relieve the congestion, a tidal flow system was introduced in 1978, allowing northbound traffic to use the western lane of the eastern tunnel. The congestion is not limited to weekday rush hours. There is often congestion with tailbacks at the weekends, especially on Sunday evenings. Due to its sharp turns with restricted headroom, high-sided vehicles can only use the left-hand lane of the western tunnel, so it was not possible to reverse the tidal flow in the evening. In April 2007, the morning tidal flow was discontinued, after reports by TfL and the Metropolitan Police (MPS) of an increase in dangerous motoring behaviour; these blamed poor driving, such as overtaking, for the decrease in safety during counterflow operations. The decision to end the counterflow was controversial, particularly as TfL and the MPS had been considering it since 2005, without properly informing affected borough councils, and an independent committee was set up to evaluate the decision. The ending of the counterflow system has brought protests from users of the tunnel and those experiencing increased congestion due to the change. In November 2007, the Mayor of London, Ken Livingstone responded to complaints from Greenwich Council about congestion in the area, with the possibility of setting up a small congestion charging zone. He clarified that this would not extend to the Blackwall Tunnel, stating "I have given that commitment right the way through my period as Mayor, and there cannot be anything that impacts on the A2 because the impact then on Lewisham is unacceptable." In 2012, TfL announced their intention to toll the tunnels to pay for the Silvertown Link crossing, suggesting it was the "most appropriate way". Responding to this, Paul Watters from the AA said "We’ve already seen the Western extension of the congestion charge dropped because it was hugely unpopular and I think tolling on the Blackwall Tunnel will be as controversial as that." In June 2013, TfL announced they would send registration details of any broken-down or over-height commercial vehicle in the tunnel to the Vehicle and Operator Services Agency (VOSA), and set up a new automatic recognition system to detect unsuitable heavy goods vehicles heading towards it. TfL commissioner Sir Peter Hendy said that "this partnership working will help improve traffic flow on one of the busiest routes in the capital." Maintenance and closures The Blackwall Tunnel has attracted criticism in the past for its perceived lack