Author: Oliver O'Brien

I was recently able to have a behind-the-scenes tour of the huge Thames Barrier structure in east London, thanks to the IET London branch – I’m not a member of the IET (although I used to be) but spotted a tweet from them advertising the tour, so was able to sign up.

As an “engineering” tour, we were able to get right onto the barrier itself, onto one of the “piers” in the middle of the river. Accessing this is fairly involved. The operational site is under very high security indeed, as befits the importance of the barrier during a flood event and the impact that an uncontrolled flood would have on various critical parts of central London, including the Canary Wharf financial district and the South Bank. Once in, getting to the pier involves crossing a short bridge over the first barrier section that is in fact completely dry at low tide) and then accessing one of two tunnels that run almost completely underneath the Thames, with stairs (for the west tunnel) or lifts (for the east tunnel) linking to the piers themselves. The two tunnels are completely separate from each other, for redundancy/safety reasons, so if one of the tunnels was breached, full access to all the piers would still be possible. The tunnels are fairly small, they have reinforced rings like a tube tunnel, but are quite a bit smaller, and contain numerous ducting cables and pipes. They are dead straight, so looking down one makes for quite an eye-catching vista.

Each pier has two “hull like” buildings which are silvery on the outside, but surprisingly made of wood on the inside. The smaller one houses the top of the aforementioned lift shafts, while the larger one houses the machinery for rotating the huge barrier pieces. Normally, a close or open event takes a couple of hours – in fact, the barrier is quite capable of closing in a couple of minutes, but this is never used, partially because tidal events are fairly predictable with around 24 hours notice (being based on tide, wind direction, upstream flow and air pressure) and partially because a sudden closure/opening would have a negative impact on the ecosystem of the river – likely impacting flora/fauna in the river, and structures on the the banks (I presume this is from sudden changes in water salinity, level or pressure).

The larger pier building also has an attractive circular window, facing upstream. From the river, it is quite a distinctive feature of the barrier as you approach it. The circular shape again is a play on the barrier piers having a boat theme.

The equipment in the piers is large and impressive. Some of it looks pretty old – the Thames having been built in the 1980s but designed in the 1970s, based on 1960s technology that had to be “proven” for a decade before, so harking back to the 1950s. But it is kept in great working order and does the job well – which is just as well, as the barrier had to close during the Spring 2014 floods nearly 50 times – almost as many times as it had closed in the preceding 30 years.

Anyway, it was a fascinating tour, and thanks to the IET London branch for organising. The tour guides were retired engineers who had worked on the barrier itself for many years, so it was very informative visit.

Stations on the tube map with multiple lines are normally shown with a white circle (except where obscured by a disabled access blob) indicating connections where you can change lines there, while continuing on a single journey (and so not have to pay for two). However, there are a number of connections not shown on the map. These are Out of Station Interchanges (OSIs) and generally involve a walk out through ticket barriers, along a road or two, and back through more barriers. However, TfL will do the maths to ensure that you still only get charged for a single journey altogether – so long as you don’t spend too long a time between the two sets of barriers. TfL is quite secretive about these “hidden” free interchanges, likely because marking/highlighting the links and limit times would be tedious* so the current list is maintained by frequent Freedom of Information Requests. I’ve taken the current list, excluded interchanges with National Rail, and added the remaining (TfL to TfL) OSIs to my Tube Data Map. The OSIs are shown by white circles, connected together with white lines and black borders. There are a few more, where I’ve already joined OSI-linked stations as being actually in the same place. Sometimes you can leave and then reenter barriers within a single barriered area – for instance, you can leave the barriers at Bank and go back in them at Monument, without paying for two journeys (so long as you take less than 15 minutes to do so). However you can also get between the two stations while staying behind the barriers. N.B. If you change the date to 2019 then it shows the OSIs that will likely be added for Crossrail, when the central section starts running then.

Many of the OSIs are for links between the Underground and Overground, as the latter network is not otherwise particularly well connected. The longest Tfl-TfL OSI is from West Ruislip to Ickenham, in outer west London – it’s over a kilometre to walk between the two, but the link helps Central Line uses get easily to and from the transport hub at Uxbridge.

* They do however highlight a few at stations, e.g. Clapham High-Street to Clapham north. Some others have some street-signs pointing the way, e.g. Seven Sisters to South Tottenham.

Map background from HERE maps.

A friend forwarded me this article which discusses this paper by researchers at the Yahoo Labs offices in Barcelona and the University of Turin. The basic idea is that they crowdsourced prettiness of places in central London, via either/or pairs photographs, to build up a field of attractiveness, then adjusted a router based on this map, to divert people along prettier, happier or quieter routes from A to B, comparing them with the shortest pedestrian routes. The data was augmented with Flickr photographs with associated locations and appropriate locations. and The article that featured this paper walked the routes and gives some commentary on the success.

Quantitatively building attractive routes is a great idea and one which is only possible with large amounts of user-submitted data – hence the photos. It reminds me of CycleStreets, whose journey planner, for cyclists, not only picks the quickest route, but adds in a quieter (and “best of both worlds”) alternative. Judging locations by their attractiveness also made me think of the (soon to be retired) ScenicOrNot project from MySociety which covered the whole of the UK, but at a much less fine-grained scale – and without the either/or normalisation.

In the particular example that the paper uses, the routes are calculated from Euston Square Station, which happens to be just around the corner from work here, to the Tate Modern gallery. It’s a little over 2 miles by the fastest route, and the alternatives calculated are only a little longer:

Above: Figure from http://dx.doi.org/10.1145/2631775.2631799

I really like the concept and hope it gets taken further – for more places and more cities. However, I would contend that local knowledge, for now, still wins the day. The scenic route misses out the Millennium Bridge which is surely one of the most scenic spots in all of London with its framed views to St Paul’s Cathedral and the Tate Modern itself. The quiet route does go this way, but the route is far from quiet when you consider the hordes of tourists normally near the cathedral and on the bridge. The pretty route goes down Kingsway which is a pretty ugly, heavily trafficked route, ignoring the nearby Lincoln Inns Fields, which is lovely. I think that the following, manually curated 3.0 mile route wins out as a much more beautiful route than the algorithmically calculated one:

Highlights include:

• Walking through UCL’s Front Quad, through the university campus
• Down Malet Street, past the imposing Senate House
• Walking through the Great Hall of the British Museum
• Bloomsbury Square garden and Lincoln’s Inn Fields
• Chancery Lane
• New Street Square (modern but attractive)
• The statue of Hodge, Dr Johnson’s Cat
• Wine Office Court, with the Ye Olde Cheshire Cheese Pub
• Fleet Street and Ludgate Hill, with the famous view to St Pauls
• The vista from St Paul’s Cathedral, across the Millennium Bridge to the Tate Modern.

Maps in this article are © Google Maps.