Are traffic lights in Canberra truly serving us, or are we stuck in a red-light district of overused infrastructure? A recent debate surrounding a proposed new set of lights on Drakeford Drive in Tuggeranong has sparked a crucial question: are traffic lights always the best solution? Let's dive into the science behind these often-maligned, yet essential, road features.
The National Transport Research Organisation (NTRO), a leading authority in transport solutions, has been advising Australian governments and companies for over 60 years. They're the go-to experts when it comes to understanding how we navigate our roads.
So, how are these traffic-controlling titans chosen? And why are they either loved or loathed?
The Hierarchy of Intersections
Australia's road design guidelines outline a clear hierarchy for intersections. These include:
- Uncontrolled (or unsignalised) intersections
- Roundabouts
- Signalised intersections (traffic lights)
- Grade-separated intersections
According to NTRO CEO Michael Caltabiano, this hierarchy represents an 'escalation' based on traffic volume and, importantly, risk. This risk considers pedestrians, cyclists, and overall active transport safety. Designers must consider the traffic volume on all 'legs' of an intersection, not just the main road, to determine the best solution for that specific location.
When Do Traffic Lights Get the Green Light?
For an uncontrolled intersection to graduate to traffic lights, the guidelines specify a critical threshold: at least 600 vehicles per hour on both roads.
Roundabouts: The Traffic Flow Architects
Roundabouts shine when traffic volumes are moderate to high and relatively balanced across all approaches. They work best when all four 'legs' of the intersection experience comparable traffic flow. However, they're not ideal when one road is a major thoroughfare and the others are smaller, unless there's a significant pedestrian or cyclist safety issue.
The Downsides of Traffic Lights
Traffic lights, while necessary in many cases, have a significant drawback: they stop traffic. The primary goal of traffic planners is to maintain safe and orderly traffic flow. Poorly placed traffic lights can also lead to 'rat runs,' where drivers seek alternative routes through residential streets, potentially overwhelming those smaller roads.
A Real-World Example: Drakeford Drive
The petition for new lights on Drakeford Drive highlights the complexities of these decisions. The petition's sponsor, ACT Labor member Caitlin Tough, cites increased traffic from new residential developments as creating a serious safety risk at the intersection of Drakeford Drive and Noorooma Street. The petition also mentions two fatal collisions at the site, one in 2011 and another in 2021.
However, according to Mr. Caltabiano, the traffic count on that section of Drakeford Drive is 'a fair way' from reaching the 600-vehicles-per-hour threshold. Additionally, a roundabout wouldn't be suitable due to the low traffic volume entering from Isabella Plains. The current crossing is a 'two-stage' crossing, designed to minimize risk by allowing drivers to focus on one direction of traffic at a time. In 2013, the government invested in improved line-marking and signage at the Noorooma Street intersection to enhance safety, and planners are likely to consider this a sufficient measure.
Looking Ahead
With Tuggeranong's population expected to grow by only 26,000 people by 2065, and with minimal residential growth in Isabella Plains, planners will consider these factors when evaluating the need for new traffic lights.
Mr. Caltabiano emphasizes that traffic lights in Canberra are generally well-placed and a necessary solution. He notes that the primary issue is the coordination of traffic lights, especially in the CBD area, which needs improvement.
But here's where it gets controversial: The article highlights the need for better coordination of traffic lights in the CBD. Could this be a sign of deeper issues in the city's traffic management strategy?
And this is the part most people miss: The decision to install traffic lights is not taken lightly. The cost is a major factor, meaning that they are only installed when truly warranted.
So, what do you think? Are traffic lights in Canberra overused? Do you agree with the current placement and coordination of traffic signals? Share your thoughts in the comments below!
