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Stat attack - has cycling really doubled on a road in Bristol since 2000? We doubt it

DfT figures from 2000 and 2013 suggest big increase - but analysis of trends gives very different outcome

Cycle campaigners in Bristol are hailing a doubling in use of bikes on a busy road in the city during the past decade as evidence of pent-up demand from people to take to two wheels - and on a road they say lacks adequate infrastructure for cyclists. But close analysis of the data reveals that at best, growth in cycling there has been marginal.

A post on the Bristol Cycling Campaign website highlights a 104 per cent increase in the number of cyclists counted on the city’s Gloucester Road between 2000 and 2013.

And yes, if you use just those two years, that's the result you get. We have to admit, it sounds impressive, and makes for bike-friendly headlines.

The campaign group says:

Who knew that Gloucester Road was a brilliantly successful cycle route?

Numbers at peak times have doubled over the last decade while motor vehicle numbers have dropped by a fifth.

We know this because traffic flow data from an annual census published online by the Office for National Statistics allow detailed analyses and comparisons for cycling levels on major routes at a local level.

About 100 census points around the city are monitored for a full day and all forms of traffic are counted.

If a road like this, with very poor provision for cycling, can show a steady increase in cycling over a sustained period we can be very confident that Bristol City Council is right in making cycling a significant part of its transport policy for the future.

People are making a big effort to use bicycles, even on roads like this. This gives the Council an opportunity, and a responsibility, to respond in an even more confident terms than their new Cycle Strategy sets out.

Take a look at the table and the graph. The numbers are impressive and the graph makes it clear.

Source: Bristol Cycling Campaign

But how "brilliantly successful" has Gloucester Road been in attracting more people to ride bikes on it?

Well, the answer is - and if you have a quick glance at those figures above, you don't have to be Carol Vorderman to work it out - it hasn't been.

The problem is that the claim that cycling has doubled in the past decade isn’t one that stands up on closer inspection, and it’s one that underlines the pitfalls in comparing two fixed points in time from the statistics, rather than examining overall trends.

Of the 14 years for which data is shown, 2000 was by far the lowest for the number of cyclists counted, at 810, compared to 1,654 in 2013, which is where that increase of 104 per cent comes from.

But choose 2001 as the base year, or 2004 – which would give a 10-year picture – and the numbers are almost identical to the latest year, at 1,645 and 1,656, respectively.

In fact, the average number of cyclists counted for the 14 years in which data are presented is 1,548. Taking the first seven years of that period, the average was 1,479, and in the latest seven years, 1,616.

That gives rather more modest growth between the two halves of the period of 9.3 per cent – and it’s worth bearing in mind that the latter seven years includes 2008-10, when Bristol was designated England’s first ‘cycling city.’

What we can say with a reasonable degree of certainty is that there has been a steady downwards trend in the number of cars and taxis counted – more than 12,000 in each of the first three years, and above 10,000 for the first half of the period, but firmly below that mark in the past seven years, for a reduction of around 20 per cent.

Buses and coaches present a different picture – the 743 recorded in 2000 is the highest in the entire 14-year period, but 2013’s figure is the second highest, and overall there appears to be little change.

So why the discrepancies in the data? It’s based on annual average daily traffic flow, and the DfT admits that at local level the figures aren’t necessarily “robust.”

Moreover, in contrast to other modes of transport, levels of cycling are particularly affected by the climate – if it’s raining, or a harsh winter, fewer people cycle.

So if that count is done on days when it's tipping down, it isn't going to reflect the true picture; likewise if the weather is particularly good. That's why you need to smooth things out over several years to identify trends.

The lesson, as with casualty statistics, is that if you want to use data to illustrate a point, it’s vital to look at the longer-term picture; looking at individual years in isolation won’t do that.

This isn't just nit-picking over numbers, because there is an important point to be made here, and one that any cyclist in Bristol - or elsewhere for that matter - should be concerned about.

Bristol Cycling Campaign's gushing praise of a doubling in levels of cycling over 10 years doesn't, as we've seen, stand up to scrutiny.

Yet its figures have been seized upon by the local paper, the Bristol Post, and as these things have a habit of doing, could become something of an urban myth for the city's cyclists and non-cyclists alike, a 'fact' to be trotted out now and again.

And in future, Bristol City Council - criticised by the self-same campaign group just last week for its "piecemeal" appoach to infrastructure - may shrug its shoulders and point to that headline figure as evidence its transport policy is helping to get more people on bikes.

Perhaps it would have been more helpful to take a step back, look at the underlying picture, and make the point that the council's approach to cycling is, at best, having a negligible effect?

Simon joined as news editor in 2009 and is now the site’s community editor, acting as a link between the team producing the content and our readers. A law and languages graduate, published translator and former retail analyst, he has reported on issues as diverse as cycling-related court cases, anti-doping investigations, the latest developments in the bike industry and the sport’s biggest races. Now back in London full-time after 15 years living in Oxford and Cambridge, he loves cycling along the Thames but misses having his former riding buddy, Elodie the miniature schnauzer, in the basket in front of him.

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Fish_n_Chips | 8 years ago

Gloucester Road was never a problem.

You lot make it sound like a horror story!

Ok driving it was slow as heck during peak times, which made it
safer for cyclists.

5th | 8 years ago

I ride Gloucester Road regularly as part of my commute, and whilst it isn't great it certainly isn't the worst road in Bristol. The traffic doesn't tend to be an issue cos it normally isn't moving, bit like the rest of town!

chrisMason | 8 years ago

Great article and good spot. As the officer responsible for transport data at Bristol Council, I thought I should clear this up!

The headline story is correct - cycling has doubled (almost) on A38 Gloucester Road and car use has gone down. Gloucester Road is now the most popular on-road route in the city, with comparable numbers to the off-road Bristol to Bath Railway Path. In the morning peak southbound 27% of all vehicles are bicycles.

This reflects the broader trend of a doubling in cycling in Bristol between 2001 and 2011, with an estimated 9% of people now cycling to work in the city.

However, as this article shows, the DfT statistics are not robust. It's not that clear from their data website, but they conduct a 12 hour count every few years and then estimate to get an annual average day 24 hour count, occasionally leading to some odd results. The actual DfT counts at this site were conducted in 2001, 2003, 2005 and 2007 only.

Luckily, we have our own count site near this location at A38 Cheltenham Road north of Arley Hill. The data is below and shows that cycling increased by 76% between 2000-2011 and cars decreased by 8%.

Year Cycle CarTaxi
1994 1165 11803
1995 1187 11832
1996 1174 12945
1997 1212 11920
1998 1103 12166
1999 1179 10901
2000 1164 11157
2001 1245 10804
2002 1269 11482
2003 1476 11001
2004 1322 11174
2005 1035 11114
2006 1793 10370
2007 1580 9757
2008 2072 10208
2009 2272 10258
2010 2285 10818
2011 2051 10284

Jimbomitch | 8 years ago

It is a well known fact that 89.435% of all stats are made up on the spot.  39

edster99 | 8 years ago

Don't choose 2003 as a base year, or it will show traffic reductions as

Bikes 19.1
Cars 12.9
Buses -3.9
All 7.6

i.e bike traffic went down more than twice as much as all motorised traffic. Theres really little to be gained by trying to bullshit with statistics when they are there to be analysed in front of you.

PonteD | 8 years ago

I'm happy I never had to ride to work along Gloucester Rd when I lived in Stoke Gifford. Even thinking about driving along it makes me shudder. I was very fortunate to have most of my commute either off road or through the Airbus site so no idiots trying to kill me, just low flying aircraft buzzing me  16

Matt eaton | 8 years ago

The bus/coach stats seem a bit whacky.

743 in 2000 but only 478 in 2004. I'd expect most of these to be local buses (I don't think there are a lot of private coaches using this road regularly) so the variation seems suspect. Timetables obviously change etc. but this would represent a massive difference in the level of bus services being provided.

Edgeley | 8 years ago

Here in Oxford, the trick to fiddle the numbers is to compare a wet day in the holidays to a sunny day when the students are here.

As the article says, only surveys taken over extended periods stand a chance of being accurate.

therevokid | 8 years ago

cycle on gloucester rd !!!! .... only in dire need ... blocked
lanes, angry bus drivers, even angrier taxi drivers, news
paper reading car drivers, texting pedestrians, rlj bike riders
(and not just the pedal variety either !) - you can keep it. I'd
rather walk.

Housecathst replied to therevokid | 8 years ago
therevokid wrote:

cycle on gloucester rd !!!! .... only in dire need ... blocked
lanes, angry bus drivers, even angrier taxi drivers, news
paper reading car drivers, texting pedestrians, rlj bike riders
(and not just the pedal variety either !) - you can keep it. I'd
rather walk.

Walking on Gloucester rd isn't much fun either, tiny pavements hemmed in by double parked cars.

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