4 ms·

Creating them by hand isn't necessarily a bad thing. The post describes that there are on the order of 20,000 cities and towns covered; I expect that many of t

Creating them by hand isn't necessarily a bad thing. The post describes that there are on the order of 20,000 cities and towns covered; I expect that many of these are municipalities that are a part of a larger group of cities. WolframAlpha says that the 20,000th largest city coincidentally has a population of about 20,000 people, barely large enough to have its own public transit. And many states, companies, and countries will have common infrastructure for getting maps of all the public transit within the country. Taking a wild guess, there are probably significantly less than 500 separate transit systems to be mapped; a team of just 10 people could cover them in a year with a full person-week given to each location. A mix of automation and manual entry is ideal for many tasks.

cbhl 11y ago
I imagine that's not enough, because changes to bus routes tends to be bursty. For example, I'd imagine thousands of those transit systems to suddenly add routes in September to coincide with the start of the school year, and then remove those routes in April or June to coincide with the end of the school year. With a team of ten, some of those systems' maps wouldn't get updated until Christmas, which would be too late to be useful.
ant6n 11y ago
For rail transit, doing it manually globally is feasible. For buses, not so sure.
nevi-me 11y ago
Yes, it's not a bad thing. You get more accurate data (crucial for estimating fares for distance-based services). We're a team of 2 people at Moving Gauteng [0], and we maintain transit data of 7 and growing transit services. We have 1100 routes mapped, with detailed schedules and other info. The problem with drawing simple lines to approximate what route the service takes is that you become limited by the inaccuracy of your data. There are many fare calculating rules, and a good deal are based on distance covered. Having a polyline that's > 95% accurate helps greatly in calculating the correct result for the user. I agree on your point that a mix of automation and manual entry's good. In some instances it's better to track the bus by GPS and snap the GPS points to a route using GIS software like ArcGIS (or even Mapbox as they have such an API). [0] https://movinggauteng.co.za https://movinggauteng.co.za
- ant6n 11y ago
  We at Transit App have about 15000 routes, which were managed by one or two people or so until relatively recently. Manual mapping, an extra task, would not be feasible. You also have to consider that just having good shapes for routes (which is often in the data anyway) doesn't mean you automagically get good transit maps. You have to decide when lines are travelling together, which Google apparently does by considering the stops that lines travel on. You can see lines stay together as long as they travel the same stops, and immediately branch at a stop when they branch, even though the physical branch happens later.
  - nevi-me 11y ago
    I presume you get data from GTFS feeds. If so, it'd be more feasible to build a service that converts a 'poorly mapped' route into something better almost automatically. Manual involvement would be necessary to only correct defects from the process. Although we manually map, we reuse most route segments, especially trains where 2 similar lines could travel 80-90% on the same tracks. We just chop and screw where necessary. The whole thing takes a few minutes to draw a new route based on existing ones.

cbhl 11y ago

I imagine that's not enough, because changes to bus routes tends to be bursty. For example, I'd imagine thousands of those transit systems to suddenly add routes in September to coincide with the start of the school year, and then remove those routes in April or June to coincide with the end of the school year. With a team of ten, some of those systems' maps wouldn't get updated until Christmas, which would be too late to be useful.

ant6n 11y ago

For rail transit, doing it manually globally is feasible. For buses, not so sure.

nevi-me 11y ago

Yes, it's not a bad thing. You get more accurate data (crucial for estimating fares for distance-based services). We're a team of 2 people at Moving Gauteng [0], and we maintain transit data of 7 and growing transit services. We have 1100 routes mapped, with detailed schedules and other info. The problem with drawing simple lines to approximate what route the service takes is that you become limited by the inaccuracy of your data. There are many fare calculating rules, and a good deal are based on distance covered. Having a polyline that's > 95% accurate helps greatly in calculating the correct result for the user. I agree on your point that a mix of automation and manual entry's good. In some instances it's better to track the bus by GPS and snap the GPS points to a route using GIS software like ArcGIS (or even Mapbox as they have such an API). [0] https://movinggauteng.co.za https://movinggauteng.co.za

ant6n 11y ago
We at Transit App have about 15000 routes, which were managed by one or two people or so until relatively recently. Manual mapping, an extra task, would not be feasible. You also have to consider that just having good shapes for routes (which is often in the data anyway) doesn't mean you automagically get good transit maps. You have to decide when lines are travelling together, which Google apparently does by considering the stops that lines travel on. You can see lines stay together as long as they travel the same stops, and immediately branch at a stop when they branch, even though the physical branch happens later.
- nevi-me 11y ago
  I presume you get data from GTFS feeds. If so, it'd be more feasible to build a service that converts a 'poorly mapped' route into something better almost automatically. Manual involvement would be necessary to only correct defects from the process. Although we manually map, we reuse most route segments, especially trains where 2 similar lines could travel 80-90% on the same tracks. We just chop and screw where necessary. The whole thing takes a few minutes to draw a new route based on existing ones.