Upvote:0
In addition to the usual maps.google, an alternative is http://livetraffic.tomtom.com.
On the left, you can enter the time you are leaving and it figures out when you'll arrive, or enter the time you want to arrive and it figures out when you should leave.
It is based on many different data points, so it is pretty accurate.
It's a good alternative to maps.google, for the specific case of estimating times (including traffic variations during the day/week).