To all great teachers, everything tells a story. Half the time they are not even looking when they stumble on a rich seam of anecdote or insight. Lessons are everywhere for those with a mind to notice them. There are few people you will ever meet who exemplify this wonderful trait more than Dr David Woodward. He is the university lecturer you wished you had. But not to worry, because after a few moments in his company you will be a student again.
Dr Woodward is a Reader in Infrastructure Engineering at Belfast’s Ulster University – which he prefers to becoming a professor, as it gives him more freedom. For the last 34 years, he has been involved in civil engineering at the university, where he teaches subjects including highways engineering and geology. He has published more than 200 academic papers related to road construction materials and his research output reads like a pirate’s cave of (sometimes hidden) treasure.
Formula One racetracks, international conferences, teaching and the depths of Ulster University’s research lab, where he works with a wheel-over, wear testing machine that must weigh a couple of tonnes, but which he bought for £1, ‘literally’.
‘This thing [he says, standing with one arm on the machine like your typical Irish uncle, only half pretending not to be proud] was originally designed about 80-odd years ago by what is now TRL for some of the very first testing work in hot rolled asphalt and Macadam mixes. You make a slab of material for testing, put the resin on the surface of the asphalt slab, and then subject it to the rotating table device with two tyres. The thing’s air conditioned to 10 degrees. It’s like a fast walking speed so it’s slow speed, high stress and basically after 100,000 wheel passes, equivalent to about five years traffic, if you’ve got a good high friction surface, you’ve got no tread left in the tyres.’
If you hadn’t already guessed, he speaks with a lilt that makes even technical details fun to listen to.
He also works as the senior scientific officer at consultancy and testing specialists, R3, which allows him free rein to explore materials in racetracks, runways and roads the world over, as well as fire up the old wear testing machine.
‘We’ve done a lot of product development on this machine,’ he says proudly. ‘There’s 3mm aggregates, and high-friction blend and natural aggregates. You’re trying to decarbonise? The calcined bauxite for a highfriction surface typically comes from China, South America, or more recently India. So, can you develop some low carbon alternative? We developed a geopolymer version by taking waste and calcining it to a high temperature and then making a geopolymer out of it. Or you just blend in your good Chinese bauxite with a natural aggregate. Or you can just really push the boat and try out ideas, crazy things, stupid things that you know are going to fail.
Any examples?
‘Oh, there’s been some fantastic disasters,’ he laughs, almost more proudly.
Dr Woodward is a kind of restless traditionalist. He doesn’t hold much with newfangled gimmicks – stick with good aggregate and good bitumen, he argues; it’s worked well so far.
‘Pretty well all the innovation that we now have on our roads was done in the late 90s and early noughties,’ he says. ‘There is no fundamentally new material.’
However, he has recently discovered a passion for supercomputing, telematics, big data, and AI.
‘Basically, the thing that uses the road, that has to be the centre. The sensor in the car where the data is coming from… I’m totally sold on high-performance computing. It is the only way of working with the amount of data, to have a revolutionary step change in how UK roads are managed.’
Dr Woodward has a supercomputer at his disposal ‘our supercomputer, Kelvin 2’ which is shared by Ulster and Queen’s University Belfast. He says he ‘hasn’t learned how it use it yet’ – the kind of humility only a mastermind could perform – but argues that the computing job is best left to programmers. The cars provide the data, the engineers the questions and the programmers with their machine learning tools should provide the answers.
His dream is that mass data will finally break down the barriers between the components of the road grip conundrum – the road surface, the tyres, the cars, the weather… all of the variables – to reveal its mysteries. It is the interaction between these elements that has always been his obsession. Dr Woodward thinks of a road at the microscopic level. Literally where the rubber meets the road.
‘Well, the way I describe it is: if your head’s sticking out of a road…Right? If you can picture this. And a tyre drives over your head. What’s happening? That’s the way you should be thinking about this big cloud of data. Think about how the tyre is interacting with the surface.’
You might laugh – the delegates at the conferences do – but this is just an opening gambit to help you picture the situation. Dr Woodward is very serious: ‘I tend to get involved when things are starting to fail or they have failed. You go on site and there is a real arguing match and people pull out specifications that say this and that. “My specification says this”. And I say, your specification is not the same as what I see. This is the problem: pieces of paper and standard test methods.’
Which brings us to the story of his PhD and the SRN specification: ‘My PhD [Laboratory Prediction of Surfacing Aggregate Performance] basically proved that if you go for higher skid resistance, it doesn’t really matter what aggregate rock type you go for, there is something that gets progressively wrong with the aggregate. If you think about a piece of stone in a road surface, if the top layer of grains is wearing away quickly to give you grip, then you are losing the macro texture scale.
‘With SMAs and thin surface materials, how a tyre interacts with that is totally different to 20mm chips in hot rolled asphalt. That amount of wear doesn’t happen as quickly. But then you bring in variability in stone. So, you can have 99 good aggregate particles and one of poor quality, which very quickly wears out and is going to be affected at a greater rate, which creates a pocket of water. Then all of a sudden the one piece of stone is three or four stones and then your three or four stones become a pothole or a ravelling type of failure.’
So, what is the ultimate conclusion?
‘You don’t need high PSV aggregate. We did a three-year study, with TRL (and Highways Agency, or was it Highways England?) into the PSV test and produced a report and the basic conclusion of the report is that PSV is just a lab test. Standard PSV could be 65 – nice number to have in a quarry – if you put it under light traffic, it could be 68; if you put that under heavy braking and turning, that could be 60. This is what you are measuring with friction devices, you are measuring how the road reaches equilibrium in relation to how it is being used.
‘Back in the lab, we came up with a standard test and a very simple modified version – we just offset the tyre – and we had reductions of about 30 PSV points. I thought it was a brilliant piece of work. It just went into a cupboard and was forgotten about. That would have re-written the whole specification of aggregate, it would have re-written the whole assessment of skid resistance.’
Why was it forgotten? ‘The politics,’ he says, in terms of the difficulty of re-writing the specification. Plus, the fact that road operators don’t talk to the tyre companies.
None of the stakeholders involved in the grip problem seem to speak to each other, Dr Woodward says, so he talks and thinks for them until the supercomputers can do it for him. In this respect his predicament represents something wider than just the toils of his subject. He is on the brink of passing human imagination into machine learning – and as a great teacher, with a brilliantly free and questioning mind, people like him are the last, best hope that our imagination can survive the journey.
The great thing about discussing big ideas is it makes the world feel more vital and the reflected glow makes all of us feel important too. Anyone can move a mountain with a big enough idea. This is why Dr Woodward is such good company. To those who impart these big ideas, who can find endless fascination in everything upwards from the very bedrock of our planet, belongs the world and all the followers in it.
Though Dr Woodward is not the type to court followers. He is a little too ironic for that: ‘There is always something wrong with a great idea,’ he warns.
As for the stories: a favourite might be the time he came into contact with the late Nobel Prize winner Seamus Heaney by gatecrashing the stage of a play he was putting on.
I shouldn’t bore you with the details. Ask him yourself, if you ever have the honour of having a pint in his company.
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