The tunnel London loves to hate is finally here. On Monday 7 April the new A1026 Silvertown Tunnel opened for business. One question remains: what’s it for?
The new tunnel crosses the Thames between North Greenwich and Silvertown - right beside the O2 Dome - linking the existing A102 Blackwall Tunnel Southern Approach with the Lower Lea Crossing, and in doing so providing a new way to cross the river near the chronically congested Blackwall Tunnels.
To say this is a rare event in London would be an understatement. For decades the city has been consistently working to reduce car use. Until the Silvertown Tunnel opened, the body that built it - Transport for London, which oversees all public transport in the capital along with its major road network - had built just one road in its 25 year history, a mile-long 30mph single carriageway bypass called the Coulsdon Relief Road. The construction of a £2bn dual carriageway tunnel is decidedly out of character.
Besides, any new road in London will be controversial. Londoners have fought roadbuilding tooth and nail since the late 1960s, but even in that context, the Silvertown Tunnel is remarkable for the universal opposition it faced. Usually some groups dislike a new infrastructure project while others are in favour, but somehow this is a road that absolutely nobody seems to like. So why did TfL do it?
Most of the debate - especially the attention-grabbing hot takes being thrown around on social media - feeds off people’s own ideas about what it’s for, perhaps because TfL and the Mayor haven’t gone out of their way to explain it. Publicity refers to faster cross-river journeys and better public transport links, neither of which offers enough detail to explain why it was built.
We’ll uncover the rationale for the Silvertown Tunnel in a moment. But before we do, perhaps we should explore some of the things that are making people so angry.
Problem: air quality
The Mayor of London, Sadiq Khan, has made air quality a key plank of his work, to the extent that he wrote and published a whole book that frames it as a personal mission. It’s central to his policy platform.
No surprise, then, that people are asking why he has simultaneously overseen construction of a new road tunnel, which will increase road space for private motor traffic.
Isn’t that contrary to his stance on air quality? Doesn’t it fly in the face of his work on London’s Ultra Low Emission Zone? This is, after all, a project he inherited: when he was elected Mayor in 2016, work had yet to start. He could have binned it if he wanted, but he didn’t - in fact he has invested significant political capital in pushing it through in the face of opposition. The loudest and most persistent anti-tunnel campaigns all focussed on its potential to worsen air quality around the tunnel and its approaches.
Problem: active travel
Public transport and active travel (meaning walking and cycling) are central to TfL’s work. The Silvertown Tunnel does accommodate public transport; two of its four lanes are reserved for buses and heavy goods vehicles, a feature settled early in the design process, and new bus routes have been created that use it. But there is no provision for walking or cycling.
Well, that’s not entirely true. There is the Silvertown Cycle Shuttle, which takes cyclists across the Thames for free. It’s an electric bus route, running about every quarter of an hour, between stops on either side of the river.
Cycle campaigners are not impressed, and understandably so. There are already ways to cross the river by loading your bike onto some other form of transport. The Shuttle doesn’t greatly improve their options; indeed, if you wish to use it for a serious journey, the time taken to reach its terminus, wait for the next bus, ride across and then get moving again represent a significant amount of inconvenience. It’s fair to say that it will be unsurprising if the Shuttle fails to draw crowds.
A new tunnel was a chance to provide a route for cyclists to simply ride across - either by building a foot and cycle tunnel, or by closing the ancient and twisty northbound bore of the Blackwall Tunnel to motor traffic (something it’s never been well suited to carry) and repurposing it for active travel. The lack of provision, in other words, is seen as proof that the Silvertown Tunnel is a regressive project that’s all about private motoring.
Problem: bad design
The new tunnel arrives on the north bank of the Thames at a messy signalised roundabout. From there, all its onward connections are cumbersome. The main approach is the Lower Lea Crossing, a dual carriageway bridge over the mouth of the River Lea that had plenty of spare capacity, but journeys between the tunnel and the A13 or the Docklands all have to negotiate a busy roundabout and multiple sets of traffic lights.
If the new tunnel is to be used to its maximum effect, it needs to be quicker and more convenient than Blackwall for those journeys. But these design choices don’t seem to achieve that, presenting a risk that traffic will continue to prefer Blackwall. Equally, if Silvertown does attract intensive use, critics fear that its awkward approaches could be easily overwhelmed.
If you’re going to all the trouble of building a new mile-long tunnel under the Thames, the argument goes, it needs to be easier to reach than this.
Problem: it’s in the wrong place
East London only has so many river crossings for road traffic. There’s Tower Bridge, which is a historical monument with a weight limit, and the Rotherhithe Tunnel, which was designed for horse traffic and is narrow enough to be mistaken for one of those little pipes that hamsters run through. Then there’s Blackwall, and after that it’s eleven miles as the crow flies to Dartford where M25 traffic finds a way across.
In that eleven mile span there is only the Woolwich Free Ferry, which is fine as far as it goes but has extremely limited capacity.
Why, then, is this new river crossing right next door to Blackwall, leaving that eleven mile gap untouched? Wouldn’t it be better to have provided an option to cross in a new location, bringing those disparate districts on the north and south banks closer together?
Back in 2016 Transport for London actually consulted on three river crossings and at one stage thought it might build them all: they were Silvertown, Gallion’s Reach and Belvedere. But only Silvertown got any further. If you could only build one, why build it where a crossing already exists?
Problem: bus lanes
Those who are content to see more road capacity across the Thames are unhappy that the new road is 50% bus lane. Even though TfL has instituted new routes to make use of the tunnel, there are still only so many buses that come this way. Is it worth reserving so much valuable road space for them?
In truth these are not just bus lanes, they are open to heavy goods vehicles too, so it won’t only be buses using them. But even so, if you use the tunnel in these first days, there is plainly one lane in use and another seemingly empty, reserved for just the occasional bus.
If you are spending all this money to build a twin-bore tunnel, if you are going to all this trouble - don’t you want to make the available space work as hard as it possibly can?
Problem: tolls
This one is really simple. Blackwall used to be free. Now, to pay for the new tunnel, both are subject to a toll.
Motorists object to being charged to use an existing tunnel that has been free since 1897, and that is surely understandable. But there is also a question about whether the toll will push traffic away to other less suitable crossings - the Rotherhithe tunnel, perhaps, or Dartford where the toll is cheaper. None of the alternatives have capacity to spare.
Problem: cost
The Silvertown Tunnel comes with a price tag of £2bn. Public transport campaigners balk at the money that has been spent increasing capacity for motor traffic. Those happy with the new road space find it hard to believe so much money has been spent to provide so little new road and such limited connections on the north bank.
Active travel campaigners, meanwhile, can only look on and despair at how this sum for a single road project compares to the budget for cycling and walking improvements across the whole of London.
Everyone’s a critic
The list above is a mix of complaints from people with all sorts of differing ideas about transport in London. It’s probably worth acknowledging, before we even start looking at the reasons TfL built the Silvertown Tunnel, that some of them are contradictory.
You are, for example, either upset with the cost of the tunnel or with the tolls, but it’s hard to object to both. The tolls were introduced to pay for it, so while £2bn is a huge amount of money for TfL to spend on a new road, it was paid for by a loan that drivers will repay in years to come. It was never money that could have been spent instead on tube upgrades or cycle facilities, nor would the tunnel have ever been built if the tolls weren’t there.
Equally, those who object to the bus and HGV lanes are unlikely to be the same people who find the Cycle Shuttle inadequate.
Method in the madness
So why was it so important for an organisation that actively discourages travel by road, and a Mayor who is determined to tackle air pollution from motor vehicles, to face down opposition from every quarter and build a new road tunnel right next to an existing one?
The question can only be answered by finding the reasons it was built. For those, we will turn to the User Charging Assessment Framework, a document published late last year. It lists the project objectives and then summarises the forecasts that have been made for each one. (Its forecasts should be the most accurate available, because they take account of the exact toll charges which were only finalised recently.)
The following are the things that the Silvertown Tunnel was built to do. Right now, we only have TfL’s forecasts to measure them against, and it remains to be seen how the opening of the new tunnel will truly affect travel patterns, and indeed life, in East and South East London. But the forecasts do provide an answer to some of the complaints and concerns that are directed at it.
Objective 1. To improve the resilience of the river crossings in the highway network in east and southeast London to cope with planned and unplanned events and incidents
Objective 2. To improve road network performance of the Blackwall Tunnel and its approach roads
Objective 7. To achieve value for money and, through road user charging, to manage congestion
These three objectives are all about journey times. The Blackwall Tunnels have been the cause of chronic, unbearable congestion for many years, and fixing that problem is not simply about enabling more people to have nicer journeys by car. The lack of options for crossing the river in East London mean that Blackwall was one of the only ways for goods, services, buses and other essential traffic to get across the Thames. The fact that it was so unbelievably oversubscribed had become a limiting factor in the performance of the road network of the whole of East and South East London.
It’s not just about capacity, either. It’s about resilience. Blackwall’s northbound bore, opened in 1897, is tiny and has a number of sharp bends. That makes it prone to accidents, and accidents mean delays at best and tunnel fires at worst. When a vehicle arrives that is too high or wide to use it, the whole approach road has to be held while it is diverted off. The southbound bore is better but still has some restrictions. As a result, Blackwall was not just congested but also deeply unreliable; indeed TfL have stated before that the tunnels only operated “normally”, without an incident that required intervention or even temporary closure, on one day in every two weeks.
So is the tunnel in the wrong place? Well, it’s in the right place to solve the problems that TfL were trying to solve at the Blackwall Tunnel. The lack of river crossings elsewhere is a separate problem, and Silvertown was never meant to fix that. You could argue that if only one crossing could be built, it should have been elsewhere, but to do that, you would need to accept that Blackwall’s problems, with all their social and economic knock-on effects, would not have been addressed.
And that problem will be addressed: we can be pretty certain it will fix the lack of resilience at Blackwall. (Cherish this clear-cut answer, there’s precious few of them in this game.) It provides a second physical route each way, so if one tunnel is closed the other remains open, massively reducing the impact when something goes wrong.
TfL estimate that morning rush hour journeys in “normal” conditions will be at least 15 minutes faster, and time savings will be even greater than that when the tendency for Blackwall to be closed or disrupted is taken into account. Journey times will become predictable.
Traffic levels overall are expected to rise slightly - a 2% increase is forecast for the first year of operation, since the route will become more attractive. Research over the last couple of years, including consultation with motorists who use the tunnels, indicates that this time saving will be worth more than the cost of the toll, so most will calculate that it’s more worthwhile to pay it and drive through than to abandon their journey or divert to another route. The effect of the toll is mainly in capping the amount of additional traffic that would otherwise be generated.
The net result is that there is expected to be roughly the same amount of traffic as before, but now with 50% more capacity to cross the river and fewer disruptive incidents to hold it up.
If traffic levels do remain roughly static, then in normal use the Lower Lea Crossing and its roundabouts and traffic lights will only be handling about a third of the traffic volumes currently passing through Blackwall. In any case, Silvertown has just one general traffic lane in each direction, so the total traffic load it can feed into those approaches is limited and is much lower than Blackwall itself. When Blackwall has to be closed, however, and Silvertown is the only available route, you can expect long delays, since its one lane will be better than nothing but no substitute for three.
Because few people are forecast to be deterred by the tolls, only marginal increases in traffic are expected at other river crossings (1% each at Rotherhithe and Dartford). Meanwhile, significant improvements are expected on approach roads thanks to reduced congestion - particularly on notorious rat runs north of the Thames like Chrisp Street, which passes through residential and shopping districts and often carried significant amounts of traffic trying to avoid the queues for Blackwall.
Finally, it’s clear that active travel simply wasn’t an objective for the scheme. Whether it should have been is open to debate, but since resilience is central to the project, and that’s delivered by having two tunnels in each direction, there is no hope of closing one of the Blackwall bores for active travel use. Including a cycle crossing would therefore have required an extra tunnel bore - a significant extra cost that might have made the project untenable. That doesn’t excuse the absence of active travel provision but it perhaps explains why TfL came up with the Cycle Shuttle.
Objective 3. To support economic and population growth, in particular in east and southeast London by providing improved cross-river transport links
Blackwall offered no room for growth - indeed it had become a critical limiting factor on the ability of East and South East London to grow. Even a city that actively discourages motor traffic must accommodate a certain amount of it; as the city grows that amount will go up, at least a bit. In most of London the existing network will absorb that increase one way or another, but Blackwall was long past that point. It is a rare place where TfL concluded that London really did need at least some extra road space to support its spiralling population.
The reduction in congestion is predicted to total 9,800 hours a day for drivers and 2,800 hours a day for public transport users - time that can now be used productively instead of idling in traffic.
Perhaps more importantly, the tunnel will save 5,800 hours a day for commercial vehicles, principally by enabling direct journeys across the river. Until now, companies have had a logistical nightmare arranging their supply chains because East and South East London were effectively two separate worlds; without paying the Congestion Charge the nearest crossings open to HGVs were Dartford, Vauxhall or the Woolwich Ferry. That made business inefficient and introduced an unbelievable penalty in extra time and distance, not to mention the lorries thundering through other parts of London that shouldn’t need to be there.
Right now the number of lorries using the Silvertown Tunnel is relatively small, because supply chains have yet to adapt to it, but the benefit it will eventually provide could be considerable and widespread.
In this light the decision to reserve half the tunnel’s capacity for bus and HGV lanes can be understood. If TfL’s forecast is right, the tunnel’s two general traffic lanes will supply enough new capacity to cater for the current level of demand, which is capped by the toll. The bus and HGV lanes prioritise the traffic that TfL considers to be most critical - public transport and goods - and protects it from the effects of congestion. In turn London’s other river crossings and street network are protected from HGVs diverting long distances to cross the river elsewhere, as they do now, and supply chains are given the greatest possible guarantee of reliable journey times.
Objective 4. To integrate with local and strategic land use policies
This amounts to making North Greenwich a nicer place to be, since it is currently being redeveloped into a high-rise residential and entertainment district. The elimination of the all-day tailback through the middle of it is expected to make it noticeably more appealing and more accessible.
Objective 5. To minimise any adverse impacts of any proposals on communities, health, safety and the environment
Ah yes, this is the big one. Under this heading you will find air quality.
While there is a forecast 2% rise in traffic levels, those vehicles are now expected to be moving, not sitting idle for long periods, and consequently air quality is actually forecast to improve.
In some places.
A bit.
The Blackwall Tunnel Northern and Southern Approaches will see the greatest benefit - naturally, since they have been all-day car parks until now - with a decrease in nitrogen dioxide concentrations between 2 and 3 micrograms per cubic metre.
Improvement, by smaller margins, is also expected on the A13 and around residential streets historically used as rat runs. Slight increases are forecast at the Tidal Basin Roundabout, where the tunnel emerges on the north bank, and at some odd spots further afield.
In general, TfL’s assessment on air quality is mostly listed as “no impact”, with some areas showing “slight positive change”. If their forecasts are broadly right, the tunnel will not be the air quality disaster that some have feared.
That’s unlikely to appease anyone campaigning against the tunnel on air quality grounds, since the Blackwall Tunnels and their approaches were already an air quality nightmare. No impact is not an improvement, it’s the status quo, and the status quo is not good. If it hadn’t been built, other interventions could have been made that might have actually improved air quality.
However, the status quo is at least no worse than before. Since the new tunnel is now a fait accompli, the promise of fewer idling vehicles and less traffic in surrounding neighbourhoods would at least be welcome, and the Mayor can claim with justification that the tunnel is not cancelling out his efforts on air quality. But while no disaster is foreseen, there is also no great cause for joy on this front.
Also under this heading is the impact on lower income communities. TfL’s new bus routes are designed to serve people who would otherwise feel little benefit - 60% of those within reach of bus stops on the new routes have no access to a car. The Cycle Shuttle is free.
Care has also been taken to mitigate the effect of the tolls on those who can least afford the increased cost. There are significant discounts for local residents in receipt of benefits, and the toll is waived for Blue Badge holders, coaches, taxis, private hire vehicles in service and others. And for the first year at least there is a discount for small businesses and charities in neighbouring Boroughs.
Objective 6. To ensure where possible that any proposals are acceptable in principle to key stakeholders, including affected boroughs
We can skip this one. TfL had a word with the Boroughs, the City and National Highways, and they all think it’s OK. Let’s move on.
The waiting game
It’s too early to say whether the Silvertown Tunnel will work out as TfL and the Mayor hope. People, and traffic patterns, are too unpredictable for that, and we’ve yet to see how it operates outside of the Easter holidays, let alone when travel patterns settle into new shapes over the coming months and years.
But what might be clearer now is the job it’s supposed to do. It’s not about capacity, it’s about reliability - finally conquering the drag that the heavily restricted and highly disruptive Blackwall Tunnels have had on East and South East London for decades.
Besides, Transport for London is not a road builder and it is not reckless. You may doubt the need for two more traffic lanes across the Thames, but consider the scarcely believable fact that TfL are the ones who built them.
This one road project - conceived in the 1990s, but descended from an earlier idea dating back to the 1960s to provide a third bore or a bridge at Blackwall - survived the total attrition of all other road projects in London. It survived TfL’s financial crisis and the ending of central Government grants for London’s road network, and received no Treasury funding whatsoever. It survived the culling of its stable mates, Gallion’s Reach and Belvedere, both considered unaffordable. It survived a change in leadership, from a bullish Conservative Mayor with a well-known penchant for bridges and tunnels to a Labour Mayor whose stated goal is to clean up London’s air.
The Silvertown Tunnel is, in other words, a unicorn. It shouldn’t be possible for it to exist. The fact that it does - that in a city where streets are routinely narrowed in favour of wider pavements and cycle facilities, where even maintaining the current level of capacity for motor traffic is unthinkable, let alone increasing it - that fact should tell you just how certain TfL must be that here, in this one place, London really, really did need a new road.
Is this a defence of the Silvertown Tunnel in the face of all its critics? No, or at least not entirely. But there has been a lot of noise and a lot of hasty judgement of a project that will take years to fully bed in and prove itself. So this is an attempt to provide a more thoughtful perspective, one that takes into account the reasons the tunnel was built and the things it is actually expected to do.
Was TfL right that this issue, above all others, was the one that had to be solved? And will the Silvertown Tunnel fix it? We don’t know. But it’s here now, like it or not, so let’s give it time, and see what this unicorn does.
Comments
Nice to understand what the actual objectives were, and how they've informed the overall plan: there's been a lot of disinformation & assumptions surrounding the project. Admittedly, TfL have been terrible at communicating them, and on the face of it the project does seem ludicrous.
Greetings from Toronto. Love this post. I've been looking at the Silvertown tunnel ever since I've heard of it, and this post just about sums up everything we've heard about it so far. On the other hand, I'd love to see you complete those Ringways pages mate. Looking forward to them.
A fantastic article, thank you.
However, I must take issue with one point you make- that providing space for active travel would have required another bore at significant extra cost. The plans for a cycling and walking route was a 3.3m wide and 2.47m high subway below the main carriageway in either or both the main bores. There are detailed plans for this subway but the extra cost £88m or 4% of the total £2.2bn bill was deemed too high and the plan binned.
I can send a copy of the subway plans if required.
I didn’t know about this! Was it proposed by TfL or submitted to them by another party?
You might have just said they have more or less finished the East Cross Route. Vital for commercial vehicles coming in via Dover.
A good balanced article. The new tunnel will be very welcome when there is a closure in one of the Blackwall tunnels (whether planned or unplanned), but doesn't seem very useful the rest of the time, due to the poor connections at the northern end.
And while TfL seem obsessed with 24 hour bus lanes now, when there is a nighttime Blackwall tunnel closure, and all traffic has to use the Silvertown tunnel, it will seem ridiculous to have the majority of vehicles crammed into one lane, with the inside lane largely empty.
I drive coach tours in and out of London from Kent and I have to say, I am extremely impressed by how the construction of the Silvertown Tunnel gives me another option and how free-flowing it has become overall. The northern portal dumping traffic onto local road infrastructure isn’t ideal (perhaps there should have been more free-flowing slip roads onto the A1261 at least?) but I believe the sudden drop in congestion is at least partially due to drivers avoiding the tunnels due to the charges in place; I have spoken to many ‘tradies’ I personally know and although some don’t seem to care and actually welcome it, others seem to overly exaggerate boycotting the charge and would strangely prefer to waste time and fuel diverting towards the Woolwich Ferry, the Rotherhithe Tunnel or Tower Bridge. I just retort: charge the customer an extra fiver per day. A colleague of mine said the charges are in place not just to recoup construction costs, but to also make driver think twice before using the crossings… obviously it’s more involved than that but it’s an interestingly simplified take.
Some call me a madman for preferring to drive around London all day than to drive in heavily congested areas of Kent such as Maidstone, Medway, Canterbury and Thanet but I believe this is heavily due to the bus lanes in and out of the capital; I can use the Silvertown Tunnel’s bus lanes and I can also use the bus lanes on East India Dock Road/Commercial Road between Aldgate East and Cotton Street whilst passing biblical amounts of traffic stretching over two miles just on that section of A13 (this is to avoid the A1203, The Highway, which is notorious for westbound congestion). I can then make my way towards Tower Bridge and turn right onto Shorter Street by Minories Car Park (bus/taxi-only) onto Tower Hill. The rest of the journey towards Westminster isn’t that bad and even if it was, I can alternatively turn right onto Great Tower Street by The Hung Drawn & Quartered pub and head towards the city centre that way, via St. Paul’s Cathedral.
Overall, I was extremely surprised it was given the green light for construction, the same going for the A122, Lower Thames Crossing. If a journey is more convenient because of a new road, I really don’t care paying for the privilege; all jobs I’ve worked which required me to use the Dartford Crossing using my personal car reimbursed me for the charges after some ‘haggling’ during the interview/introduction stage. The M6 Toll is a good example of me preferring to use it if the M6 is congested, despite its high cost.
I lived very near here until recently. I always felt that there were a lot of well meaning folks from West London sat in their lovely Kensington apartments telling East Londoners that they can't have free or easy river crossings. There are 15 road bridges in London (I think) and I wonder what would happen if all the West London crossings were tolled in the same way.
Great article btw
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Sources
- Length of TLRN: Transport for London Highway Asset Management Plan [PDF], September 2007.
- Stated reasons "faster cross-river journeys" and "more public transport services": "The new Silvertown tunnel is now open", Transport for London.
- Silvertown and Blackwall Tunnels User Charges: User Charging Assessment Framework [PDF], Transport for London, November 2024.
Another outstanding Article.
Lets hope, as all return to work and school that it works and it does improve air quality (if only a little bit!)
A couple of annoying (to me) issues
1) All the signage on approach is nicely bracketed into the retaining wall, except the "Congestion charge / Camera sign" which is posted... clearly an after thought.
2) Both exits are immediately complicated as shown on your video, either by a multi directional roundabout with traffic lights or a merge/diverge junction... just as your eyes get use to the light again...and the tunnel lights to prepare you didn't seem to be on.
Did I also see on the Southern Approach the Congestion Avoidance signs obstructing the main junction sign?
Any how BRILLIANT... I should have kept up my desire to be a road engineer :)