Propensity to Cycle, and the importance of main roads

The National Propensity to Cycle Tool (PCT) is a powerful planning tool which shows existing commuting cycling trips (based on mapping the 2011 census), and then uses that data to illustrate where the main cycle flows are, or should be, and therefore where cycling infrastructure should be prioritised.

Importantly, it doesn’t just cover existing cycling flows; it can be updated to show what (commuter) cycling levels would be like if we had the same propensity to cycle as Dutch people (adjusted for hilliness), and where people would choose to cycle, based on directness.

The purpose of the route allocation is to see on which routes the most provision might be necessary as cycling grows rather than to show where people currently cycle. We recognise that many people currently choose longer routes to avoid busy roads. But for cycling to reach its potential safe direct routes are needed. The Route Network layer is therefore intended to show where (on which routes) investment is most needed rather than where people currently cycle.

I’ve been playing around with it over the last few days, based on the town of Horsham, and the results are quite instructive. Based on the census results, cycling to work levels are currently a fairly miserable 3% of all trips to work in the town centre.

Screen Shot 2016-05-25 at 16.05.29

I say ‘miserable’ because the town is flat and compact – only around 3 miles across, and with all trips (even from some surrounding villages) less than 2 miles from the centre.

Screen Shot 2016-05-18 at 15.23.24Despite this favourable geography, the town (population around 60,000) is dominated by car commuting – between 40 and 50% of trips to work are driven.

The Propensity to Cycle Tool is great because it allows us to visualise alternative scenarios, and how to prioritise designing for them. We can plot the cycling trips currently being made from area to area (in the 2011 census) as straight lines.

Screen Shot 2016-05-25 at 17.16.21

Then (and here’s the clever bit) we can see how those trips would be made by the most direct routes, mapped onto the road network.

Screen Shot 2016-05-25 at 17.17.07

The levels of cycling can then be changed by shifting from the 2011 census to either the (unambitious) government target of doubling cycling levels, ‘gender equality’, ‘Go Dutch’, or ‘Ebikes’.

Screen Shot 2016-05-25 at 17.17.39

What is really interesting (but unsurprising) is that the routes being taken don’t change as the levels of cycling increase, as you can see from the ‘Go Dutch’ scenario shown above. It’s unsurprising, of course, because people will still choose the direct routes, regardless of whether they happen to be part of a small number of cycling commuters, or part of a town with mass cycling. Why would they change to less direct routes?

The great thing about this tool is that it shows exactly where interventions should be prioritised. I can see clearly from the map above that two of the most important routes (at least for commuting) in Horsham are the two roads north of the town centre – North Parade, and North Street.

Screen Shot 2016-05-25 at 17.17.39 Arrows

It just so happens that these are two roads where there is plenty of space to incorporate high-quality cycling infrastructure, with only the loss of some grass, and central hatching – and the existing, poor, cycle lanes.


North Street

Screen Shot 2016-05-25 at 17.58.42

North Parade

So if, for instance, we were looking to prioritise where to invest in cycling infrastructure for the most benefit (rather than just looking to do tokenistic improvements ) these two roads would be among the main priorities. The PCT tool even allows you to click on the roads in question, to bring up helpful information. For instance, ‘Going Dutch’ would mean taking nearly 200 car commuters off this particular road.

Screen Shot 2016-05-25 at 17.20.07

If it wasn’t already clear, main roads are quite obviously where interventions are required, and where they will be most useful. They are main roads for a reason; they tend to form the most direct routes, and they also connect between the places people are coming from, and going to. The Propensity to Cycle Tool isn’t really showing the equivalent of back street, or ‘Quietway’, routes. The cycle flows are all on the major roads, or on the distributor roads that connect up residential streets.

What will make this tool really powerful is when it is released in ‘Version 2’ next year, because it will incorporate other journeys, not just commuting – because obviously only a minority of the trips we make are actually trips to and from work.

Version 2 will go beyond commuting data to incorporate other trip purposes, including education trips at route and area level and other non-commuting trips at area level.

Apparently commuting flows are actually a good approximation for travel flows in general, but incorporating trips for education, leisure and shopping will make the case for cycling even more powerful.

This entry was posted in Horsham, Infrastructure, Propensity to Cycle. Bookmark the permalink.

22 Responses to Propensity to Cycle, and the importance of main roads

  1. stripymoggie says:

    Are there any plans to take PCT UK-wide?

    • ORiordan says:

      I assume that is up to the devolved administrations in Scotland, Wales and N Ireland.

    • I’m not sure – I think it would be easily transferable, given it is just based on Census data. So there’s no reason why it shouldn’t be used for the rest of the UK, assuming census travel patterns are collected in a similar way.

      • Matthew Phillips says:

        The censuses for Scotland and for Northern Ireland are separate from the census for England and Wales, but they did take place at the same time and included identical questions for travel patterns.

  2. Pete says:

    Wow – I’ve always thought that a town that really wanted to solve its traffic problem (fitted as standard across UK towns) would need to survey the population, work out where they are going regularly (e.g. commuting) and provide infrastructure accordingly. What you are saying is that the data already exists, and with this tool it will make the process really really easy.

    Now we need a town council with the vision to make a plan and the desire to provide for cycling in a serious way. Maybe Leicester would be a good place to start at the moment.

  3. Matthew Phillips says:

    Unfortunately the tool (or at least this public version) is using the population-weighted centroids of the census districts for the origin and destination of flows. If your town is relatively easy to get around that might work OK, but in some places it produces results which have to be treated with caution. For example, in Durham, the district which includes the city centre and university has its centroid located on the peninsula, close to the cathedral. This means that the routes it identifies for the main flows miss some of the most popular streets for cycling in Durham, that is, those leading to the main university campus.

    The 2011 census questionnaire goes down to address level for the origin and destination of commuting trips, but of course those data cannot be released at that level of detail. It would be helpful to have data at some level of aggregation between the census district and the exact address.

  4. Notak says:

    It’s predict and provide for cycling!

    (Not actually as cynical as that sounds – just an irresistibly obvious comparison.) It sounds like a great tool. But, having clicked on the link in the text, all I get is a description. It says it’s free to use, open-access, blah blah, but is it possible for the general public to play with it?

    • ORiordan says:

      You need to click on a region on the map, then the link in the pop-up to get to the detail. I haven’t got my head around how it works after this, however!

  5. I suggest reminding everyone who is going to complain about tree loss, and for that matter, flower and grass loss and other plants that they’d rather not lose. All trees except on the largest fields are going to need to be removed at some point. We might not know when, but it will need to happen. Trees simply get too big. Their roots make a mash out of kerb lines and asphalt too if it gets too big. It is fine to remove these trees to make room for cycling and walking. You can plant more trees. Some trees we already have are capable of being relocated, maybe even in the same street. The one thing that do grow on trees are of course trees, and tree seeds are as cheap as rice. And hey, if you don’t remove them and you don’t get the high quality cycleways, then you will be faced with ever more cars. Which is more important, a few trees that can be expended or cycling and walking, especially as the cycling and walking infrastructure can keep you safer and literally save lives?

    • paulc says:

      the Dutch tend to keep their trees either well away, or else as a barrier between motor vehicles and cycles…

    • Clark in Vancouver says:

      I would add that if we didn’t include cycling infrastructure and instead continued forcing everyone to use a car for every trip that we would still have to remove the trees to make room for that. (Not to mention we have to remove parking spots and then eventually entire blocks of buildings would have to go to make room.)

  6. marmotte27 says:

    You can now even contemplate giving many of the most direct routes to cycle traffic like the Dutch did. Motor traffic can easily take longer routes (and if it encourages even more people to take the bike instead of the car, so much the better!

  7. rdrf says:

    Re-trees being felled: This is regularly done to roadside trees after motorists have driven off the road and crashed into them, for “road safety” reasons. .So it could be done for a cycle track.

  8. Re “the importance of main roads”
    Isn’t the assumption that cycling trips will use the same routes as current motoring trips built into the tool (as it’s based on the Cyclestreets routing)?

    There may be cases where deviations from the motoring routes would be preferable. Why cycle alongside the by-pass when you can cycle though the city centre? Not everywhere has the same limitations on space as inner London!

    Nevertheless the tool is a welcome step forward from basing cycle proposals on what is thought would meet the least public resistance, or on what looks pretty on a map! Both rather subjective approaches.

  9. MJ Ray says:

    One problem with the tool is that the methodology seems to favour directing money to radial routes in urban areas. If used widely, it will become much harder to get suburban and rural barrier roads fixed and hinder any attempt to “Go Dutch” with a direct interurban network like the Netherlands.

    • The tool’s logic doesn’t take the availability of public transport into account. So it will indicate a lower public transport share than would be practical on routes into urban centres, but a higher one on routes where a good bus/rail service is impractical.

    • paulc says:

      the tool uses the centroids of the wards and completely ignored a main road (Painswick Road) running into Gloucester that was the divider between two wards… In fact it also ignored the extension of Painswick Road into Gloucester that is a notorious high pollution zone…

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