Putting buses at the heart of air quality


The 5th Annual UK Bus Summit welcomed over 250 delegates to the QEII Centre in London, last week. The UK Bus Summit is the premier bus event covering all parts of the UK. Held right at the heart of Westminster to elevate the importance of bus at the centre of local and national decision making, the event allows the opportunity to compare and contrast bus policy throughout England, Scotland, Wales and Northern Ireland.

"Putting buses at the heart of air quality" was the theme of the fourth and final session of the UK Bus Summit earlier this month. David Fowler reports on this below.

Of all the challenges facing the bus industry, air quality is one of the biggest. "I think it is both a risk and an opportunity," said Stagecoach UK Bus managing director Mark Threapleton, opening the final session of the 2019 UK Bus Summit. "The difference depends on how we tackle it."

An estimated 40,000 premature deaths annually in the UK are attributed to poor air quality.

"We as operators fully recognise that something needs to be done and done quickly, and we need to be at the heart of a solution," he added.

In the short-term, however, diesel power would have to bridge the gap until the challenges surrounding zero-emission technology were fully resolved.

"The local bus is not the cause of the problem," he continued, "but part of the solution. But in too many areas the value of the bus is not recognised. There is a more urgent need than ever for local and national bodies to form partnerships to integrate buses into air quality strategy."

Because one bus had the capacity of up to 75 cars, encouraging more people to travel by bus had the potential to reduce the air quality problem.

"But converting all buses to Euro VI or zero emissions will not solve the problem on its own, because of congestion," Mr Threapleton said. In nose-to-tail traffic emissions rose fourfold, he said.

And though the move to non-diesel vehicles was inevitable, there were a number of significant barriers to be overcome before the adoption of electric buses became widespread.

The main one was the upfront cost of an electric bus, twice that of a diesel bus. Battery prices were beginning to fall but it was estimated that it cold be another 10 years before upgrade costs reached parity.

Second was obsolescence. Some recent hybrids were considered obsolete after six years compared with a normal expected life of 15 years. Third, "many local electricity networks do not offer the capacity required to sustain an electric vehicle fleet". This would require substantial investment in infrastructure such as substations. "All these can be overcome, but not quickly or cheaply," he said.

And to overcome congestion "there need to be radical decisions on road space to favour high capacity vehicles', he said. "Local authorities need to be brave to encourage modal shift, and operators need to be brave and take risks. I'm convinced the only way to tackle congestion and air quality is a partnership of equals," he concluded.

Birmingham City Council cabinet member for transport and environment Cllr Waseem Zaffar said Birmingham was a city with an ambitious growth strategy, whose population was forecast to grow by 150,000 by 2031. This would make the role of the bus "crucial".

The city was currently over-reliant on cars. 61% of journeys to work were by car; a quarter of journeys every day were less than a mile. As much as 83% of Birmingham's vehicle fleet were cars, and 46% of these were diesels.

The city was one of five that had been required by ministers to develop plans for a clean air zone. This would be targeted on the A4540, to improve air quality in the area of highest exceedance in the shortest possible time, and including bus priority lane enforcement and traffic management systems to prioritise buses, as well as introducing controlled parking zones.

An air quality strategy, in collaboration with Transport for West Midlands and Tyseley Energy Park, would go beyond that. This would be a city-wide policy framework, with modal shift to public transport as a focus. Introduction of bus priority measures more widely would be a priority.

"Birmingham has until now shied away from re-allocating road space," Mr Zaffar said.

The council was collaborating with Tyseley Energy Park to create the first of a network of low/zero emission refuelling hubs for commercial vehicles including buses, and with TfL, other cities and bus operators to introduce 20 hydrogen buses in Birmingham by 2020.

"People jumping into cars to go round the corner has to stop," he said. "We want people to get on to public transport, walk or cycle." Buses were vital to that aim, but in turn this meant reliable bus journeys were essential.

Glasgow City Council convenor for sustainability and carbon reduction Anna Richardson said that Glasgow had a low level of car ownership, at just under 50%. Monitoring showed that air quality was improving. "The measures we've taken are working, but not quickly enough," she said, "especially for NOx in the city centre."

In September 2017 the council made a commitment to introduce a low emission zone by 2018, a policy which was primarily about health and tackling inequality. But Ms Richardson had insisted on taking an evidence-based approach to the implementation of the LEZ.

Initial modelling work showed that buses were the main contributor to the problem, she added. "The most effective way to reduce the number of air quality breaches was to upgrade all buses operating in the city centre to Euro VI standard."

Over the next four years the city will require incremental improvement. "By 31 December, 20% of bus journeys through Glasgow will have to be in Euro VI vehicles," she said. By December 2022 all buses will have to comply, and by the same date all vehicles in the city centre will be subject to the LEZ. She added that at the time of devising the policy, only 12-14% of buses in Glasgow were Euro VI, with a significant proportion still Euro III or IV.

"We were all conscious of possible unintended consequences that might affect our more vulnerable communities the hardest," she continued.

"We worked in partnership with the bus operators to make sure that we didn't put in place requirements that could lead to routes being cut or fares being increased. For many neighbourhoods the bus service is a lifeline, so it was crucial that the LEZ was brought in at a realistic pace."

The council will introduce bus priority measures to reduce journey times.

The Glasgow Bus Partnership was established last year, to develop shared objectives and allow the council and operators to work together more constructively, with better use of data to drive improvements.

In pursuit of more sustainable transport, the council could implement policies to discourage car use, through parking policies or road re-allocation, "but the bus network must be there as a backbone, " she said.

"It could be deemed a success if every vehicle in the city became low or zero emission. But if we still have the same number of private cars on our roads, we will still have slow bus journeys and congested unwelcoming streets. We cannot treat the LEZ as a magic bullet, but it can be a crucial part of wider strategic thinking that will change the transport choices that Glasgow can take, with bus as an essential key player."

Diesel engine manufacturer Cummins celebrated its 100th anniversary on the day of the conference. Cummins Europe director of certification and compliance Peter Williams described how the company had responded to emissions legislation and what it planned for the future.

With the introduction of Euro VI in 2013, the permitted level of NOx emissions was reduced by 80% from Euro V, and particulate material by 50%. Mr Williams pointed out that the regulations called for compliance over a range of operating conditions and that the manufacturer continued to be responsible for compliance for the engine's useful life – 300,000km or six years.

In on-road emissions testing Cummins engines performed at around 50% below the Euro VI limit for NOx. A bus emitted less NOx than a car – 0.5g/km compared with 0.8g/km – despite being heavier and carrying more passengers.

The regulations continued to evolve. Euro VI phase D, in September, would focus on urban operation and phase E, in 2021, would include an in-use cold start test and tighten up on particle measurement. Euro VII was being developed for 2026.

"This is challenging but as a technology provider we welcome the challenge," he said.

Particulate emissions are moving towards effectively zero, with 99% being eliminated at Euro VI.

Meanwhile stop/start technology on a non-hybrid bus eliminated 8.5 minutes of idling hourly (on a London duty cycle with 20 stops) and saved up to 8% of fuel. A diesel/electric hybrid typically reduced emissions (NOx and CO2) and fuel consumption by 33%.

Cummins had developed a Euro VI re-power package, fully certified to Phase D, which would allow any existing bus to operate in London's ultra-low emission zone.

And the company was embracing energy diversity by investing $500m in alternative powertrains – electric and CNG – to complement diesel.

Optare commercial director Robert Drewery looked back on a decade of development of electric buses. The company's EV Solo was introduced in March 2009. It had 50 miles range, carried 35 passengers and stored 80 kWh of energy. It used a diesel-powered heater.

The latest generation of electric bus would go into service in March, with a range of 150 miles, capacity to carry 60 passengers and with 240 kWh.

He summarised the lessons learned. First, "electric buses deliver". Experience showed that they achieved over 95% availability and could operate for 15 hours a day, which would rise to 18 "before long". Electric buses were initially favoured on park and ride routes, which were short and allowed opportunity charging at each end of the route; now they could cope with everything from park and ride to Transport for London operations.

Charging remained operationally the biggest challenge, Mr Drewery said, adding that "less is more". Charging ages batteries – the faster the charge the shorter the battery life. Fast charging or high charge demand is also expensive. In the early days a lot of opportunity charging had been used, but now the focus was moving to overnight charging.

Efficiency remains key. Bus battery energy is a precious resource. This is made even more acute by the fact that diesel-powered heating is no longer acceptable and electric, zero emission heating is expected. Future developments will depend on lightweight platforms with efficient drivelines and systems, Mr Drewery predicted.

Meanwhile innovation is accelerating, with impetus provided by the clean air agenda. Developments from electric car manufacturers have also helped, he said. "With the arrival of Tesla, the industry woke up and realised 'electric vehicles are doable'," he said. Involvement by tier one suppliers will improve quality and aftermarket care and drive down costs. And battery chemistry is improving, doubling energy density every 15 years.

Costs are coming down. The battery accounts for 50% of the cost premium of electric buses. But costs per kWh more than halved between 2010 and 2017, and it is predicted they will reach €100/ kWh by 2025, reducing the electric vehicle premium by 35%. Volume production will bring additional savings and whole-life costs are being reduced through extended warranties.

Mr Drewery predicted that in the next decade there would be a 30% increase in available energy, allowing over 200 miles on a single charge. Whole life costs would be less than for diesel. "Technology will deliver and we'll overcome the challenges," he said.