Tuesday, July 30, 2013

Cycling–what is it all about

There has been a bit of discussion on Twitter recently about the Bristol-Bath bike path. With John Usher of Sustrans discussing the issue on BBC Radio Bristol


So what is the fuss about? Well the Bristol/Bath bike path is a victim of its own shared-use success.  Whilst many of us think of it as a bike path – actually it is a path which cyclists can share with pedestrians, dog walkers, prams and the like. It follows the route of an old railway line and forms part of NCN4.

Bristol – Bath Bike path 

Well to my mind there is a clue in the name – SUSTRANS – Sustainable transport – healthier, cleaner and cheaper and journeysAt its simplest the bicycle is an efficient way of converting physical energy into motion. We might choose to cycle for different reasons but ultimately it is a form of transport, with benefits.

Now I am not claiming all my maths is correct but whether we realise or not we cyclists like to maintain momentum. Lose it and it costs significant levels of energy and significant delays. If you have to stop 20 times on a 16Km journey then it can increase the journey time by 15 minutes and make it feel like you have cycled another 2Km on top in terms of energy consumption. In a car you tend not to notice petrol consumption, except perhaps when you fill up – you notice it when you are supplying the motive power.

I believe that the Bristol Bath path was what set in motion the Sustrans movement. It is straight, direct, more or less and has a decent surface. All the things that matter to a cyclist getting from A to B. As Sustrans has evolved I wonder whether the organisation has lost sight of the original ideals. There are some fantastic Sustrans routes – but they tend to be for the cycle tourist – willing to wend there way through twists and turns in order to enjoy a peaceful ride.  Don’t get me wrong  when I want a bit of time cogitating along with a bit of fresh air and exercise then the National Cycle Network is great – but “easier journeys” it isn’t!

An example of what I mean. Follow NCN51 out of Cambridge towards Newmarket and when you reach Bottisham you have this choice. Cycle to Newmarket 15 miles, drive to Newmarket 6 miles.

Sustrans NCN 51 to Newmarket

Or zoomed in.

Sustrans NCN 51 to Newmarket

The bottom lines is that If you want cycling to to become a real choice then the journeys need to be  healthier, cleaner, safer, cheaper and easier journeys. To get people to switch their method of transport focus has to be on the easier and cheaper and safer. Healthier and cleaner come for free once you get people cycling.

  • Cheaper and easier journeys cannot be implemented by cheap infrastructure.
  • Easier journeys cannot be implemented by relying on shared-use infrastructure
  • Easier journeys need to be direct for places regularly visited
  • Easier journeys need to allow cyclists to maintain their momentum without slowing and stopping all the time.
  • Safer journeys cannot be implemented with a lick of pain here and there and a twist and a turn and constant change of surface.
  • Safer journeys need segregated cycle routes

If a shared path is useful it is almost bound to create conflict.


Here are some of my calculations

At its simplest the bicycle is an efficient way of converting physical energy into motion. According to work by Professor D Mackay:

a cyclist at 21Km/h consumes about 3% of the energy per kilometre of a lone car driver on the motorway – about 2.4kWh per 100km

What’s more a bicycle is more efficient than walking – according to Wikipedia(!) cycling requires around half the energy compared with walking.  This website suggests that cycling can be up to five times more efficient than walking (it depends upon the speed the cyclist travels at).

So on the face of it a bicycle represents a pretty good sweet-spot as a transportation choice without even comparing the health benefits and the fact that bikes don’t pollute (noise or air) take up far less space (rest and motion) and do far less damage to the road (and pavement) surfaces.

The downsides are that cycling is open to the elements, less fast and can be tiring over longer distances. It can also be harder (but not impossible) to transport other people (children for instance) or shopping.

Now my personal view having cycled, driven and caught the train to commute over the years is that for commuting a round trip of 20 miles is fine. I have done more, but accept that for some it might seem too long. Part of the issue is not the energy consumed but time. Assuming a speed of  10mph (16Km/h) then one leg of the commute takes 1 hour, at 16mph (25.6Km/h) the journey time is 37.5 minutes.

The average commute time for men in Britain is apparently 58 minutes and for women 47minutes but varies by region – chart in this article by the DM. So time is precious when commuting, whether by bike or motor vehicle/train.

The other aspect that concerns the efficiency of cycling is momentum. Every time you slow down the energy required to get back up to speed is proportional to the square of the velocity you wish to achieve.  I wrote about it here. I reckon that at the speed I travel every stop adds the energy equivalent of 100m onto the journey.

Then there is of course the issue of lost time, assuming I cycle at 25.6Km/h and it takes me  say 200m to get up to that speed from a stop, it would then it would add approximately 30 (28) seconds onto the journey time. That is not to mention the actual delay from the cause of the stop.

So on a 16Km journey (10miles) at a steady speed of 25.6Km it would take 37.5minutes – if you had to stop say 20 times, with an average stop of 15 seconds then the overall journey time would extend by 20 x (30 + 15 ) seconds, which comes to 15 minutes. If my maths is correct. In addition the journey would feel as if you had cycled an additional 20 x 100m – 2Km.


  1. An interesting post. It does take a formidable act of willpower sometimes to commute to work - at least on my part. I commute from Willingham to Bar Hill, a distance of 5.5 miles in the car. As I'm not suicidal enough to risk the B1050 on a bike it's 8.5 miles cycling. I cross Oakington airfield (I'm usually overtaken by around a dozen cars on this supposedly prohibited to motorized traffic road) then take the road to Dry Drayton (quite a fast road, but cars tend to give lots of room as it's more tidal than the B1050) then negotiate the Bar Hill "cycle"-way's annoying pinch-points. It usually takes around 40 minutes, which isn't too bad a time.

    1. I used to live in Willingham with a 14-mile cycle commute - when I was doing it regularly it was great - a refreshing end to the working day. If I stopped for a few days it got harder and harder to start cycling again. Generally it took being stuck in traffic on the way through Cottenham and Histon to remind me I could be doing better things with my time.

      I reckon Bar Hill's one of the worst places to cycle to/from in this area. The fact that the A14 exists tends to drive a lot of traffic along the country lanes nearby as well.

      Well done - when the cycle route is longer than the "driving route" it does tend to create a psychological barrier.

  2. The Bristol-Bath bike path is a converted railway line, and since it is shared with more vulnerable users, people need to be respectful of that fact. No problem.

    From a cyclist's point of view, one of the big attractions of these paths is that rarely do you need to come to an absolute stop, which means of course, the all-important momentum can be maintained to some extent at least.

    There were a few things in the middle of your piece that I would like to take issue with ...

    You write: "Cheaper and easier journeys cannot be implemented by cheap infrastructure."

    Cycling: the way ahead writes: "While it is as beneficial as swimming, cycling is much easier to do on a daily basis as it does not require the setting aside of a particular hour and the public equipment needed (roads) already exists everywhere and only requires a few adaptations."

    You write: "Safer journeys cannot be implemented with a lick of [paint] here and there..."

    The Cycling Dutchman writes: "Slowing motorised traffic down on local through roads in the Netherlands is achieved by a relatively cheap method: just a different lick of paint!"

    You write: "Safer journeys need segregated cycle routes."

    Cycling: the way ahead writes: "Cycle paths are one way of guaranteeing safety, among others."

    Just one more thing, if you don't mind. If the authorities had £200m to spend on cycling, a really snazzy cycle network would of course be just the ticket. But what if they only had £2m to spend? What do you think? Just a couple of high-profile schemes, or a network which functions at a minimum level? What do you think, Jamie? Would you answer the question, or not?

  3. Hiya you raise some good points, and thank you for taking the time. I believe that if we want more people cycling as a means of transport then we will need appropriate infrastructure to encourage all those non-cyclists to switch. By considering what the barriers are it ought to help us do better.

    I enjoy cycling along Sustrans route,they are great for leisure - I don't think they make for easier journeys as they can be tricky to follow (I got lost in Boston on NCN1 yesterday.) They tend to be narrow, use a variety of different surfaces and use all manner of routes - shared-use, cycle lanes on roads, bridleway and permissive routes.

    If we want people to switch from cars to bicycles for transport then scenic routes nice though they are aren't going to cut it.

    As you say the Bristol to Bath Railway path is a shared-use path. So despite the fact it connects two cities almost centre to centre, is fairly flat and fairly wide, with a smooth surface with has few junctions it has significant compromises as a commuting route. It is a victim of its own success and I would suggest we need to reconsider its fitness for purpose. Apparently it was used for 2.4 million trips in 2007 and that number increase by 10% per year. (If it did continue to increase at that level that would be 4 million trips by 2012 - although I can't find any data to support this.)

    So given that level of usage why can't we justify more expenditure on decent cycle facilities. Why are we relying on a Charity and the good will of volunteers. Here in Cambridgeshire everyone moans about the A14 - they don't offer to volunteer their time to build it though.

    The question I raise is are we taking cycling as a means of transport seriously.

    So my take on the points you raise.

    If we want more people to switch to cycling for transport then we have to take the infrastructure more seriously. Whilst making a few adaptations might be a low-cost way to create cycle routes if is is successful then it will also create conflict with other users of those routes. The number of killed or seriously injured cyclists is on the rise. At a rate greater then the increase in cyclists - not an encouraging message.

    I would agree that in the Netherlands a lick of paint is a cheap method of slowing down traffic they also spend a lot of money on decent infrastructure. Motorists have more empathy for cyclists.

    Here in the UK we have various cities implementing 20 mph zones and yet the Police here in Cambridge seem to feel that fully enforcing the limit will be "unpractical".

    Perhaps it might be fairer to say that safer journeys either need segregated cycle routes or a significant change in motorists' behaviour.

    In answer to your question there was a time when I would have agreed that with only £2m then it might be better spent on a network of functions. However I no longer believe that to be the case. I would observe that money is wasted by building cycle infrastructure that fails to attract cyclists. Butt Lane between Milton and Histon is one road where the creation of a cycle route has so far has failed to materialise but still cost money. Half a cycle route equates to no cycle route.

    I believe that it is better to do fewer things to a higher standard than a bunch of things poorly. So I would start with a couple of high-profile schemes - and build from there.

    My own experience of the Cambridge Guided Busway shared-use path is that better facilities do seem to attract more cyclists from families to time-triallers. There are walkers who use it, but you tend not to get too large a mismatch between the types of traffic - which is what seems to exacerbate the situation on the Bristol Bath Railway path.

    Personally I would not spend over a £1bn on a short stretch of the A14 I would use the money to build decent cycling infrastructure.

    Sorry a bit of a ramble - I just feel that cycling needs some real investment and that the number of users justifies it.

  4. Thank you for your reply. Most people I ask tend not to answer the question I posed at the end, so I really do appreciate you taking the time to respond.

    The strategy you are advocating is a bottom-up (or piecemeal) approach. I have yet to read any evidence that suggests this is a good way forward. Indeed, I note that you did not quote anybody. If you are able to quote somebody, I would be most interested in the details.

    In his blog on the Lessons from Copenhagen, David Arditti quotes Johan Diepens of the Dutch Cycling Embassy. He writes: "He showed some maps of the cycle and road networks in Dutch cities, [and] said that in planning for cycling, the critical thing is to design your network correctly. Everything else, he said, was trivial."

    Cycling: the way ahead says: "Reproducing apparently effective action taken elsewhere could have negative consequences if the concerted and coherent programme on which such actions were based is not taken into account. On the contrary, it is preferable to draw inspiration from known examples with due caution."

    I totally agree with your concluding point, which says that cycling needs some real investment and that the number of users justifies it. I just think this investment should be made within the framework provided by a functioning cycle network. As you say, "Structure provides a framework to push and experiment".

    Regarding your point about the Bristol-Bath railway path, the level of usage does indeed mean that we should be able to justify more expenditure improving the quality of this route. It is ridiculous that we should be relying on a charity and the good will of volunteers to provide for this.

    I agree with most of what you are saying, actually. However, I think your assertion that "introducing" a network to the point where it functions - by doing as much as possible as quickly as possible - by making the minimum change for the maximum effect - is about doing "a bunch of things poorly" ... no, this is a gross misrepresentation of my proposal. Seriously, Jamie, Cycling: the way ahead describes it as "a prudent course to follow." It's just one of the first steps, that's all.

    You write that half a cycle route equates to no cycle route, and yet you also suggest that doing a few things to a high standard, and then build from there, is the best way forward. I'm sorry, I can't make any sense of it.

    And now it feels like I am rambling, so I'll close now, and thank you again for taking the time to respond.

    P.S. I love your photos, by the way.

  5. No problem. I have always been a believer in working through ideas. I do agree that a strategy, or long term direction is needed. I reckon that the strategy also needs to be integrated with transport strategies and social strategies and health strategies. Perhaps that is why many of our cities are in such a mess. There has been no underlying direction - whether it be how to deal with car parking, getting to and from school or the implementation of 20 mph speed limit.

    The concern I do have is that when national and local government talks about cycling and then acts the results are underwhelming at best. For instance there are many documents detailing what cycle infrastructure should look like here in the UK but too often good practice is ignored in the name of expediency.

    When I talk about half a cycle route - I mean a route that has been planned to get from a to b, say a group of houses to a school. There are several instances here in Cambridge where the whole route is compromised by no completing. That damages the cause for cycling more than not building the route at all I feel.

    That route should help build towards an overall network. I suppose the issue at question is what would the minimum acceptable level for the network be. I feel that in order to get a real modal shift that minimum level is pretty high in my mind.

    Thanks for the comment on the pictures - I am thinking of a series on how I feel that current cycle paths in Cambridge are a compromise too far.

  6. Thank you for your reply. Like you, I think it is good practice to talk through ideas. As has been noted: "A perennial problem in cycle route network planning is the reliance on bright ideas and pet projects that may not have been critically evaluated for usefulness and value for money."

    I totally agree that in order to get a real modal shift, the level at which the network needs to function has to be pretty high. The question is, how to get there?

    Essentially there are just two options: bottom-up (adjustment) or top-down (holistic). There is no evidence to suggest that a bottom-up approach is effective. Indeed—sorry to labour the point—I note that you are still unable to quote anyone in support of this strategy.

    "Introducing" a network to the point where it functions is not the final step. No, the final step is to develop the network further "on the basis of priority interventions and a timetable." Clearly this must be done well. Your point that it would need to be integrated with transport strategies and social strategies and health strategies is well made.

    Finally, I very much hope you go ahead with your idea to show how the current cycle provision in Cambridge is a compromise too far. I have undertaken my own study of Cambridge, but I would stress that I was looking at it from the perspective of the penultimate step, and not of the ultimate step.