With which speeds are the driving times of the routes calculated?
There are several different sources for vehicle speeds. Generally, average speeds per vehicle are assigned to the roads in the map. They will be used when no time context is given with the request, that means for options[trafficMode]=AVERAGE without a start or arrival time. Once a start or arrival time is specified, historical traffic data is used to provide more accurate speed information depending on the time of day when a road is passed.
Can I modify the speeds of the vehicle?
With the parameter options[maximumSpeed] it is possible to limit the maximum speed [km/h] of the vehicle. This can have a direct impact on the course of the route for example when reducing the speed such that highways are as fast as trunk roads. Then, the route distances may decrease as detours on highways and motorways will no longer be faster.
Another parameter related to the speed of the vehicle is options[speedFactor]. Contrary to the limitation of the maximum speed, this parameter does not influence the course of the route. Instead, the speed on all roads the route passes will be scaled with the value of the parameter and the driving times will be recalculated with the new speed value. The requested results will be calculated according to the new driving times.
Try it in the Speeds code sample.
Refer also to the Traffic Modes concept.