Antwerp N177: a semi-flexible feeder service on a real corridor

The earlier work on the semi-flexible feeder service was tested on generated benchmark instances. This case study asks what happens on an actual corridor, using real road-network data and a real incumbent network as the benchmark.

The setting is the N177 between Boom and central Antwerp, a suburban corridor that is poorly served relative to its proximity to the city. The simulated service places 8 mandatory and 56 optional bus stops along it, serves 100 passenger requests over a two-hour window, and guarantees a maximum headway of 20 minutes with a vehicle capacity of 20. Requests were generated on a realistic road network rather than assumed to be uniformly spread, and the results are compared against more than 20 existing De Lijn bus lines serving the same area.

The findings:

• Service quality improved by 31.6% on the global objective, and average user ride time dropped by 22% compared with the existing transit options.
• Acceptance saturates at around 90% once roughly 12 buses are available — beyond that, extra vehicles add little.
• There is a genuine trade-off in how much freedom the optimizer is given: with only 3 buses a near-perfect solution is achievable for accepted requests, but the global objective suffers. The sweet spot in the degree of optimization freedom is intermediate, not extreme — the same Goldilocks logic that runs through the service design itself.

The instance generation for this study was done with a custom generator built on OpenStreetMap road networks, so the demand and travel times reflect the actual corridor rather than an abstract network.