Silvertown: Another Road To Nowhere?

The Mayor of London often talks about the challenges the Capital faces with air pollution and he backs a £1b tunnel in East London. In this week's guest blog post the Silvertown Mole goes digging in the SIlvertown dirt so you don't have to.

What is the Silvertown Tunnel?

It's a proposed £1bn twin-bore, four lane tunnel between the Greenwich Peninsula & Silvertown. But, effectively, it's a doubling of the existing Blackwall Tunnel; or you could see it as a massively expensive road widening scheme, widening the Blackwall Tunnel from four lanes to eight.

What's the point of widening the road at Blackwall from four lanes to eight in the most expensive place possible when the approach road to the South has only six lanes?
Good question. Unless TfL have some massive road widening project on the A12 they haven't told us about, at least two lanes worth of this new capacity will never be used. (And, as it turns out, even using the other two lanes fully makes things worse..)

So, what's the purpose of the tunnel?

Fourfold, according to TfL;

1) To relieve congestion at the Blackwall Tunnel, 

2) To provide an alternative option ('resilience') when one of the Blackwall bores is closed 

3) To enable future economic growth in East London

4) To enable new cross-river bus routes. It also aims to do all of this without a significant increase in traffic or pollution. 

Will it achieve these objectives?

It will likely achieve the first two.

TfL aim to double traffic capacity across the river, but not allow any actual increase in traffic. 

Won't traffic increase sharply when drivers no longer have to queue?

TfL will toll both the Blackwall and the Silvertown Tunnel. In their estimation, the level of the toll they propose will almost exactly compensate for the removal of queues. (see http://content.tfl.gov.uk/st-silvertown-traffic-forecasting-report.pdf P33); and with the tolls in place, they estimate that instead of 100K vehicles a day taking the Blackwall tunnel 75K will take Blackwall and 25K Silvertown. 

So, effectively, instead of drivers at peak hours waiting in a queue, nobody will queue and drivers at all times will pay a toll? 

That's basically it. 'In terms of capacity: The Silvertown Project adds 100K vehicles/day of extra capacity to  Blackwall - but it only ever actually uses 10K of this extra capacity -  5K in the morning peak, and 5K in the evening peak (represented by the  green blocks above the black line in the images). (And, of course  similar congestion benefits could be achieved by using a smart toll to  redistribute these trips to times of day when Blackwall has excess  capacity - and one would save £1bn in the process).

Does the project do anything to support the Mayor's active travel priorities?

Not really. There's a proposal for a cross-river cycle bus, but historically, at the Dartford Tunnel, for example, these kinds of services have not been successful (http://blog.nationalarchives.gov.uk/blog/ill-fated-cycle-bus/). And they can't take cargo bikes, zero emissions logistics vehicles, etc. 

But the tunnel will enable new bus services?

Debatable. There are suggestions that the tunnel could enable new routes, but so far TfL only have user suggestions as to what these routes might be (https://consultations.tfl.gov.uk/rivercrossings/silvertown/#Further%20benefits) not data on actual demand. And there's only one bus through the Blackwall tunnel right now. Maybe delays reduce demand. Maybe there just isn't that much demand for short cross-river journeys at this point. TfL doesn't know, and they've only committed to research the question until the tunnel is nearly built. 

So does the tunnel do anything at all for the Mayor's local air pollution reduction / carbon reduction priorities?

Nope. The project expects (at best) to maintain provision for existing levels of heavy motor traffic, and existing levels of pollution. At worst, it'll enable much more traffic & pollution. And then there's the pollution & carbon cost of building it. 

OK, so, at Silvertown, TfL are proposing building a new tunnel that's capable of carrying 100K vehicles a day, but that will only ever actually be used by 25K/day? How does that make sense?

Very good question.

Maybe, in future, traffic will increase due to growth in East London, and extra cross-river capacity will be needed? Shouldn't we provide for the future?

Well, perhaps. But the tunnel is being built on an explicit promise that traffic (and pollution) won't go up in the future, and that the toll will be used to hold it to existing levels. (https://consultations.tfl.gov.uk/rivercrossings/silvertown/#User) That promise was key to planning consent. And to the health of surrounding communities.

So, the tunnel can't enable growth in East London?

Not if growth implies increased traffic, & TfL holds to its promise not to let traffic & pollution increase.

Ok, so let's say we believe TfL's promise that traffic levels won't be allowed to increase. Why, then, are they building this tunnel with capacity of 100K/day to take no more than 25K vehicles/day? Isn't there a cheaper option?

Well, yes. TfL could build a single-bore two lane tunnel with a bike & pedestrian pathway (and emergency escape) under the roadway. This will certainly provide all the extra capacity they think they need (for example, the single-bore Rotherhithe Tunnel carries 45K vehicles/day). 

So would this single-bore option provide all the benefits of TfL's Silvertown Tunnel?

Pretty much, in terms of congestion & resilience. They might need to run this tunnel in one (reversible, according to peak) direction only for motor vehicles, for safety reasons, - but given that congestion in the Blackwall tunnel is tidal - northbound in the morning and southbound in the evening that won't impact congestion benefits. 

It would require running any new buses mostly through the Blackwall Tunnel. But that's where most demand appears to be anyway. And, of course it would provide a new cycling/walking/zero emission logistics route that the existing proposal doesn't. 

Is there demand here for a cycle/pedestrian route?

Good question. TfL analysed adding a cycle/pedestrian tunnel in their initial optioneering & decided it wasn't financially viable. But, since then, they've changed the way they analyse cycle demand, bringing in electric bikes, cargo bikes etc - but no-one has done a new analysis.

How much would this option save?

Maybe £300m, compared to the existing proposal. The single bore would need to be a little wider than one of the individual bores in the existing proposal.

Did TfL ever consider/evaluate this option? 

No. 

Why not?

Your guess is as good as mine. 

Ok. Let's go back to that toll. Couldn't TfL reduce congestion and queuing just by smart- tolling Blackwall?

Yes. But that wouldn't provide the resilience benefits of Silvertown.

Is resilience, alone, worth £1bn?

Good question. And one that, to the best of my knowledge, TfL haven't answered.

What happens if TfL have got their calculations wrong, and the toll isn't high enough to balance out the induced traffic from creation of extra capacity and removal of queues?

Traffic (and pollution) will increase. 

What about the mitigation strategy in the Development Consent Order (DCO)?

Good point. For six years after the tunnel opens, TfL has to monitor environmental impacts, in consultation with the Silvertown Tunnel Implementation Group, and recommend mitigation strategies.

So, TfL will increase the toll, and traffic and pollution won't go up?

Well, it depends on the Mayor. TfL is obliged to investigate, and consult, and propose mitigation strategies, but according to the DCO (https://infrastructure.planninginspectorate.gov.uk/wp-content/ipc/uploads/projects/TR010021/TR010021-001716-3.1%20Draft%20DCO%20R6%20pdf.pdf) page 41, item 54,  the final decision on toll levels is the Mayor's.

So, in theory a future Mayor could remove the Silvertown and Blackwall tolls entirely?

Absolutely. At any time. They'd need to consult the public on the proposal, but it's an executive decision for the Mayor.

Would this be likely?

Well, it might not be popular with those living near the tunnel, but it might be very popular with drivers. And it's the kind of pre-election commitment mayors like to make. Like the removal of the Congestion Charge Western Extension. 

So what happens if the tunnel is built and the toll is not increased in line with inflation, or reduced, or removed?

Traffic and pollution will increase. There won't be new queues at the tunnel (because capacity has been increased so much) - instead we'll see new traffic, congestion, and pollution in the surrounding area, as nearby roads and approach roads hit their own capacity. 

Has TfL modelled what will happen if the tunnel is built and the toll is reduced or removed? 

Yes. At least in terms of traffic, but not in terms of air quality It's here (http://content.tfl.gov.uk/st-silvertown-traffic-forecasting-report.pdf).  Look at page 52 onwards. The maps on page 58, 61, 63 give a good idea of what will happen to traffic (and air quality) if the toll is removed. 

Their conclusion (P79): The option of introducing the Silvertown Tunnel without road user charging has some considerable negative impacts on the surrounding network, notably in Greenwich in the evening peak, and the impact over the three host boroughs as a whole mounts to no net improvement. While the no charge scenario shows improved resilience compared to the reference case, the high levels of traffic forecast throughout the day would in effect mean that the tunnels would struggle to recover from an unplanned incident.

So if a future Mayor decides to remove the toll, the £1bn Silvertown tunnel will bring exactly no benefit whatsoever?

Correct. TfL's words, not mine. Though it will bring lots of new traffic (a back-of-the-envelope calculation indicates about 15-20K new vehicles driving through the tunnel and surrounding area), congestion, and air pollution. 

Ok, so what are the conclusions here?

Depends on your priorities. But:

1) Whether they support a new crossing at Silvertown or not, nobody should be supporting the scheme TfL are proposing. There's at least one much cheaper (probably about £300m cheaper..) option that has essentially the same outcomes in terms of congestion, resilience & new bus options - and better active travel benefits. And it'll be East Londoners who end up paying for all the excess road capacity that's being created in TfL's scheme.

2) If you support any new scheme here, you've got to believe that the resilience benefits alone are worth the £700m+ cost (because the congestion benefits can be mostly achieved with tolls) - and that it's more useful to spend at least £700m on this than on schemes that might, say, enable active travel, or zero emissions logistics. 

3) If you think that the scheme will contribute to growth in East London by taking new growth-related traffic then you've got to also accept that it can only do this if TfL breaks the promise it has made, and allows traffic, pollution and area-wide congestion to increase, and local communities to suffer. 

4) If you think that any version of the Silvertown Tunnel can be built without a sharp increase in local traffic, pollution, and congestion, then you've got to also believe that all future Mayors will keep the toll high enough to restrict traffic, despite the electoral temptations of big giveaways to drivers..

5) If you think London's priorities should be 1) acting on the urgent climate crisis, and 2) air pollution threats to public health - then you should not support this scheme. Instead, a smart toll on Blackwall (or, better, on all of London's roads..) should be used to reduce congestion at peak, and the money used to enable public transport & active travel. 

Infrastructure Creates Culture

We often hear about cycling culture which in itself sets up the mode as something other people do, yet the tenuous idea still exists.

This subject has been written about by others and I'm not even sure I can bring anything new to the discussion, other than an engineer's eye and my own prejudices I guess. 

I am approaching my 23rd year as a post-graduate civil engineer and one way or another, I have been involved in building stuff. The reason we build stuff is for people to use it and hopefully it will make people's lives better.

My first job was with a utilities contractor where we basically laid telecoms ducts in the street, constructed chambers and ran the odd armoured cable to houses and businesses. Without the construction of this stuff, people wouldn't have had telephone services and so until we connected people, they weren't involved in telephone culture.

Fast forward to 2018 and the amount of data being carried through wires and cables in 100mm plastic tubes in the ground is astonishing and one could (I suggest) sensibly argue that we have a pretty mature communications culture. Unless people had spent the last several decades digging trenches in streets, we wouldn't have this "culture".

That all being the case, given the UK's tiny mode share for cycling, why would anyone talk about a cycling culture? Apart from some specific locations, cycling is seen as a weird way to travel and so whenever something is proposed which would enable cycling, we are often told that it's a waste of money because nobody cycles. 

We've heard the saying that nobody can see the demand for a bridge by the number of people swimming across the river and this holds for transport more generally. The data is there, the examples are there - unless we build for cycling, people won't do it and then we cannot claim to have the culture. In fact, I find the whole culture discussion to be an excuse not to confront the infrastructure issue.

Like the digital pulses through the glass and copper cables, unless the infrastructure is provided, the flow along it is not enabled. Telecommunications rely on a network of connections and cycling is the same. London's Embankment cycleway is (roughly speaking) carrying a quarter of wheeled traffic in a quarter of the space taken by asphalt surfacing, but we are already seeing congestion at junctions which will always be the weak point in any system of flow. 

Cycling 'culture'

It is a good problem to have to a certain extent, but when one considers the parallel routes which don't provide any meaningful protection from traffic, cycle trips are nowhere near the same. In other words, people will be diverting to use the Embankment cycleway, even if it makes their journey longer. The cycling culture of central London is concentrated to a few corridors and the more progressive boroughs. The rest of the Capital has a similar mode share as the rest of the UK. 

We are also too obsessed with routes. It is difficult because one has to start somewhere and the classic approach has been to build routes and this perhaps shows some obsession with thinking too much about commuting or leisure. By this I mean, we  built routes into town centres for commuting, but unless someone lives very close to the route, they will have to get to it. For leisure, we have routes which may go through lovely parks and open spaces, but they are no use for transport.

With telecommunications networks, we generally don't rely on single routes to take all of our signals because in the event of damage or another failure, we have taken a big hit on our capacity. With a proper network, we have the ability to cope with a failure by rerouting the data flow a different way or coping with a reduced flow.

One route for cycling, even though it isn't great

quality is a nightmare to go around when it is

closed - a 500m diversion in this case.

This is resilience. Even better than coping with a failure, we can build in adaptability which means that a temporary fix can maintain most of the flow or we might undertake repairs when demand is lower.

A cycling culture is created where there are sufficient main roads and streets with protected layouts connected with each other and genuinely quiet residential and commercial streets. A cycling culture is created where this network does not rely on a single route and is sufficiently resilient to provide alternatives for people which are at least as convenient to pass the disruption.

A cycling culture is where people planning roadworks or other events have properly taken people cycling into account and they have alternative ways of getting people around the works in safety and comfort. Unless the basics are dealt with (and interventions don't need to be pretty; this can come after review and tweaking), then we won't see the indicators of a cycling culture such as people of all ages, women, children, disabled people, ordinary clothes for short trips, cargocycles, adapted cycles and so on.

So, for me at least, I will continue to bang on about throwing the kerbs, asphalt, traffic signals and bollards around as it is the correct mix of these elements in the right place that gives us a cycling culture.

The Long Walk Home

It's Living Streets' National Walking Month and to celebrate, I took a walk home from work.

As most following this blog will know, my usual commute is by cycle and at around 3.5 miles, it's a perfect distance - far enough to be able to zone out from the stresses of the day, but short enough to avoid getting too warm. Plus, the journey time reliability is way better than car or bus.

I chose to walk home because I wouldn't have any time constraints and it would just allow me to wander around, rather than sticking to my usual cycling route. As it turned out I walked 5.3 miles which was a bit more direct than it felt, but it turned out to be an interesting two-and-a-half hours.

In order to walk home, I had to get to work. I missed my usual direct bus which meant getting one which went all round the houses;

So, I'm talking about suburbia here and although I'm based in Outer London, the things that I saw can be found anywhere in the country.

I tweeted my progress and so most of the rest of this post will be those tweets - some will have more explanation (and they're screen grabs because Blogger hasn't got an embed tool). So, here we go;

 This is not unusual, many town centres have dual carriageways skirting them with limited crossing opportunities and plenty of guardrail to keep people out of the road.

When you do get a surface-level crossing, it's never direct because that would remove motor traffic capacity. 

The reason I knew this was working for a BT contractor in the mid-1990's. There is a whole different language out there! 

It was just nice to see the clutter out of the way. Where things are placed kerbside, they will often have a half-a-metre set-back from the kerb (otherwise they'll be clipped) and so that's even less footway space. A great deal of footway clutter is there because of the need to regulate driving. 

Suburban places are often crossed by railways, large roads and rivers which means crossing opportunities are limited and so they funnel all transport modes together. Sometimes we get footbridges which are often a remnant of an historic right of way or public footpath. They can be secluded and lonely. This one just had steps, so it's not accessible to all.

There are countless railway bridges dating from the 1950s (and before). Their construction often means that the footways cannot take any heavy loads and so the risk of a lorry being driven onto the footway presents a real risk of damage or partial collapse (called Accidental Wheel Loading); plus with brick parapets (the walls), they cannot take an impact from a heavy vehicle.

Rail crashes such as Great Heck and Oxshott showed the impacts of vehicles being driven (or crashed) onto railway lines. The type of temporary barrier show here (MASS) are designed to stop people driving onto the footway and for lorries, the shape redirects the line of travel back onto the road.

Just Google "in and out driveways" or "carriage drives and you'll see that this style of carcentric front garden design is a suburban aspiration. Throw in high walls and electric gates and you can have your very own fortress - an Englishman's home is his castle after all.

It's easy to sneer, but what we have here is a design which makes the street feel more like a canyon to those walking and with a lack of intervisibility between the occupants driving out and people walking along the footway.

A curiously clumsy sign which essentially shows an overnight area-wide parking ban for lorries and buses. This is often in place over entire areas. The curious timings were a quirk of the regulations which meant that timings couldn't straddle midnight. I can't recall if this has changed in the current rules.

This area has no modal filtering and there are limited crossing points over the railways. This means that driving is as easy as walking for short trips and so people are "happy" to sit in traffic jams. This street is also a bus route so you'll sit in the same traffic jam on the bus. A huge challenge for enabling active travel.

In London, we have the London Plan which amongst other things has a minimum cycle parking standard for new developments. Here, Tesco pays lip service with unusable cycle parking while customers block a layby which is meant to be for loading.

I'm a big fan of rain gardens which are features designed to slow the progression of rainfall from the sky to the sewer. The castellated kerb edge allows water to drain into the planting bed where it will be used by the plants, soak into the ground and if really needed, overflow into the surface water sewer. 

This was the same bridge I was stuck in a traffic jam on the bus from the morning. At peak times it is stuffed, off peak it is quieter, but with speeding drivers.

I took this photo 400m from a railway station, but because of poor bus connectivity, the estate has a Public Transport Accessibility Level of 2 (poor) and so we have lots of cars which need to be stored. On the footway as usual. For those in London, TfL has mapped PTAL for the whole capital.

This is actually very clever. Pioneered by National Grid Gas (now Cadent), they have lorry mounted machines which can cut a core through the road surface and then vacuum the material underneath to get at a gas pipe for repairs. Afterwards, the material is replaced and the original core is used as a plug for the road surface which is sealed into place.

This system reduces noise, vibration and waste materials and is safer for operatives who don't need to physically dig around live services.

The large roads around towns and cities are huge barriers to walking and crossing points are sporadic. Here, we have the solution which forces people to take a long diversion with switchback ramps or steps.

Permit Parking Areas mean that we only need entry/ exit signs and some repeater signs for a parking scheme. The only paint needed will be double yellow lines where you cannot park. A lighter touch for self-contained estates and far less clutter.

Cul-de-sacs with open and accessible active travel links mean walking and cycling is quicker than having to drive the long way round.

Sadly benches are often taken out because of anti-social behaviour - in other words, people don't like younger people gathering at them. They are vital for those who want to walk, but need places to rest from time to time to enable it.

Parking and cars is a theme of my walk. This is the case almost everywhere in urban and especially suburban UK.

So there we have it, a snapshot of suburbia which I think you'd find pretty much anywhere. Walking should be the natural mode for short local trips, but in places dominated by car use and car parking, it always feels second best.