A 24-hour strike by London Underground drivers has begun, causing huge disruption to tube services and on the roads.

About half of London’s tube drivers are taking part in the action in a dispute over the introduction of a four-day working week. A second strike is planned for Thursday.

Hopes of a resolution had been high after threatened action in May was suspended. However, despite 11th-hour negotiations at Acas between RMT union representatives and Transport for London (TfL), the RMT went ahead with the strike on Tuesday.

TfL urged customers to check before travel, with about half of all tube services expected to run.

On Tuesday morning, TfL reported severe delays on the Bakerloo, District, Hammersmith and City, Victoria, Piccadilly and Northern lines.

Drivers in the Aslef union, a slight majority of those working on the tube, have welcomed the four-day week proposals and are not on strike, limiting the impact of the RMT’s action.

Other rail services, including the Elizabeth line, the London Overground and the Docklands Light Railway, were running as normal. Buses were operating as usual but were very busy and slowed by additional traffic on the roads.

The RMT blamed TfL’s “refusal to engage meaningfully” with concerns over the proposed working patterns. A spokesperson said: “Despite our best efforts in Acas talks, TfL have failed to provide assurances on our members’ deeply held concerns around fatigue, reduced flexibility, shift lengths and the impact these proposals could have in a safety-critical role like tube driving. We remain available for meaningful talks, but strike action tomorrow will now go ahead.”

A TfL spokesperson said: “It is bitterly disappointing that despite five hours of meetings with the RMT at Acas and repeated assurances that the four-day working week proposals will remain voluntary, RMT has chosen to continue with its disruptive strike action. We will do all we can to provide as much service as possible during this action.”

TfL’s chief operating officer, Claire Mann, said: “Our proposals are, and have always been, clear. The completely voluntary four-day week has been designed to improve work-life balance and any of our tube drivers who do not wish to take up the new proposed way of working and associated changes to working arrangements can remain on a five-day working pattern.”

The strikes were scheduled for 24 hours from 00.01 on Tuesday and Thursday – potentially slightly less disruptive than the previous walkouts that ran over two 24-hour periods starting from midday, affecting four days in April.

Business groups said the threat of strikes had already been disruptive. Ed Richardson, of BusinessLDN, said: “For many businesses that rely on people visiting in person, the impact of these strikes will have already been felt through cancelled bookings and people changing their plans. We urge both sides to reach a sustainable agreement to put an end to the damaging uncertainty hanging over businesses and London’s economy.”