The Thames Barrier

Central London was last flooded in 1928. 14 people lost their lives as the Thames River overflowed its banks, the flow swelled by a tidal surge. Almost 50 years later, more than 300 people died when a storm surge in 1953 overwhelmed England's east coast before sweeping up the Thames Estuary. Such events prompted calls for a flood protection barrier on the lower reaches of the Thames. In 1966 a Government report recommended the instalation of a moveable wall.

However, it was another 14 years before such a barrier was finally completed. The Thames Barrier, sited eight kilometres downstream from Greenwich, finally swung into action in October 1982. Its ten movable gates are positioned end-to-end across the river, stretching for more than 500 metres. The rotating mechanism for each gate are housed in gleaming stainless steel covers reminiscent of Sydney's iconic Opera House.

The four largest gates each have an opening providing a clear width of 61 metres. Each main gate is constructed as a hollow steel-plated structure over 20 metres high, weighing with counterweights, about 3,700 tonnes. All ten gates remain on the river bed during normal 6.4 metres tides, rising only when tidal surges are forecast. The barrier has been used at least 92 times since it was first activated in February 1983.

On average the barrier is raised four times a year. However it's likely to get plenty of use in the coming decades. London is currently sinking at a rate of 60 cms every century. Add a little global warming and you're looking at a lot of rising tides! Some estimates suggest that the barrier could in use at least twice a month within twenty years.

Today I decided to see this modern engineering marvel for myself. The barrier is relatively easy to reach from Swiss Cottage. A 40-minute journey on the Jubilee Line takes you to Canning Town station. A quick escalator transfer to the Dockland Light Railway (DLR) gets you onto the new London City Airport line. The track runs on a series of raised pillars, with a new station convienently located just opposite the Thames Barrier.

The Barrier looks every bit as impressive as photos suggest. When I arrived this afternoon the tide was at its lowest point. You could see that the Thames has a remarkable tidal range at this point. After a brisk walk in the new Thames Barrier Park, I jumped back on the DLR and continued past the airport to the end of the new line. A short walk then took me to the Woolwich Ferry.

This is a free ferry crossing, one of only four such crossings still operating on the Thames. Ferries have been operating here since the 14th Century. Its remarkable that such a service still exists in the heart of a city the size of London. It's likely to disappear around 2013 when the proposed Thames Gateway bridge opens. A final decision on this bridge is expected some time this year.

The ferry was surpisingly busy. It was packed from end to end with cars and people. Rather than catch it myself, I decided to cross the Thames on foot using the Woolwich foot tunnel. This 504 metre pedestrian tunnel lies about 15 metres below the river bed. It was opened in 1912, and much like the Greenwich Foot Tunnel it was built to give South London workers swift access to employers in the city's docklands.

From the tunnel's south exit I joined the Capital Ring. This walking route circles the city linking more than 125 kms of urban pathways. I only walked six kilometres today, passing the southern shore of the Thames Barrier and eventually finishing at North Greenwich tube station. This section of the Capital Ring also marks the start of the Thames Path, another walking route that takes you 180 miles to the soure of the river itself.

The most dominant feature along this section of the Thames is the infamous Millennium Dome. Its bold white roof and tapering yellow support towers can be seen from almost any vantage point.The dome is currently being converted into an arena with capacity for 23,000 spectators. A shopping complex, hotel and casino are also planned.

These developments have been mired in political controversy, leading to the downfall of at least one Government Minister since our arrival in London. However, the dome does appear to be encouraging regeneration of the area, thus achieving at least one of its original goals. An array of colourful apartments are under construction in a style akin to that of Sydney's Meriton apartments.

The view today was spectacular. As I walked along the riverbank the dome was framed by the towers of Canary Wharf, which in turn were framed by dark, racing, winter clouds. All in all, a great afternoon exploring parts of London I've always wanted to see but never ventured into until now.