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.