But none of the companies would grant any of its competitors running powers over its lines, and as the municipal authorities decided that all five lines should enter the city side by side, the engineers found themselves confronted with the following problem:—How is each line to reach its destination, without crossing any of its competitor’s tracks?
How would you extricate them from this dilemma?
Fig. 9.—The quarrelsome railways.
12. Another Railway Problem
This problem is shown in [Fig. 10]. In the railway A, B, C there are two sidings, A, D and C, E; which meet at F. At this latter place there is only sufficient space to contain one car of the size of G or H, and there is no room for the engine, I. Consequently, if this engine is sent up either of the sidings it must return by the same tracks.
Fig. 10.—The second railway problem.
The point to be discovered is: How can the engine, I, transpose the two cars G and H, by simply using the rails shown in the illustration?