The way the humble road is designed and built today is vastly different to the dusty trails beaten in the early days of the motor car.
But how often do you think about the level of detail that goes into what might be perceived as slapping down some hot bitumen and flicking some paint over the top?
Australia has some of the most advanced road making capacities in the world, with ample resources and highly skilled engineers constantly studying the most efficient and effective methods to build our highways and byways.
AutoTalk was hosted by the Australian Road Resources Board (ARRB) at the shiny new Port Melbourne headquarters to listen and learn how the next wave of road makers acquire knowledge and experience in building the simplest C-road to designing major intersections and development projects as part of council and state government funding programmes.
The first thing to know is that there is so much more to know than could be crammed into one day, which is why the 30 or so beginners and mid-level engineers and all-round thinkers present on the day came from far and wide, including Geelong and east Gippsland.
ARRB senior technology leader David Milling, from Brisbane, and Noel O’Callaghan, the principal professional engineer with ARRB in Adelaide, hosted the two-day event, talking through the eight stages of Geometric Road Design.
“It’s about understanding how road design relates to road safety risks,” Milling says.
“We don’t do road design specifically, but we provide advice on getting safety systems into road designs,” he explains, using the example of drainage on modern toll roads and major highway upgrades which are shaped to specifically direct a vehicle over the top – and not roll the car – in the event it leaves the road.
And the conscious thinking about how to make a road as safe yet functional as possible doesn’t stop with cars.
Motorcyclists, considered a vulnerable road user along with cyclists, pedestrians and scooter riders, have to be accounted for, as do trucks from light rigid all the way up to double, triple and quad-trailer road trains.
How do you design a road that stops a road train from rolling, or keeps it from leaving the road at 100km/h, but also doesn’t allow light vehicles to be demolished if they do the same?
“We have to know how the road is catering for vehicles, what industry might be along the road, the budget to start with, and how heavy the traffic flow will be, then there’s the road classification,” Milling says.
More often than not, multiple designs will be made, which are then assessed, scrutinised and often simulated before it progresses into execution stages.
“We think about location, function and traffic, geometry the landscape might impose on the project such as slopes, soil type, flooding and water flow have to be taken into account; that determines what materials you may have to use,” he says.
Asphalt mix determines what kind of road noise vehicles will make when they run over it at certain speeds.
Milling explains a case on the Pacific Hwy in Brisbane and the Gold Coast where the wrong aggregate mix was used and residents over 200 metres away were furious at the noise generated.
“That was an expensive mistake which required resurfacing,” Milling reveals.
The correct kind of asphalt can save $100,000 per lane of every kilometre of construction, reduce 25% of the required thickness, which also saves greenhouse gas emissions during material and project construction.
“We also need to identify safety risks, traffic control and consider maintenance costs,” he adds, explaining how design teams will sometimes run cost analysis on whether a project can afford to extend the life and durability of the road by using premium materials, more cost effective designs and reducing or extending the time it takes to complete the construction.
“Humans as road users will continue to make mistakes, it’s inevitable, but the community shouldn’t be penalised when they do make mistakes,” Milling says.
“That said, we also need to consider emergency services who need access points when drivers do make mistakes, poor road design would force first responders to backtrack, perform unnecessary turns and be forced to sit in traffic,” he acknowledges, referring not only to wire rope barriers, but road shoulders, kerb designs, lane width and run-off areas.
Road design becomes as technical as thinking about effective drainage that reduces erosion, road degradation and eliminates aquaplaning.
One example shown looks like a fairly innocuous section of highway, but upon closer inspection could cause accidents, a prematurely deteriorating road surface and offers almost no room for an average family car to safely pull over out of harm’s way.
Choosing what type of crash barrier to use can be another quandary for road designers.
A simple design change in how the barrier is mounted to the road could determine whether a B-double truck slams into a semi-rigid barrier and grinds to a paint-scraping (but ultimately safe) halt, or snaps the steel railing like an old rubber band and sends it tumbling down a hillside.
For this reason, engineers have to carefully study crash energy on a range of vehicles, from light little hatchbacks which can bounce off angled bridge concrete posts and vertices, to high-roof coaches and flatbed rigid trucks or a Kenworth prime mover all of which have a high centre of gravity.
Some 19 different shapes, sizes and weights at anywhere from 50km/h up to 100km/h all behave differently and need to be accounted for.
“Often the design is modified during construction, but a good design will sort these issues out before construction,” O’Callaghan puts simply.
“The road needs to be consistent and uniform so there are no surprises to drivers; we need to look at how various elements combine; ideally you want to design a road that means drivers don’t make mistakes,” he adds.
“The role of the designer is to develop workable solutions to building new and upgrading old roads; it’s a combination of knowledge and experience, having one doesn’t always guarantee the other, which is why we use criteria, collaborate and study design parameters to continually improve how we design our roads.
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The ARRB started out as a small team with a 160-series Nissan Patrol with a primitive form of road scanning equipment bolted to the front.
There is now a full-scale laboratory testing every manner of road surface, a library full of books only an engineer would call engaging reading and a large team consulting with governments, road authorities and infrastructure businesses all working to build our towns and cities, and connect them.
Scientists analyse hundreds of rock samples on benches in state-of-the-art testing facilities.
But that’s a story for another day.
Next time you’re out on the same boring old road you use every day, take a closer look and appreciate the thinking and care that’s gone into help you get where you’re going.
It certainly beats a bumpy, dusty trail stamped out by horses and carts.
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