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.

 
 
 
 

How collecting food waste could slow climate change – and save us money

Cleaning up. Image: Getty.

Food waste is a global problem, and one that’s driving climate change. Here in the UK, the country’s biodegradable waste goes to a landfill, where it breaks down to produce methane, a gas that is roughly 30 times as bad as carbon dioxide.

And yet there’s a simple solution. With the exception of garden waste, which often contains lignin from woody matter, all biodegradable materials, including much of our food waste, could instead be processed in anaerobic digesters. This decomposition in an atmosphere devoid of oxygen produces biogas, which can then be used to generate heat and electricity.

This is more or less the same process that takes place in landfill sites, except that the biogas can’t escape from an anaerobic digester as it can from landfill – meaning the breakdown of the organic matter takes place in an environment that is enclosed and controlled.

The result is biogas consisting of 60 per cent methane and 40 per cent carbon dioxide, which can be burnt in order to generate heat or used as a fuel for vehicles. It could also be used to generate electricity after the biogas has been scrubbed, which can then either power the anaerobic digester or be exported to the national grid. The process also produces digestate, a solid and liquid residue that can be returned to farmland as a soil conditioner. The amount of biogas and the quality of digestate varies according to what feedstock is used in the digester.

This process is already widely used both across Europe – particularly in Denmark, Sweden, Germany and Austria – and elsewhere globally, particularly in India and Thailand. What's more, this move towards separate food waste collection is already happening in countries outside the UK, and its momentum is increasing according to the World Biogas Association. Already, major cities, including New York, Paris, Oslo, Copenhagen, Auckland, San Francisco, Mexico City and many others are regularly collecting food waste from their citizens. The decisions to do so are usually taken at city level, but enabling legislation from national governments assist in this.


At present the UK is lagging behind. Only 109 local authorities in England, about 33 per cent of the total number, collect food waste as of May 2018, according to the Anaerobic Digestion and Bioresources Association (ADBA). Yet making a separate food waste collection mandatory across the UK and running the food waste through anaerobic digesters, could supply enough biogas to generate 36 per cent of UK electricity, according to a 2007 Friends of the Earth report. This percentage could be increased again if food waste from restaurants, cafeteria and retailers was also collected. 

ADBA’s research also suggests that universal separate household food waste collections would trigger the construction of around 80 new anaerobic digester plants for food waste processing. This would add an extra 187 megawatts equivalent (MWe) of capacity, powering 285,000 extra homes – representing all the homes in a city the size of Glasgow. Data from WRAP suggests that further food waste collection from businesses would add around a further 10 per cent, depending on the quality of the feedstock collected and what exemptions were applied (for example, it might only apply to businesses collecting more than 50 kilograms per week or the lower threshold of 5kg).

A 38 per cent improvement in food waste collection from flats in Ealing alone could generate £26,000 of annual savings for the London borough, £28,000 in revenue for a local anaerobic digester (based on electricity sales to the national grid) and reductions in carbon dioxide emissions of around 270 tonnes, found Londoners Lab, a collaborative project consisting of Greater London Authority, University College London, Ferrovial Services Centre of Excellence for Cities and Future Cities Catapult.

ADBA has been campaigning on this issue for a while, but the good news is that the government finally signalled its intention to introduce separate food waste collections in its forthcoming Resources & Waste Strategy, which will ensure that all homes and suitable businesses in England will have access to food waste collections by 2023. The next step, following the government announcement, is a consultation, but it is widely acknowledged that additional funding would be needed by local authorities to achieve this, as the business case isn’t currently strong enough.