The toll calculator estimates costs (tolls + gas) for all logical routes between your origin (start location) and destination. It shows you the cheapest, the fastest, and other relevant routes on a Google map. To help you choose between routes, it displays cost, time, distance and other information for each route.
The travel times and gas costs vary based on traffic congestion, accidents, road closures, etc. For example, your vehicle consumes more fuel in stop and go traffic. Every time you search, the travel times and gas estimates may be different. The toll calculator shows tolls at the time of your travel for variable priced toll roads. As you can see the estimates of fuel consumed and gas expenses, travel times, and tolls are dynamic. Therefore, the cheapest route and the fastest routes may change for the same origin and destination.
Tollguru™ considers the following factors to calculate tolls for your vehicle
For roads where truck tolls are based on weight and height, Tollguru™ uses a relationship between weight, height
and number of axles to calculate tolls. Please refer to individual state pages to see
truck toll payment information for your state.
If a method of payment cannot be used throughout a route, it is shown as
Link: http://tollguru.com/faq/how-does-toll-calculator-calculates-tolls