Traffic Signal Pie: Double Standards

Something crystalised in my mind a little while back as I contemplated crossing a side street at a signalised junction - the idea of double standards in traffic signal design. 

The idea had been in my head for some time, and it developed from my work with Robert Weetman on the design of side road junctions. Consideration of signalised junctions wasn't part of our scope per se (as we are looking at priority junctions), but we did recognise that they are still a tool that would be needed within the overall design of a road network.

The actual junction that finally nudged me to write this is the junction of the A12 Eastern Avenue with Aldborough Road North & South. The A12 is a Transport for London strategic road and a dual carriageway with a 40mph speed limit. It's a two lanes in each direction affair, but flares out to four approach lanes (including right turn filters) and three exit lanes. This junction is very much about stuffing motor traffic though.

The side streets have two lane approaches and single lane exits. The northern arm has a left turn slip road which curiously has a zebra crossing over it, but which uncontrolled for pedestrians over the northern arm (see above). You can also just see the staggered pedestrian crossing over the main carriageway (the eastern side of the junction).

The crossing of the main carriageway is pretty standard with people crossing the southern half with a green man when main road traffic is held and crossing the northern half when the side roads run with traffic turning from south to east being held at an internal stop line. 

The western side of the junction has a period subway to cross the main road which is as attractive as you might imagine (above). And like the northern arm, the southern is uncontrolled (below).

The zebra crossing over the left turn slip road is a little unusual, but this type junction with a green man crossing on the main road crossing, but nothing on the side roads is very common and essentially there for motor traffic flow. 

Because this is is a flow-focussed design, having single stage pedestrian crossings over the side roads would require an "all-red" to motors which isn't apparently acceptable because it takes too much capacity from driving. You do find junctions which at least provide green men on all arms with multi-stage crossings even if still flow-focussed. Barley Lane to the east is a good example, but this will always be a space and motor-capacity debate.

You might think the double standard here is just that drivers get most of the capacity at the junction. That is of course true, but the issue goes far deeper than that when we think about this in terms of pedestrian-friendliness. There are a set of factors which affect the pedestrian experience which I will restate here:

• Background vehicle speed 
• Through traffic volume 
• Turning speed 
• Turning vehicle size 
• Turning levels and complexity of traffic movement 
• Visibility character and crossing distance 
• Presence/absence of physical barriers to pedestrian movement

I would recommend you go and read Robert Weetman's blog post on "factors and features" if you want a more in-depth explanation of these, but I will refer to some of them when applied to crossing the side road arms of a signalised junction.

Signals are there to control flows of traffic, including pedestrians and cyclists. In the context of junctions like Aldborough Road, signals enable side road traffic streams to gain access to, and the ability to cross the main road. Traffic signals also provide time within their set-up to give crossing opportunities by holding motor traffic streams to allow people to cross, even if that isn't specifically with a pedestrian signal, although you almost need to know the sequence to stand a change.

It is important to understand that traffic signals are not safety devices, because they rely on people obeying the rules, rather than being inherently safe. I am not suggesting that traffic signals are unsafe, but they are a rules-based feature that can have catastrophic impacts from non-compliance, often with those carrying the least energy coming of worst.

If we wanted to create a junction which is safer than traffic signals, then we would be grade-separating everything which is complex and costly in established urban areas. There are things we can do within traffic signal arrangements to mitigate the risks, but this will always be in balance with capacity and efficiency. Back to my junction example where pedestrians are not given a green man to cross, notwithstanding the point that signals cannot be perfect.

If you start to think about the factors above and how they might influence conditions for people trying to cross the side roads, you soon realise that the issues are not there in the background more generally as you would have with an ordinary side road junction, they become concentrated because of the traffic signals.

While a crossing pedestrian won't have to judge traffic gaps coming from the full range of turning movements at once, the underlying volumes of passing traffic on the main road are ever present. My example has a refuge in both side roads which means crossing traffic leaving the side road will at least be simpler as it is only one stream from one direction which is often directly held at a red signal. Crossing the second stage is much more difficult because the signals will operate to provide an almost constant stream of traffic, but with their directions ever changing as the junction runs though its cycle.

It is arguable that crossing from the refuge might be simplest because one can see oncoming traffic which makes judging gaps easier than crossing to the refuge. Younger and older people have more trouble assessing speed and therefore gaps, and of course visually impaired people and people who cannot move quickly will also have a hard time crossing. There will also be signalised junctions without refuges and these could be even more difficult to cross.

I have been around the houses a bit here, but I will at this point suggest that signalised junctions can never be pedestrian-friendly as defined by situations where drivers are likely to yield to pedestrians crossing the side road. This is because there is one additional factor - the green traffic signal.

Green traffic signals for drivers (and cyclists) are an invitation to proceed but only if your exit is clear (unless waiting to turn right) and in any case, caution should be exercised. The problem is, however, that some people treat a green signal as affording total priority and they behave in that way. I am sure we can all provide anecdotes of drivers moving from a green signal using their horns at people trying to cross in front of them!

I'm being a little unfair to lay the behaviour we see completely at the feet of drivers (and cyclists) though, because there is also the ideas of social pressure and cultural pressure. Social pressure is where people react to a green signal in a way where they don't want to hold other people up - horns being sounded by their impatient followers. Cultural pressure comes from a long history of green meaning go (as different from meaning proceed with caution). This might come from learned behaviour from people's peers, what they see in the media or perhaps even how they were taught.

This stuff is hard to deal with in design terms, and one of my favourite examples is where there is the need to give way shortly after a signal such as with the left turn slip road in the photograph above. I guarantee that there will be people missing the give way because they are just reacting to the green signal.

As an aside, a green man signal (more properly called a "pedestrian signal") is an invitation to cross, but in a rules-based system, the safety of someone crossing relies on everyone else behaving. This is why I will always push back when people describe traffic signals being safety devices. The other thing to note is that there is no legal force to disobeying a red man in the UK because (in theory) people can cross where and when they like.

Amusingly Rule 21 of the Highway Code states:

"There may be special signals for pedestrians. You should only start to cross the road when the green figure shows. If you have started to cross the road and the green figure goes out, you should still have time to reach the other side, but do not delay. If no pedestrian signals have been provided, watch carefully and do not cross until the traffic lights are red and the traffic has stopped. Keep looking and check for traffic that may be turning the corner. Remember that traffic lights may let traffic move in some lanes while traffic in other lanes has stopped."

It's amusing because the junction in my example is very much the second two-thirds of the rule which is actually telling people that in fact they are fully responsible for crossing the road and wishing them luck in doing so; this starts to pull at the double standard thread.

When one undertakes design work for a junction, the general approach is to separate conflicting traffic movements in time and sometimes space. While "traffic" is very much all road users, including pedestrians and cyclists, when we get to the actual detail, we find pedestrians are treated differently to drivers and cyclists because they are not vehicle-based (a cycle is a vehicle in this context). This may just be a result of the ability of people to cross where and when they like (in theory) as accrued as right from antiquity.

Each traffic movement will have a "phase" and when a series of phases run together that is called a "stage", but a stage cannot have conflicting phases. That is why main road traffic moving ahead doesn't run on green at the same time as a side road joining or crossing it - we'd obviously have carnage on our hands.

Where we have phases for a specific movement, we'll see green arrows used and if a driver (or cyclist) sees one of these, then they will have an exclusive right of way. This means we can do clever things like having left turns into and right turns out from a side road running together.

There is a bit of an exception where two opposing traffic phases run together and that's where drivers (and cyclists) can enter the junction to wait until they can turn right. In some cases, a driver (or cyclist) might have entered the junction on a standard green signal and then after a while, they get a right turn green arrow. This will be because the oncoming phase will have been stopped to allow the right turn to clear (called an "early cut-off").

Where there are cycle-specific signals, the same applies and that is why in the UK, we cannot use the Dutch-style simultaneous green because of the issue of "ahead" flows being in conflict with those coming from the side.

Pedestrians are treated differently. They can cross all arms of a junction at once, and they can also do that plus crossing diagonally because they are trusted to negotiate with each other. I don't know for sure, but I suspect this arises from the basic ability of people to cross when or where they like and in theory, a bunch of people might just all decide to freestyle it at a junction anyway.

The non-conflicting phase approach also applies to pedestrian phases insofar as we can't give a green to drivers (and/ or cyclists) to proceed at the same time as pedestrians cross the same space because that is risky, but all bets are off when we don't give pedestrians their own crossing phase. This is the nub of the double standard I am talking about.

A traffic/ pedestrian conflict only exists when we give pedestrians their own crossing phase. Where we don't, the conflict apparently disappears, even where we suggest a place to cross with dropped kerbs and tactile paving as with my example. 

People undertaking the design of junctions are expected follow certain rules and there is guidance to help them. They are also expected to undertake a level of risk assessment on their designs to help support their approach. When it comes to making a decision not to provide pedestrian phases, I am sure the risk assessments are undertaken, except the balance ends up lying with favouring motor traffic and it then becomes the responsibility of the crossing pedestrian to undertake their own "dynamic" risk assessment whenever they choose to cross.

This is at the heart of the double standard. We have created rules and expend our design efforts to make these junctions as safe as we can for drivers. We do for cyclists too, but that's limited to those happy to mix with traffic and in terms of the A12, I assure you I am exercising the Boateng defence vigorously. 

However, when it becomes a bit tricky because we want to maximise motor traffic capacity, all care for the most vulnerable evaporates and any thoughts of ensuring we design out conflicting phases is thrown out the of the window as we throw people under the bus.

I have said that junctions controlled by traffic signals can never be pedestrian-friendly and to some extent, that doesn't really matter. If we tackle roads and streets at the network-level, deploying area-wide traffic management policies, then we can actually make loads of side road junctions pedestrian-friendly, even if we have to go through stages to get there.

This does mean that some junctions, like my A12 example, will require traffic signals and that's fine in terms of the wider prize. However, if we are interested in equality and accessibility, we should be providing pedestrian phases wherever pedestrians are expected to cross the roads within a signalised junction; unless there is a way to provide decent grade-separation.

I won't get into the details around staggered and two-stage crossings, but suffice to say layouts should meet a standard of accessibility, and in the interim we might not provide crossings on every arm, so long as every pedestrian route through is accommodated somehow.

This is not even a radical proposition in my view. This should be the absolute basic standard for new and refurbished signalised junctions. If this means a loss of motor traffic capacity and more congestion, then so be it. Perhaps that will act as a wakeup call for everyone to realise that we have scarified pedestrians at the altar of the motorcar.

I would go as far as to say any designer who is not planning to provide this basic level of service should be held to account for their decisions. To anyone under pressure from their boss on subjects like this, then my message is you really need to start to refuse to work in that way if you can, otherwise you need to carefully document things and get your boss to confirm their instructions in writing. Oh and councillors - this is on you as well.

If not, I guess we could try the tried and tested UK approach of putting up a sign where the push button might otherwise be.

I am not a traffic signals expert, but as ever, this blog helps me learn as well as run through ideas and develop my views. If you are interested in traffic signals, my other posts on the subject and listed below. 

Why "traffic signal pie"? Well, for any given junction size and layout, there will be a maximum pie of capacity to be served. It's just we serve too much to drivers and in some cases, pedestrians hardly see a crumb.

First Slice, January 2014 - a look at standalone crossings

Second Slice, March 2014 - the SCOOT system

Third Slice, July 2014 - protected junctions.

A Midnight Feast (For Some), November 2014 - a deconstruction of the Greater London Authority Conservative's idea of switching of traffic signals at night. Which obviously ignores those not driving.

So Near, Yet So Far, March 2015 - a comparison between nearside and farside pedestrian.

The Great Switch Off? No, It Runs Far Deeper, January 2016 - a look at a report from the libertarian and very motor-centric Institute of Economic Affairs.

Staggering! July 2017 - a look at why pedestrian crossings at junctions are often staggered.

Time for T, March 2018 - an exploration of a real life idea to connect a side road junction with a quiet local cycle route to a main road with cycle tracks.

Just Rephase the Lights, March 2018 - a pushback on the parlance.

Partially Protected Turns, January 2019 - a novel approach to a protected junction design where side road space is limited.

More Partially Protected Turns, February 2019 - the second part.

The Long Wait, June 2019 - me moaning about a local toucan crossing.

Automatic for the People, November 2019 - all about push-buttons.

Begging the Question, September 2020 - more on push-buttons and especially how they are a pain for people cycling.

Critical Crossings, February 2022 - my views on how we should react to how we treat different modes in an emergency response to signal failure.

Innie vs Outie, May 2022 - a look at the Dutch vs CYCLOPS protected junction designs.

It's Not As Simple As That

Back in August 2020, there was a report claiming that a Low Traffic Neighbourhood (LTN) in Ealing showed an increase in driven trip miles over 50%. In the last few days, we have had more of this on a scheme in Islington and I thought it worth publishing a thread of my own analysis from the Ealing scheme and to offer a few other observations on the current "analysis".

The following was originally posted on Twitter on 8th August 2020 as a result of me trying to reproduce the results of a report undertaken by R. Witt for the Midhurst and Leighton LTN which was covered at the time by the "Ealing Today" website.

The general thrust was that the LTN increased traffic on the "boundary roads" and the analysis looked at distances from destinations on the boundary roads to locations in the centre of each "cell" of the LTN. The "before" data was the basic direct distances between the centres and destinations and the "after" data was the new routes that people would take. What R Witt had done was to create a spreadsheet traffic model.

The original thread follows below (with some typos corrected) and I will pick things up again after the table at the end:

That Ealing LTN discussion yesterday which showed an increase of 52% of trip length comparing the before & after driven journey lengths between each cell and a series of boundary road destinations. Notwithstanding the fact that it's a simplistic analysis, it's been bugging me.

I've run the numbers with another assumption that once someone has driven to the destination point (which are all short journeys) they may well actually be driving further, and therefore the percentage increase between the no LTN state and the post LTN state must reduce with the overall distance travelled. I think I am applying the same logic, so feel free to call me out on my mathematics at the end of this thread.

In the original analysis, we have 6 traffic cells set up in the LTN and 9 "destinations" on boundary roads. For the with/ without scenarios, the shortest distance between the centroid of each traffic cell and each destination is calculated and made up of the distance from the centroid to the boundary road plus the distance travelled on the boundary road to get to the destination. 

Each combination is added up to give a total mileage in the before and after state. I've actually found a couple of minor rounding errors which takes us from 52% in the original paper to 53.4% with my initial check of the figures - this may just be in how things were measured and rounded up - the tolerance of 0.01 mile is 16 metres or about 20 of my lanky paces. It's of no consequence to the model.

The model is a 6 (traffic cells) by 9 (destinations) matrix or 54 possible combinations. So if we assume for each of these trips, once a person gets to the destination, they actually drive another mile. We will then need to add one mile to each trip which I've applied to the destination calculation (I can't apply this to both the first mileage in the LTN and second on boundary roads because that's double counting). So with this extra mile, the percentage increase created by the LTN falls from 53.4% to 20%.

If we add 3 miles then this increase drops again to 9%. Given that this is a perfectly cyclable distance, the LTN will have no impact on that. At 5 miles, we're at 6% which is cyclable but I can see people wanting to drive or get a taxi.

At 10 miles, we're at 3% and if we're driving out to see Auntie Doris who lives 50 miles away in Milton Keynes, then we are at an increase of 0.63%. I'm simply applying the same logic to the original model which I contend only supports those wanting to drive short trips.

The model does not consider car ownership/ access, mode split, cost, journey time, behaviour and all of the other interesting variables which are thrown into the mix when we look at how and why people travel. I think I am right, please take me to task.

OK, that's a social media thread, but I also wrote a post about some of the wider issues, including that those of us who support LTNs need to acknowledge some of the issues raised by those with concerns - that post also referenced the report linked above.

So, why have I dug all of this out again? Well, in the Times over the last few days, a well known opponent of LTNs has used his platform in the paper to have a whine about the Mildmay LTN in Islington. If you can stand it, the piece is HERE, with the usual suspects quoted.

The thrust is that the LTN will generate 1.4 million extra miles driven to get around the LTN each year. Let's pause a second and consider that in 2024, Islington had 225 million miles driven in the borough. The actual existing main roads are on the border of the LTN are in Hackney, and that borough had 274 million miles driven in the borough in the same year.

The "analysis" basically takes Islington's traffic data for King Henry's Walk which is unclassified and not a "main road" as asserted in the piece. The data apparently shows between 6,800 and 12,000 vehicles use the street very day, but we're not given any more detail. 

There is then a calculation which takes the lower flow quoted and asserts the traffic will need to go an extra 0.55 miles as a result of the LTN by drivers having to use classified roads; the A104 and A10 to be precise. These are main roads managed for long distance through-traffic. 

The 1.4 million miles comes from the volumes assumed to be diverting, multiplied by the diversion distance and then multiplied by 365 days - 1.37 million miles. That assumes the traffic volumes are the same 7 days a week, which isn't usually the case, but we told get told any more.

As with the Ealing report, this is a simplistic approach. Given the person's long opposition to LTNs and their role as a journalist, it would be reasonable to suggest that they know full well how simplistic this is. There is no discussion about the origin and destination of trips, or where traffic might reassign at the network level.

There is, however, a concession to evaporation being possible, at 15%, which takes the diverting traffic miles down to 1.1 million miles, or about 0.5% of the annual driven mileage in Islington or 0.4% for Hackney. I don't know what the 15% figure is based on, but on face value, we are not actually talking about a large number of extra miles, especially give how that just before Covid in 2019, there were 242 and 286 million miles driven in each borough respectively - overall flows are dropping and have been for years.

The piece whines that because of the other LTNs in the wider area, the main road is essentially the only route that can be used. Well, that's actually the point isn't it. Longer distance traffic using the routes designed, maintained and managed for those flows (for better or worse).

It's actually a non-story and while I think this bleating should generally be ignored, it is still occasionally worth explaining what the numbers quoted by the professional anti-LTN folks represent, because they really don't stand up to basic scrutiny. As those of us battle-hardened in the area will know, there is no amount of data, modelling or logic that will ever satisfy the hard-core anti.

A Street Corner In Rotterdam

Back in the summer, I visited Rotterdam, one of my favourite Dutch cities and this time, stayed in a neighbourhood on the southern edge of the city centre.

Rotterdam is a great city to explore and it's also a great base for trips out to other places by cycle or public transport. However, this post is about a junction outside our hotel.

The photograph above is the view west along Witte de Withstraat at its junction with William Boothlaan (left) and Hartmansstraat (right). We stayed in the H3 Hotel Rotterdam which is on the corner to the left and we were in a room facing Witte de Withstraat.

Of course, staying somewhere a few nights can't possibly give you a local's perspective, but watching the ebb and flow of life was interesting, especially as our stay was either side of a weekend so we got to see life during the week as well as a weekend. From the early start of the street cleaning crew, through the morning deliveries and into the afternoon and evening of the restaurants and shops, it's a busy and every changing place.

Above is a view from within the junction, looking to the south-east towards the Bazar restaurant. The words above read "in alles is een oogopslag" - "In everything, there is a glance" and is there to promote the work of the poet JH Leopold from the city, with the full poem HERE. Nothing to do with the general design of the street, but Rotterdam is full of these little pieces of local culture.

Of course, it was the street design that interested me. Witte de Withstraat is the main road which has one-way for general traffic westbound (2-way for cycling of course) and with the side streets two-way for all traffic. There are zebra crossings on each arm. The main road is subject to a 30km/h speed limit, whereas quite bizarely, the side roads are the usual urban 50km/h!

The carriageway is surfaced in 100mm x 200mm block pavers (above) with road markings in white units and with the standard 300mm concrete tiles for the footway. The kerbs are concrete with a stone-effect finish and drainage gullies sit in the kerb line so as not to be damaged by heavy vehicles. All very standard for a Dutch street, but so much nicer than the sea of asphalt we often see in the UK. It is also practical because the paving elements can be lifted for works and they are easily replaced.

The photograph above is view of the junction showing that it sits on a speed table, the ramp being denoted by the long and short lines. The detail of that and the zebra crossing is easily seen where they are formed by the block pavers - much more flexibility than the UK and given the local context, the crossing are marked with standard upright signs. 

It is also worth noting the bollards just behind the kerb edge (above) because Dutch drivers are just as bad at parking on the footway and just as scared about damaging their paintwork as UK drivers. The bollards do help to force slower turns at the junction and in a more effective way than the raised table does. In the Netherlands drivers are required to give way to people crossing or obviously waiting to cross (Article 49 of the Dutch Traffic Regulations). Drivers are also not permitted to wait within 5 metres of a crossing.

The other little detail to note is the tactile paving. There is a trade-off between accommodating the pedestrian desire line and ending up having to cut tactile paving into a curve. In this example, there is a very practical approach which has blocks of blister tactile paving two tiles deep (so people are less likely to step over and miss them), but laid out set back from the kerb to avoid cutting them in. They are laid to the width of the stripes. The bollards are at risk of a visually impaired person colliding with them, but I suspect there would be drivers on the footway otherwise.

One final detail is the way the parking bays are inset from the carriageway as a result of the footway being built out at the junction. The photograph above is at the kerb edge looking east along Witte de Withstraat. Yes, the van is parked facing the wrong way in the one-way street. The hatched bay is for Disabled drivers.

The narrowing of the carriageway is helpful in terms of slowing turning drivers, reducing the crossing distance at the zebra crossings, discouraging parking at the junction and it puts the "obviously waiting to cross" pedestrians right in the field of view for drivers and cyclists; all features which help with "pedestrian-friendliness". It also provides somewhere visible for traffic signs and potentially other things such as cycle parking or greening which is not on the general pedestrian design line.

The crossroads doesn't have marked priority for traffic and so drivers arriving at the junction are expected to give way to traffic arriving from their right (including cycles) as is the standard Dutch rule which helps to control driver speed at unmarked junctions, although my observations here did tend to see lots of "might is right" from drivers on the main drag. 

Despite the tightness of the geometry at the junction, there was some pretty poor right turning behaviour from some drivers who did so at excessive speed and with some intimidation of pedestrians trying to cross. This was more evident in the evenings where it was pretty clear the drivers were showing off.

At the network level, Witte de Withstraat runs in parallel to large roads to the north and south of the immediate neighbourhood. While the local one-way streets tend to deal with some of the potential rat-runs. Witte de Withstraat could be attractive for those wanting to cut between Westblaak to the north-east and Westzeedijk to the south-west if the main roads got a little busy (but only in that direction). 

This could be why the street felt too busy with motor traffic at certain times of the day and evening, and probably explains why zebra crossings are used at the junction - if traffic was light, the zebra crossings wouldn't be needed.

The weekend evenings had another layer of interest where Witte de Withstraat was closed Friday, Saturday and Sunday evenings to the west of the junction. As best as I can find out this was done for the summer to support the street's evening economy and got extended, but it also happens for other events. There are definitely some tensions with the traffic here and this might explain the 30km/h speed limit on the street.

I do like to share stories of the big and impressing pieces of infrastructure, but I also think it is interesting to stop and observe things which initially appear mundane, but where it actually turns out there are many layers to unpeel.

Back To The Future In East Oxford

I have been doing some work in Oxford, and on a recent visit, I had the chance to look at some historic traffic calming in East Oxford which has sent me down some research rabbit holes.

If "East Oxford" rings a bell, it could be the East Oxford Low Traffic Neighbourhoods (LTNs) project which has been the subject of some controversy. I say controversy as a shorthand really, because I think much of the framing is dishonest, but I have written about that before.

LTNs are a key tool in our box for delivering a Safe System (call it Sustainable Safety, Vision Zero or whatever) and they are decades old and nothing new. What was interesting about East Oxford is that it had all been tried before, but to learn more we need to jump into our DeLorean and head back to 1985.

In East Oxford in the early 1980's, there was a movement to deal with rat-running on the side streets in the area, which got as far as an experimental project being developed and deployed at the start of 1985 in the Divinity Road area.

I have tried to search online for the traffic order without success and so I am going on the account from a website dedicated against LTNs in East Oxford, which is as you'd expect. There are also Oxford Mail stories from 2020 and 2021 which mentions it, but I guess history is recorded by the "victors".

The arguments of the 1980s are identical to those we hear in the 2020s. They are rooted in the evolution and intertwining of highway law and public perception that driving (and parking) should be unrestricted, unless that basic premise is modified nationally (e.g. national speed limits) or locally with a traffic regulation order. This means we are having to expend significant resources to change the status quo which itself is often supported by powerful and/ or noisy voices.

Indeed, the anti-LTN account I link to above ticks off the boxes of someone who thinks they should have a bigger say because they have lived somewhere a long time, (driving) locals predicting chaos with no patience, and various attributions presented as facts rather than the opinions that they are. Fine. Whatever.

In the event, the experiment simply wasn't allowed to to run properly and objectively and it all collapsed. As a compromise, traffic calming interventions were proposed and this echoes the contemporary anti-LTN position with vague platitudes that things should work for all road users, as cover for side streets taking pressure off main roads. 

The problem is of course, that physics and bio mechanics do not operate on an equal level and the most vulnerable need the most protection. On residential streets, this has to be speed and volume reduction to a point where those walking, wheeling and cycling are not put at significant risk by high driver speeds and traffic volumes. 

For East Oxford, the failure to get the LTN to stick didn't tackle the rat-running in the area, but it did lead to the fall back position of traffic calming which is a good addition to the case study because we know that it didn't solve the problems in the long term, gives the more recent introduction of the LTNs in the area more gravity; it's a live case study of the decades.

For the Divinity Road area in particular, Danny Yee talks about how the traffic calming added after the abandoned experiment failed to deal with traffic flow, which isn't a surprise. He was also my guide around the city and we did pass through lots of East Oxford and some of the traffic calming I saw caught my eye.

The photograph above is Howard Street which is one-way for the most part and has a series of chicanes with alternating car parking and raised junctions.

The one-way working was not part of this scheme. This happened in 1972 when the street was made one-way between Cricket Road and Iffley Road. I can't find out why this was the case, but I wonder if this was an early reaction to traffic flow in the area being impacted by car ownership and this narrow section of street not working for two-way flows. 

The parallel (and also narrow) Magdalen Road is even more interesting. In 1964, it was made one-way but in the other direction between Iffley Road and St Mary's Road. This was extended in 1972 to continue the one-way working as far as Ridgefield Road. Taken with the 1972 order for Howard Street, this reinforces my view that this was about (motor) traffic flow through the residential streets acting as part of the main road network.

The traffic calming came in late 1989 as part of an experimental scheme which covered both Howard Street and Magdalen Road, both of which connect Iffley Road to Cowley Road, a pair of arterial routes into the city centre. The traffic notice actually gives us the "why" which is great to find:

"At present both roads suffer from large volumes of traffic which use them as short cuts. A lot of the traffic travels at speed. The Council proposes to alter the appearance of the roads by providing tree and shrub planting in planting boxes at either end of areas of parking. The areas of parking will also be protected by kerbing, bollards or similar installations. The present parking arrangements will themselves be altered so that parking is staggered along the roads. The roads will become less obviously straight and should reduce vehicle speeds."

The measures stuck and were made permanent in mid-1991 which came with various adjustments, although the traffic order doesn't tell us more more than that.

The photograph above is in Magdalen Road at the junction with Hurst Street showing one of the junction speed tables, and the chicanes created with parking bays. Remember, that this was one-way (in the direction the person is cycling) when the traffic calming was built; in fact the area of stone cobbles on the left used to have a bell-bollard and a tree which physically created part of a chicane.

The photograph above shows a ramp to one of the raised tables. This is interesting as we have a set of precast concrete ramps which are very much like the Dutch "intritbanden" units (entrance kerbs). They are far steeper than we tend to see these days in terms of speed table gradient, but they are compatible with the current road hump regulations. The anti-LTN piece I linked to earlier describes these humps as "vicious (and now illegal)" which again shows it is impossible to find a solution that actually has an impact that these people will support. 

The latest East Oxford LTN project removed the one-way working on Magdalen Road and a short section of Howard Street, as well as adding two-way cycling to the remaining section of one-way working. The project encompasses a larger area than I have researched, but when trawling through the Gazette, I did see lots of other roads popping up with various bits of traffic management and parking control schemes over the decades.

I've only scratched the surface of East Oxford here, but it's an interesting arc of the best part of 60 years of motorisation with the ebb and flow of how we've tried to both accommodate increasing levels of traffic, the backlash this created and then the backlash that trying to deal with the problems also creates. It also shows us that schemes sticking is almost random, but that the arguments are always the same.

In design terms, I actually liked the speed tables and chicanes created with the planters, although things aren't perfect because there aren't flush kerbs to cross the roads at the junctions, let alone the tactile paving that would go with them. This really is something that should be sorted out as part of the LTN scheme.

They do, however, give some local identity and work to show people that different behaviour is expected. This is lost on those wanting to blast through and so it has taken the new LTNs to complete the puzzle. It's a shame that many modern LTN schemes don't come with street enhancements like this.

There are lots of these interesting stories, experiments and ideas out there, but we rarely hear about their planning and engineering away from the confrontation and controversy which is often fuelled by the media. For example, the filter on Howard Street shown in the photograph above has been described the (far) right wing press as the UK's most hated bollard and even the BBC can't cover the story without giving air-time to conspiracy cranks.

This makes sharing knowledge and learning more difficult. The UK has got itself into a position where we won't admit our streets not working properly as it immediately opens a crack for the status quo folks to exploit. It also means that the technical side of things has to attain perfection, whereas those against change are never held to the same standards. This all makes things risk adverse politically and professionally which keeps things the same.

I've seen things you people wouldn't believe: Spring 2025 Part 2 - Dafne Schippersbrug

My Spring 2025 trip to the Netherlands included some time in Utrecht, one of my favourite cities, and another chance to have a look at an interesting piece of design.

My first post from this trip where I rode the F325 Fast Cycle Route between Arnhem and Nijmegen can be read HERE.

In 2023, I rode over the Dafne Schippersbrug, named after Dutch athlete, Dafne Schippers, but there wasn't much time to have a proper look as I was on a ride around Utrecht with Mark Wagenbuur (Bicycle Dutch) and my youngest daughter. I was determined to have a closer look and that was a task for this trip.

The bridge itself (above) opened in 2017 and was built to provide a walking, wheeling and cycling link to an expanding neighbourhood to the west of the Amsterdam-Rijnkanaal (Amsterdam Rhine-canal), and where the A2 motorway is covered over and forms the Willem-Alexander Park. The bridge also took advantage of the need to replace the local primary school (Montessorischool Oog in Al) which allowed some really clever design work to take place.

The land to the west of the canal is being redeveloped and has changed even in the 18-month gap between my visits. I arrived on the western canal path, heading north and the route to access the bridge is via local residential streets. I had to go a little way north before looping back to cross, but that was because of works. The final layout will use a couple of very quiet streets closer to the bridge; and of course, the main access to the bridge comes from the west anyway and where the ground is higher than the canal path.

The main span is a suspension bridge with a pair of outward raking pylons at each end from which the main cables are suspended and with vertical hanger cables holding the deck. The photograph above is looking east towards the city centre with a wide two-way cycle track and pedestrian path. These are separated by a white line which would be lighter weight than adding a raised footway and being at one level, it is easier to drain and treat for winter ice forming- something which tends to happen in cold, damp and windy places, such as over a canal!

While the western access ramp from the canal uses local streets, the eastern side is a little different as it needed to tie into the existing street levels. This is where the replacement of the primary school comes into play because the roof of the school forms part of the access ramp. The photograph above is the school viewed from ground level to the east and you can see the edge rail and people cycling on the roof.

It is worth looking at this with the old street layout and school HERE. Quite a conventional street layout, complete with bollards to keep drivers off the footway. Yes, Dutch drivers can be as bad as those in the UK!

The photograph above is from the school roof looking back towards a long curving ramp which takes people up to the bridge which sits 9 metres over the canal, showing that the flat Netherlands needs a few artificial hills to cross big pieces of infrastructure!

The photograph above gives a slightly different view of the ramp from a little street which was created as part of the development adding a few more homes to the neighbourhood.

The ramp eventually meets street level and cycle traffic is integrated with general traffic on 30km/h low traffic streets with red surfacing providing clear wayfinding for its status as a main cycle route. 

The cycle route connects to cycle tracks on Lessinglaan which is a busier road, but cycle traffic can also cross to access more low traffic streets and a cycle street which runs towards the city centre. The exit from the street leading from the bridge is cycles only and so drivers have to take a more convoluted way out of the area.

The bridge is a nice piece of engineering, but the real skill here is how access to it has been designed in with development on both sides of the canal and of course, the integration with the new school is inspired. As well as this, a more detailed poke around the street layouts on both sides shows that the crossing is all set up to create a direct link to the city with drivers taking other routes which really is classic unravelling of the cycling and motoring networks.

I shall leave you with a video of my cycle around this wonderful piece of urban, landscape and engineering design, but you can see my 2023 crossing and compare the progress of the development on the west.