Traffic information company Inrix said the accident led to delays on the M11, the A12 and the A406 North Circular.
The worst of the hold-ups were on the M11 and drivers were being advised to leave an hour extra for their journeys.
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The capital's theatres also generate more searches than those in any other city, according to research by Google.
Union officials are expected to meet next week to plan further stoppages if talks fail to resolve the dispute.
Natalie Sharp and Christine Bicknell appeared in court over an alleged incident at a Lidl superstore in Wallington, south London.