Are traffic lights overused in Canberra? Photo: James Coleman.
Most traffic lights in the ACT are correctly placed – but a national transport research body says that will change if a new set on Tuggeranong’s Drakeford Drive is approved.
The National Transport Research Organisation (NTRO) has offered “innovative research and practical solutions across all modes of transport including roads, rail, ports and airports” to Australian governments and companies for more than 60 years.
With a petition currently before the ACT Government for new lights to be installed at the intersection of Drakeford Drive and Noorooma Street in Isabella Plains, we decided to pick NTRO CEO Michael Caltabiano’s brains about how traffic lights are chosen – and why they’re either loved or loathed.
How are traffic lights chosen? Over say, roundabouts?
Australia road design guidelines lay out four levels of intersections – including uncontrolled (or unsignalised), roundabouts, signalised and grade-separated.
“That’s a sort of escalation as a consequence of traffic growth, but also risk: Are there pedestrians, are there cyclists – is there an active transport risk?” Mr Caltabiano says.
“Designers have to balance volume increases on all of the intersection’s ‘legs’ – so it’s not just about one main thoroughfare – and choose a solution based on the needs of that specific location.”
For an uncontrolled intersection to become a signalised intersection, the guidelines stipulate that volume on both roads has to reach at least 600 vehicles per hour.
“That triggers the start of looking at signalisation.”
Roundabouts only work when all streets carry comparable levels of traffic. Photo: Michelle Kroll.
Where do roundabouts fit in?
“Roundabouts are a great measure for distributing moderate to high, balanced volumes of traffic – so roundabouts function where all four legs have an equivalent volume of traffic,” Mr Caltabiano explains.
“They don’t tend to function very well when there’s a main road and little side roads – that’s not what they’re designed for, unless there’s an overarching pedestrian or cyclist problem.”
And the cons to traffic lights?
“They stop traffic. Planners should be aiming to keep traffic moving in a safe and orderly way – that’s the highest order priority – and they’ve got to use the mechanisms and tools available to them to keep the traffic moving in a safe and effective way.”
Poorly placed traffic lights also have knock-on effects like pushing motorists to use rat runs through adjacent streets – increasing pressure on smaller streets that are really not up to the job.
Badly placed traffic lights can cause more problems than they fix. Photo: James Coleman.
Can I have an example?
In the petition for the new Drakeford Drive lights, the sponsoring ACT Labor member Caitlin Tough writes that “newer residential developments in the area have increased traffic along Drakeford Drive and surrounding streets” to the point the intersection has become “a serious safety risk”.
“During peak hours, the only way many motorists can cross is by dangerously accelerating beyond the speed limit to make it through momentary gaps in traffic,” it reads.
The petition also cites two fatal collisions at the site, one in 2011 involving an 18-year-old boy on a motorbike, and another in 2021 involving a 78-year-old woman in a two-car crash.
The petition currently has five signatures – well short of the 500 it needs to be tabled within the ACT Legislative Assembly. But using what we’ve learnt so far, there’s another reason it probably won’t get up.
Mr Caltabiano lives around the corner from this intersection and says while the NTRO doesn’t have the traffic-count data, anecdotally, that portion of Drakeford Drive is “a fair way” from reaching the 600-vehicles-per-hour point.
A roundabout wouldn’t work either, because “only very small amounts of traffic” are entering from Isabella Plains.
“You’ve also got Isabella Drive and Johnson Road to the north and to the south of this, which are big roundabouts to circulate traffic … and you’ve got multiple outlets in Isabella Plains to get to those big roundabouts.”
Noorooma Street and Drakeford Drive is what’s called a “two-stage” intersection. Photo: Screenshot, Google Maps.
The current crossing is called a “two-stage” crossing, where motorists only have to cross one carriageway at a time.
“So you focus on just looking at traffic coming on your right, you cross to the middle, and then you focus left.”
In 2013, the government poured about $20,000 of Black Spot Program funding into the Noorooma Street intersection for better line-marking and signage to improve safety, and Mr Caltabiano says it’s likely the planners will conclude it’s still up to the job.
“They’ll have a look at the Isabella Drive roundabout and the Johnson Drive roundabout and how Noorooma Street feeds into that, they’ll look at generators of traffic – so if there’s a school or aged-care facility nearby, and they’ll come down and literally count traffic.”
Additional line-marking and signage was installed along Noorooma Street in 2013 to improve safety. Photo: Screenshot, Google Maps.
According to the Australia Bureau of Statistic’s latest growth predictions for the ACT, Tuggeranong is only expected to grow by 26,000 people by 2065 (91,387 to 117,994).
And honing in on Isabella Plains, only about 150 houses have been added to the suburb in the past 15 years.
“So there’s not a lot of residential growth expected, and that’s one of the things planners will look at … It’s never just one thing, ever.”
So why so much hate for Drakeford Drive (and Hindmarsh Drive) then?
Mr Caltabiano says the track record is good for most of the ACT’s traffic lights being the best solution to whatever problem was there before.
“They’re very expensive as well, so nobody’s going to make a multi-million-dollar decision to put in traffic lights where they’re not warranted.”
But it’s not quite a perfect score for the ACT’s planners.
“The only issue in Canberra with traffic lights is the coordination of the traffic lights, particularly in the CBD area. And that needs massive improvement.
“But the location of them and the purpose of them – I’ve not heard of any issues with that.”
