12th June: The Rotherhithe Tunnel

On this date in 1908 the Rotherhithe Tunnel was opened. For those who aren't familiar with it, it's a tunnel under the River Thames.

1. The road which travels through the tunnel is the A101. The tunnel consists of a single bore, 4,860 feet (1,481m) long, carrying a two-lane carriageway 48 feet (14.5m) below the high-water level of the Thames, with a maximum depth of 75 feet (23m) below the surface.
2. It was designed by Sir Maurice Fitzmaurice, the Engineer to the London County Council, whose other projects during his career included the Woolwich foot tunnel and the Aswan Dam.
3. Authorisation to build a tunnel under the River Thames connecting Limehouse to Rotherhithe came from the Thames Tunnel (Rotherhithe and Ratcliff) Act 1900. The decision was very unpopular with local residents as about 3,000 of them were forced to move to make way for it.
4. Back in 1908, most traffic was Horse drawn - so that is what the tunnel was designed for. The ventilation shafts were not originally put there to deal with car fumes, but the smell of horse poo. Also part of the reason for the sharp bends is to stop horses bolting towards the light at the end, although another reason was to avoid the docks on either side of the river.
5. At the time of its construction, the tunnel was said to be the largest subaqueous tunnel in existence.
6. When it opened, 2,600 vehicles a day used the tunnel. By 2005 usage was over 34,000 vehicles a day.
7. And about 20 pedestrians. Surprisingly, the Rotherhithe Tunnel is open to pedestrians and it's perfectly legal to take a walk through it, though not a particularly pleasant one! The original ventilation shafts, or cupolas, decorative red brick buildings, have spiral staircases for pedestrian access, but they were closed after being damaged in World War II and have never re-opened.
8. The pedestrian walkways were originally designed for the people who had the unenviable task of shovelling up all the horse manure in the early days.
9. A 2003 survey rated the tunnel the tenth most dangerous tunnel in Europe due to its poor safety features. It's also vulnerable to flooding as happened in the 1928 Thames flood. The speed limit is 20 miles per hour (32 km/h), enforced with average speed cameras; and large vehicles are banned because of the sharp bends. It closes overnight once a week for inspection and maintenance.
10. There is a £1million project underway to provide the tunnel with a public address system and radio and mobile phone reception.