Google Maps traffic error?

Hello everyone,

I was just looking for a route to the Baltic Sea (7 hours) and noticed something strange: When you look at the map with traffic data activated, a long traffic jam is shown halfway along the route. However, when I calculate the route, the traffic jam is no longer shown. However, if you take a route from a location immediately before the traffic jam and one after it, the traffic jam is shown, including the delay and detour (20 minutes faster). Why is that? Is there any way to calculate the route with all the traffic data so that you get a realistic time, including traffic jams? Or is it only calculated for 2 hours in advance or so, and when you get within a certain time of the traffic jam, the route is only updated?

Thanks!