Shortest Path Algorithms in Transportation Networks

Shortest Path problems are among the most studied network flow optimization problems with interesting applications in a wide range of fields. One such application is in the field of GPS routing systems. These systems need to quickly solve large shortest path problems but are typically embedded in devices with limited memory and external storage. Conventional techniques for solving shortest paths within large networks cannot be used as they are either too slow or require huge amounts of storage. In this project we have tried to reduce the runtime of conventional techniques by exploiting the physical structure of the road network and using network pre-processing techniques. Our algorithms may not guarantee optimal results but can offer significant savings in terms of memory requirements and processing speed. Our work uses heuristic estimates to bind the search and directs it towards a destination. We also associate a radius with each node that gives a measure of importance for roads in the network. The farther we get from either the origin or destination the more selective we become about the roads we travel with greater importance (i.e. roads with larger radii).By using these techniques we were able to dramatically reduce the runtime performance compared to conventional techniques while still maintaining an acceptable level of accuracy. KeywordsRouting, Shortest Path, Network, Radius.