Tango Blue — tango.blue

The Buenos Aires map

Tango Blue (tango.blue) publishes a map of public transport in Buenos Aires and places to see across Argentina, on one screen. Tango Blue is a separate business from Kuon R&D; KUON GEO provides two parts of how the map is made, the method for rebuilding routes from vehicle traces and the two-layer data design. It runs in a browser, with nothing to install and no account.

What the map does

Sources: the City of Buenos Aires API Transporte (vehicle positions every 30 seconds), the metropolitan route shapes published by the Argentine Ministry of Transport, the city stop registry, and OpenStreetMap.

How to use it

1. Open the map. There is no app.
2. Pick layers from the list. Stack only what you need.
3. Turn on bus stops and tap one. It shows the routes serving that stop and the minutes to the next bus, so the route number is not needed.
4. Turn on the location layer for the six nearest stops. Location is used only when that layer is on.
5. Set a start and an end point on the map to get the bus to take and the walking legs.

Three things to know about the bus

There are 138 routes and the same number branches to different destinations, so a route map alone is hard to follow. The system itself is simple.

First, you cannot pay cash. You need a SUBE card, sold at Subte ticket windows, kiosks with the SUBE sticker and airport counters. Foreigners can use one without registering.

Second, buses do not stop unless you signal. Put your arm out when you see yours. This is the mistake visitors make most.

Third, tell the driver your destination before tapping, because the fare depends on distance. Press the button before your stop.

What KUON GEO provides

Tango Blue edits and publishes the map. KUON GEO provides the method, in two parts.

First, the two-layer data design. Positions received from the city's live API are kept unaltered as the original; anything derived, such as routes and stop assignments, lives in a separate layer. A list of base stations and the live position of a bus are built the same way. The 122 m height offset in the Tokachi logs was only findable because the raw record had been kept as it was. Rewrite the original and there is nothing left to check against.

Second, the method for rebuilding routes from vehicle traces. Positions every 30 seconds are grouped into traces per vehicle; for each service and direction one backbone trace is chosen, densified to 30 m and matched against the national route shapes, and a line number is assigned when at least 75% of its points fall on that shape. Stops within 40 m of the backbone are attached from the city registry, and every 20 minutes only the services that changed are rebuilt. Services that cannot be resolved are left unnumbered.

The full method and its limits are on Tango Blue's page How this map is made. Both businesses were founded by Kotaro Asahina. Reporting and photography on the ground are by Shino Onaga, who is not involved in the map or bus data.