Four thoughts on TfL’s plans to colour code its bus routes

This one’s red. Image: Getty.

So, here’s a thing:

The short version: Transport for London (TfL) is trialling a new colour-coding system for bus routes. Each bus will get its own colour, which will be used on the “spider maps” showing bus routes around a particular area, as well as on signs at stops, and in big numbers on the side of each bus.

At the moment this is only a pilot. Initially, it’s been trialled on seven bus routes around Barkingside, out in the far east; in the summer, it’ll spread to Hayes in the west. But if it works, it could be rolled out further.

So – will it work? Some thoughts.


There aren’t that many colours

London has a lot of bus routes. A lot. Even excluding special services like night buses, school buses and so on, there are over 500 routes.

There are of course an infinite number of colours, so this wouldn’t be a problem – except that there’s a limit to the number the human eye can instantly distinguish. You can get away with a light blue and a dark blue; but throw in any more blues than that, and users have to consciously try to follow a line rather than simply see it at a glance.

One result of this is that no metro map in the world contains more than 15 shades; only a dozen use more than 10. (Lots more analysis on this stuff here.) So the implication that each bus will get an identifying colour like each tube line does is very clearly nonsense.

And buses cross each others’ paths

Not every bus needs a unique colour, of course: you can have multiple buses numbered in violet, providing they don’t go anywhere near each other.

The difficulty is they probably will – and TfL has started with an easy bit of town. There are only seven buses in Barkingside. It’s easy enough, then, to give them all a unique colour:

The Barkingside spider map: click to expand Image: TfL.

But five of those routes go to Ilford, where they cross paths with 12 more. Two of them go to Romford, from where they meet another 19 buses.

And the Romford one: click to expand. Image: TfL.

Even thinking about the maths does my head in – but it seems unlikely to me that every bus in London can be given a colour different from that of every bus it ever shares a stop with. At some bus stops, there’ll be two buses in violet.

The problem is the maps

That’s not necessarily a critical flaw: the big colourful numbers on the side of each bus will still help you when identifying buses from a distance. If a violet 25 and a violet 101 happen to share a stop at some point, well, those numbers look different enough that nobody’s going to confuse them. The colour coding will still be useful.

Except – those numbers aren’t just for the sides of buses, or the stop signs. They’re also meant to match those shown on spider maps, like those above.

I am unconvinced it will be possible to do this in such a way that no map needs to use the same colour for multiple different routes. In fact, I suspect it’ll happen rather a lot.

And I’m not sure a world in which three buses are shown on a single map in the same colour is one in which buses are more accessible than the world we’re living in now.

What about service flexibility?

There’s another issue. The whole point of rotating bus blinds is that the same bus can be used on several different routes. Historically, you’d turn a handle, and both the destination and the number shown on the front of the bus would change.

Old London bus blinds in the London Transport Museum. Image: Leif Jørgensen/Wikimedia.

This meant a degree of flexibility: if a bus broke down, another could be swapped over from a different route to plug the gap. Even today, when London’s bus services are provided by a dozen different companies, each of them generally runs enough routes to retain these advantages.

One quick way to remove this flexibility, though, is to paint the route number on the side of the bus in big colourful numbers, so that a 150 is a 150 is a 150.

I don’t want to be down on this idea. I think it sounds lovely: you’ll be able to spot your bus from further away, and giving bus routes colours should give them a stronger identity, something for people to latch onto. All this should make the bus network more usable to those who find it a bit intimidating.

But – I just can’t see how it’s going to work in practice. I’m sure it’ll work in Barkingside and Hayes. But how can it work in a network of over 500 buses?

I fear this may be one of those ideas where the theory is better than the reality.

You can read more on public transport map colour schemes here, if you so wish.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and also has a Facebook page now for some reason. 

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The IPPC report on the melting ice caps makes for terrifying reading

A Greeland iceberg, 2007. Image: Getty.

Earlier this year, the Intergovernmental Panel on Climate Change (IPCC) – the UN body responsible for communicating the science of climate breakdown – released its long-awaited Special Report on the Ocean and Cryosphere in a Changing Climate.

Based on almost 7,000 peer-reviewed research articles, the report is a cutting-edge crash course in how human-caused climate breakdown is changing our ice and oceans and what it means for humanity and the living planet. In a nutshell, the news isn’t good.

Cryosphere in decline

Most of us rarely come into contact with the cryosphere, but it is a critical part of our climate system. The term refers to the frozen parts of our planet – the great ice sheets of Greenland and Antarctica, the icebergs that break off and drift in the oceans, the glaciers on our high mountain ranges, our winter snow, the ice on lakes and the polar oceans, and the frozen ground in much of the Arctic landscape called permafrost.

The cryosphere is shrinking. Snow cover is reducing, glaciers and ice sheets are melting and permafrost is thawing. We’ve known this for most of my 25-year career, but the report highlights that melting is accelerating, with potentially disastrous consequences for humanity and marine and high mountain ecosystems.

At the moment, we’re on track to lose more than half of all the permafrost by the end of the century. Thousands of roads and buildings sit on this frozen soil – and their foundations are slowly transitioning to mud. Permafrost also stores almost twice the amount of carbon as is present in the atmosphere. While increased plant growth may be able to offset some of the release of carbon from newly thawed soils, much will be released to the atmosphere, significantly accelerating the pace of global heating.

Sea ice is declining rapidly, and an ice-free Arctic ocean will become a regular summer occurrence as things stand. Indigenous peoples who live in the Arctic are already having to change how they hunt and travel, and some coastal communities are already planning for relocation. Populations of seals, walruses, polar bears, whales and other mammals and sea birds who depend on the ice may crash if sea ice is regularly absent. And as water in its bright-white solid form is much more effective at reflecting heat from the sun, its rapid loss is also accelerating global heating.

Glaciers are also melting. If emissions continue on their current trajectory, smaller glaciers will shrink by more than 80 per cent by the end of the century. This retreat will place increasing strain on the hundreds of millions of people globally who rely on glaciers for water, agriculture, and power. Dangerous landslides, avalanches, rockfalls and floods will become increasingly normal in mountain areas.


Rising oceans, rising problems

All this melting ice means that sea levels are rising. While seas rose globally by around 15cm during the 20th century, they’re now rising more than twice as fast –- and this rate is accelerating.

Thanks to research from myself and others, we now better understand how Antarctica and Greenland’s ice sheets interact with the oceans. As a result, the latest report has upgraded its long-term estimates for how much sea level is expected to rise. Uncertainties still remain, but we’re headed for a rise of between 60 and 110cm by 2100.

Of course, sea level isn’t static. Intense rainfall and cyclones – themselves exacerbated by climate breakdown – can cause water to surge metres above the normal level. The IPCC’s report is very clear: these extreme storm surges we used to expect once per century will now be expected every year by mid-century. In addition to rapidly curbing emissions, we must invest millions to protect at-risk coastal and low-lying areas from flooding and loss of life.

Ocean ecosystems

Up to now, the ocean has taken up more than 90 per cent of the excess heat in the global climate system. Warming to date has already reduced the mixing between water layers and, as a consequence, has reduced the supply of oxygen and nutrients for marine life. By 2100 the ocean will take up five to seven times more heat than it has done in the past 50 years if we don’t change our emissions trajectory. Marine heatwaves are also projected to be more intense, last longer and occur 50 times more often. To top it off, the ocean is becoming more acidic as it continues to absorb a proportion of the carbon dioxide we emit.

Collectively, these pressures place marine life across the globe under unprecedented threat. Some species may move to new waters, but others less able to adapt will decline or even die out. This could cause major problems for communities that depend on local seafood. As it stands, coral reefs – beautiful ecosystems that support thousands of species – will be nearly totally wiped out by the end of the century.

Between the lines

While the document makes some striking statements, it is actually relatively conservative with its conclusions – perhaps because it had to be approved by the 195 nations that ratify the IPCC’s reports. Right now, I would expect that sea level rise and ice melt will occur faster than the report predicts. Ten years ago, I might have said the opposite. But the latest science is painting an increasingly grave picture for the future of our oceans and cryosphere – particularly if we carry on with “business as usual”.

The difference between 1.5°C and 2°C of heating is especially important for the icy poles, which warm much faster than the global average. At 1.5°C of warming, the probability of an ice-free September in the Arctic ocean is one in 100. But at 2°C, we’d expect to see this happening about one-third of the time. Rising sea levels, ocean warming and acidification, melting glaciers, and permafrost also will also happen faster – and with it, the risks to humanity and the living planet increase. It’s up to us and the leaders we choose to stem the rising tide of climate and ecological breakdown.

Mark Brandon, Professor of Polar Oceanography, The Open University.

This article is republished from The Conversation under a Creative Commons license. Read the original article.