with a maximum authorised mass of over 2 tonnes. Increased enforcement of these rules from early 2020 led to controversy about confusing signage, as some vans and similar vehicles had attracted fines. In the first 8 months of 2021, a total of 75,387 violations were issued, generating over £5m of revenue for TfL. The speed limit is and is enforced using average speed cameras. The tunnel bore was originally lined throughout with white glazed tiles, installed by two separate contractors, Boote's installed the tiling for north half and Edwards for the south. A band of brown tiles at the centre point of the tunnel demarcated the boundary. After repeated failures of the tiling in the southern half, these were removed in 2011 and replaced with a sprayed gunite surface, detracting significantly the look and feel of the tunnel. The shafts are lined with white glazed bricks, Shaw's installing them for shafts 3 and 4 on the north side and Stourbridge for shafts 1 and 2 on the south side. White glazed brickwork is used externally on the approach roads. A 2003 survey rated the tunnel the tenth most dangerous tunnel in Europe due to its poor safety features. Its proximity to the river also makes it vulnerable to flooding, as happened in the 1928 Thames flood. Usage Like many other London tunnels and bridges, the tunnel carries far more traffic than it was designed for. Shortly after opening 2,600 vehicles a day, mostly horse-drawn, and 14,000 pedestrians a day were using the tunnel – figures which were seen as easily justifying the expense of its construction. By 1955, usage had quadrupled to 10,500 vehicles a day and by 1997 usage had tripled again, to over 34,000 vehicles a day. The heavy usage, particularly during rush hours, can lead to significant congestion and tailbacks. The junctions at either side of the tunnel constrain further growth and therefore current traffic levels have remained at 1997 levels. Pedestrian numbers are now very low at around 20 per day, whilst cyclists number between 150 and 200 per day. The launch of the Ford Model T car only months after the tunnel opened initiated a rapid increase in car ownership and by the late 1920s motor vehicles had all but replaced horse-drawn vehicles, which were banned from the tunnel in 1952. The original ventilation system consisted of two fans supplying fresh air in each of