a few thoughts on the exciting world of social media

So how do you get from Shoreditch to the South Bank? Well, as Tom from Boris Watch pointed out, you take a number 243 bus. Or you wait 15 years – one way or another. Or you practice, baby. Or you get a haircut. Anyway, so much for taking the opportunity to reuse what I thought was quite a good joke. If journalism is the first draft of history – an ill-thought out exercise in speed-typing riddled with basic factual errors that aspires one day to be edited into ideological propaganda – and blogging is the first draft of journalism, then Twitter is evidently a lot of old cock.

I wanted to flag this article on how the tube map is a lie. Apparently, people tend to underestimate how long their routes will take when using the Beck map, not just tourists but natives (or as we call ’em round here, slightly less recent immigrants) too.

I think the explanation, and the fix, are as follows. Beck’s key insight was to analogise the system to an electrical circuit and draw a schematic diagram of it, showing the key components (stations) and how they interconnect. However, the problem is that we expect a map to show geographical information whereas the Beck map shows logical information.

The fix is, I think, to adopt cold potato routing. The Internet normally uses hot-potato routing – networks hand over traffic to each other at the first possible interconnection point, trying to get rid of it as soon as possible. This has some advantages – it avoids the situation where traffic for Network B is routed into Network A, carried across it, and then carried back towards its source because the furthest interconnect point has failed.

Occasionally this causes a pathological equilibrium – consider a network with customers on both coasts of the US and interconnections with another similar network. Under hot-potato routing, traffic from a customer of A on the East Coast to a customer of B on the West Coast could get routed into B on the East Coast, back out to A, and eventually into B on the West Coast.

Cold-potato routing is the opposite. You carry the traffic as far towards its destination as you can yourself, then hand it off. Roughly, cold is more efficient but hot is more robust. Basically, the recommendation from this would be to avoid changes as far as possible, including changing between modes of transport – which includes, of course, getting onto the tube in the first place. When everything breaks down – every five minutes – of course you can revert to hot potato to route around the break.

You’ll note that Tom’s solution gets it in a one-r.


  1. skidmarx

    Cycle.

    If one were travelling from the Post Office Tower to the London School of Economics in Houghton Street, the fastest way (at least before the abandonment of the Routemaster) was to take the Northern Line from Goodge Street to Charing Cross, followed by getting on the first bus eastbound along the Strand, quite hard to predict with any map.

    In an area that is tube-poor, say Mare Street in Hackney, the priority is to get onto the first piece of transport going in approximately the right direction, and if a bus, intersecting with a predictably timed rail service ASAP(a tube, or an overground service with a known timetable), as rail is almost always faster than bus (does make me wonder if Liverpool Street-Waterloo via Tottenham Court Road or Bank might do the original business, though I realise the interchanges cost).




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