Transport for London (TfL) has ruled out extending the popular Superloop SL4 bus route to Bromley North, citing significant costs, despite the route's strong passenger numbers. The decision was confirmed in response to a Freedom of Information request, after some passengers suggested the southern terminus should move from Grove Park to Bromley North.
SL4 route launched with Silvertown Tunnel
The SL4 service, running between Canary Wharf and Grove Park, launched on April 7, 2025, to coincide with the opening of the Silvertown Tunnel. Initially, passengers were offered free journeys to encourage bus ridership and discourage driving. The free trial ended on May 26, 2026, with fares set at £1.75, yet the latest journey figures show passenger numbers have held steady at roughly 210,000 per month.
Along with passengers on the 108 and 129 routes, more than 11 per cent of trips through both Silvertown and Blackwall tunnels are now made by bus. This represents a 290 per cent increase compared to before the former crossing opened, according to TfL data.
Extension proposal deemed not feasible
TfL confirmed that a number of customers have suggested extending the SL4's southern terminus from Grove Park to Bromley North. However, the authority stated that the costs are significant and the scheme was not deemed feasible. If the extension were to proceed, some passengers claim it would provide a more useful destination, offering an interchange with the SL3 and SL5 routes, rather than ending near Grove Park bus garage, where traffic often builds when buses enter and leave.
TfL said any future proposals would be developed with relevant South London boroughs before going to public consultation.
Superloop network expansion continues
Last weekend, London's Superloop network expanded again with the launch of the SL12 between Gants Hill and Rainham. In late 2024, bus cuts in Romford led to severe backlash from former Havering Council leader Ray Morgon, who criticised Sir Sadiq Khan for expanding ULEZ while snubbing the area during the initial Superloop launch.
Next year, the SL13 between Hendon and Ealing Broadway and the SL15 between Clapham Junction and Eltham are expected to launch, completing the second phase of the mayor's express bus scheme. The SL4's future remains unchanged, with no extension to Bromley planned.
