Why the A315 is the best route for CS9

There’s been some talk about routing CS9 down the A4 instead of Chiswick High Road and King Street (aka the A315). Fans of this idea have touted it as a perfect pain-free solution, given the existence of a cycle track of sorts on it (in reality, legalised cycling on the pavement), and its distance from residential areas. But there are downsides to this route that its proponents haven’t mentioned. We really wish people pushing the A4 route were willing to look into the details. We also think the local political parties who have been advocating the A4 for CS9 without any consideration of the issues it raises, especially to the residents who would be most directly affected, have been particularly negligent in this regard.

Let’s look at the four big reasons why the A315 is the best route, and the things that proponents of the A4 route don’t want you to hear.

1. A significant majority of people prefer the A315

Firstly, look at the number of people cycling down the A4 as opposed to the A315. Department for Transport traffic counts show between three to six times more people cycling along the A315 compared to the A4.

Source: https://www.dft.gov.uk/traffic-counts/
People who cycle have already voted for their choice of route. Protected cycle infrastructure along the A315 is therefore a considerably better investment in terms of the number of people who will use the route.
To emphasise this, the TfL consultation showed 60% support for the A315 route.

Advocates for alternative routes need to show evidence they are better used than the A315, and are supported by the public.

2. Because cyclist and pedestrian safety along the A315 needs to be improved

The A315 has a poor record for pedestrian and cyclist safety and has been claimed to the “fourth most dangerous road in Britain” based upon collisions per distance travelled. The collision rate along Chiswick High Rd and King St is representative of the overall road. Each star represents a collision involving a cycle or pedestrian between 2005 and 2016. It’s not pretty.


Source: https://bikedata.cyclestreets.net/#17/51.49257/-0.25328/opencyclemap

Advocates for alternative routes need to explain their proposals to improve cyclist and pedestrian safety along the A315.

3. Because it will be used for ALL types of journeys

Transport for London research has identified 8.17 million daily trips made by motorised modes that could be cycled. Of these, 6.47 million trips could be cycled by most people in less than 20 minutes.
Over half (53%) of potentially cyclable trips are for shopping and leisure while 17% are for commuting.
Even for current cycling trips in London, over half (51%) are for shopping and leisure while 28% are for commuting. That demonstrates huge potential for increased cycling in London.


Cycle superhighways being “only for commuters” is a myth. To be used by the maximum number of people, the routes must cater for people using them for shopping and leisure purposes as well as going to work. That means the routes must go through the main town centres of Hammersmith, Chiswick, Brentford and Hounslow and not bypass them, as a route along the A4 would do.
Like any mode of transport, the purpose of people using the route will change by time of day and day of week. At 8am on a weekday, CS9 will have mainly people going to work. During other times however, it will be people going shopping or visiting the other amenities along the route.
There is substantial evidence that cycling improves the local economy. Research on London shopping streets has found people coming by car visit less often and spend less per month than people using other modes of transport. We understand the concerns of businesses to any possible downsides, but the it is wrong to claim that these concerns confirm a loss in trade will occur, when in fact quite the opposite will most likely occur if past schemes are any guide.

Advocates for alternative routes need to show why they would be used for people shopping and visiting other amenities.

4. Because the people who are proposing the A4 don’t understand the problems it would cause

Now for the elephant in the room. Invariably we find that people proposing the A4 have done no investigation into what would be required to turn it into a proper cycle route rather than the current situation, which is cycling on a pavement shared with pedestrians.
With the A4 option, CS9 would either be two segregated tracks on either side of the A4, or a two-way segregated track on one side. On the north side, the subway tunnels produce pinch points, leaving only room for one lane of CS9. That would require removing pedestrian access from one direction to the subways. On the south side there are also pinch points, leaving room for only a single lane of CS9, for example between Sutton Court Road and Eastbourne Road, in this case with complete loss of the pedestrian access. Therefore CS9 would have to be one lane on each side the A4, and it would require losing portions of pedestrian access along both sides.
If we want a dedicated cycleway and not just the current shared use provision, this would also require closing down pedestrian access to the existing tunnels, removing parking in front of people’s homes on the A4, compulsory purchase of strips of front gardens and cutting down scores of trees, like the current row of approximately 68 trees in the Chiswick section of the A4.
• What would you do here, where there’s not space to put in CS9 and keep any pavement for pedestrians?
• Maybe there’s more room on the south side?
• And after cutting off chunks of pedestrian access to make the space for CS9, you then have to start on the trees, and then finish with the parking!
We certainly don’t think that TfL would be up for rejigging the A4 a few feet first one way and then the other to allow CS9 to snake around the subway entrances, trees and and parking, and it actually gets more challenging towards Hammersmith with several subways built right up to the side of the road.
However, there are residential properties on the A4 which require access, thus making it impossible to take any more pavement space. So now a lane of the A4 is required, displacing traffic to Chiswick High Road and King Street. If we’re going to build a “proper superhighway” along the A4, closing down a lane would lead to considerable traffic displacement to the High Road. Not great for anyone. The A4 carries six times the traffic of the High Road (90,000 vehicles per day vs. 15,000 on the A315), so even if only 10% were displaced from a one third cut in capacity for a lane closure, that would add more than 50% to the traffic along the High Road.
As they say, where there’s a will there’s a way. Just maybe not in this case, hopefully.

People proposing the A4 have different motivations for doing so. It is the most convenient route for some people, and they would like to see the cycling facilities improved there, as do we. For others, proposing the A4 seems to be a coded way of saying “get those cyclists away from me”, and others may genuinely think it is a better solution but without actually having to look the detail. Whatever their motivations, advocates of the A4 route really need to provide more than the most basic of evidence for why their proposal is the better option, rather than relying on guesswork and gut feelings for their case.

In conclusion, we see no other route but to place CS9 along the route that has received clear majority backing in the consultation. With the growth of cycling as a mode of everyday transport in London, doing nothing is not an option, and although it’s fine to suggest alternatives, we need to hear clear, evidence-based reasoning for these options.

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