Interactive algorithm laboratory / 01

Watch a route
become inevitable.

Pick two points. RouteLab runs four exact shortest-path methods over the same graph, then exposes every settled node and relaxed edge.

These are curated teaching fixtures, not live journey planning.

Copenhagen

Harbour crossings, metro links, and cycle corridors

ForwardBackwardRoute

00 / 12

Map click sets destination

Best known time—

Route length0 m

Path nodes—

No route exists for this travel profile.

Same answer, different work / 02

The algorithm race

All four methods must return Dijkstra’s exact optimum. The useful difference is how much of the graph they need to touch.

What is actually here

Graph model

One contract, four solvers

Every solver consumes the same typed graph and query. Edge weights change with walking, cycling, transit, and accessibility choices.

Correctness

Dijkstra stays the oracle

Automated tests compare A*, bidirectional search, and ALT against Dijkstra across both fixtures and several travel profiles.

Heuristics

Lower bounds, never guesses

A* derives a safe geometric scale from the graph. ALT uses landmark distance inequalities. Both preserve optimality.

Data honesty

Illustrative, not navigational

Curated educational fixture based on approximate public geography; not a live OSM or transit feed.

Read the data note ↘

Data note / 04

Small graphs on purpose.

This browser demo is designed for inspection: each search can be replayed node by node. The repository documents how the graph contract could be fed by properly licensed OpenStreetMap and GTFS importers, but those pipelines are not passed off as complete.