Why build the Silvertown Tunnel?

Over the last 30 years east London has changed with the redevelopment of former industrial areas into major commercial and residential districts. The development of Canary Wharf, Stratford, the Royal Docks and the Greenwich Peninsula has had a major impact on the demand for travel across the wider area.

The river, once a major barrier to north-south movement, has been crossed five times between Rotherhithe and Woolwich by new railway lines. The existing East London Line at Wapping has been transformed and the Emirates Air Line Cable Car has been introduced to provide a dedicated crossing for pedestrians and cyclists. The first Crossrail trains will enter service in late 2018, providing a further cross-river rail link at Woolwich.

The map below shows the cross-river public transport links that are available in east London.

Public transport cross-river links in east London

There has not however been a comparable investment in London’s road network. London’s roads are a vital part of our transport network. Roads link our communities; providing access to education, jobs and services and enabling businesses to trade, creating new employment. Whilst it is important that as many trips as possible are made by public transport, there will always be a need for some journeys to be made by road. For example, while there are over 6.5 million journeys made by bus every weekday; freight and other vital services are moved almost exclusively by road.

The lack of crossings for vehicles

The average distance between vehicle crossings in central London is 1km, and in west London it is 2km. In east London however the average distance between river crossings is 8km.

In east London, where there is a comparative scarcity of crossings for vehicles, the River Thames is a natural barrier to movement by road. There are also some restrictions on existing river crossings. For example there is a height and width restriction on the Rotherhithe Tunnel, and a 4m height restriction on the northbound bore of the Blackwall Tunnel. This scarcity of crossings causes a number of associated connectivity problems that will get much worse if we do not take action to tackle them.

The map below compares the number of river crossings for vehicles in east London with those in central and west London.

River crossings for vehicles in London

Growth in London

The population of London will grow in future. By 2031, there will be around 10m people living here, with much of the growth expected to take place in east London. The map below highlights those areas where the most significant growth in east London could take place.

Areas of opportunity for growth in east London

The extra population will put further pressure on London’s road network, even if the vast majority of the new trips are made by public transport. The table below compares trips to work by car made by residents of Greenwich, Newham and Tower Hamlets in 2001 and 2011.

Change in trips to Trips to work by Trips to work by Borough work by car, 2001 car in 2001 car in 2011 - 2011 Greenwich 33,500 33,900 +1% Newham 25,300 27,700 +9% Tower Hamlets 13,200 14,400 +9% TOTAL 72,000 76,000 +6%

The total number of trips to work by bus in these boroughs has grown even more, as shown in the following table.

Borough Trips to work by Trips to work by Change in trips to bus in 2001 bus in 2011 work by bus, 2001 - 2011 Greenwich 12,400 19,100 +54% Newham 10,500 17,500 +66% Tower Hamlets 7,700 14,800 +92% TOTAL 30,600 51,400 +68%

As the population of these boroughs has grown, so the total number of trips to work by car and by bus has increased. New road capacity to relieve the congestion at Blackwall will also enable new bus connections to be provided that will support growth in the surrounding area.

London’s population has and will also continue to have a growing demand for goods and services. A recent TfL study showed that almost 90 per cent of all goods moved in London are transported by road. Around a third of the current total use made of the Blackwall Tunnel is by freight vehicles. Irrespective of how the additional population will travel in future, Londoners will always demand goods and services, which for the most part will be transported by road.

The problems at the Blackwall Tunnel

The demand to cross the river by road in east London is focussed on a limited number of crossings. The Rotherhithe Tunnel and Woolwich Ferry offer much less capacity than the Blackwall Tunnel. The Blackwall Tunnel provides a key, strategic link connecting the A12 and A13 to the A102 and A2. The tunnel is used principally by cars, although it also provides a key route for freight vehicles and other traffic. The table below shows which vehicles use the tunnel, day by day.

Proportion of total vehicles Vehicle Type using the tunnel in each direction per day Car 68% Light Good Vehicles 18% Heavy Goods Vehicles 8% Motorbikes 3% Taxis & Private Hire 2% Vehicles Buses & Coaches 1% Table showing the use made of the Blackwall Tunnel in each direction by vehicle type

Demand to cross the river by vehicle from areas throughout east and southeast London is at its most intense at Blackwall. This causes a number of problems which are described in this section.

Demand for the Blackwall Tunnel

The charts below show the use that is currently made of the tunnel in each direction during an average week in 2013, showing how demand regularly meets or exceeds the optimal operational capacity of the tunnel.

Chart showing northbound flow at the Blackwall Tunnel

Chart showing southbound flow at the Blackwall Tunnel

There is regular queuing on the approaches to the Blackwall Tunnel, particularly so during the busy peak periods, with journeys on the approach to and through the tunnel often taking up to 20 minutes or more. The Blackwall Tunnel was simply not designed to cope with the current level of demand.

Congestion on the approach to the Blackwall Tunnel

Incidents at the Blackwall Tunnel

There are a large number of occasions in which a vehicle breakdown, an overheight vehicle or an accident causes disruption and consequential delays at the Blackwall Tunnel. From November 2012 – November 2013, there were almost 1,100 unplanned incidents at Blackwall which caused disruption to the smooth operation of the tunnel. The table below provides a breakdown of the nature of these incidents.

Nature of incident No of incidents in 2013 Overheight vehicle attempting to access 649 the northbound bore Vehicle breakdown on the approach to or 234 within the tunnel Other – eg. Debris within the tunnel 86 Road traffic accident 67 Table to show incidents at the Blackwall Tunnel in 2013

The duration of these incidents can vary from a few minutes to, in extreme cases, several hours. Irrespective of its nature and duration however, any incident at the Blackwall Tunnel makes the congestion here much worse, causing knock-on effects across a much wider area.

TfL has taken a number of steps to improve the performance of the Blackwall Tunnel and reduce as far as possible those incidents which disrupt the smooth operation of the tunnel. These steps include:

• Introducing a new dedicated Roads Response Team, based at Blackwall. The team is made up of a number of traffic Police officers who respond to and clear incidents at the tunnel as quickly as possible, reducing the time the tunnel must be closed; • Installing a new automatic overheight vehicle detection system, to reduce the number of incidents in which large vehicles attempt to gain access to the northbound bore of the tunnel, where there is a 4m height restriction; • Refurbishing the northbound bore of the Blackwall Tunnel to reduce the number of instances in which it is necessary to close the bore for routine or emergency maintenance.

The automatic overheight vehicle detection system at the Blackwall Tunnel

While these steps have had an effect in reducing the number of incidents at the tunnel, the volume of incidents here remains a serious issue given the very significant disruption they cause.

To illustrate this point, we wanted to outline the impact of a recent incident at the Blackwall Tunnel. On 11 September 2014, it was necessary to close the northbound bore of the Blackwall Tunnel from around 6.45am until just before 7am while we carried out emergency repairs to fix a loose panel.

Traffic began to queue as soon as the closure was put into place. At just before 7am, and even though the tunnel had been fully reopened, the volume of traffic trying to cross the river was so great that the queue for the tunnel extended as far back as the A206 Woolwich Road. We posted signs on the approach to the tunnel and used social media to warn drivers to avoid the area.

The traffic queue continued to build however and by just before 7.30am it had extended as far back as the A2 Kidbrooke Interchange. The queuing affected local bus services, delaying bus passengers.

The queue did not fully clear until just after 9am, when traffic flow returned to normal levels for this area. The lack of an alternative crossing for vehicles meant that a closure of the Blackwall Tunnel lasting less than 15 minutes caused over two hours of disruption to the travelling public.

Clearly, there is the potential for an incident to disrupt traffic flow on any road in the network. In some places however it is comparatively easy for the network to ‘recover’ from an incident, since there are ample opportunities for traffic to divert away from a disrupted section of road to convenient alternative routes. At the Blackwall Tunnel however, the nearest alternative river crossings are the Rotherhithe Tunnel and Woolwich Ferry. The road network in east London is generally much less resilient than in many other areas specifically because there are so few alternative river crossings that traffic can use in the event of an incident at the Blackwall Tunnel.

The wider consequences of the problems at the Blackwall Tunnel

Impacts on air quality

In ‘stop/start’ traffic conditions, vehicle engines work less efficiently and so produce greater emissions per kilometre travelled. In common with other parts of London, air quality can be a problem in the Blackwall area at certain times, and this is undoubtedly exacerbated by the heavy traffic demand here and the resulting congestion.

Effects on businesses

The lack of resilience at Blackwall and in the wider network also causes difficulties for businesses, which in turn affect the London and UK economy. We surveyed 800 businesses in east London to understand what impacts the comparative lack of river crossings has on their activities. Around 65 per cent of the businesses surveyed felt that the congestion associated with the lack of river crossings in east London was acting as a constraint on the development of their business. Just under half of all those businesses surveyed said that they would expect to recruit more staff if new river crossings for vehicles were built, since the new crossing would give them more ready access to their suppliers, customers and the workforce.

The pressure of London’s increasing population

As the key strategic cross-river highway link for east London, there is already significant demand for the Blackwall Tunnel. With London’s population growing this demand will also grow. By 2021, which is the earliest that a new crossing could be built, there would be considerable additional pressure on key strategic routes, including the A13, A406 North Circular Road, A2 and the A102, as highlighted in the map below.

Map to show routes where traffic flow will significantly increase in 2021

This increase in traffic would add to the pressure on capacity at key road junctions, leading to worsening delay for all road users. The map below indicates those junctions where we expect there will be the most significant increase in delays during the morning peak period in 2021.

Map to show junction delays in 2021

Overall, our modelling predicts that delays in the morning peak across east and southeast London would increase by over 20 per cent in 2021, on average.

The lack of resilience and its consequential adverse impacts faced today at Blackwall can only get much worse in future if nothing further is done.

Options we have considered for resolving the problems

We have considered a wide range of options that might resolve the constraints at the Blackwall Tunnel described above. In this section we describe those options we assessed but did not consider suitable, and set out our reasoning for rejecting them.

Demand management at the Blackwall Tunnel

We considered whether the problems caused by a lack of resilience at the Blackwall Tunnel could be resolved by charging motorists to use the tunnel, without building any new infrastructure. In this case, the charge would be intended to dissuade some motorists from using the tunnel – they might switch instead to public transport options, or re-time or re-route their journey.

Although a charge at the Blackwall Tunnel might reduce demand, it could not prevent incidents at the tunnel, which is a significant cause of congestion across a wide area. The new Silvertown Tunnel will significantly reduce incidents at the Blackwall Tunnel caused by overheight vehicles, which exacerbate the congestion in and around the area. It would also provide an alternative route should an incident take place.

We concluded that a charge at the Blackwall Tunnel without any increase in new crossing capacity was not a suitable option, since it would not address our wider objective of reducing incidents at the Blackwall Tunnel and providing more resilience and choice for people crossing the river. In addition, although charging would reduce some demand to cross at the Blackwall Tunnel, there would still be significant congestion and adverse impacts on alternative crossing routes.

Further investment in public transport

The investment in cross-river rail links has vastly improved public transport connectivity between east and southeast London. Even so, some communities in southeast London have quicker links to employment centres north of the river than others. The map below shows rail, Tube and DLR links from southeast London and journey times to Canary Wharf.

Southeast London rail, Tube and DLR links and journey times to Canary Wharf

We considered whether it might be possible to alleviate the congestion at the Blackwall Tunnel by introducing an additional public transport option. We considered specifically whether some current users of the Blackwall Tunnel might switch to public transport if, say, DLR services were extended along a corridor via Kidbrooke and Eltham to Falconwood, which is an area not currently served directly by cross river rail services.

Almost 70 per cent of those currently using the Blackwall Tunnel are car drivers. We undertook roadside interviews with a sample of users to determine which areas motorists were travelling to and from. The map below highlights the origin and destination of journeys made by motorists using the Blackwall Tunnel in the morning peak period. The map also indicates the area that would be served by an extended DLR service to Falconwood. We found that only around four per cent of motorists using the Blackwall Tunnel were travelling both to and from an area that would be served by the DLR if it were extended along this corridor. Even assuming that all of these users switched to an extended DLR service, this would make only a very small impact on demand for the Blackwall Tunnel, and therefore on relieving congestion here. This is demonstrated in the map below.

Map to show the origin and destination of trips by motorists using the Blackwall Tunnel, and the route of a potential DLR extension to Falconwood

Introducing a new ferry crossing at Silvertown

We considered whether it would be possible to address the demand and congestion issues at the Blackwall Tunnel by introducing a new cross-river ferry service to link Silvertown with the Greenwich Peninsula.

A new ferry could be introduced at a much lower cost compared to a new public transport service or a fixed road link, but would have the capacity to carry far fewer vehicles and passengers. The Blackwall Tunnel has the capacity to carry around 3,000 vehicles per hour, while a ferry, on average, might carry perhaps only around 200 vehicles per hour in each direction. A journey across the river would also take longer via a ferry than a bridge or tunnel.

One advantage of a new ferry crossing over the current situation at the Blackwall Tunnel is that it would offer an accessible way across the river for over-height vehicles – the northbound bore of the existing tunnel is not accessible to vehicles over 4m high. This could reduce the number of incidents at the tunnel in which these vehicles try to gain access to the northbound bore, but must be stopped and turned back, disrupting traffic. Incidents at the Blackwall Tunnel have a number of different causes however: disruption is not only caused by overheight vehicles trying to gain access to the northbound bore.

A further complication is that there is significant development planned for the Greenwich Peninsula. A new ferry crossing at Silvertown would require new access roads and queuing areas to be built, and this could conflict with the planned development, especially at the Greenwich Peninsula.

For these reasons, we concluded that a new ferry service at Silvertown would not be the best option for addressing congestion and a lack of resilience at the Blackwall Tunnel and improving cross-river connectivity.

A bridge at Silvertown

A number of tall sea-going ships use the eastern part of the Thames, and consequently any new bridge constructed to the east of Tower Bridge must provide at least 50m of headroom above the high-water mark to allow shipping to pass beneath, as shown in the image below.

Bridge clearance requirements along the Thames

This requires long, sloping approach ramps to enable traffic to access the main bridge deck. These ramps would require considerable land for construction on each bank of the river; however, this land is simply not available, nor is such a bridge compatible with proposals for redevelopment of the area, since there is considerable development planned in the Greenwich Peninsula area.

We considered whether the issues at Blackwall could be resolved by building a new ‘lifting’ bridge at Silvertown. A central section of the bridge would be lifted clear to provide the space for tall ships to pass beneath, so that the approach ramps could be shorter and not need so much land to construct.

While a bridge would offer considerable capacity for vehicles, a lifting bridge would be closed to traffic during those periods when shipping needed to pass. Current data shows that the lifting bridge would need to open frequently – potentially for around 10-15 tall ships per day - with each closure lasting for at least 20 minutes, or longer depending on tidal conditions. Traffic would need to be held or diverted to the Blackwall Tunnel during these periods and the number of tall ships using the river may increase in future.

Given that a lifting bridge would not be available to traffic for significant periods while shipping passed, we did not consider a lifting bridge to be a feasible option.

Conclusion

Having considered the alternative options, we concluded that we should build a new tunnel at Silvertown, with associated user charging at both the Silvertown and Blackwall Tunnels, to manage demand and help fund the new infrastructure. We concluded that this was the most appropriate option because it would:

• Provide additional cross-river capacity, reducing congestion at the Blackwall Tunnel; • Improve the resilience of the road network in east London by providing an alternative route across the river in the event of an incident at Blackwall; • Support future growth in London’s population.