The trouble with the Thames

Published on 26 July 2018

The Silvertown Tunnel took another step closer to being built a couple of months ago. But it faces stiff opposition, and no proposal for a new river crossing in East London has succeeded since the first Dartford Tunnel opened in 1959.

Transport for London now have Development Consent to build the Silvertown Tunnel, a new road link across the Thames between North Greenwich and Silvertown, close to the existing Blackwall Tunnel. It's taken a very long time to reach a point where construction now looks likely - and on the way, two other planned river crossings have been abandoned. Why are TfL still so keen to build a new road tunnel at all?

Let's take a step back.

The story so far

East of Tower Bridge, there aren't many links between the roads north and south of the Thames. There's the A101 Rotherhithe Tunnel, opened in 1908 and subject to strict speed, size and height restrictions; there's the A102 Blackwall Tunnel, with a Victorian northbound bore and a 1960s southbound bore, which means some heavy vehicles can only use it southbound; and there's Dartford, with its twin tunnels and cable-stayed bridge, which is subject to a toll. Oh yes, and the Woolwich Free Ferry, which is really only suitable if you have time on your hands.

Nobody is really happy with this situation.

Blackwall suffers chronic congestion in both directions, with morning rush hour queues often persisting until the end of the evening rush hour, and the slightest hold-up (such as an overheight lorry being diverted off the approach road) having almost unbelievably severe consequences. The traffic problem at Blackwall is hard to overstate; TfL's own figures show that, on average, it operates without some sort of incident on only one day in every two weeks, but even without incidents, "normal" operation means queueing for up to half an hour to get through.

The usual state of affairs on the Blackwall Tunnel Southern Approach. Click to enlarge
The usual state of affairs on the Blackwall Tunnel Southern Approach. Click to enlarge

Rotherhithe permits only light traffic and has no approach roads to speak of, so it is not much use for many journeys simply because it's hard to actually get to it, especially on the south side.

Dartford is well outside London - eleven miles east of Blackwall, the previous crossing, and is tolled. It's also the river crossing that carries M25 traffic over the Thames, so it has its own problems dealing with traffic that has no business in London. Nonetheless, plenty of journeys to and from places in outer East London go via Dartford simply because the alternatives are far away and far too slow.

Since the 1960s, there have been plans to increase the number and capacity of river crossings to sort this problem out:

  • A third bore at Blackwall to carry six lanes over the river instead of four, planned since the late 1960s. By the 1980s a bridge was being proposed to double capacity, with a total of eight lanes. Neither were built.
  • A new tunnel at Gallions Reach, near Thamesmead, was proposed in the late 1960s as an eight-lane motorway (part of Ringway 2). The plan returned in the 1980s as a bridge called the East London River Crossing, an extension of the North Circular Road; it came back again in the 2000s as a dual carriageway with parallel bus route or tram tracks; and it returned yet again in 2012 as the Gallions Reach Crossing, this time with two traffic lanes and two public transport lanes.
  • A local crossing at Belvedere, near Erith, was mooted as a possibility for one of the later stages of the Thamesmead development that did not take place. It was resurrected in 2012 as the Belvedere Crossing, again with two traffic lanes and two bus lanes.

So what is the Silvertown Tunnel?

It's the latest attempt to unblock Blackwall, and successor to the third bore tunnel and then the bridge scheme. It would provide a dual two-lane tunnel immediately east of Blackwall, effectively doubling the number of traffic lanes under the river and removing height restrictions for northbound vehicles. One lane in each direction is proposed to be reserved for buses and HGVs.

At the south end, the new road will merge into the A102 Blackwall Tunnel Southern Approach - a three-lane road with capacity far in excess of the Blackwall Tunnel, so there's room to accommodate additional traffic. At the north end, plans show a slightly disappointing signalised junction that will allow traffic to join the A1020 Lower Lea Crossing, with connections to the A13 and the Docklands.

The proposed layout of the new tunnel. Click to enlarge
The proposed layout of the new tunnel. Click to enlarge

New road capacity here will be the answer to the prayers of every motorist who queues every day to cross the river, not to mention the many companies who have business on both sides of the river but struggle to get from north to south in a timely manner. It'll make life much easier for hauliers who currently have to divert via Blackwall (or the slow Woolwich Ferry) to avoid the low roof of the northbound Blackwall Tunnel.

What won't answer their prayers will be the "road user charge" - for which read "toll" - that will be introduced on the new Silvertown Tunnel and the existing Blackwall Tunnel to pay for it. The charge will be collected electronically, as at Dartford, and will be matched with the cost of the Dartford Crossing so there's no financial incentive to choose one over the other.

The new tunnel faces still opposition from residents' groups, environmental campaigners and lobbyists promoting public transport and cycling, who see it as a concession to private motoring and a source of increased air pollution on the North Greenwich peninsula.

Will it be built?

Almost certainly yes, now that it has Development Consent. No public inquiry is required or will be held. But the price of its arrival on the TfL road network in a few years' time will be steep.

First is the reputational hit that Sadiq Khan, Mayor of London, has taken for endorsing and pursuing it. His election manifesto made clear that he supported it and he's seeing it through, but since election he's made it his business to clean up London's air - and building new roads is not a universally acknowledged way of doing that. In this case, however, the new tunnel is expected to significantly reduce delays on the approaches to the tunnels, and shorter jams mean fewer engines idling and lower emissions.

An artist's impression of the southern portal of the Silvertown Tunnel, complete with bus and HGV lanes. Click to enlarge
An artist's impression of the southern portal of the Silvertown Tunnel, complete with bus and HGV lanes. Click to enlarge

Second is the other new infrastructure that's fallen by the wayside to prop it up. Thanks to Khan's pledge to freeze public transport fares, the end of direct Government grants and an unexpected decline in passenger numbers, TfL is facing serious financial pressures at the moment. When Khan became Mayor, there were two other new river crossings in development - Gallions Reach and Belvedere - that had been announced by his predecessor, Boris Johnson. In the last year, those proposals have silently been removed from TfL's website and publicity material no longer discusses them. £2bn has been saved, and Silvertown is the last river crossing still in the game.

Is it worth it?

All of this brings us back to the central question, which is why Silvertown is still being pursued by a public transport organisation that has only built two miles of new road in the eighteen years it has managed all of London's major road infrastructure, and whose main focus on the highway network is in improving the urban environment and lowering traffic speeds.

Further east, at Gallions Reach and Belvedere, the two new bridges were supposed to support new housing development on both sides of the river, in the Thames Gateway region; development that has been on the cards for more than a decade but is still proving stubbornly difficult to get started. Ditching those crossings won't delay an already stalled project, though it won't help it get going any sooner.

The case for Silvertown is different. It’s still to do with population growth, but not directly to do with new housing.

Its purpose is, obviously, to relieve the chronic congestion that plagues the Blackwall Tunnels each day. Blackwall already represents an enormous time penalty on road journeys between South East London and most of the rest of the conurbation, and adds an unacceptable level of uncertainty to journeys. The result is that even with present population levels, the existing tunnels are a noticeable drag on the economy and quality of life in this part of London. They also represent a major air quality problem thanks to the queues that form in the morning rush and last all day - something that must be addressed now the Greenwich Peninsula is beginning to bristle with dozens of new high-rise apartment blocks.

Queues at Blackwall again. This queue is because the tunnel is closed due to a vehicle on fire, but it could really be anything. Click to enlarge
Queues at Blackwall again. This queue is because the tunnel is closed due to a vehicle on fire, but it could really be anything. Click to enlarge

The population of London is forecast to grow by several million in the coming years. Demand for travel across the river will increase with it, and Blackwall will continue to increase in popularity because it is close to central London, has good onwards links in all directions and - perhaps crucially - because it is close to the economic hub of the Docklands.

The point of the Silvertown Tunnel is, therefore, not so much to generate new capacity for any specific new development, but to unblock a serious existing problem in order that it does not become a limiting factor in the ability of South East London to grow. By introducing a “user charge” – or toll – to both the new tunnel and to Blackwall, it’s hoped that journeys that could be made just as easily by other means will be strongly discouraged, and those that really do have to be made by road will be faster and more reliable.

None of that means that Silvertown will be popular. The motoring lobby - in the form of the motoring clubs, the Road Haulage Association, the ABD, and so on - should be the ones to support it and to bolster TfL’s case. But they remain dead set against it if Blackwall will be tolled. The user charge certainly seems a little unfair: it applies a toll to a crossing that has been free since 1897, and it means residents of East London must pay to do something that is, and will continue to be, free for those in the West.

The Silvertown Tunnel is, therefore, absolutely necessary and a clear potential benefit to people across East London, and yet it's very short of supporters. That is ultimately why no new crossings of the Thames have been made in this part of the world since 1959: they might be needed but they have never been popular. And until spades actually hit the ground, Silvertown's future isn't guaranteed, because even the people it's supposed to benefit are unwilling to cheer it on.


Patrickov 1 August 2018

I fear if Blackwall was tolled with Silvertown, and both at Dartford levels, many motorists would simply switch to inner London crossings like Rotherithe or even Tower Bridge. Meanwhile I think TfL should also consider providing bus links across both Blackwall and Silvertown, as suggested in the prop-up model.

YNM 2 August 2018

What puzzles me is why the 3rd tunnel option was thrown out of the water completely. The one and only building they have to knock down is a building right between the two current tunnel at the north portal - it says "london highways alliance" which is a TfL agency. If the entry had to be done with a cut-and-cover tunnel that'd cost some car garages and one back road during the construction period. There's absolutely nothing to knock down on the southern portals.

My own analysis after first hearing about this over rantyhighwaymen's blog and downloading the many many papers TfL and DfT had over this is that they didn't want to improve the flow of traffic, they want to increase development on both Silvertown and Canary Wharf. The road layout that Silvertown Tunnel connects to is best suited for this usage and not to relieve Blackwall Tunnels as is.

TL;DR it's a move that pretends to be one thing while it's not that thing at all.

Mikey C 6 August 2018

Given the choice of which crossing to build, my preference all along is the East London River crossing, as this gets people out of the area, especially as TfL are trying to downgrade the tunnel approach road north of the river with pedestrian lights to improve the area...

HOWEVER this need proper link roads on the south side to connect to the A2, the Ringway 2 plan to go through Oxleas Woods was unacceptable, but the later plan to dump traffic in Plumstead/Thamesmead was also unacceptable, which has rather killed the whole idea. A shame, when the connection to the A406 on the other side would be so easy...

Ringway 2 -style crossing would be best indeed. Sadly, I don't think there isn't enough courage and enthusiasm left for an ambitious road tunneling work between A13/A406 roundabout and A2 at Eltham Park...

Stephen 7 August 2018

Wouldn't the cheapest way to put a new crossing in be to stop the useless Woolwich ferry and build a bridge there instead? It would just be the cost of the actual bridge as access roads are already there. If this was built in addition to the Silvertown tunnel it would further relieve congestion at the tunnels. This would also have the additional benefit of allowing buses to cross and improving public transport links on both sides of the river thus reducing the need to drive. There would no longer be the one hour wait to get on to the ferry or no ferry at all in bad weather.

That idea runs into two unfortunate problems. One is that the approach roads aren't there at all - the North and South Circular between the A13 and A2 are appallingly low quality and struggle to carry the traffic they already have. Coming off the Woolwich Ferry northbound, for example, exiting the ferry terminal means turning right at a Give Way sign on an urban high street.

The other problem is that a bridge would need to be at a high level to clear shipping, and the surrounding environment, especially to the south, doesn't leave much room for long approach viaducts.

This is why the location for a new bridge or tunnel has always been further east and not at Woolwich.

On the south side, the way to gain the appropriate height is easy - just start the approach viaduct from the appropriate distance up John Wilson Street, although this wouldn't come cheap and would need some thought for how to connect to the A206 (not simple). This would still leave the problem of the north side though - and you can't just sail above North Woolwich as you would quickly interfere with the airport flight path.

And all of that tends to drive up the cost pretty fast, and that's ignoring the objections of those who would end up living in the shadow of said bridge and approach viaduct. A tunnel would probably end up being the cheaper option for a Woolwich fixed link. There's still the issue of the A206 and A205, because this link would sure as hell be heavily used.

Crinan Dunbar 20 August 2018

They should have found a way to re-use the Crossrail tunnel boring machines,. The ones making the Woolwich Crossrail tunnels would have been the easiest to use to bore a North Woolwich - Thamesmead bore.

Are you really sure? Those are to bore tunnels for train lines - I thought the proposal was to have at least three lanes going down each tunnel, which is going to need a far wider tunnel than that could bore.

Also those boring machines are specific for that project, and wouldn't be suitable for any other project especially one that is in a different area. Easier and cheaper to build a whole new boring machine that is specced for this particular project taking into account the area, the length, the size of the tunnels, etc.

Add new comment

About text formats

Restricted HTML

  • Allowed HTML tags: <a href hreflang> <em> <strong> <cite> <blockquote cite> <code> <ul type> <ol start type> <li> <dl> <dt> <dd> <h2 id> <h3 id> <h4 id> <h5 id> <h6 id>
  • Lines and paragraphs break automatically.
  • Web page addresses and email addresses turn into links automatically.
All comments posted to are moderated before appearing online. Your comment won't be visible immediately.


Picture credits

  • Artist's impression of Silvertown Tunnel portal and plan of the tunnel are copyright Transport for London.

What's new

Sorry, wrong number

Road numbering is a system with clear rules. What happens when the people responsible for numbering roads don't follow them?

We need to talk about Wisley

National Highways are spending a third of a billion pounds rebuilding one of the most congested junctions on the M25. Is it money well spent?

Oxford's Ground Zero

Oxford's Zero Emission Zone is just a trial, but transport policy in Oxford has become the catalyst for pitched battles and drawn in protestors from across the UK. What's happening to this genteel university town?

Share this page

Have you seen...

Old Motorway Photos

A gallery of images sent in by visitors to the site of original photos of motorways — including some impressive views of the M4 and M11 under construction.

About this page


Last updated