Unit 2 sec 1.6

       The assumptions made about distances on the roads and the possible average speed, together with the methods and formulas for calculating the predicted times taken, from the elements of a mathematical model, usually called simply model. Changing the assumptions made or the formulas used would result in a different model.

    This may account for some of the discrepancies in the times predicted by the route planner – they have used different models with different assumptions.

    Many other routes could have been taken, and different routes are likely to take different times.

    

    A route planner computer program stores a network of roads, and a time for travelling along each section of a road is determined from a suitable model. An algorithm – set of instructions to solve a problem step by step – is then used to check the distances and times of all the possible routes systematically and select the shortest or quickest, as appropriate.

The word data means facts of statistics, so the case the new data might include the addition of the new roads to the maps or more up–to-date estimate of the travel speed.

Ø The mathematics had identified several key problems to solve after discussions with user.

Ø They use a wide range of different sources of reliable data, obtained from government departments and reputable organisations, which they update frequently. They also include data provided by users.

Ø Some simplification and assumptions had to be made so that key problems can be solved quickly enough while users of the website wait.

Ø The mathematical model is continually being refined and updated to provide a more reliable prediction.

      Whichever method you choose, you may now be more aware of how different factors can affect the journey time, such as average speeds along different sections of the road. If you decide to use a route planner, perhaps the best advice is to monitor how well the predictions for the journey times match reality in case, and to choose a route planner that gives the most reliable results. They are unlikely to be this accurate in practice because road conditions are so changeable.