Monday, 29 June 2015

Study Tour round-up (June 2015 with Cambridge Cycling Campaign)

Study Tour participants from Cambridge riding on a canal-side cycle-path in Assen.
Our study tours in Assen and Groningen have been quite popular this year. The feedback section of the study tour website shows where most of the people have visited from and there are plans for more visitors. The photos below show some of what we currently demonstrate on study tours:

This photo may not appear to have much connection with cycling, but the top of this hill gives me a chance to illustrate how unraveling of cycling routes from driving routes creates excellent conditions for cycling.

While our bikes waited at the bottom of the hill, they were passed by a stream of cyclists. The intensity of this stream varies (more at rush hour) but true mass cycling means that there is almost always someone in sight on a bike, even at quiet times of the day.

Wide cycle-paths, separating people from motorized traffic as here emerging from a bicycle tunnel ,result in conditions where smiling is normal while riding a bike.

Room to spread out without getting in anyone's way.

Explaining and demonstrating how even residential streets which are very close to main roads are not affected by the noise of traffic, reducing everyone's stress and fostering good relationships between neighbours.

Cycle-parking for bus passengers and a bus-stop by-pass which is virtually invisible to cyclists. Note that the 3.8 m wide cycle-path is designed to facilitate efficient cycling and therefore does not narrow as it passes the bus-stop.

Assen city centre. Demonstrating a junction which used to have traffic lights to deal with high volumes of motorized traffic now no longer needs them because the centre no longer has through motorized traffic. See a photo of how this used to be.

The school run in Assen. Children ride their own bikes and have a great degree of freedom. Dutch children are recognized by UNICEF as having the best well-being in the world.
Indoor cycle-parking at a new primary school.
Not just pretty pictures
Pretty pictures do not make cycling normal. In order to make cycling attractive to everyone the infrastructure has to be designed such that it invites people to cycle. Cycling has to be efficient and convenient and also very safe (most importantly: very subjectively safe).

Therefore, as well as the more photogenic subjects, we also took a close look at in such things as the following:
  1. The safest roundabout design for cyclists. Design details are very important.
  2. The safest and most efficient traffic light design for cyclists as well as the quite different design used for most larger junctions.
  3. Traffic lights which default to green for cyclists
  4. Town centre from which through traffic has been removed
  5. Residential streets providing plenty of car parking spaces but on which moving cars are rare.
  6. Direct convenient and safe cycling routes to Assen city centre from suburbs, villages and even other cities.
A city which demonstrates much good practice
Everyone can reach everywhere in Assen by bicycle. Rather than being carried on parents' bicycles, even small children routinely ride to the city centre on their own bikes using the same well-designed fine grid of high quality cycle routes as everyone else uses, regardless of age or ability.

Why isn't everywhere like this ? All cities could plan in the same way. We can show you, your politicians and your planners what has been achieved and how it affects everyday life. Everyone stands to benefit from better living conditions. Even determined drivers benefit from better cycling infrastructure.

More information
More information, including video, is available on the study tour website.

Our next open tour is at the start of September. You can reserve a place on that tour now (private tours are also available).
Book a place on the next tour

Friday, 12 June 2015

The Slow-Turbo Roundabout. A promising new Dutch roundabout design and why you should NOT copy it

A few days ago a new Dutch "slow turbo" roundabout design appeared in images on Twitter. Ordinarily, turbo roundabouts are used in the Netherlands to deal with large volumes of high speed motor vehicles in locations such as motorway junctions, which are rarely visible to cyclists and pedestrians, but this new design is intended to be used in areas with high volumes of cyclists and pedestrians:
A promising design, but with unproven safety record so don't copy this yet.
This roundabout is interesting because it combines the safe layout of the proven safest Dutch roundabout design with priority for cyclists at the crossings, when similar layouts have previously only been used where drivers are given priority at the crossings. Extra care has been taken in the design to try to ensure cyclist safety at these priority crossings - a factor which has been proven in the past to lead to a sharp reduction in safety.

A particularly poor "with priority"
design. No sight-lines, no reaction time
Frequent injuries at this location.
This design attempts to reduce the safety problem for cyclists with priority at roundabout arm crossings by a number of measures:

  1. It slows both cyclists (by tight corner radii) and drivers (by use of narrow lanes with raised tables), giving both more time to react at the crossing.
  2. Good sight lines are ensured because cyclists and drivers cross at right angles to one another.
  3. While turbo-roundabouts require multiple lanes, this design keeps the cycle crossings far enough from the roundabout that cyclists are required to cross only one lane of motor vehicles at a time.
  4. A generously sized safe refuge is provided between the two streams of traffic.
  5. The crossings being placed at a considerable distance from the roundabout itself means that the moment in time when drivers negotiate with cyclists on the crossing is distinctly different from that when they have to negotiate with other drivers on the roundabout.

Why it may not be so safe as is hoped
I think there is great promise in this design but I must sound a note of caution.

Raised tables slow motor vehicles where
cyclists have priority at the crossings, but
they resemble less successful crossings.
I am enthusiastic about the possibilities for this type of roundabout because it follows the good design principles of the proven safe Dutch roundabout design as I discussed in the previous section and that it also gives cyclists priority (everyone wants priority), but I also see reasons why it may fail to be safe. For instance:
  1. The distance between the crossings and the roundabout is quite large, but for drivers entering the roundabout the distance between the crossing and the point where they need to choose a lane is very short. This may distract drivers such that they are less likely to notice cyclists.
  2. Raised tables on straight roads have only a slight effect of slowing drivers. When I looked at three different priority crossings a few days ago, the crossings where drivers were effectively slowed had more measures than just a raised table and the example which barely slowed drivers at all looked very much like these crossings.
  3. This isn't the first time that priority has been combined with a layout which provides better sight-lines. For example, one attempt to design a roundabout in Eindhoven combining good sight-lines with cyclist priority resulted in some injuries.
I remain hopeful about this design, but we must keep in mind that it is an experiment.

Experiments are not always successful
Without experimentation we can never discover new and perhaps better ways of doing things. The Netherlands leads the world in cycling infrastructure design, and experimentation continues here. This is a good thing. But ideas should only be adopted more widely if they have been proven to work safely and efficiently.

Experiments which didn't work out so well include an experimental cycle-path surface which was installed near Assen in 2009, but then replaced again in 2013 after it had proven not to provide an adequately comfortable surface for cycling.

There was also the Zwolle "fietsrotonde" for which bold claims were made in advance, but where poor design caused injuries within months of opening.

As of right now, there is precisely one roundabout of this new design in the world. It should be viewed as a brave and worthwhile experiment and it may eventually form the basis for yet safer conditions for cyclists in the Netherlands, but it should not yet form the basis for other experimentation elsewhere. We do not yet have long term accident statistics for this design and it is premature to make any claim about whether or not this new design is in fact safe.

Note also that the new design requires a very large footprint in order to provide the required sight-lines and space for the lanes of the turbo roundabout. As such, it's unlikely to be able to be applied everywhere.

What to adopt in other countries
For experimentation elsewhere it makes most sense to copy the proven safest Dutch designs. So far as roundabouts are concerned, this is it:
This design provides the best basis for emulation elsewhere. Such roundabouts have the the best safety record within the Netherlands and are likely to remain safe even if aspects of the design are compromised.
The safest design currently in use in the Netherlands, shown in this photo, places the emphasis on cyclists to look after their own safety rather than relying upon perfect driver behaviour to keep cyclists safe. This is one of the reasons why this design is successful. The same principles have also been shown to work on similarly designed roundabouts with considerably smaller footprints.

Awful roundabout design from London
widely described as "Dutch", but
actually nothing of the sort.
The details of any design are important. Distance between roundabouts and crossings, heights of raised tables, lane widths, road camber, geometry are all important and none of these should be taken as being the sole reason why Dutch roundabout designs are safe for cyclists. It should also be noted that roundabouts are only used by cyclists in the Netherlands where traffic volumes and speeds are relatively low and are controlled. Unfortunately, it is not uncommon for designers elsewhere to completely misunderstand how Dutch roundabouts achieve their safety. "Cargo-cult" style copies of Dutch roundabouts built in the UK in Bedford, Cambridge and York without the safety features of the Dutch roundabouts which provided inspiration and as a result they are not so safe.

In order to try to assist planners and campaigners alike to make the right choices, we offer cycling study tours which take a unique, independent, view of Dutch cycling infrastructure and which explain everything in plain (native) English. Book a place to discover more about what works well and should inspire new infrastructure design elsewhere as well as what works less well and should not be copied.

Find out how how things really work in the Netherlands before trying to copy anything.

Wednesday, 3 June 2015

Safe cycle priority road crossings

I've covered several types of road crossing for cyclists in the past. Those with traffic lights, where cyclists have to wait for motorists but can stop in the middle of the road, those where there is equal priority between cyclists and motorists. Sometimes it's possible to give cyclist priority over roads when cycle-paths and roads cross but this can only be safely achieved if certain conditions are met. It is not enough simply to put up a give-way (yield) sign and expect that drivers will obey it.


Driver behaviour is more effectively controlled by road layout than by signs or speed limits. In order for it to be safe to give cyclists priority at a crossing, the speed of cars on the road needs to be controlled and traffic volumes need to be low. The junction needs to be designed such that it gives obvious visual priority to cyclists, and sight lines need to be good enough that drivers and cyclists can see each other and respond accordingly. This is not the same concept as "making eye contact". If people driving and cycling are surprised by the other party because they cannot see them in time then they are less likely to be able to respond safely.

First example in the video. Cycle priority crossing of a minor road. 30 km/h speed limit on the road, raised table starts 20 m and 14 m away from the crossing. Bend in road naturally slows cars. The cycle-path is three metres wide and runs at a distance of six metres from the parallel road.
Second example. This road has a 30 km/h speed limit, but it is a much busier road than the other two, providing a route by car to local shops and other facilities. Raised table starts 5 m and 12.6 m from the cycle crossing. Bend in road naturally slows cars. Cycle-path is 3.5 m wide and runs perpendicular to the road.

Third example. The raised table almost doesn't exist in this case and there is no bend in the road so drivers pass over this crossing at far higher speeds than the other two. Note how drivers may not be able to see cyclists coming from North or South until they are close to the crossing due to being obscured by buildings and vegetation and then there is a chance that a driver will misinterpret the intentions of a cyclist so not slow down for them. Note also how the curves on cycle-paths, especially North of the crossing, are far less helpful for cyclists than the other two examples. Cycle-path is 3 m wide and at the point of the turn it's just 3 m from the parallel road.
While the third example is the one which I believe is least satisfactory (see the video for why), collisions between cars and bikes are only recorded as having happened at the second example. There is a rational explanation for this. The second example is located adjacent to the local facilities of a suburb (shops / doctor / health / church) and this results in considerably more cycle and car traffic than the other two which located within residential streets. Three collisions with cyclists occurred over the 2007-2012 period at the second example, one of which caused an injury.

Curve radii and approach visibility
The recommendation of the CROW Design Manual for Bicycle Traffic for curve radii is particularly relevant to cycle priority crossings. The manual says that on curves with below 5 m radius, "cycling speed drops below 12 km/h and the cyclist has to work hard to remain upright" and suggests appropriate curve radii as follows:

  1. cycle connections that form part of the basic network should have a radius of greater than 10 m, geared to a design speed of 20 km/h;
  2. cycle routes and main cycle routes should have a radius of greater than 20 m, geared to a design speed of 30 km/h
Note that this refers to cycle-paths having a design speed of 30 km/h. Cycle facilities should not be designed to slow cyclists, but to enable efficient cycling. The first two examples above conform to this recommendation, while the third, especially when approached from the east, does not. This causes a problem for cyclists and motorists.
CROW recommended visibility at crossings by road width (crossing distance) and speed.
The requirement for approach visibility should also be noted. Take into account that these speeds are 85th percentile speeds in actual use, not merely the posted speed limit, and that the required sight lines more than double in length for any crossing of a 50 km/h road vs. a 30 km/h road. Also note that wide roads require more visibility than narrow roads because crossing times are longer.

All the roads shown in the above examples are under 7 m in width and in all those cases there is a 30 km/h speed limit so sight lines of about 50 m in length are required. All three examples include additional measures to control speed. In the first example, the posted speed limit and additional measures are adequate for a 50 m sight line. In the second example they are marginal (though helped enormously by the curve in the cycle-path which places cyclists in a more visible position and the curve in the road which slows drivers). The third example does not meet the requirements because the speed of cars is excessive and the sight-lines are not long enough.

Related: Note that it has been understood for many years in the Netherlands that posting a lower speed limit is not enough to ensure lower speeds.

Difficult to retrofit
It is very difficult to successfully retrofit crossings of this type because existing streets are often too straight, existing paths often not visible enough. While cycle priority crossings are fairly unusual in the Netherlands, retro-fitted cycle priority crossings are even more rare. All the examples of priority junctions in Assen were designed as integral parts of the road design. Those used as examples in the video and images above date from when those parts of Assen were designed and built in the late 1970s through to the 1980s.

Cycle priority is not the same as pedestrian priority
People sometimes ask why cyclists are not given permission to cross with priority on all pedestrian priority (zebra) crossings. There are good reasons why this should not be so. In many locations, it would be difficult for a cyclist to be The risk of a cyclist emerging quickly from behind a building or because there are inadequate sight lines. Cyclists are much faster than pedestrians and they require space in order to make a turn.

This crossing of a busy road gives priority for pedestrians over both cyclists and drivers. but there is no place within this layout to provide a safe priority cycle crossing. In any case, any cycle crossing would be better slightly further North on desire lines.

This location has a parallel cycle and pedestrian crossing. Pedestrians have priority while cyclists do not. This is a relatively busy through route for cars with a 50 km/h speed limit. As a result a cyclist emerging at speed from the side roads may appear in front of a driver before the driver has had an adequate chance to response and therefore there is too high a chance that a driver won't stop in time. But they have much more time to react to a pedestrian due to the slower speed of pedestrians.

In this location cyclists have priority over side road crossings which are parallel with the main road. These roads have 30 km/h speed limits and speeds are further reduced by the junction, the small corner radii and the raised tables. However only pedestrians have been priority over the 50 km/h main road.

At a very large busy junction, this example joining the 70 km/h ring road to a 50 km/h main route out of the city, neither cyclists nor pedestrians are given priority over motor traffic in any direction. On a road like this with many lanes of traffic, higher speeds and much to look out for it would be dangerous to give priority to cyclists or pedestrians. Priority can be given for cyclists and pedestrians by other means. In other locations in Assen this is done by use of tunnels and very quick reacting light controlled crossings.

Hook turns
A possible solution which people sometimes think of to the problem of turning across traffic is the hook turn. We have precisely one example of this in Assen. It's a relic from the past which has somehow survived on a quiet residential street and it's shown in the photo below. Note that the hook starts with a cycle-path in the top right hand corner of the image and continues more than 60 metres to the junction which it serves in order that it could provide a gradual enough transition for cyclists. The crossing is then assisted by a large raised table. Despite all of this, it's actually quite awkward to use. It perhaps made a little more sense decades ago when this was a busier route, but it certainly doesn't help in this situation now. I don't recommend this type of infrastructure.

A generously proportioned 60 metre long hook turn assisted by a raised table. But it's still awkward to use.
"Visual priority"
The Alternative Department of Transport blog recently coined the phrase "visual priority" to refer to where priority at a crossing is indicated by the design of the street and not merely by signs. The red surfacing continuing through each of the junctions shown in the video at the top of this blog post is a good example. I like this term, it's concise and obvious, so I have used it too. Most examples of crossings in the Netherlands benefit from good visual priority. Of course, good visual priority is only one factor. In itself it is no guarantee of success. As you will see from the video, the third example of a junction with a short raised table which coincides only with the crossing itself is not successful at slowing cars even though the visual priority is good. Junctions must also encourage safe behaviour by other means, such as use of bends on roads and level changes using a raised tables to slow drivers, bends on cycle-paths to improve sight lines, and we must of course realise that there is no one-size-fits-all solution. The majority of junctions are not suitable for a cycle priority treatment for reasons of sight-line or traffic speeds and volumes.

Real examples in real-life usage
It's not possible to completely understand infrastructure like this from reading blog posts and watching youtube videos. On our study tours we demonstrate real life examples.

Friday, 29 May 2015

A car crash so quiet that we didn't know it had happened

On Monday morning there was quite a serious car crash just 70 m from our home. We didn't know about it until later in the day when it was reported on the local news. This may seem like an unlikely story, and you may wonder how it could be possible that we would miss such a thing so close to our home, but this actually makes a good example of how successfully Dutch residential areas are insulated from the effects of major roads, even when they pass nearby.

The crashed car, by the closest bus-stop to our home. Photo: RTV Drenthe.
The huge road on which the crash took place. The car in the photo above is in the same position as the bus in the photo below.
Our home is on the left of the Google Maps measurement tool, the crashed car was on its right.

The road on which this crash occurred is the ring-road of Assen. This has a 70 km/h speed limit (43 mph), this being the highest speed limit that you will generally find is allowed on a road within a city in the Netherlands. The relatively low speed for what is not far off an urban motorway does of course help to keep noise levels down, but you'll also note that the photos above show a noise barrier alongside this road. The barrier is extremely effective at reducing noise, and also makes it next to impossible to see the road. This is why it was possible that we didn't even know the crash had happened until later in the day.

Cyclists are often unaffected by crashing cars
The cycle-route skips past the traffic
lights
and goes nowhere near the road
The cycle-path which we use to ride into the city is visible on the image from Google Maps above. It passes almost exactly under where the crash occurred so cyclists who were riding here even as the crash occurred may well not have noticed it happening, and will not have been put in danger.

By using this tunnel, cyclists not only cycle in a safe and almost entirely noise free environment but also skip past a set of traffic lights.

The tunnel and noise barrier between them reduce danger for cyclists, reduce noise and also reduce how often cyclists have to stop on their journeys. These factors add together to make cycling more pleasant and relaxing and also to offer the prospect of faster and shorter journeys if you travel by bike.

Measuring noise levels - how effective is the barrier?
It's quite straightforward to measure the effect of a noise barrier if we have the right equipment. The photo on the right shows my SPL meter measuring the sound level in our front garden, a mere 50 metres from the road. The glimpse of blue in the centre top of the photo is as much as we can see of the noise barrier, which is otherwise completely invisible due to trees. My meter barely ever registers any noise here. Set on the lowest possible range of 60 dBA, the needle very rarely moves from the -10 dB setting due to traffic noise, indicating a level which barely ever rises above 50 dBA. Birds in trees nearby make a subjectively louder sound than traffic noise. 50 dBA is the sort of level sometimes described as being equivalent to an "average home interior" or "moderate rainfall"

My SPL meter barely moves
on this side of the barrier
By comparison, on the other side of the barrier I have to adjust my meter's range so that it is not overloaded by the sound. When standing there, the meter often shows figures of 82 dBA or higher as I am passed by cars, and can peak higher yet for buses, trucks and motorbikes, so it would appear that our front garden is at least 30 dB quieter than the road-side.

The inverse-square law does not apply
Readers with a physics or maths background will probably have thought of the inverse-square law by now. According to the inverse-square law, you would expect that a ten times difference in distance from the source of a sound would bring a 20 dB difference in sound level, which is a good part of what I have measured. However, you have to be careful with that assumption in this case. The inverse-square law applies only for measurements in a free field and with a point source.

While noise from aircraft travelling overhead is attenuated due to the inverse-square law, but when considering noise from motor vehicles on roads we usually have neither a free field (airborne sound bounces from the road more than it propagates through it) nor a point source. A busy road with many cars on it (such as during rush-hour when I made my measurements) approximates more closely to a line-source than it does to a point.

Noise from roads is so pervasive in large part because it is not attenuated by distance to the extent that you might hope it would be.

Besides, if you need further evidence of the effectiveness of the barriers, I should point out that my meter still measures only slightly over 50 dBA even if I stand very close to the quiet side of the barrier, when my distance from the noise source (cars on the road) is only about double that of standing on the noise side.

Barriers also reduce air pollution
It has been shown that air pollution from motor vehicles is also reduced in the local immediate downwind area behind noise barriers. This is due to the pollution being lifted to a higher level where it is blown away more quickly. We breath cleaner air as a result of the noise barrier.

And help to encourage neighbourlyness
Children play on our street because it's
quiet and traffic free, This is normal
in Dutch residential streets.
This is all part of creating a pleasant residential environment. Research has found that streets which are quiet (both in terms of through traffic and noise) lead to better relationships with your neighbours.

Quietness is not unusual in the Netherlands
On our study tours we demonstrate the surprising quietness of Dutch residential areas and also how even motorways with vehicles travelling at 130 km/h (80 mph) now cause comparatively little noise nuisance.

Monday, 18 May 2015

How much do the Dutch really cycle ? How is it is measured ? Which are really the top ten cycling cities of the world ?

Lists are popular on the internet. As a result, there are often attempts to make lists which rank such things as cycling cities. Such lists are always false. There is no common methodology between different countries and so there is no reliable way to make a ranking. In reality it's quite difficult even to pin down the "correct" figure for one city in one country, let alone to find comparable figures for a range of cities in different countries. I've intended to write about this problem for several years but a recent online discussion led me to a Dutch language article about methodologies for measuring modal split in the Netherlands which made a very good start towards an explanation so I asked the Fietsberaad if I could translate it. Beneath the article you'll find an additional summary from me.


Do Appingedammers make 18%, 30%, 38% or 53% of their journeys by car?

Modal split figures show the relatively popularity of different transport modes. Modal splits can be measured in a number of different ways. The modal split usually shows the proportions either of kilometres travelled or of journeys made as car drivers, car passengers, by train, bus / subway or tram, bicycle, moped and by walking. The statistics often make use of OViN, a statistics from the BCS, based on a survey of a representative sample of residents of the area being measured. The accuracy of this technique is known to have limitations.

In this article we give a picture of the differences that exist in the modal split figures due to:
  • the different units used to measure the modal split
  • the method in which modal split is measured
  • the different groups or time periods which the modal split covers.
  • the error margin.

Units
The modal split is often given as a single figure, an unambigious concept. However there are several types of modal split in circulation, amongst which the most used are:
  • the modal split determined from number of journeys per mode
  • the modal split according to the number of kilometers traveled per mode.
In our example, we'll look at the modal split of Appingedam (a town of 12000 people in the province of Groningen). These are the figures from OViN 2010-2013 for the number of journeys made per mode in Appingedam:
Car driver
Car passenger
Train
Bus/Tram/
Subway
Bicycle
Walking
Total
28%
14%
2%
1%
33%
22%
100%

But by kilometres travelled the numbers look like this:
Car driver
Car passenger
Train
Bus/Tram/
Subway
Bicycle
Walking
Total
53%
28%
4%
2%
9%
4%
100%





Because journeys by car, train, bus, tram, and subway are on average longer than journeys by bicycle or by walking, their share of the modal split becomes when figures are given per kilometre travelled rather than per journey.

Method
There are many methods to gather data to calculate a modal split. For example through counters on the street or through surveys. in the future there will perhaps be more use made from other sources of information, for example details from mobile telephones or from public transport subscriptions cards.

When there is no data available from local sources, use is often made of the OViN data (onderzoeks verplaatsinsgeddrag in Nederland - Dutch travel behaviour survey) or one of its predecessors (OVG, MON). This is a survey by the CBS using a representative sample of the Dutch population. The data is collected in such a way that modal split figures can be given. As an example, here are the CBS figures for Rotterdam:


Number of journeys per person per day

Car driver
Car passenger
Train
Bus/Tram/
Subway
Bicycle
Walking
Total
OViN
2010-2013
0,57
0,31
0,07
0,26
0,46
0,65
2,31
modal split
25%
13%
3%
11%
20%
28%
100%
MON
2004-2007
0,66
0,34
0,07
0,28
0,49
0,61
2,46
modal split
27%
14%
3%
12%
20%
25%
100%












From these figures we draw a conclusion that the modal split changes very little and that the number of cycling journeys has stayed the same.

The local government's own figures show a different picture. For 15 years, Rotterdam has counted cycle usage at fixed points in the city and found consistent growth in cycling while the car traffic in and around the inner city has stayed the same.

Figure: Development in car traffic around cordons (1986=100)
(Binnenkordon = inner city area)
source: Rotterdamse Mobiliteitsagenda 2015-2018
Figure: Cycling intensity around the fixed counting points (work days, saturday, sunday):
bron: Rotterdamse Mobiliteitsagenda 2015-2018
Rotterdam therefore concludes:

Cycling traffic around the city centre of Rotterdam has grown by around 60% in the last ten years.

According to the traffic counts, cycling has grown significantly in the inner city. However, we would draw a totally different conclusion from looking at figures from OViN for the entire council area:



Number of kilometres travelled per person per day

Car driver
Cra passenger
Train
Bus/Tram/
Subway
Bicycle
Walking
Total
OViN
2010-2013
10,23
5,17
2,97
2,07
1,87
1,08
23,39
modal split
44%
22%
13%
9%
8%
5%
100%
MON
2004-2007
11,38
5,87
3,14
2,66
1,68
0,78
25,52
modal split
45%
23%
12%
10%
7%
3%
100%












According to the figures for kilometres travelled (table above) cycling kilometres have grown by 11% while the growth for all transport modes is 7%. This could indicate that people are now more willing to travel for longer distances. When we look at the error margins (see below) we find that these differences are not significant: but there could still be growth in the numbers of journeys or distance being made by bicycle.

The smaller city of Delft also shows a good improvement. According to the CBS figures, the share of journeys per bicycle has grown by 6% between 2004-2007 and 2010-2013. The bicycle share is therefore now 39% in Delft, placing it amongst leading cities such as Groningen, Zwolle and Leeuwarden. Considering the high proportion of public transport (10%) this is a good result. The share of car usage fell bv 4% over the same period. What's more, the error margins from the CBS data are relatively good (13% for bicycle to 45% for bus and tram), and Delft's cordon counts appear to confirm this result:

Figure: Cordon counts for car traffic in Delft, index 2002=100
(Delft = whole city, Buitenring = outer ring, Binnen ring = inner ring)


Source: Gemeente Delft
Groups and periods
In the previous examples, not only are the methods used different (cordon counting vs. surveys) but also the groups of people counted differ. Rotterdam has counted how many people pass a cordon around the inner cty while the OViN figures measure the entire city. We also need to consider the lengths of bicycle journeys being made: if cycling distances double then the change of an individual cyclist being counted can also double. It's important to plan in advance what we wish to measure. Visitors or only residents ? Which year ? Which period (rush hour, morning rush, whole day ?)

These distinctions naturally produce different results. These are the 2004-2008 figures for modal split for all traffic in, from and to Appingedam:
Car driver
Car passenger
Public transport
Bicycle
Walking
Other
Total
38%
17%
2%
22%
19%
2%
100%


While these are the figures for nearly the same period (2004-2007) but just for residents of Appingedam::
Car driver
Car passenger
Train
Bus/ Tram/ Subway
Bicycle
Walking
Total
30%
18%
1%
0%
24%
27%
100%

That cars are used more in the first example than the second can be easily explained in that fewer people make the longer journeys between towns by walking and cycling.

Another distinction is in the presentation of the figures. The second example separated train travel from other public transport.

The following figure shows modal splits reported by the city of ’s-Hertogenbosch in 2014, showing modal splits for 2004-2006, for 2010-2011 and their ambition for 2015. Note that car passengers and drivers are combined and walking is omitted:

Auto=car passengers and drivers combined, OV=public transport, Fiets=cycling. Walking share omitted (it's around 20%)

Below are figures from a different methodology for a slightly different period:


's-Hertogenbosch modal split by journey

Car driver
Car passenger
Train
Bus/Tram/
Subway
Bicycle
Walking
Total
2010-2013
33%
16%
3%
1%
27%
20%
100%
2004-2007
34%
18%
3%
1%
25%
19%
100%








modal split by distance travelled

Car driver
Car passenger
Train
Bus/Tram/
Subway
Bicycle
Walking
Total
2010-2013
51%
24%
12%
1%
9%
3%
100%
2004-2007
51%
28%
11%
2%
7%
2%
100%








Not only is the period different but also the data sources differ. The tables make use of the new set of OViN data which used the same methodology as in previous years. Walking was missed out from the city's own figures. It's a significant part of the total and missing this out made cycling, public transport and driving seem more significant than the reality.

Note that totals again add up to 100%, even though the categories of "mopeds" and "others" are omitted. These are extremely small percentages and are often omitted because they affect the figures rather less than does omitting walking. The figure below shows the modal split for the entire country including mopeds (bromfietsen) at just 1% of the total:

Modal split for the whole of the Netherlands. Source: KiM, Mobiliteitsbalans 2013
auto=car, trein=train, fiets=cycling,lopen=walking,bromfiets=moped, overig=other


Error margins
To finish, we have error margins. Figures are often presented as if they represent an absolute truth, but that it very often not the case. Any sample or measurement will not only have some errors, but also they can never represent all journeys made. In sampling people typically aim for a 95% confidence interval. Such a confidence level indicates that we have a high degree of confidence that our result is relevant. It means that we are 95% certain that the true figure is within the intervals given. Note that is can say nothing about any individual sample nor can we say that 95% of samples are within the interval (the language of the Dutch original is slighty confusing).

Such an error margin also applies to the OVin figures. But how can you express that in modal split ? As an example again take the proportions of journeys per mode for Appingedam and take the minimum and maximum values according to the error margins:


Number of journeys per person per day - Appingedam

Car driver
Car passenger
Train
Bus/Tram/
Subway
Fiets
Walking
Total
OViN
2010 t/m 2013
0,72
0,35
0,04
0,01
0,85
0,56
2,54
Average modal split
28%
14%
2%
1%
33%
22%
100%
Relative error margin (95%)
25 %
36 %
139 %
340 %
24 %
34 %
14 %
All minima modal split
31%
13%
-1%
-2%
37%
21%
100%
All maxima modal split
27%
14%
3%
2%
31%
23%
100%
Car minima* modal split
18%
16%
3%
2%
35%
25%
100%



















*) In this table the modal split calculated for journeys by car is reduced by considering the effect of the error margins for other modes. There are many possible variations. This example is given to show the sensitivity of modal split data.

In Appingedam there are few journeys by public transport. This is also a small town and therefore the sample size is small. These factors result in a large margin of error. The relatively high error margin makes meaningful comparison with other towns difficult. For public transport it's impossible.

A large city like Amsterdam, which also has higher usage of public transport, gives us a larger sample and therefore much lower error margins for all modes. Therefore we have relatively trustworthy modal splits for this city:


Number of jouneys per person per day - Amsterdam

Car driver
Car passenger
Train
Bus/Tram/
Subway
Bicycle
Walking
Total
OViN
2010 t/m 2013
0,44
0,24
0,10
0,27
0,85
0,66
2,56
Average
modal split
17%
9%
4%
11%
33%
26%
100%
Relative error margin (95%)
7%
9%
11%
9%
5%
6%
3%
All minima
modal split
17%
9%
4%
10%
34%
26%
100%
All maxima modal split
17%
10%
4%
11%
33%
26%
100%
Car minima* modal split
15%
10%
4%
11%
33%
26%
100%




















*) Here the modal split is calculated for car journeys is reduced by adjusting all the other modes to their maximum values using the relative error margin. There are many possible variations as to how this could be done. the idea is to demonstrate the sensitivity of the figures to the error margins.


Under registration
Beside the inaccuracy due to sampling, there is also another source of error due to how correspondents to surveys under record their shorter journeys. For instance, people forget about the short walked journeys from the front door of their home to their car and between car parks and shops. From research is is become apparent that due to under-reporting figures for walked journeys should be 1.57 times higher than they are reported.

Conclusion
The examples given above demonstrate that there is no single modal split figure. Readers must always look at how the statistics were gathered and what they relate to. On the basis of the CBS figures shown above, we can answer the original question by saying that Appingedam residents make 18, 27, 28, 30, 31, or 38 % of their journeys as the driver of a car. Or by saying that 53% of the distance that Appingedammers travel is as the driver of a car.


Dutch data, Dutch modal split, my summary
All of the above relates to how the Dutch collect data about modal split in the Netherlands. As you see above, there can be significant variations in figures even from one methodology, but even here there are actually different methodologies which result in different results and those results can have different interpretations. As a result, different figures can be found for the same Dutch town, and this means it is difficult to reliably compare different towns. i.e. it's difficult to make sensible comparisons even within this country. However, at least within this country it is usually possible with a bit of effort to find data which has been collected in the same way in different places, though even when we are comparing Dutch cities with each other we must still be careful about error margins as they can be more significant than the apparent reported differences in modal splits.

What is good about (most) Dutch methodologies
Dutch methodologies as shown above (especially OViN) usually can be expected to take into account the modal split for the entire population being considered. By this I mean the entire town or city which is being considered and everyone of every age group within that location (group). They also usually take the entire year (i.e. winter and summer) into consideration (period). For instance, anonymous looking bicycle counters in the Netherlands are typically put in place for a year in order to gather counts which will not be unduly influenced by the weather on one day vs. another. These Dutch methodologies are used to build so accurate a picture as possible so that while the results cannot always be compared very meaningfully with other towns, they should be comparable over time within the same location. This makes it possible to build up a picture of progress over time.

Other statistics and why I criticize them
Unfortunately, statistics are sometimes gathered for entirely different reasons. For instance it's quite common to see published figures which are for commuters only. On some occasions this is because statistics are traditionally collected about commuters in that location but on other occasions these figures are used because it makes it possible to report higher and more impressive sounding figures than would be the case otherwise. The problem with counting only commuters is that only adults of working age (for whom subjective safety is relatively unimportant relative to children or older people) will be counted. This creates a false

Other ways in which figures can be collected so that they are not times you'll find figures quoted which relate only to journeys in part of a city. I've also seen examples of counts performed only on sunny days, or on peak days for student traffic, or where part day counts are extrapolated as if they relate to the whole day (all those things and more in one instance). Such figures are more applicable to use for politicians to placate local cyclists or to boast about what they claim to have achieved, or for marketing people to sell their city to cycling tourists.

Lastly, there's a tendency in some places to publish targets aggressively and it is sometimes the case that people go on to re-publish targets as if they have been met. Anyone can set a target. Achieving it is something quite different.

Whatever caused the confusion, presenting figures in a way which inflates them does not help to further understanding. It hides problems and does nothing to further cycling. Having figures from inconsistent methodologies or which do not cover the entire population makes it difficult to tell whether real progress is being made.

In the past I've criticized the use of modal split statistics gathered elsewhere and I'll probably continue to do so. For instance, I've written about how statistics from Cambridge, New York, London, and of course Copenhagen (multiple times) have been published and used in a way which confuses rather than enlightens. Copenhagen is an extreme case because while in reality somewhere around 1/5 to 1/4 of all trips are genuinely by bike in the city this has been reported by various means as anything up to 40%.

Sadly, the Dutch don't always publish useful figures either. I've criticized figures from Amsterdam (38% pushed to 47%) and Groningen (50% reported as 59%) in the past when they missed out walking from their statistics to produce a higher figure to present internationally, showing a higher cycling share than exists in reality. The figures produced by 's-Hertogenbosch used as examples in the article above show more of the same (actual 27% reported as a range of figures stretching up to 44%). These figures have also been reported elsewhere as fact and indeed I once reproduced that claim myself.

We all need to be skeptical about claims, especially when they are made in a way which could be seen as promotional.

Why ranked comparisons of cities make no sense at all
Even modal-split data which appears to cover the same group and period in different countries, and which is gathered in a reliable and consistent manner will vary so much in methodology that comparisons made are largely meaningless. In reality, figures from different countries vary greatly in group and period and this makes the comparisons completely unreliable. As result, any ranking produced on the basis of the results of such a comparison will be meaningless.

While I have on occasion quoted figures from Dutch or other cities, you won't ever read a "top ten cycling cities" list on this blog. I've never ranked cities in this way because it wouldn't mean anything. Such a ranking this could only create a false impression of having more information than actually exists and this would mislead readers. People who produce lists of "top cycling cities" do so either out of ignorance about how these statistics cannot be compared or for commercial reasons. i.e. to sell something.

How much cycling is there in the Netherlands ?
The overall figure for cycling in the Netherlands as a percentage of trips has not varied appreciably in many years. According to the graph above, 27% of all trips in the Netherlands are by bicycle. This is the highest figure for any country in the world (certainly amongst relatively wealthy nations where people have a choice of transport modes). If we're interested in green modes of transport, we can add on the 16% of journeys made by walking and note that relatively prosperous Dutch people make a massive 43% of their journeys by human power - a reasonably reliable statistic which is something truly to be proud of.

Using a different methodology, the Flash Eurobarometer came to a similar conclusion about the overal cycling and walking share of the Netherlands, left, in orange.
This is great news, however we should always also recognise the flip side. If 27% of journeys are by bike and 43% of journeys are by the two genuinely green modes (walking and cycling), then that still means that 73% of journeys are not by bicycle and 57% are by non-green motorized forms of transport. If we look at trips by distance, this gets worse. The Dutch cover 73% of their distance travelled by private car alone.

While what has been achieved in the Netherlands is wonderful, there is still more that can be achieved. What's more, what has so painstakingly been achieved could still quite easily be lost. There is no space for complacency.