Three buses come along at once. Which should you take?

Typical. Bloody typical. Two London buses serving the same route, bunched up in the Clapton area. Image: Felix O, via Flickr.

It’s typical – you’re waiting at a bus stop for ages, then three buses come along at once. Should you just hop on the first one, or skip to the second or third? Various tech companies are trying to produce apps to help commuters plan for this type of event. But until those are up and running, some basic knowledge of the transport system – and a bit of mathematics – can help you make the call.

Studies have actually proven that buses which run at short intervals often cluster in threes. The theory goes that, when there’s been a delay, the first bus picks up all the waiting passengers: those who have been waiting for some time, and those who have only been there a few minutes and had planned to get a slightly later bus.

This brings about further delays, because – as we all know – more congested vehicles take longer to load and unload. So the first bus often gets caught in a vicious circle of delay and overcrowding.

The simple solution is to get on the second bus. It’s likely to be less crowded, and to arrive at its destination first. This is because bus operators often instruct the second bus to overtake the first, in order to minimise delays.

The risk in opting for the second bus is that the buses may have already changed order. Look to see if the road before your stop has multiple lanes, which could have allowed the second bus to overtake. And check to see if there are plenty of seats on the first bus – if there are, then jump on that one.


And what about the third bus? This should be avoided wherever possible, because two things, which could cause more problems, are likely to happen. It could be instructed to get in front of the first two buses by skipping a stop – which could be yours.

It could also be ordered to terminate before the advertised destination, so that it can return earlier and prevent the delays that the first bus could carry forward into the journey in the opposite direction, by replacing it.

The ConversationSo, when you’ve got to choose between a three buses, our advice is to target the second, consider the first and ignore the third.

Marcus Mayers, Visiting Research Fellow, University of Huddersfield and David Bamford, Professor of Operations Management, University of Huddersfield.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

Tackling toxic air in our cities is also a matter of social justice

Oh, lovely. Image: Getty.

Clean Air Zones are often dismissed by critics as socially unfair. The thinking goes that charging older and more polluting private cars will disproportionately impact lower income households who cannot afford expensive cleaner alternatives such as electric vehicles.

But this argument doesn’t consider who is most affected by polluted air. When comparing the latest deprivation data to nitrogen dioxide background concentration data, the relationship is clear: the most polluted areas are also disproportionately poorer.

In UK cities, 16 per cent of people living in the most polluted areas also live in one of the top 10 per cent most deprived neighbourhoods, against 2 per cent who live in the least deprived areas.

The graph below shows the average background concentration of NO2 compared against neighbourhoods ranked by deprivation. For all English cities in aggregate, pollution levels rise as neighbourhoods become more deprived (although interestingly this pattern doesn’t hold for more rural areas).

Average NO2 concentration and deprivation levels. Source: IMD, MHCLG (2019); background mapping for local authorities, Defra (2019).

The graph also shows the cities in which the gap in pollution concentration between the most and the least deprived areas is the highest, which includes some of the UK’s largest urban areas.  In Sheffield, Leeds and Birmingham, there is a respective 46, 42 and 33 per cent difference in NO2 concentration between the poorest and the wealthiest areas – almost double the national urban average gap, at around 26 per cent.

One possible explanation for these inequalities in exposure to toxic air is that low-income people are more likely to live near busy roads. Our data on roadside pollution suggests that, in London, 50 per cent of roads located in the most deprived areas are above legal limits, against 4 per cent in the least deprived. In a number of large cities (Birmingham, Manchester, Sheffield), none of the roads located in the least deprived areas are estimated to be breaching legal limits.

This has a knock-on impact on health. Poor quality air is known to cause health issues such as cardiovascular disease, lung cancer and asthma. Given the particularly poor quality of air in deprived areas, this is likely to contribute to the gap in health and life expectancy inequalities as well as economic ones between neighbourhoods.


The financial impact of policies such as clean air zones on poorer people is a valid concern. But it is not a justifiable reason for inaction. Mitigating policies such as scrappage schemes, which have been put in place in London, can deal with the former concern while still targeting an issue that disproportionately affects the poor.

As the Centre for Cities’ Cities Outlook report showed, people are dying across the country as a result of the air that they breathe. Clean air zones are one of a number of policies that cities can use to help reduce this, with benefits for their poorer residents in particular.

Valentine Quinio is a researcher at the Centre for Cities, on whose blog this post first appeared.