Saturday, 21 March 2020


The past few weeks have been strange, worrying and pretty hard to grasp with the Coronavirus spreading across the planet.

The situation has been quickly changing, although the UK's approach has made many people uneasy with the usual stupid gung-ho exceptionalism which make every problem an enemy to be defeated. But the recriminations are for another day.

At work, my firm has been exceptional and despite staff at all levels being very worried about what is happening (with the odd and understandable tempers flaring), a crisis management team was quickly developed and people have pulled together. On Tuesday, we were sent to work from home until further notice. 

One of the little views between the station and
my office in the City of London.

As I traveled back mid-morning on my empty Crossrail train with my laptop, keyboard and some odds and ends I had grabbed, it was frankly surreal to be wondering when I would be making the trip again. I have been used to getting up to go to work for almost 25 years and working from home was only ever occasional when it meant saving some travelling time to or from a site.

A very quiet Liverpool Street station on Tuesday.

When I got home, I set my laptop up, grabbed a cuppa and immediately dialed into an on-line meeting. Luckily, my firm operates a decentralised model and so I am quite used to the technology which supports it, but even so it was still strange; but the IT guys have did us proud and it was seamless. At the end of the working week, I packed up my kitchen-table based workstation for the weekend because I have already realised that there needs to be moments when you formally change what you are doing.

This has extended to the commute which has gone from my cycle-train-walk model to a circular commute by cycle which has greatly amused my youngest when I announce that I am leaving the office to go home each day. It's also odd for my new coworker, Mrs RH who has worked from home for many years.

My family and I are very fortunate that we have a safe place to be in and it's important to recognise that privilege. I'm going to work very hard to not to moan about the situation because there are people risking themselves every day to care for the sick and to feed us. Being an engineer who specialises in throwing kerbs and tarmac around is not very important in the grand scheme of things.

I want to be able to help in the only way I know how and that's with writing and talking about civil engineering. I know we have Twitter to chat (which is frankly a lifesaver from that point of view), but if you have a subject you are interested in and would like to know more about, perhaps you're trying to keep some learning going for your children or you're a student now distance learning, then please get in contact and I'll write it up as a blog post;

We're in uncharted history and we can only plan a few days ahead. So, let's try and keep each other connected and entertained. Get out for a socially distant walk or cycle. Oh and;


Saturday, 14 March 2020

Footway Parking Fail: Redux

I detest footway parking. It's antisocial, anti-people, damages the very fabric of the footway and helps to perpetuate the dominance of cars in our streets and places.

It's back in the news again (for England at least) with an announcement by the Government that there will be a 12-week consultation on footway parking in the summer which doesn't quite match the headline suggesting that something is actually being done - "Transport Secretary acts to make pavements safer for pedestrians"; I'm a cynic, but I hope this is the beginning of the end.

I've gone into detail before on the subject from a legal point of view and indeed offered views on how we've got here. I'm not going to go through the legals again and as for getting to where we are, it remains a combination of people not thinking of others when they park and a political decision not to deal with it is previously. So, fingers crossed.

When we look at the attitudes of some people, it's no small wonder when we see the "leadership" from motoring organisations. In response to the news, the AA said;

"An outright ban could lead to unintended consequences with parking chaos becoming more widespread. A better solution would be for councils to make a street-by-street assessment and where pavement parking could be allowed it be clearly marked and signed."

When the ban was being talked about at the end of last year, the RAC said;

"The issue of pavement parking is divisive, with motorists often left with little option but to park on the kerb on some narrower residential roads, to allow access for other cars and emergency services. But for many pedestrians including wheelchair users and those with visual impairments, these cars block vital paths, leaving them feeling isolated and unable to access services."

The statements are reflective of the attitudes I have experienced from people more generally in that most are mortified that they might be stopping disabled people from using the streets, but because of the need to get emergency vehicles through, they have no option but to park on the footway; it never seems to dawn on somebody that the solution might actually be for them to park somewhere else.

English traffic authorities outside of London and Exeter (which have general bans) have the powers to ban footway parking, but in an echo of the AA's position, they effectively have to review this on a street by street basis and cover a ban with a traffic order such as can be seen in parts of Stevenage;

A ban using current powers requires the entry and exit from an area to be clearly signed (above) and for repeater signs to be provided within the area (below);

This is the general UK approach to our roads and streets in that you can do what you like unless it's banned. For example, we have a National Speed Limit, a 30mph speed limit in built up areas, but apart from that pretty much anything goes (in the general sense) unless we regulate with other speed limits, parking controls, one-way systems and so on. 

The problem with the approach is as well as costing money with design and implementation we also have to advertise proposals (and consult with reasonable governance) and if this is in an area where many people park on the footway, it will turn into a populist "vote" in line with the way restrictions on the "freedom" to drive often court controversy.

The good thing about a national ban is that immediately the tables are turned and people now have to confront their priorities. In London, the footway parking ban has exemptions where a borough, The City and TfL can mark and sign an area for footway parking. In theory, the marking should be the footway and carriageway (to mark the bay - it can be fully on the footway) and the signage has to mark the start and end of a run of bays.

In practice, the marking and signing of bays is very lax and in some areas, footway parking is simply tolerated. There is no requirement for a traffic order to allow it, although there should be a formal decision to designate footway parking. In my local authority days there was at one point a list of "exempted" streets and even when it was done more professionally, decisions were made at delegated officer level which made it easy for politicians to push for it, but not take responsibility. 

At one point, the function was under my responsibility - I did allow it in designs a few times, but these were always in locations where wide verges were tarmacked over and where the general footway area wasn't impacted. They were also for bus stop accessibility schemes where I needed to get cars out of the way for bus stops and not maintaining parking wasn't politically possible (of course, it doesn't make it right!)

I'd like to see a complete ban, but my feeling is that we will probably end up with the London model. I would like to see traffic orders being required to permit footway parking because at least there is a formal process which will be easier to challenge that some of London's murky practices. A process which requires a level of formality might mean that people have to design the footway parking scheme and therefore become open to scrutiny with their choices - and let's face it, the principal choice being made is that of available width.

A very common footway width is 1.8m which I assume has it's roots in imperial antiquity and indeed the guidance on width from an accessibility point of view is quite old - Inclusive Mobility. For a wheelchair user and an ambulant person walking side by side, Inclusive Mobility suggests 1.5m as the minimum. Side by side is important because walking is often a social activity and given that people use wheelchairs it is right that we ensure social interaction by providing space. 

Of course, in the real world, we have things on the street such as lighting columns, occasional overhanging hedges and indeed wing mirrors from parked vehicles and so 1.5m is too narrow and 1.8m gives a bit of buffer space. In fact for lightly used footways, 2m is probably the reasonable minimum to provide - it's certainly the recommended width in Manual for Streets with additional width space for other street activities take place;

Given that quite a lot of footway parking takes place on tight residential streets which weren't designed for lots of car parking, a 2m footway being our reasonable basic provision for low pedestrian flows frankly blows most footway parking out of the water. The photograph below is a street in Cambridge which is pretty typical - here, bays are marked to try and regiment parking which is partially on the footway to keep a clear space through the middle for traffic to pass.

This is head in the sand stuff because the footways aren't even 2m wide and so we end up perhaps with a usable footway of just over 1m - that is not conducive to social walking and it's questionable whether or not wheelchair or mobility scooter users will actually get past - and this is an arrangement which has been designed. I'm afraid the answer here is parking in the carriageway on one side (I'll come back to this later).

In most areas, footway parking enforcement is a police responsibility and with a few noble exceptions, it is roundly tolerated and indeed encouraged to "keep the road clear". When enforcement takes place, it's when there is an obstruction and often only on complaint that proactive enforcement. One persons "you can squeeze through" is another's access prevent and why should walking be about squeezing through all the time? Walking should be attractive, easy, accessible and enabled.

When pedestrian flows start to get higher, we are no longer looking at the basic space needed to walk down the street, we are into comfort levels. For a given width, there's a "comfortable" capacity and as things get busier, it becomes less comfortable. Perhaps crowding means some people step into the carriageway - it's a common sight by schools and so footway parking can take an otherwise comfortable situation and degrade its quality.

Going back to the example from Cambridge. There will be some thinking that it is very easy for me to suggest taking away half of the parking capacity of the street - where will people park - other streets might be equally filled up. Well yes, it is very easy for me to say and we need more people saying it. Footway parking is a symptom of our car-sick approach to spacial and transport planning. 

We need to change how our streets and urban places operate so people don't need so many cars and as a long term plan, we can get cars off the footway and then off the streets completely and that is, I'm afraid why I am cynical. I'm not seeing any leadership from government on this and so local authorities need to be bold. The ones that are bold are already changing streets, so perhaps a footway parking ban might wake a few more up.

Oh, and as a parting shot, I normally go on about the Dutch approach and in urban places, they are obviously getting the problem sorted. In less urban places, it hasn't been fully cracked as yet!

Sunday, 8 March 2020

Beyond the Bicycle: Room For Manoeuvre

As regular readers will know, one of my cycles is a Christiania box tricycle. Acquiring it has taught me quite a bit about how different cycles handle, but of course there's so many configurations out there.

My tricycle is known as a "tadpole" because it has two wheels at the front and one at the back - a fat body and a tail like a tadpole! The braking system consists of a rear coaster brake (aka a back pedal brake) and a pair of disc brakes on the front which are operated by a standard lever. The front brakes can also be held on with the press of a button to act as a handbrake to stop the cycle rolling off.

In terms of steering, there is a handle on the box and the box pivots above the axle connecting the front wheels. To turn left, one pushes the handle on the box to the right which is completely different to a standard cycle.

Handling is completely different to a two-wheeled cycle (and two-wheeled cycles all handle in their own ways). For a start, you are now under the control of the crossfall of the surface you are riding on - this means a slope sideways compared to the line of travel. 

We need crossfalls to make sure a surface sheds water, but as a tricycle rider a steep crossfall will mean you're having to lean into the slope (so if the crossfall sheds water to your left, you'll lean to the right) and when you are in motion, it will tend to pull you to the low side. If a road has a camber, it can mean that you'll stay towards the centre where the slope isn't too steep.

As you can see in the image above, as the crossfall increases, the action of the centre of gravity of shifts to the low side of the cycle and this pulls it towards the low spot - the steeper it is the more pronounced the pull and so at speed this can create a safety risk. There's of course complications with the load in the box, the weight and height of the rider and so on but the point is that once the rider in on three wheels, the ability to stay vertical when the crossfall changes has gone.

The third image (1 in 12) is at the steeper end of the slope for a dropped kerb. It very common for dropped kerbs to be used to transition between the carriageways and cycle tracks (often shared use). On a 2-wheel cycle, the change from the flattish crossfall to a steeper cross fall is generally easy to negotiate; with three wheels, the cycle is tipped and so as a rider, you have to make the transition more slowly and lean into the the change. With the example above, the cycle is coming towards us and so the rider will be leaning to our right.

The image above is pretty common layout and so in order to move from the carriageway to the shared-use cycle track, the rider will push the handle on the box to the right. As the left wheel goes over the kerb, the whole cycle starts to tilt to the right and the rider leans left to compensate for the shift. The right hand wheel goes over the kerb just before the rear wheel and to the whole tricycle is now tilting to the right. Immediately, the tilt reduces as the tricycle goes up the sloping side of the dropped kerb to join the path (below).

It's easier to show you how this works rather than describe or draw it because as one becomes proficient, one anticipates what is happening and one moves in the saddle to compensate for the shifting forces. 

However, this kind of transition cannot easily be performed at speed such is the risk of tipping over because the turn (left in this case) coupled with being tipped to the right both force the rider to the right. If one doesn't compensate for the two, then one is tipped off and into the road.

The photograph below shows how transitions should be done to make it safe for tricycles in that it is a slope along the line of travel rather than across the line of travel (ignoring the horrible cycle lane).

So the principles here are avoiding steep crossfalls and not mixing changes in crossfall with having to turn. For a really interesting experience, some of the bus stop bypasses on CS2 in Whitechapel bring all sorts of movements into play in a very short distance and there is one site in particular which always catches me out;

The red arrows show the crossfall towards some road gullies. As one cycles along, the crossfall is to the left. As one passes the first gully, the cycle track then bends left at the start of the bypass and so one will tend to lean left to counteract the forces pushing out to the right. However, in a very short distance, the crossfall switches to the right as the cycle track bends to the right. The problem is, the tricycle tilts to the right, but unless one corrects shifts the lean from the left to the right quick enough, one risks falling off to the left.

Speed of course is another factor. At very low speeds, the tricycle can be turned very sharply. So in the case of turning through 90°, doing so at a very low speed allows precise positioning, even if the crossfall isn't desirable.

The photo above was taken with the camera level. We were coming out of the retail park onto a shared use path which had dropped kerbs over the site access. The turn was sharp and so with the tilt of the dropped kerb I would have to lean away from the slope (towards the bush) otherwise the tricycle would tip into the road. This is the opposite of what I said above and so shows the difference in handling at low speed and higher speeds (and this makes it really tricky to explain).

The cruising speed for the tricycle is around about 12mph (20km/h). It's slower uphill and faster downhill which brings more dynamics. The tricycle weighs about 35kg, can carry a load of up to 100kg plus the rider. It actually handles a little better with some load. Whether or not it is loaded, the tricycle takes effort to get going and it takes a bit of distance to stop.

I also find it more stable when I'm pedalling or braking (using the pedal brake) because I am braced against the pedals. If I've spun out on the pedals (going downhill) I have to switch to touching the rear brake a bit to stay braced. Under no circumstances can I use the front brake at speed because it forces the weight forward and the steering becomes twitchy - I need to slow with the rear brake and use the front brakes for a stop as the speed drops right off.

Going faster means that I need to keep further away from kerbs (whether an upstand or a drop next to me) to allow a bit of wobble room. Like any other cycle, I'll be anticipating what is going on and making corrections for speed and positioning of the tricycle itself as well as my body position.  I have to try and spot potholes a long way ahead because I'm thinking of missing them with three wheels which are not in line. I'm now proficient to the point where I can go reasonably quickly around gentle corners by leaning into them and if I'm showing off, I can do so by lifting my outside wheel off the ground!

It's taken me quite a lot of words and some images to try and explain how my tricycle handles. It is completely different to my main two-wheel cycle and that in turn is different to my folding cycle. Different riding positions, centres of gravity, wheel sizes and so on. On one of my Netherlands trips, I rode a large bakfiets which has different handling characteristics again;

While it was easier to cope with changes in crossfall, the steering on a backfiets is initially unexpected. A standard cycle has the handlebars over the front wheel and it's pretty intuitive. A bakfiets has the handlebars in the centre of the cycle (or a touch further back) and they're connected by control rods to the front wheel. When turning, you have to start a touch before you would with a standard cycle because the front wheel is much further forward. It doesn't take long to get used to it, but it is different to a standard cycle.

Every configuration is a bit different. We might be towing a trailer which changes how a cycle feels. A tandem has two (or more) people adjusting their positioning. There are side by side tandems, recumbents, tandems with one rider upright and the other recumbent, all sorts of cargo cycles and many others, so how can designers accommodate them all?

One way to check a design is using swept path analysis. In my day job, I use AutoCAD which has swept path analysis for all sorts of vehicles. In short, I can design a layout and drive little cars, lorries and buses around on the screen to check it works. It's very motor vehicle based and the whole dynamic of people leaning can't be replicated, but someone cleverer than me has had a go to replicate various types of cycle which give an idea of the space needed;

The image above shows the approximate space needed to perform a U-turn with different configurations at a relatively slow speed. The Design Cycle is taken from the Design Manual for Roads & Bridges standard CD195 "Designing for Cycle Traffic" which has commentary on the space needed for people cycling in a fair bit of detail. The Design Cycle is an all-encompassing configuration which can be used as a proxy - if it works on a layout, then so will most cycles. 

Swept path analysis will show that as the speed increases, more space is needed to change direction and so a tight layout with tight turns will soon show up as needing people to travel slowly, whereas more space and gentle curves will show that people can cycle at a decent speed (which is the point of transport cycling).

The clever engineers at Sustrans are doing even better things with other software which has included allowances for rider lean and real-world testing of different cycles. Hopefully there will be a commercial release before long and with any luck, other providers will see the value in tools for cycling infrastructure design. What using the Design Cycle does confirm, however, is that staggered barriers are impossible to pass;

As you can see from the photograph above, there's no way I'm going to be able to turn round this barrier and across that crossing.

With the Autotrack model, I have played around with the Christiania model quite a bit and it's pretty accurate, but it can't replicate the effetcs of crossfalls and gradients so experience needs to play a part. My message to engineers is they really need to get some experience of riding some different configurations of cycle. 

I know it's easier said than done and so there are a few of us thinking how we might be able to facilitate the experience as some continuing professional development. Beyond that, there are plenty of people on social media with different types of cycle - ask them how their machines handle and what helps or hinders them.

Saturday, 29 February 2020

Country Life

I realise I spend a fair bit of time writing about urban cycling infrastructure and so this week I thought it was time to talk about the rural experience.

I think there are three strands to this; cycling within villages, cycling between villages and towns (or other villages) and what to do with motor traffic.

The UK has developed an extensive network of high speed roads with many bypassing towns and villages, but what we haven't done, is to go back into those towns and villages to return the space to people and nor have we reconnected these places for cycling. So, we end up seeing both the main roads and the towns/ villages full of traffic. We also have parts of the country which haven't been so touched by high speed road building and so even relatively small roads are busy with fast moving motor traffic.

The effect of this, together with poor bus services and a lack of rail, means that lots of people living in rural places have to drive if they want to get anywhere and if they have no access to a car, they are pretty much left high and dry or reliant on other people. Of course, it doesn't have to be this way if we copy the experience from the other side of the North Sea.

The Dutch have grasped cycling provision for rural areas and like urban areas, they look to provide separate cycling and driving networks. Where they come close is along the regional roads which are similar to UK single-carriageway A-roads and which are still used for long-distance traffic.

Not all national roads have cycling infrastructure associated with them of course, it's just that they happen to coincide from time to time such as here on the N290 north of Hulst in South Zeeland;

In this particular case, as one heads south to the town of Hulst, the cycle track peels away from the N290 and provides a direct link to the town centre which changes from a cycle track to simply mixing with traffic on quiet streets. The town centre probably has too much motor traffic, but speeds are slow and the town is extensively filtered so it is all managed.

To the north, the cycle track peels away from the N290 as it bypasses the village of Terhole. As the road bypasses Hulst and Terhole, it takes the longer route and so cycling between the destinations is shorter.

Within the village limits, the cycle track continues for a while (above) until it's safe to cycle on the main village street (below);

Of course, there is a risk that in the event the N290 is congested, then people might be tempted to cut through the village and so the road is narrow and traffic calmed to try and make it less attractive and to be honest, we are well away from any large towns so congestion isn't an issue.

To the northwest of Terhole, there are other villages which are connected to the N290 by another road. Because the road provides a connection and the design speed is 50mph, there's a separate cycle track.

As with Terhole, the route changes as it enters the village with the cycle track going some distance before people are returned to cycle on the road where the speed limit drops to 30mph such as in Vogelwaarde;

This time, the traffic calming is a little more engineered, but the space needed for cycling is clearly shown. Only at the village core do things change again with the use of imprinted asphalt and a narrower road.

North again and the cycle track reappears before the edge of the village and the whole logical approach continues again and again;

Perhaps the villages don't always feel completely safe because you are mixing with traffic, but in fact there often isn't space to keep cycle tracks going (or there's too much car parking taking up the space in some cases), but the protection is absolutely needed and provided along the fast roads.

It's not all the same of course, there are sometimes just general country lanes without separate cycle tracks and like the UK, people are concerned about speeding drivers;

The difference is that these Dutch country lanes are being used to access farms and small groups of houses rather than being a main road to anywhere - that's what the regional roads are for and on the whole, access to this small country lanes is by the people who need to be there (that is not to say safety improvements couldn't be made).

Sometimes there will be some rural modal filtering because of the risk of a country lane being a short cut;

The photograph is just on the edge of Hengstdijk and it's essentially a road that motor traffic is banned from unless it's local access. The road itself is signposted as a route to be used for cycling rather than a parallel road which has no cycling provision and in fact, where cycling isn't permitted as a result because of mixing fast traffic with slower cycling. Even in a rural context, the roads system separates cycling from fast moving traffic which is a pillar of the Dutch approach.

There are different treatments across the Netherlands and different ways of laying things out, but the three principles are;

  • Long distance motor traffic is routed onto the national road network,
  • Cycling between towns and villages will be either on cycle tracks next to higher speed roads or genuinely quiet country lanes, but as a coherent and direct network,
  • Drivers who need to enter villages are invited to slow down and they expect people to be cycling.
Trying to make a network operate without those three principles will end up compromising the quality of provision for cycling to the point it fails. In fact, there is an argument that Vogelwaarde is a partial failure because people can drive through to get to other places perhaps too easily.

But this doesn't just apply to the Netherlands, a similar approach can be seen all across northern Europe (with varying degrees of success and deployment). The key is that cycle traffic has been planned for as a useful rural mode of transport and with the emerging popularity of e-cycles, there is the perfect storm of some pretty good infrastructure and the means to travel longer distances without a car.

Using Hulst as an example, somebody living in Hengstdijk (5 miles away as the crow flies) could easily cycle into town within 35 minutes and an e-cycle will knock more time off that. Driving will generally be about 20 minutes but destination parking is a pain that people cycling don't have to worry about.

How do we apply this to the UK? Well, we've got to copy the three principles above and for a large part of the country, this means we are going to have to build cycle tracks in the countryside to connect places together and this means acquiring land rather than trying to squeeze things in all the time which also ends up compromised. 

If the highway width is too narrow, then we acquire a strip of land. It might be on the other side of a hedgerow and in some cases, we might need to route our cycle track behind houses which are too close to the road to add a cycle track. We don't seem to have a problem with acquiring land for motorways after all. If you pick a small town and look at the villages which can be accessed within 5 to 10 miles (the further being e-cycle territory) it really shows the potential, but if you look at the roads, it shows you the task we have ahead.

Hulst has a population of about 27,500 people, the same as St Neots in Cambridgeshire. If we look at the places within 5 miles of the town centre we can get as far as Buckden (which I conveniently know quite well). However, to cycle from Buckden to St Neots it's either a direct 25 minutes along the A1 or an indirect 35 minutes through country lanes.

The former is on a narrow path, very close to a dual carriageway and when one reaches St Neots, the route in isn't a nice quiet direct link as with Hulst, it's sharing busy roads with protection having given up long before the town centre. 

The latter includes busy roads performing a connector function to other villages and a lovely section of country lane with the national speed limit - roadies cycling it on a sunny Sunday morning might be OK, but it's of no use to someone wanting to do some shopping in St Neots or someone wanting to catch the train. We might be managing the first principle with the A1, but we are roundly failing on the other two.

We have to look at this at the network level and we'll have to build cycle tracks, make people who wish to drive go round the long way (and some might then just cycle) and sometimes, we might need to build some roads but only as part of a coordinated approach which leads to the three principles being met.

Saturday, 22 February 2020

Chislehurst Crossing Challenge

The Chislehurst War Memorial junction in Bromley, Southeast London is a good example of a layout where traffic control design has just evolved over the years and people on foot have simply been ignored.

Local campaign group, the Ashfield Lane Road Safety Group, has been pushing to have pedestrian signals added to the junction, especially as it's a location crossed by local school children.

The junction is formed by the A222 Bromley Road/ Bromley Lane and the A208 Centre Common Road/ Royal Parade. Despite being A-roads, 3 of the arms are single traffic lane approaches with Bromley Lane being a two-lane approach;

The junction is skew - that is, the arms are not at 90° to each other, they form a shape like the flag of St. Andrew;

You might just notice the red lines on the aerial view above; that's me highlighting the position of the stop lines for traffic on the approaches to the junction. The narrow traffic lanes and fairly tight corners means that when large vehicles are turning, waiting drivers need to be set right back as the drivers of large vehicles need the full width of the road to turn and over quite a distance.

As the network, there's other, smaller roads further away from the junction which look to me that they will have a rat-running problem with some people driving to avoid the junction. The junction itself sits within the north of the pair of Chislehurst Commons which may well explain which the junction has never been enlarged - there's a local act of Parliament giving local management powers to a board of trustees.

Anyway, back to the junction. The method of control is quite simple with two traffic stages running with east-west traffic together and north-south traffic running together. At the end of each stage there will be an all red period to allow right turners to clear the junction before the next one comes in. For people wanting to cross the road, they either have to fine a gap in flowing traffic or to try and cross in the all red period.

So what is the solution for foot traffic? The narrow roads, limited space and the fact the junction is in the common means that it won't be widened and so the solution is to add a third traffic stage which would run an all-round green man.

The image above shows roughly where I'd look to place the pedestrian crossings (red) to keep them on the desire line as far as possible, but away from the corners and turning traffic as well as where tactile paving would be a pain to detail. The blue crossing is an optional diagonal crossing on the shortest diagonal. The staging diagram would be as follows;

The diagonal arm has a 12m crossing distance and the longest side road crossing is Bromley Lane at 9 metres (the eastern arm of the junction in the image above). Crossing distance is important as it informs the time people have to cross and from a traffic signals design point of view there will be pressure to keep delay to motor traffic to a minimum, not only because the politics of all of this stuff, but also because delayed drivers will rat-run more.

There is a compelling argument to look at these issues in an holistic way at the network level (into which we bring cycling for transport), but in the short term, it would be relatively straight-forward to add a pedestrian stage, even if the diagonal were omitted, because it should be a basic level of human decency to provide crossings at signalised junctions.

I hope the local road safety group can push the council to work with Transport for London (the signals authority) to get green men added to this junction and hopefully this post will help explain what needs to happen.