an issue if part of that initial route is not available later during the day. An example would be a bridge, that only opens at certain ties, or a street that is closed during certain hours.

[Maximilian Vogel]

Hello,

Your understanding is correct. Let me explain how time dependent restrictions are handled.

Whether or not time dependent road restrictions are used in the calculation of the route course depends on the selected horizon and the time period in which the road restriction is active. There three cases that can be distinguished:

1. Horizon is completely contained by the duration of the restriction: Restriction is considered.
2. Horizon and duration of the restriction are disjoint: Restriction is not considered.
3. Horizon and duration of the restriction overlap: Restriction is not considered.

How this affects the traveltime depends on how the road restriction is modeled. There are two cases:

1. PTV_TruckAttributes: A road is explicitly closed for a certain "time period. This has no influence on the traveltime. For the algorithm the road is either open or closed, but it is not "waited" until the road is opened again.
2. PTV_TrafficIncidents: The absolute speed with which a road can be driven is just set to 0. The duration of this restriction expires at some point and the algorithm just "waits" until this period is over. Hence you will be able to observe continuous increases (or decreases) in the traveltime profile.

I've prepared a few screenshots to illustrate this:
PTV_TruckAttributes
location: 48.999088273233575, 8.387809395790102

Note: You won't be able to reproduce this with the standard showcase. I had to hack into it a bit as the vehicle profile is hard coded to "van".

PTV_TrafficIncidents
location: 49.57119241259122, 6.282012462615968

I did not include two more screenshots for the first 2 cases as they do not differ from the 2 cases with PTV_TruckAttributes (in one case the road is taken because the incident ist valid and in the other case the detour is taken because the incident is valid). Only the case where the horizon and the timedomain overlap is interesting. You can see that the route takes the closed road. But when calculating the exact traveltimes at different start times, the road is still closed for some more hours, therefore there is a high traveltime. The later it starts the less it has to wait.

I hope this helps.