The Thames Barge Driving Race under oars' or "sweeps" and ride tidal river currents alone, up river. The event commemorates the skills of lightermen who moved freight this way along the Thames up until the 1930s and in a wider context it encourages ongoing interest in moving cargo via water and as a way to recruit younger people back into river trades.The teams are normally made up of employees of Thames Lighterage companies, Port of London Authority or are sponsored by local businesses. The best places to view the race are Tower Bridge, London Bridge and Westminster Bridge. During the 1970s Britain suffered a major
Tunnels underneath the River Thames the Port of London, which until the 1980s required large ships to be able to access the river as far upstream as the City of London. Until the construction of the Queen Elizabeth II Bridge in 1991, the easternmost bridge on the Thames was Tower Bridge in central London. Even now, the Dartford Crossing provides the only way to cross the Thames by road between London and the sea (with predictable results for traffic congestion). The width of the river downstream meant that tunnels were the only options for crossings before improvements in technology allowed the construction of high bridges