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Doug Wilson: The road to sustainable transportation

24 June 2021
Wilson’s expertise in roading and driver behaviour feeds into developing technologies to charge electric vehicles in motion.

In one sense, Doug Wilson’s story starts in New York in 1901. No, he wasn’t there. But in a photo he likes to refer to, taken of a major street there at the time, almost all the vehicles on the road are horse-drawn buggies. There’s one motor car. Ten years later, another photo of the same street shows the reverse – a lot of cars and one horse-drawn buggy.

That’s the kind of change the Waipapa Taumata Rau, University of Auckland senior lecturer wants to see now, on a similar timeframe.

In the 21st century, Wilson, a member of the Department of Civil and Environmental Engineering, wants people to move away from the internal combustion engine, not to it.

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Doug Wilson

His expertise isn’t in building electric vehicles (EVs), nor in wirelessly charging EVs – that’s more the remit of some of his University of Auckland colleagues such as Grant Covic. Still, Wilson is playing an important role in driving the electric car revolution.

Wilson is a transportation engineer and a founding member of the University’s Transportation Research Centre. His expertise lies in areas such as pavement materials, traffic flows, highway safety and driver behaviour. Over the years, UniServices has often helped him find industry partners and government funding for his research. In a world where his colleagues are developing ways for EVs to be charged as they drive, his is a crucial skill set.

If cars could be charged almost anywhere, the charging load could be spread out over the city and throughout the day. Cars wouldn’t have to be fully charged at home; just topped up.
“We need to make decisions now about assets that will be constructed over the next few years and that will last 50 years. If we get these decisions wrong, we’re going to have to live with those infrastructure systems over the long term.”

Doug Wilson

The price of getting the infrastructure wrong

Currently, EVs need to be plugged in. They make up only about 0.5 percent of the vehicle fleet in New Zealand, so the fact that they draw a lot of power, mostly when they’re plugged in at night, isn’t a big deal yet. That could be about to change.

A house draws about two kilowatts of electricity per hour, according to Covic. Plugging in an electric car at the slowest charge level also draws about two kilowatts an hour, doubling consumption. If a car arrives home with its battery completely depleted, it could take as long as 30 hours to fully charge at that level. Overnight charging requires around eight kilowatts an hour, which could overload the local transformer if there are many electric cars on a block doing the same thing.

Also, not everyone has a garage or private driveway. Plenty of people park on the street. Now imagine all those people running fat extension cords across the sidewalk. What if you use a wheelchair or push a pram? Clearly, for all the sustainability advantages of widespread EV adoption, there are challenges ahead.

“We need to make decisions now about assets that will be constructed over the next few years and that will last 50 years,” says Wilson. “If we get these decisions wrong, we’re going to have to live with those infrastructure systems over the long term.”

Wireless charging

Electric vehicle concept design

One of the key tools in making electric-vehicle cities run smoothly will be wireless charging, according to Wilson and his colleagues.

As a first step, that means making it easy for cars to be charged wherever they’re parked – after all, most cars are parked upwards of 90 percent of the time. At home, wireless charging would mean not having to worry about plugging in cords during downpours – a safety hazard – or about children tripping over cords as they play.

Wireless charging pads that sit over a driveway already exist. The next step, according to Wilson, is charging pads that are flush with the pavement. Having pads that don’t stick up would make them easier to use in car parks, which would enable cars to be charged at workplaces, malls and beaches. 

If cars could be charged almost anywhere, the charging load could be spread out over the city and throughout the day. Cars wouldn’t have to be fully charged at home; just topped up. That would solve the problem of big electricity draws at night and minimize future demands on the local network.

Charging moving vehicles

The next step in the EV revolution, which University of Auckland researchers are working on in partnership with the U.S.-based Advancing Sustainability through Powered Infrastructure for Roadway Electrification (ASPIRE), is charging vehicles as they’re being driven.

Dynamic charging isn’t just a cool idea – it’s a necessary part of getting an electric light and heavy vehicle fleet moving around the country, says Wilson. That’s because many trucks are on the move close to 24/7, with any down time being costly. Trucks also need a lot of power. Without the ability to top up efficiently on the move, electrifying trucks – currently big carbon emitters – may never make economic sense.

Simply putting charging pads flush with the road isn’t ideal because their different surfaces may make them slippery and cause crashes. Like maintenance holes, they may also cause road surfaces around them to crack and fail.

Putting charging pads below road surfaces isn’t easy, though, because overlying layers and increased distance reduce charging efficiency. Different road pavement types present challenges too. Concrete, often used in North America, is rigid and durable but expensive to build and repair. Asphalt mix, typically used in New Zealand cities, costs less but is thinner and more flexible than concrete. Because charging pads are rigid, asphalt mix may be prone to cracking around them.

Outside urban areas, New Zealand roads are mostly built of unbound granular pavements with only a thin layer of asphalt mix or bituminous surfacing on top. They’re the only economic option where traffic volumes are low.

However, they’re not good candidates for hosting charging pads, which need asphalt 15 to 22 centimetres deep to go around them. This may make it difficult to install dynamic charging lanes in rural areas outside higher-trafficked state highways, says Wilson.

There’s more to consider too. Where should dynamic charging lanes be located?

It probably makes most economic sense to have about a kilometre’s worth of charging pads in high-traffic-volume areas, particularly where vehicles have to go uphill.

However, which places should be prioritized? How should the infrastructure be paid for? Should charging lanes be toll lanes? If so, safety may become an increased concern as people change lanes to get into or avoid charging lanes. 

“Optimisation of all these things becomes very difficult in decision-making,” says Wilson. 

“The pace of change needs to be so much quicker than it’s been if we’re going to meet climate change targets and make well-informed decisions for the future.”

Doug Wilson

Encouraging change

Researchers are working on technical solutions, such as modelling changes to traffic flows and encapsulating charging pads into composite road pavement systems to make them more durable. However, to achieve the big-picture goal – lowering emissions – people’s behaviours must also change. Some of Wilson’s research, with a team that includes Tumanako Fa’aui, Tam Larkin, Andrea RaithPrakash RanjitkarBasil Sharp and Selena Sheng, focuses on encouraging that change.

An important part of lowering transportation emissions is reducing the distance people travel alone by car, says Wilson. That means designing cities to encourage people to live more local and travel more by foot, bike and micro-mobility solutions such as e-scooters. This may necessitate investing in safely designed paths. Another part of the solution is encouraging people to share travel more, which means making bus and train travel more efficient and planning future solutions such as shared autonomous shuttles to effectively connect people with public transit.

Even once EVs are widespread and transport emissions are reduced, traffic congestion will still be a problem. Wilson says we’ll have to carefully evaluate emerging technologies to ensure they don’t exacerbate the issue, as might occur if people use autonomous vehicles to go to work and then send empty cars home or off to find parking.

“Perverse outcomes can emerge if we don’t appropriately plan and manage the system,” says Wilson.

Wilson’s research takes a holistic view of future transport. He examines a range of sustainable modes of transportation as well as topics including congestion charges, transport-related taxes, and the social and well-being dimensions of transportation policies. All these areas need to be considered in the transition away from fossil fuels, says Wilson. 

“The pace of change needs to be so much quicker than it’s been if we’re going to meet climate change targets and make well-informed decisions for the future.”

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