Ridership on London's SL4 bus route has risen despite the reintroduction of the standard £1.75 fare, according to new Transport for London (TfL) data. The free trial on the Superloop route between Grove Park and Canary Wharf ended on May 26, 2026, after being extended by Mayor Sadiq Khan. In the first month after charges resumed, 211,786 passengers used the SL4, up from 202,685 in the same period in 2025.
Ridership trends across cross-river routes
The SL4 was one of four routes that benefited from the free trial, which was introduced to encourage drivers to use public transport following the opening of the Silvertown Tunnel on April 7, 2025. The trial also covered the 108, N108, and 129 routes, which use both the Silvertown and Blackwall tunnels.
Data from TfL shows that the 129 route between Gallions Reach and Lewisham saw ridership increase from 318,924 to 320,927 in the same comparison period. The night bus N108 between Stratford and Lewisham also saw a rise, from 11,540 to 12,125 passengers.
However, not all routes experienced growth. The 108 bus saw a 15 per cent drop in ridership, falling from 340,791 to 289,274 passengers.
Silvertown Tunnel's impact on journey times
The increase in cross-river bus services from six per hour to 21 was a key part of the mayor's strategy to promote the Silvertown Tunnel. TfL's first-year report on the tunnel indicates that the East London road network has become more reliable, with peak journey times through the Blackwall Tunnel dropping by 58 per cent in the morning and 47 per cent in the evening.
Mayor Sadiq Khan said: "This analysis shows that the Silvertown Tunnel is proving a success, not only cutting journey times but encouraging more sustainable transport so we can keep cleaning up our air. I'm particularly pleased to see major reductions in congestion at the Blackwall Tunnel benefitting businesses and local residents. The Silvertown Tunnel is already transforming travel across the Thames as we continue building a greener, fairer, better London for everyone."
Broader implications for London's transport network
The continued use of these bus routes suggests that passengers have adapted to the end of the free trial, which may indicate a lasting shift towards public transport. TfL will monitor these trends to assess the long-term viability of the enhanced cross-river bus network.
The success of the tunnel in reducing congestion at Blackwall is a significant achievement, but the drop in ridership on the 108 route highlights the need for ongoing evaluation. As London continues to recover from the pandemic and adapt to new infrastructure, these figures will be crucial for future transport planning.
