We are planning to write an application which have to track the user driving in his truck in the cities like New York city accurate upto which lane he was driving on. In the cities with those tall buildings, its not possible to get good GPS signal. So we are planning to use hardwares with accelerometers and magnetometers sensors to make up for the lost GPS signals. We tried with some Android tablets, but the sensors are not accurate enough. Right now we are going to try some hardwares from Trimble with geo position correction and motions sensors.
So any kind of suggestions on tracking a vehicle without a GPS device is welcome.