(without frames    contens    library)

3. EXAMPLE

We will demonstrate the algorithm by means of an example. Figure 2 shows "Heimplatz", a famous square and quasi a benchmark crossing in Zürich. Trams, pedestrians, and individual traffic use the two crossings 507 (A) and 508 (B) with the following phases: A1 - A5 and B1 - B6 (cars), A6 - A10 and B7 - B13 (pedestrians), A11 - A12 and B14 - B20, B23 (trams). To keep the paper readable we will only discuss the tram phases which have to be optimised in the top hierarchical layer. The resulting problem is depicted in Fig. 3: two closely coupled crossings. 5 different tram routings (also called lines) pass the crossing: number 3, 5, 8 and 9, and number E, a rarely used route of trams not operating on schedule. There are stops for all lines, except for E, namely before phases B20 and after B17 for line 3, and before A12 and after A11 for all other lines. Detectors are placed in such a way that trams and their corresponding routings are detected and reported in good time (about 1 minute before arriving at the crossing).