In life-threatening emergency situations, the ability of emergency medical service (EMS) providers to arrive at the emergency scene within a few minutes may make the difference between survival or death. To realize such extremely short response times at affordable cost, efficient planning of EMS systems is crucial. In this article we will discuss the Testing Interface For Ambulance Research (TIFAR) simulation tool that can be used by EMS managers and researchers to evaluate the effectiveness of different dispatch strategies. The accuracy of TIFAR is assessed by comparing the TIFAR-based performance indicators against a real EMS system in the Netherlands. The results show that TIFAR performs extremely well.
The computation of shortest paths between different locations on a road network appears to be a key problem in many applications. Often, a shortest path is required in a very short time. In this article, we try to find an answer to the question of which shortest path algorithm for the one-to-one shortest path problem runs fastest on a large real-road network. An extensive computational study is presented, in which six existing algorithms and a new label correcting algorithm are implemented in several variants and compared on the real-road network of The Netherlands. In total, 168 versions are implemented, of which 18 versions are variants of the new algorithm and 60 versions are new by the application of bidirectional search. In the first part of the article we present a mathematical framework and a review of existing algorithms. We then describe combinations of existing algorithms with bidirectional search and heuristic-estimate techniques based on Euclidean distance and landmarks. We also present some useful static reduction techniques. In the final part of the article we present results from computational tests on The Netherlands road network. The new algorithm, which combines concepts from previous work on buckets and label-correcting techniques, has generally the shortest running times of any of the tested algorithms.
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