# Data source for bus isochrones

**URL:** <https://ask.openrouteservice.org/t/data-source-for-bus-isochrones/7949>\
**Category:** openrouteservice\
**Created:** [July 6, 2026, 11:59am UTC](https://ask.openrouteservice.org/t/data-source-for-bus-isochrones/7949 "2026-07-06T11:59:47Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Marielle\_Wilke](https://ask.openrouteservice.org/user_avatar/ask.openrouteservice.org/marielle_wilke/32/4452_2.png) [@Marielle\_Wilke](https://ask.openrouteservice.org/u/Marielle_Wilke)\
**Post date:** [July 6, 2026, 11:59am UTC](https://ask.openrouteservice.org/t/data-source-for-bus-isochrones/7949/1 "2026-07-06T11:59:47Z")

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How are isochrones calculated for buses? Are the actual timetables used as the basis for the data? Or is the distance travelled by a car adjusted to the average speed of a bus, thereby reducing the area covered by the isochrones?

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**Author:** ![andrzej](https://ask.openrouteservice.org/user_avatar/ask.openrouteservice.org/andrzej/32/10_2.png) [@andrzej](https://ask.openrouteservice.org/u/andrzej)\
**Post date:** [July 6, 2026, 2:10pm UTC](https://ask.openrouteservice.org/t/data-source-for-bus-isochrones/7949/2 "2026-07-06T14:10:33Z")

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The latter scenario, based on the average road-type specific speeds defined in [heavyvehicle.json](https://github.com/GIScience/openrouteservice/blob/main/ors-engine/src/main/resources/resources/services/routing/speed_limits/heavyvehicle.json).

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**Author:** ![Marielle\_Wilke](https://ask.openrouteservice.org/user_avatar/ask.openrouteservice.org/marielle_wilke/32/4452_2.png) [@Marielle\_Wilke](https://ask.openrouteservice.org/u/Marielle_Wilke)\
**Post date:** [July 6, 2026, 2:20pm UTC](https://ask.openrouteservice.org/t/data-source-for-bus-isochrones/7949/3 "2026-07-06T14:20:53Z")

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> [@Marielle\_Wilke](#):
>
> How are isochrones calculated for buses? Are the actual timetables used as the basis for the data? Or is the distance travelled by a car adjusted to the average speed of a bus, thereby reducing the area covered by the isochrones?

Thanks for the reply.  
So no GTFS data is used to generate the isochrones?

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**Author:** ![sascha](https://ask.openrouteservice.org/user_avatar/ask.openrouteservice.org/sascha/32/715_2.png) [@sascha](https://ask.openrouteservice.org/u/sascha)\
**Post date:** [July 13, 2026, 3:02pm UTC](https://ask.openrouteservice.org/t/data-source-for-bus-isochrones/7949/4 "2026-07-13T15:02:52Z")

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Exactly.  
You might be interested in this news: [Introducing a new service for public transport routing – HeiGIT](https://heigit.org/introducing-a-new-service-for-public-transport-routing/).