Life On The Edge

As a kerb nerd, I'm going to talk about something which is a bit counter-intuitive this week and that is we should not use kerbs!

Actually, it's more specific than that because kerbs remain very useful components of our toolbox. The issue I am interested in this week is where a footway or cycle track meets a verge - a situation which on the whole doesn't actually need kerbs to be used.

It's perhaps worth reminding ourselves about what kerbs are for;

• Retain the edge of the top layers of a pavement,
• A demarcation between different areas or uses of a highway,
• To provide a check or channel for surface water management,
• To provide restraint to prevent vehicles leaving the carriageway.

For a footway or a cycle track meeting a verge, we might need to manage surface water, but we don't need demarcation (the edge of the surface does that), we don't need to restrain out of control people walking or cycling and it's pretty rare we actually need to retain the edge of the top layers of the pavement (the term used in its technical sense).

In my view, it is the first use which is where things go wrong and it is usually down to the specification being used. Footways and cycle tracks are usually fairly lightly constructed which reflects their users, although there are problems which motor vehicles are driven onto them.

When we build carriageways (roads), we are concerned with transferring loads from motor vehicles from the point where their tyres meet the surfacing, through the pavement layers to the weaker underlying soils.

The sketch above shows how the load from the wheel is transferred down through the pavement layers into the underlying soil (or sub grade) on what is called a "flexible" construction with asphalt surfacing. The underlying soils will normally be too weak to support traffic loading directly and so we're building up layers of materials to compensate.

The immediate surfacing material is of the highest quality and deals with sealing the pavement from water ingress and provids skidding resistance. In many cases, there will be two further asphalt layers which do structural work, but with cheaper materials which need to have a certain thickness to transfer the load as well as resist wheel rutting.

At sub base level in a flexible pavement, we are using a graded stone (or reclaimed crushed concrete and other materials) from 75mm in size down to dust (to a specification for good compaction) and then below that a capping layer of lower quality stone or other materials. The red triangle essentially shows that the load at the surface requires an ever larger area of the lower (and cheaper) layers to support the wheel which has a small contact area with the surfacing.

I hope you're still with me. The layers are varied and sometimes omitted such as the capping where the underlying soil is better at supporting loads. There are other designs of pavement available such as reinforced concrete and all manner of clever sheet materials to add strength, but let's keep it simple.

For footways and cycle tracks, we're generally not needing to transfer any loading from people - they simply don't cause damage as they walk or cycle along. We don't just leave grass or mud at the surface of course, a surfaced path is more comfortable to use and we can shed water off the surface (or we can use permeable materials and clever underlying materials and systems to deal with water).

In fact, the limiting issue is the ability to construct footways and cycle tracks in the first place because at the absolute minimum, we need to be able to use a roller (usually vibrating) to compact the sub grade and the layers above. In fact, I think all asphalt surfaces should be laid by machine unless it is localised repair or reinstatement. If we simply compacted surfacing on the soil below, it would just get bashed into the ground when we roll it, so we need a bit of sub base to give a minimum pavement depth (There are different types and classes of roller depending on what the situation is).

The other dimension is that top soil is no good for building paths on. It has organic materials which rot down leading to settlement and plant seeds or roots can grow through to the pavement - we need to be founding our paths on the subsoil which means a certain thickness of construction. Beyond that, we need to assess maintenance - how heavy will the street sweeper be that cleans the footway or cycle track? How likely are we to get maintenance vehicles using it? What is the likelihood of people parking on it (cars, vans or lorries)? A perfectly competently built path for only walking and cycling use can be destroyed in one sitting by an HGV being driven over it.

In the Design Manual for Roads & Bridges, there is a whole document around footway and cycle track pavement design which goes into detail of the options available based on the strength of the sub grade soil and the type of loading. I'll not go through the detail of this because I have given a flavour above but I'll pick on one of the combinations because it gets me back to kerbs. With decent ground conditions and no chance of over-run, the recommended specification is 20mm of asphalt surfacing, a 50mm asphalt layer below that (called the binder course) and a 100mm sub base - a total thickness of 170mm.

The standard edging kerb is 50mm wide and 150mm deep. In general terms, it will be laid on a 100mm concrete bed with a 100mm concrete surround - in other words, to a depth of 250mm. This is where it all goes wrong. 

The photograph below shows some recent repair work to a shared-use path near where I live. It's not immediately obvious what's going on, but essentially the old surfacing was removed (which looked like two asphalt layers to me) and some of the edging kerbs were replaced. 

In the photographs above and below you can see that for the replacement edging kerbs, a trench was dug and new kerbs laid on concrete. In some places new sub base was laid between the edging kerbs and the whole thing was resurfaced (badly).

Around 8 weeks later, there are signs of failure in terms of cracks along the path returning as well as dips forming in the new surfacing (photograph below). It's not a location where vehicles tend to get and hopefully me riding my Dutch bike isn't that heavy!

It's not an isolate case. Elsewhere along this road, there have been attempts to repair cracks in the shared-use path. The photograph below shows a repair where the edging kerbs were replaced within a trench. It has failed again with a new crack as well as the joint between the old and new surfacing opening up.

The photograph below is slightly different because the failure is in an area which the edge of the path was rebuilt following water main works. But, it's the same pattern of failure. The water company would have only replaced what it took out.

It's not easy to see what is going on, but the photograph below is a close up of the crack. At the top you can just make out the concrete backing which is helping to support the edging kerb, which is a nice little clue in the mystery.

Now, my area is built on London Clay which is notorious for moving about as it dries out and shrinks in the summer and then absorbs water and expands in the winter (and when frost penetration could be another problem). This means that whatever we do, we have to accept that paved surfaces might be impacted - worse where there are tree roots sucking water out of the ground. There is a limit to how deep anyone should dig to find a decent sub grade and around my way, it will be metres before you get something better which means we work with what we have.

The sketch above shows a little of what is happening. The edging and the concrete surrounding it are not acting flexibly - that is, if the clay is shrinking or expanding then it's acting almost like a solid beam along the path and so a crack is induced roughly along the edge of the concrete surround. The bedding concrete is laid straight on the soil which is moving around because the kerb and its bed are deeper than the pavement construction.

In the photographs, the reason the crack isn't always straight (aside from the stone within the surfacing being irregular) is the lack of quality control on the edging kerb backing concrete - you can see the ragged line of this in the second photograph of this blog - they are wasting concrete and not keeping everything neat and tidy.

There are two ways to design this out. First, the edging kerb sitting on its concrete bed needs to be supported on sub base rather than directly on the soil which is created by the condition of having the minimum path thickness. In the image below, the sub base goes under the edging kerb and its concrete bed. It has to extend beyond to make sure it is fully supported.

If you think about it, this is what would happen with a road because everything is so much thicker to take motor traffic loading which means kerbs are supported. The following image is an extract from a standard construction detail showing this for both the road edge kerb and edging kerb (it is a very heavy duty detail);

It's not immediately obvious, but if you look at the photograph above, the three kerb lines are all supported on the sub base which extends beyond the two outer kerb lines.

The second way to design out the problem is to dispense with the kerb altogether which does run counter-intuitive to some people;

The image above has our 100mm of sub base, 50mm of asphalt binder and 20mm of asphalt surfacing. Assuming the sub grade soil is appropriate for the job and we're not getting vehicles on this (other than very lightweight sweepers maybe), we simply don't have the conditions for an edge failure. Each layer is a bit wider than the last to ensure support and the asphalt layer edges stand up on their own (because that is what asphalt does when there are no vehicles running on the edge).

The photograph above is (yes you've guessed it) of a Dutch cycle track which hasn't got edging kerbs. You can clearly see the red surfacing and the black binder course below which is stepped out in support. The dotted lines you can see will have been left by the asphalt crew making sure the surface was properly set out. The photograph below shows the same cycle track without edgings on both sides.

Unless a kerb is needed to manage water or there is a local issue such as trying to prevent soil from an embankment washing onto the path, the lack of edging kerbs makes things far easier to maintain because there will be failures that need to be repaired from time to time. Vegetation management is important because if it encroaches, it can break the edge of the path and sometimes stop water flowing away (but that's no different to where you've a flush edging kerb anyway. 

If the path is constructed from block paving or small slabs, then edging kerbs are used to restrain them, but can still be subject to movement which leads to failure in the paving, so it is no less important to get the detailing correct.

So, the next time you see a crack along an asphalt path in a bit from the edge, you'll know what has probably happened and how it should be fixed. Unfortunately, what will probably happen is the same mistake will be made again and people will be left scratching their heads.

#LDNCycleSafari Goes Solo: A12 Redbridge And The Green Man

A few weeks ago, I went for a look around Lea Bridge Road in Waltham Forest, but the journey there uncovered a couple of interesting roundabouts which are worth a closer look.

I used the A12 to get to Waltham Forest because perversely it feels safer than the parallel A118 through the various town and district centres. It's not all marked for cycling, but I'm not sure too many people were bothered. In fact, Transport for London really should undertake a review and put an upgrade plan into place. 

The first point of interest is the Redbridge Roundabout, which is a huge signalised roundabout where the A12 Eastern Avenue meets the A406 North Circular Road. It's a well known spot for traffic congestion which seems to get attention near election times with promises to spend money to "sort it out." Of course that always means works which will accommodate drivers and nothing to deal with the severance the junction and the large roads create.

Westbound approach on the A12. Yes that is an advisory

cycle lane on a 40mph dual carriageway.

The junction is a relic of the 1970s and part of the ambitious motorway building plans which didn't come off as part of the Ringways project - the "Motorway That Wasn't" covered by roads.org.uk in this article. The A406 was originally going to be the M15 with the A12 running through the junction connecting to the M15 with slip roads. It never came to pass and so we are left with the A406 and no free-flow of the A12 meaning that people driving along the A12 have to go through the roundabout.

What did get built, however, was a grade-separated walking and cycling route which takes people into the centre of the roundabout at a level below the road. Within this area, the A406 towers above and when one looks from the right position, the civil engineering is striking;

The North Circular carried over the junction on a large viaduct.

The space within the roundabout is nice and open and surprisingly calm given it's within a traffic maelstrom; unfortunately access to this urban curiosity is not great, requiring the usual tight ramps and narrow tunnels which is the British approach to treating those not driving;

Anyone cycling is treated to staggered barriers, confusing signage and tight turns to get to the ramps on the outside of the roundabout, although at least you don't have to mix with traffic. However, it's a lonely place and not somewhere anyone would want to linger.

On the western side of the roundabout, there isn't an advisory cycle lane to contend with, but there's no confirmation that one can cycle on the footway. There's no way anyone other than the fit and the brave (and maybe deranged) would cycle on the carriageway here and in any case, the George Green Tunnel (under George Green) isn't for anyone other than drivers.

Let's be honest though, it's a pretty hostile environment all round and not designed for people at all. This section of the A12 was originally going to be an extension of the M11, but what was eventually built as an extension of the A12 to the Blackwall Tunnel known as the East Cross Route.

The exit before the George Green Tunnel, heading west.

A couple of kilometres to the west of the Redbridge Roundabout is the Green Man Roundabout, named after the pub which still stands by the junction, although now an O'Neill's with the name lost to history. At least the pub is still there, so many others have been lost to road building and redevelopment with junction names being the only visible trace of their existence! The A12 goes under the roundabout into an underpass with slip roads back up to local roads.

The Green Man Roundabout, like Redbridge, has grade-separated walking and cycling infrastructure and it is so much better. It shows that if we put our minds to it, we can treat people with a little bit of respect. The late 1990s vintage is maybe showing its age and is need of a good tidy up, but it's eminently usable.

The photograph above is taken in the middle of the roundabout looking east. There is clearly defined walking and cycling space and if you have a look around on Google maps and Streetview, it will become clear that in fact, there is a walking and cycling network around and through the junction which is completely independent of the main roads.

The road of the roundabout is actually raised a little above grade and so with the space available, the ramps into the underpasses carrying the walking and cycling network are relatively gentle. The little crossroads in the centre is raised which keeps things feeling open and they give a little nudge to get going down into the next underpass to leave the roundabout.

Beyond the roundabout, the walking and cycling infrastructure returns to the default position which is a shame because a wider scheme of upgrades together with a tidy up could make for a really good local network between Redbridge and Waltham Forest. Luckily, it's a short cycle north along the A114 Whipps Cross Road (on a shared path) to get to Lea Bridge Road.

Tackling The Main Roads

So last week, I wrote about Low Traffic Neighbourhoods and how it was my opinion that we needed a little honesty from those objecting to them as to why they are objecting to them.

The post had a few comments (I've published all received) and unfortunately a few have kind of reinforced the point I was making. There were people projecting onto others with the usual tropes of why nobody is thinking of elderly people, disabled people and NHS workers (home visits). There was a comment about the schemes pushing traffic from where wealthy car owners live onto the main roads where less well-off people live. There was also a comment about going the extra mile (yes I smiled) to listen to concerns which I cannot disagree with.

Then we had a description of the idea as being draconian, the idea that international experience can just be dismissed and that apparently LTNs will make it difficult to access places of worship so people will have to stop practicing their religion. Actually, none of these comments are new to me, I have literally heard it all before. 

A low traffic neighbourhood in Utrecht. Completely

permeable to walking and cycling. Motors go the long

way around (and there are still plenty of cars in the city).

Politically, it's easy to support something which is generating lots of noise. In my local government experience, noise usually meant that some people didn't like something and therefore "noisy" support was quite rare. Also, when I say "people didn't like something", this was almost exclusively because the scheme was going to "take" something away from their ability to drive and park where they like. 

Zebra crossings take away parking spaces (I want to park there), permit parking costs people money (I don't want to pay for a permit), pay-and-display would kill the local shops (I don't want to pay for my 5 minute drive to buy a newspaper), 20mph speed limits cause pollution (despite driving a SUV), filtering that street will stop ambulances (but I'm happy to be part of the problem causing congestion that stops ambulances). Won't somebody think of the children (despite nobody actually asking the children what they want to see).

Newcomen Street, London. Filtered. The horror. This should

be a cabbies' rat run not space to socialise outside the pub.

In many cases, the responses to traffic consultations tended to be around people that support something that will add to the community benefit (quieter streets, a road which is safer to cross, slower drivers passing a school, improvements to bus services) versus people who saw the scheme taking something away from them personally (I now have to pay, it takes me longer to drive round the corner, you're stopping me parking in dangerous places) - I think it's important to try and prise the real objections from people while being mindful of concerns because real objections may simply get lost in the noise.

It's with all of this in mind that I turn to the main roads. Lots of noisy people are saying LTNs will push drivers back to the main roads and that we must tackle them first (or at least at the same time as LTNs). These are reasonable concerns, but before I dive in with some ideas I think it's worth saying that we have a couple of issues to try and work through. First is how we have got to where we are in terms of the levels of traffic on our roads and streets. This has happened over decades and as a response to government and local policies which have pushed and prioritised both the use of private cars and lorries for logistics, whether it's planning policy, local road building, fuel duty policies and so on.

Heading out of London on the A127 towards the M25 on

a week day evening. Where was the consultation for this

level of congestion and community severance?

Experiences vary with location of course. The Department for Transport's forecasting has always shown significant traffic growth which is never quite matched by reality, although the growth is still there. There is evidence to suggest that road building induces traffic, but it is a complex situation. What we do know is, however, is there's little ability to expand road capacity in our urban places to cope with the "end of the pipe" problem where people leave the strategic road network.

It would be equally possible to have a traffic reduction forecast based on developing policies which specifically set out to achieve that (which incidentally the Mayor of London has). The fact that the government still has growth forecast means that tackling main roads will already have that pressure even if we do nothing.

An urban arterial road in Amsterdam. People have a

genuine travel choice here.

My second point is kind of at the opposite end of the scale. While it's easy for me to say that I wasn't consulted on the country getting to where it's at, I could respond by saying it's the consequence of who we've voted for over the years. If we are going for change which happens quickly, it is very easy to cry foul of not being consulted despite, equally, local authorities also being voted in (see my comment on the Mayor of London seeking to reduce traffic for example). We seem to have the boiled frog meeting the stages of grief, to mix models. OK, here's my ideas on reducing main road traffic

Widespread use of Controlled Parking Zones.

This is an incredibly powerful thing in our toolbox because without the management of kerbside space we'll get nowhere. For main roads, this is vital because it underpins other things we might need to do. For example, if we are pursuing a motor traffic reduction policy, we will need to make cycling and buses (and maybe trams) more attractive and this will require changes to how road space is divided up at the basic level. Walking is important, but at this stage, I'm looking at trips for bus or cycling distance.

In dividing up this road space we may well need to clear car parking out of the way for bus lanes or other bus priority measures to successfully work or to provide space for cycle tracks as they have done in Copenhagen;

If you don't manage parking on an area basis, you'll just push parking into side streets which will add to the traffic problems in the areas that LTN opponents say can be dealt with by dealing with the main roads.

Care is needed in designing CPZs because you tend to find people on the edges don't consider themselves to have a parking problem, but they will if a CPZ comes in. You'll also get push back from residents who feel they should be able to park for free.

Limiting the number of permits residents can obtain.

With a CPZ in place, we can use local policy to influence how many permits residents in the area can have which helps with how we apportion road space. Maybe we have decided to rework kerbside operation on the main road so that there is no parking at peak times (because traffic flow is important), but as we are in transition to a low car future, we need to provide some visitor parking for shops, businesses and residents on the main road.

Having a CPZ in place gets us control and limiting permits will free up space at the end of streets so we can provide some parking for visitors and maybe residents who cannot park on the main road. I would tend to put visitor parking first because there are often concerns about the needs of disabled drivers and people visiting shops, business and residents (accommodating tradespeople is a common worry). Rationing can be by number, cost or some other system, but limiting numbers allows us to play around with the ratio of residents' vs visitor parking bays.

If we throw in other uses such as parklets and cycle parking, then we have a set of uses that can be adjusted over time as our low traffic future develops.

Emissions-based pricing of residents' permits to speed up adoption of cleaner vehicles.

This is a slight side-issue, but whether we like it or not, cars will be with use for some time and so we can provide cheaper permits for cleaner cars - we should very much charge for electric vehicles, it's just that dirtier vehicles should be charged much more. 

This will have the effect over time of people either deciding to switch to cleaner vehicles (which at least helps with air quality in the medium term) or decide to give up vehicles because their old one costs a fortune to park or the emerging improvements to cycling and public. There should be a clear message from the local authority that prices will be going up, even for electric car owners and maybe permit costs will start to reflect the value of public space.

Size-based limits on residents' vehicles.

A step on from emissions is looking at the size of vehicles. There are some authorities which limit the sizes of vehicles which are eligible for residents' permits. For example the London Borough of Hackney has a limit of 2.27m in height, 5.25m in length and the unladen weight must not exceed 3,500kg. This is in the realm of stopping large commercial vehicles being parked in the street which may be owned by or registered to a resident. 

In a low car future, we may push down those limits so that when people do need to park, we can be more efficient with the space or perhaps we have bands to allow people to keep their current vehicle, but gradually make changes to the process.

Charging for destination parking.

This is another tool linked to the need for CPZs because the second we charge for something, someone will try and find the same for free and that could mean more people driving around uncontrolled streets trying to find a free space. I extend charging to any public car park under local authority control. If a private operator can undercut the price, then good luck to them because it's not going to be long-term.

Destination parking charging is immediately powerful because it allows rationing of street space and it provides revenue to run the parking management service and for transport scheme investment. Don't shy away from it being a revenue raising wheeze because it partly is - celebrate it even.

Year on year of removing on-street car parking.

We now have quite a lot of control and we can play around with different scenarios. If we have been clever, we'll start to see empty parking bays whether paid for or residents' parking. This gives an opportunity to repurpose the space. 

I like the use of parklets, especially if they manage surface water, but before we know it, there will be large areas of unused asphalt. Clever changes of use means that we can have less paved areas (from a surface water management point of view) and physically less area needing long term maintenance in terms of resurfacing.

One word of warning for people who don't want LTN though. If we open up empty carriageways with reduced parking demand, we positively invite people to cut through the area, often as speed, so you'll need to come up with a way to manage that.

Workplace parking levies.

So far, I have discussed some pretty common concepts that many authorities are already using, but they are never going to raise enough money for significant investment in the main roads. Workplace parking levies (WPLs) are an incredibly powerful tool for raising funds for investment in alternatives to the private car. For example, Nottingham's WPL has helped fund extensions to the city's tram network.

WPLs can be controversial as some see it as a "tax" on jobs, but it at least requires businesses to confront their attitudes to staff travel, how they use valuable land and for staff, it provides a genuine alternative (trams are great because they tend to get decent priority for road space). Having a variety of options is also good for resilience because you are not relying on a single mode.

Closing and redeveloping of council car parks.

There is often a tension between the need for councils to bring in revenue and the use of private cars in towns and cities in terms of space, road danger, pollution, congestion and so on. This is especially stark in two-tier authorities where the county runs the highway network and the district owns a car park.

Borough Market in London. This used to be a car park,

but now put to a better use.

Horsham is an excellent example because it recently spent £8m on rebuilding a multistorey car park in the town centre. According to Visit Horsham, the car parking capacity has gone up 189 spaces from the previous car park to 516 (wider) spaces, but that's still £15.5k per space. I have no idea how long the project will take to break even, but that's another discussion.

What Horsham has now done is locked in a certain level of car dependency and for the business model to work, it is reliant on people driving in on the town's main roads and thus working against any plans to try and make it easier to cycle and get the bus into town because the argument will be around keeping motor capacity. 

Maybe a better model to have followed would be to build a mixed-use residential-led development to provide a rental income. Rather than having residents drive into the town centre, having residents in the town centre would not only remove traffic from the network, it would create a captive audience who would spend their money locally (because people on foot spend more money than people driving).

Beyond this, gradually removing parking other than for blue badge holders in parks will allow space to go back to parks (less to maintain, depaving etc) assuming they are within the CPZ area.

Bus priority.

There's no one size fits all here, but both links and junctions need to be looked at in order to buses to ensure people can rely on them for journey time certainty (and this does link back to my first suggestion). When I say bus priority I mean exactly that through the use of bus lanes, bus pre-signals at junctions (such as here near Crawley), advanced signal detection etc - it's a bit old, but this is a useful note.

The other useful thing about bus priority is that it can provide a little extra space for emergency vehicles to get past congestion, but I'm not sure I every remember anyone campaigning for bus lanes on main roads to help ambulances.

Use of traffic signal timings to stack longer distance traffic outside of the built up areas. 

This will depend on who controls the traffic signals because it varies across the UK. However in theory, we could use signals to manage the flow of vehicles coming into a town. Rather than having the congestion on the main roads where people live and work, we could stack the traffic further out and ration access only when things are moving in the centre.

It's not a new concept (most things aren't) and there's a good write up here of the technique called "Inbound Traffic Flow Control" which as well as only letting people drive in when there's capacity, it can be used to help buses or other vehicles to bypass queues (either on the main road or another dedicated route).

Constant review and tightening of policies to make driving into town unattractive.

This could well be a mix of the things I've already mentioned, but we're now moving into heavier management such as congestion charges, road pricing.

Away from London, Durham has a tiny congestion charging scheme in the historic city core, although the area covered isn't exactly a series of main roads. Road pricing has been talked about for years and never delivered, but one of its uses is to charge more at busier times to dissuade people from driving. Like parking charges, however, there's a risk that we actually make it easier for the more well off to drive when we're trying to reduce traffic volumes generally.

Hackney has an interesting development with its Ultra Low Emission Streets which ban the most polluting vehicles being driven through areas with poor air quality. This is a useful stop gap until more of the fleet is cleaner, but eventually, if all vehicles meet the criteria, we've still got congestion creeping back. 

Personally, I'm in favour of changes to the street and transport mix which can be backed up with kerbs and asphalt which give a real alternative such as trams and cycle tracks. Even bus lanes are at political whim such as Coventry which infamously revoked a number of bus lanes to improve traffic flow. Constantly reviewing measures for performance is a good idea, but taking out bus lanes to improve traffic flow is very short sighted because bus service reliability will degrade and people will stop using the services.

Lea Bridge Road, Waltham Forest. Kerbs and asphalt locking

in a real alternative to local trips.

Development of consolidation hubs to switch some deliveries to cargobikes and electric vans.

This is an area which could be both businesses adapting to the other policies on how traffic is managed or as a response to a more organised approach. 

For example in London, Pedalme is a cycle-logistics company which realised that it could serve a large part of central and inner London using electric cargocycles in a way which would be far more efficient than using vans. The use of cargocycles means that as we reallocate road space for cycling, the method of delivery becomes even more attractive as the time advantages improve.

A Pedalme bike delivering in a street during

a pedestrianised time of day in this street.

The Heart of London Business Alliance shows what can be achieved if businesses work together. It's consolidated waste collection project has removed vehicles from the road and improved business recycling rates.

Traffic circulation plans so people who are driving in or HGVs delivering go out the way they came.

This is probably too far for those objecting to LTNs because in fact, a traffic circulation plan will need to use modal filters. For a town or city centre, people can drive in, but they must go back out they way they came in because the area is split off into "traffic cells" and people cannot drive between cells unless they go out to the edge and back in using a different route. The traffic circulation plans of Ghent and Oslo are quite well known, but in the UK, Birmingham is the front runner to do something on a large scale.

As main road capacity demand reduces, we can take more space back for people.

This is probably quite obvious and I've covered this already where parking is removed, but maybe by now we can be radical with some very large interventions such as introducing public squares, closing some main roads to motor traffic completely and having much more space for things such as trams. The photograph below is of Rue Jean-Pierre Probst in Luxembourg City. This used to be a road with one-way for general traffic and two-way for buses. It's now a tram route with space for walking and cycling.

Here's an interesting story about Alexanderplein in Amsterdam where the city turned off the traffic signals at the intersection. The scheme is part of a wider project to reduce motor traffic and improve access for walking, cycling and public transport. It seems counter intuitive, but in general, traffic signals are a product of motor traffic and being able to switch them off at a large intersection shows a great deal of progress.

Conclusion

I'll go back to one of the arguments being made by LTN objectors which is that main roads should be dealt with first or at the same time as LTNs are developed. I'm not actually sure what "dealing with the main roads" actually means in the minds of LTN objectors, but if the concerns are around congestion and air pollution, then little of what I have set out is achievable quickly. 

Of course, bus lanes, protected cycle lanes (as opposed to kerbed cycle tracks) and parking controls can be rolled out quickly with experimental traffic orders, but just look at how people have lost the plot with pop-up schemes in reaction to the Covid-19 crisis - would LTN objectors really support rapid roadspace reallocation? 

Rapid roadspace reallocation in the City of London.

Some of the longer term policy decisions require substantial political capital and time to implement. Traffic signal upgrades may take 15 to 20 years to deal with as kit becomes life expired. Workplace Parking Levies take years to get into place and so the funding for transport works are a long way off (if they were easy and politically acceptable, we'd have them everywhere).

Traffic circulation plans imply immediate opposition from LTN objectors because they use filters; and indeed if we did deal with main roads first, then it is certain that drivers will switch to side streets if they thought it would give them an advantage.

LTNs can be quickly and cheaply deployed and in every part of the world where walking, cycling and public transport are prioritised, LTNs are a core feature - they are the gateway to more substantial traffic reduction policies. Main road schemes take time and money and sometimes years of planning. 

So what is to be done? If we don't put in LTNs, then we need to provide protection for people walking and cycling but putting in cycle tracks and crossings in side streets would be a very odd thing to do - is there even space? Investing lots of money in side streets won't help the case to invest on our main roads (and we really do).

So, my call to action for LTN objectors beyond some honesty in their objections is a plea for them to actually tell me what they are suggesting we do to deal with main roads and how they will achieve general motor traffic reduction. In both cases, how long do they see it taking, where is the political support and how much do they think their ideas will cost. 

One word of friendly advice, however, have a little look at who is supporting your objections because you'll see people and groups with a vested interest in maintaining the status quo. They aren't supporting you because they are worried about pollution and road danger, they want to carry on driving everywhere and they really don't care about your cause and your community.

Update 30-10-20

Well, this post has struck a nerve somewhere because it has been nominated for the 2020 Active Travel Academy Media Awards under the blogs category. Thanks whoever nominated me!

Update 26-11-20

And this piece was commended in the awards. Thanks to the judges!

Low Traffic Neighbourhoods - Injecting A Little Honesty

I'll say from the outset that I am a supporter of Low Traffic Neighbourhoods (LTNs) and as a result, I am trying to overcome my confirmation bias when engaging with people who do not support them. However, I don't think there's enough honesty coming forth from some of the objectors.

For those who don't know, low traffic neighbourhoods are areas which maybe take no more than 15 minutes to walk across and from which through-motor traffic has been removed using modal filters to create a system of filtered permeability (I've written a whole guide to it for City Infinity). They are an integral part of the Sustainable Safety approach pioneered in the Netherlands and can be seen all over the world.

In the UK, they are a hot topic at the moment, but they have been around forever such as this example from Leicester which has been in for so long, the trees within it are mature;

LTNs cannot transform places on their own; main roads need dealing with to make walking and cycling safer along them for the simple reason of that's where many shops and services are located. However, LTNs are fundamental part of urban traffic management policy (in the widest sense) in places which try to give people genuine choices about how they travel their shorter trips.

Some designs of filter do permanently remove a section of road from motor vehicle access because it's genuinely surplus to requirements and nobody needs motor access. Some prevent motor vehicle access some of the time (school streets and pedestrian zones for example). However, the vast majority of designs do not prevent motor vehicle access at all, they just stop people driving through the area and out the other side. 

In the photograph below taken in the Vauban neighbourhood of Freiburg, Germany, you can just make out a car parked in the street. There was a guy vacuuming it and so he needed to be close to his home to run out a power cable. You cannot drive through this neighbourhood to get somewhere else (the main roads are for that), but you can get your car to your home to clean it in the same way that a taxi can drop you off there or maybe a supermarket can deliver some shopping. As a result, the street is quiet.

Here's a residential street in Copenhagen. Here, people can park their cars and their cycles. There are no cycle tracks here, but the traffic management has been designed so that the only people who need to be here either live here or have business here;

Low traffic neighbourhoods can also benefit town and city centres. Here we have Luxembourg City which has plenty of motor vehicle access, it's just that it's managed. Some areas have time restrictions, some don't, but the arrangements make it undesirable, if not impossible, to drive through and out the other side. People walking and cycling can go everywhere.

Personally, I think that the whole idea is wonderful and these places are almost always lovely to walk around and safe to cycle through. But of course, we know that there are people who disagree with the approach and that's fine.

What I want though, is to get under the skin of some of the objections. Now there are people who need to drive or be driven - and I really mean need. A LTN won't stop this, but depending on where they live in relation to a proposed filter their preferred route may well be impacted by a scheme. Their preferred route may have been the shortest route to their destination (I'll come back to that) or it's the easiest in terms of congestion or a particular junction. 

The issue of distance is interesting. There's a scheme being planned in London where somebody has commissioned a report to prove that an LTN will mean people have to drive further. Have a read for yourself if it takes your fancy. The LTN uses a series of filters to create a series of "traffic cells" which are all accessible by motor vehicle from the (main) roads circling the LTN, but you can't drive between cells without going back out onto the main roads. The report uses a simple Excel sheet to "prove" that the LTN will increase driving distances from each cell to a series of destinations on the boundary roads.

The mathematics appear fine, but they simply show a before and after distance between each cell and each destination and with that, the cumulative distance between each cell and destination is longer. If you think through the logic, then numerically it has to be the case because the filters stop people driving through the LTN. If you need to drive and your destination is beyond a filter, then you are going have to go the long way round. This report gives a mileage of 32.36 miles for "before" and 49.11 miles for "after" which is a 52% increase and is presented as such for the people in the LTN.

The problem with this type of analysis is that is doesn't present the entire picture. As I mentioned earlier, LTNs are maybe a 15 minute walk and so driving from one of the cells to any point on a boundary road is a short distance and so I have to conclude that those using this as "proof" against filtering actually want to maintain the ability to drive short distances. If you were driving a longer distance, say 20 miles, then the increase at the start or end of your trip (coming home), depending on the route you were taking could be longer than the no LTN condition, but it's a small percentage of that 20 miles. The other problem with this approach is that it simply doesn't model each choice of people person living in the LTN and it doesn't model the choices of those who did cut through.

I don't want to dwell on this one scheme and the piece of analysis, but we should widen our thinking beyond people who need to drive to people who want to drive. It may be that under normal circumstances they drop off a member of the family somewhere as part of their longer drive to work. If the LTN is substantially increasing their mileage in percentage terms, then their trip is already short and in fact they and their family member might be nudged enough to try walking or cycling - yes, LTNs do make driving short journeys less convenient (that's a nudge feature as well as making things safer). You might see the same people reducing the car-based trips to the large supermarket in favour of a bit more local shopping. that's good for them and the local shops.

For the people in the LTNs who need to drive, as well as removing the people who were driving through the area, we've also removed some of the people who we've nudged out of their cars which means that we'll probably reduce the demands on the boundary road junctions which will make it easier for those who need to drive (or be driven) to get in and out of their traffic cell. It's obviously more complex than that because we're also concerned about the impact on boundary roads and indeed other adjacent places without LTNs. In traffic modelling terms, this can be an issue because it can be difficult to model behaviors. 

Many models work by "traffic reassignment" which simply means that if you stop it flowing in one place, it will divert elsewhere, like water. Look at how sat-navs work, a road is congested ahead and so a sat-nav re-routes you somewhere else. The problem with this is traffic is more like (but not precisely) a gas because it can expand or contract depending on what's happening in capacity terms. Behaviour will show is that the potential short to medium increase in traffic on a boundary road might be enough to make some people stop making their trip. For example, someone driving for an hour might be at the very end of their threshold and another 10 minutes is enough to get them to switch to the train or stop making that trip (which may well have other consequences way beyond modelling).

An LTN will change traffic patterns, and in the short to medium term, we may well see an increase in traffic on boundary roads. We might also see patterns change and some people start using other residential streets a bit further away because it might be easier than going on the boundary road in question. That is an issue which people in and around a proposed LTN may very rightly be concerned about in terms of congestion, pollution and an increase in road danger and something which should be acknowledged, although from a traffic reduction point of view, it can't be done by making changes to main roads in isolation because that will push people to drive through local streets that are not filtered. Unless you've the resources to do both at once, LTNs should be delivered first.

In the long term people will adapt to the new reality and there is only so much capacity available and so things will have to find a level again. The skill there is having a regional approach which tackles longer distance car trips in urban areas which are a detriment to the wider community. Space should be given to walking and cycling on main roads, destination parking should be constrained, buses and trams should be given priority and so on. As well as making it harder to drive, we make it easier to travel by other means and those who need to drive can do so more easily, or at least it's no worse than before.

I think the other problem in the whole LTN debate is around whose time do we value the most and who gets a say in a scheme. One of the big problems we have with UK traffic management is the law creates a playing field heavily skewed towards driving because the general approach is for people to do what they want unless limited by law (national speed limits or local traffic orders). As soon as someone looks an putting in an LTN, they are immediately impacting the long established status quo. At a societal or cultural level we also have this whole area of thinking around people only having worth if they are going to work or driving. Imagine someone who walks their child to school and then carries on to care for a relative or maybe doing some voluntary work - do we price them into our economic models?

Do we consult children about LTNs, or do we listen to the well organised and well motivated people (whether for or against)? What value do we put on children being about to cycle to meet their friends rather than being driven (independence for the child and parent). What value do we put on an older person who can invest in an e-bike to get to their shops because the LTN gives them a safer route and some confidence? In fact, what value do we place on those local shops where people on foot spend the most money compared with retail parks? The matter of improvements for well being and society are hardly discussed.

I started this post challenging objectors to be truthful in their motivations, but I'll throw that over to people who support LTNs too. Acknowledge the points that people might have and where there are genuine issues thrown up, work hard to understand them and to try and solve them. However, when someone is projecting their views onto others or they are being circumspect then firmly challenge them. Equally, if you are against an LTN (or any scheme) because it will impact on your ability to drive where and when you like, then please be honest about it. I will disagree with you, but I will at least respect your position.

Fossil Fuel Addicts, Shock Jocks, Plumbers & The Unhinged

It is often said that unless you're getting a backlash, you're not doing anything meaningful; and maybe this past week more than any other time this has been true for walking and cycling.

This week the government published three important things. First was the very long awaited update to the English cycling infrastructure design guidance - Local Transport Note 1/20, Cycle Infrastructure Design. This is a very important because in the absence of any other understanding of how to design for cycling, it's something which any local authority or consulting engineer can pick up and understand what is required. That on its own won't make for good design because you need competent people, but at the very least it sets out the minimum requirements stall which might mean that the first reaction is to get someone in who knows what they are doing.

There is nothing radical about LTN1/20 as such, but for the first time it brings UK design guidance up to date following legislative changes brought in with the Traffic Signs Regulations & General Direction 2016 (parallel zebra crossings, low level traffic signals etc) as well as current professional practice. I say UK, but this is aimed at England and Northern Ireland because Wales and Scotland have their own guidance.

The government also launched a consultation on some major revisions to the Highway Code which (if incorporated) will update the HC to again reflect the change in things we're allowed to design now. It is also proposing changes which would give (in theory) a little more help to walking and cycling such as advising drivers (and cyclists) that people crossing side streets (walking or cycling) should be left to complete the crossing before anyone turns in - in fact, someone looking like they want to cross (including at a zebra or parallel zebra crossing) should be afforded the same courtesy.

The HC will not make our streets safer per se because reasonable and courteous people will already behave properly and let's face it, the HC is only used by people on Twitter to argue points; but it shows a political direction of travel and the courts will use the HC as a part of testing how someone has behaved. Please take a look and respond to the consultation here.

The third thing published is far more radical and is the thing that has really wound up a few people and got a certain part of the media up in arms. Once you get past the stupid attempt at gaming Google searches by the PM referring to people not being able to get fridge-freezers on cargobikes (which is nonsense), Gear Change: a bold vision for cycling and walking actually is a genuinely bold vision. The document is full of facts about how pursuing policies based around walking and cycling can improve health, social and economic outcomes for people and where they live. This is probably my favourite graphic from the document because it's about design;

It's also a great explanation of why some people are losing the plot over plans to change how streets are managed and how people are prioritised. We've had radio shock-jocks ranting about lycra-clad cyclists, fossil fuel industry sock-puppets going on about needing to share the roads and the owner of a London-based plumbing company rationally describing people who want to cycle as fascists. Of course, such nonsense inevitably stokes up hatred from other people which at worst means people die on the streets.

The Vision also comes at a time where as part of their responses to Covid, some local authorities are trying to create safer walking and cycling space in our communities. In some cases, this has led to noisy protests and in at least two things I have read, people suggesting the schemes are like genocide to local businesses. We've also heard from motoring groups who also talk about balance and sharing and freight transport organisations which can see a challenge to their current business model which relies on the community to absorb the externalised costs of their operations.

Maybe you think I am not being forgiving in lumping the obvious loons in with the more respectable organisations, but for me, it's a spectrum and a little bit of digging shows that the main difference between these people and organisations is language rather than intent. We've followed their model for decades and look where it's got us.

There is plenty of dissonance with government of course, with the £27bn plan to expand the English strategic road network (although some of this cost is for maintenance) and a planning system which is still leading to car-centric development. It is possible to dislike a government, but welcome a particular policy however.

But, the counter to this is that we are starting to hear new voices above the screaming insults and crocodile smiles. Hyper local action groups are being formed to amplify the silent majority who would actually love to see different streets. Electronic citizen spaces, social media and people on the ground are starting to push back. The Bike Is Best campaign has undertaken some research which suggests that for every person against local measures to enable cycling are supported by 6.5 people.

This may be a surprise to many given what we see in the media and what many politicians say, but when we have political lobbying by fuel, motoring and haulage interests as well as people in the media who use outgrouping to create outrage for "debate" shows and for website clicks, it's clear that some see people being able to travel under their own steam as a threat, whether financially or politically.

Of course, a week is a long time in politics, but for the first time in a decade of being into active travel design, I'm cautiously hopeful.