Moving observer methods are commonly used for travel time surveys. In this method, the observer travels in a vehicle, which is a part of the traffic stream and notes the time required for the vehicle to travel between two specified points. The problem with the moving observer method is that to get a representative value of the travel time, different drivers should repeat the method. Another disadvantage of this method is that the exact variation of the speed of the vehicle along the link cannot be studied. The variation of the speed of the vehicle along the network gives an idea about the traffic conditions on the road. Therefore, the moving observer method cannot be used for studying the localized traffic effects. Some of these effects can be overcome by using GPS-GIS integrated systems.