Cheltenham Standard

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Background

What is the Cheltenham Standard?

A scheme for describing how suitable an all-purpose road is for cyclists, originally devised in the UK town of Cheltenham.

It's now on the way to becoming a National Cycle Mapping Standard, and is being adopted by many local groups.

There are five levels of suitability:

  1. Quiet roads with little traffic and low traffic speeds. Generally suitable for all cyclists. These are mostly non-distributor residential streets or roads through parks. (Yellow on the original Cheltenham map.)
  2. Through routes with moderate traffic and low speeds. Suitable for Level II and Level III cyclists; perhaps Level I at less busy times. Shopping streets and industrial premises should be classified green as minimum due to the complexity of the traffic environment. (Green)
  3. Busy roads, including A or B roads, where road design is traditional and does not lead to excessive speed. Few HGVs. Road width allows safe overtaking of cyclists over the greater part of its length. Suitable only for Level II and Level III cyclists. (Blue)
  4. Busy principal roads, perhaps with some HGVs. Road width restricted, leading to increased risk from overtaking vehicles. Traffic speed high relative to road width with drivers less willing to cede right of way to cyclists. Complex junctions. Suitable for Level III cyclists and some Level II. (Red)
  5. Fast, busy roads with frequent HGVs. Motor vehicle-orientated road design, such as use of slip roads, large roundabouts. Restricted lane width. Suitable only for Level III cyclists. (Purple)

(Level I/II/II refers to the UK National Cycle Training Standard).

What does the Cheltenham Standard bring to OSM?

At present, OSM cycling cartography (and to a lesser extent, route-planning) are oriented towards cycle-specific features: for example, bike parking, the National and London Cycle Networks. In some circumstances, this is all the cyclist needs - for example, if he/she is in a city with a dense cycle network (e.g. London), or is following a long-distance NCN route.

But often, the best route for the cyclist will take in other roads. If we had information about the suitability of such roads, our maps and route-planning would be better than anything currently available for the cyclist - once again keeping OSM ahead of the curve. And the best people to assess such suitability are local cyclists - in other words, OSM mappers.

Mapping 'suitability for cyclists' on OSM

The three great virtues of the OSM mapper: laziness, impatience and hubris

Tagging should be easy. Where possible, tagging should not impose extra burdens on the mapper.

Fortunately, our highway tag actually approximates really well to the Cheltenham Standard:

Cheltenham Standard highway=
Yellow (quiet roads) residential
unclassified
living_street
Green (through routes) tertiary
Blue (busy traditional roads) secondary
primary
Red (busy principal roads) primary
Purple (fast busy roads) trunk

...which means that, for the majority of roads, there is little need to add an extra tag for cycle suitability.

The challenge is finding a way to tag routes whose highway tag belies their cycle suitability. For example, a highway=secondary/primary in the Hebrides might have minimal traffic and low speeds, promoting it to green or even yellow. This is particularly the case with highway=primary, which does not fit easily into one single category.

There are two different approaches that could be taken.

Option 1: "map what's on the ground"

One approach often used in OSM is to record the raw data, and let the software (renderer/route-planner) make the decision.

The criteria that inform a Cheltenham-style "suitability" rating are traffic volume, average speed, and the complexity of road junctions. Traffic volumes and average speeds are, however, difficult to record, especially within the short timeframe that an OSM "mapper on a mission" will generally devote to one street. Similarly, road junction information is (in theory) already in the database, but in practice is difficult to parse programmatically - especially for a renderer.

A "easiest thing possible" may be a simple, subjective tagging scheme based on estimates, such as

traffic_volume=low
average_speed=25mph

though this does run the risk of implying a level of certainty that isn't there.

(See also Cycleway#On-Road_Cycling_(Cycle_Friendly_Streets))

Option 2: specific tagging for cycle suitability

The other approach is to expressly tag using a Cheltenham-type scheme where the cycle suitability differs from that implied by other tags (principally the highway tag).

There is no suggestion that the actual Cheltenham colour names should be adopted - that would be silly. However, any of the following approaches could work, taking the "busy traditional road" as an example:

  • bicycle:suitability=level3 (the 'tracktype' approach)
  • bicycle:suitability=moderate
  • bicycle:highway=secondary
  • cycleway=secondary (repurposing the 'cycleway' tag; may need composite values, e.g. cycleway=secondary;lane)

Do not vote here

This Is Not A Voting Page. But do add your thoughts, e.g. on the discussion page.

--Richard 13:40, 10 September 2008 (UTC)