This is a collection of routes that have traditionally been hard to navigate for routing engines. They may be used as test cases for routing engines.
- Freeway routes where there is a frontage road. Think Hwy 101 near Morgan Hill or 680 where there is a frontage road and the router wants to route onto that and then back on the fwy.
- US 101 interchange at Oregon Expressway and Embarcadero. http://www.openstreetmap.org/relation/1544955#map=17/37.44840/-122.12105&layers=D
- Place de la Concorde in Paris (12 streets converging on a huge open area with no lane markings or single centerlines. http://www.openstreetmap.org/way/105177513
- The 5-level interchange in L.A.
- Shibuya Crossing and Shinjuku Crossing in Tokyo.
- Swindon roundabout http://www.openstreetmap.org/node/15722121
- Michigan jug handles http://en.wikipedia.org/wiki/Michigan_left
- A one way freeway in Adelaide, South Australia that changes direction in the afternoon. http://en.wikipedia.org/wiki/Southern_Expressway