Understanding the impacts of Silvertown Tunnel
There are three main types of monitoring that we have taken before the Silvertown Tunnel opens on traffic, air quality and the economic impacts of the tunnel. This monitoring will continue for at least three years after the opening in spring 2025.
The monitoring reports are available on the Silvertown Tunnel Implementation Group page in the section Monitoring and mitigation reporting.
Changes to traffic
To understand how the Silvertown Tunnel will affect existing roads and local communities, we've been updating our traffic and air quality modelling.
We've shared the results of our monitoring with STIG and physical highway mitigation works are proposed at three locations and signal optimisation at 11 locations. The locations of these mitigation measures are outlined on the traffic mitigation map below.
The mitigations will be completed before the tunnel opens in spring 2025. This is to ensure that there are no adverse impacts on local communities when the tunnel opens. Once the Silvertown Tunnel opens, we'll continue to monitor the impacts on highways and air quality and will complete further mitigation work if necessary.
Air quality
Without the Silvertown Tunnel, congestion and air quality around the Blackwall Tunnel were predicted to get worse as London's population grows.
User charges for both tunnels, as well as the new cross-river bus network, will help us manage the environmental impact of traffic. We're committed to ensuring the scheme delivers an overall improvement in air quality by reducing congestion currently seen at the Blackwall Tunnel.
Air quality in London has improved since we were granted permission to build the Silvertown Tunnel following the introduction of policies from the Mayor's Transport Strategy to improve air quality. This includes the London-wide expansion of the Ultra-Low Emission Zone (ULEZ), which has seen improvements in air quality across the capital.
Given this, and the time since our original 2016 assessments, we have to update air quality forecasts. This is to see how much air quality has improved and compare it to actual air quality once the tunnel opens.
The forecasts also inform decisions about the user charge, which is the main way to control demand and cut congestion levels. We'll continue to monitor air quality once the tunnel opens, to help identify if any new localised mitigations, beyond the user charge, may be needed.
Since December 2020, we've been monitoring air quality and specifically nitrogen dioxide (NO2) to ensure that the impacts of the Silvertown Tunnel are fully understood.
As part of our monitoring network, we've 38 diffusion tubes and three continuous monitoring stations recording nitrogen dioxide (NO2) across five boroughs: Greenwich, Newham, Tower Hamlets, Southwark and Lewisham.
The three continuous monitoring stations sample the air around the unit at 15-minute intervals and the data is reported live on the London Air Quality Network website. Other monitors are diffusion tubes installed on lamp posts on key roads and provide us with monthly averages of NO2 levels.
We've completed baseline data for 2020-21 and 2021-22 and the full reports are available on the Silvertown Tunnel Implementation Group page. Both reports include air quality data from selected local authorities, to give us an understanding of actual air quality levels on roads around the scheme before it opens. The baseline monitoring report for 2023 will be published later in 2024.
Socio-economic changes
When the Silvertown Tunnel opens, it is expected to increase access to jobs and homes in East London. Through socio-economic monitoring, we'll measure changes in personal and business travel, and assess the impacts on businesses. Where possible, this monitoring will also seek to determine what changes are related to the new Silvertown Tunnel.