Whoopsie! Sydney’s road planners just discovered induced demand is a thing, after opening a new motorway.
For those outside Sydney, the New South Wales state government recently opened a new spaghetti intersection just west of Sydney’s Central Business District.
It was supposed to solve traffic. Instead, it’s turned into a giant car park:
"For the third straight day, motorists and bus passengers endured bumper-to-bumper traffic on the City West Link and Victoria Road. A trip from Haberfield to the Anzac Bridge on the City West Link averaged an agonising 44 minutes in the morning peak on Wednesday.
"Several months ago, Transport for NSW’s modelling had suggested traffic from the interchange would add only five to 10 minutes to trips on Victoria Road through Drummoyne and over the Iron Cove Bridge during morning peaks.
“Those travel delays have now blown out.”
So what do motorists say when their shiny new road that was supposed to solve traffic instead turns into a massive traffic jam?
‘Dude! Just one more lane!’
From the article:
"[Roads Minister John] Graham and his Transport boss Josh Murray appear reluctant to do what many motorists reckon is the obvious solution.
“That is, add lanes or make changes at the pinch-points that are causing the pain. A three-lane to one merge point from Victoria Road onto the Anzac Bridge, along with two lanes merging into one on the City West Link, are proving to be painful bottlenecks.”
#roads #traffic #cars @fuck_cars @sydneytrains @urbanism #urbanism #UrbanPlanning #motorways #fuckcars
The volume of cars is a scale factor that determines the impact of traffic causing behaviors and conditions for free flowing highways (no traffic lights, stop signs, etc.). Following too closely and improper lane changing are two specific behaviors that actually create slow downs. There are numerous models that simulate this.
Yes, yes, I’m well aware of how it works (I’m a former traffic engineer IRL). Although it’s true the behaviors trigger the slowdowns, it’s the traffic volume that creates the conditions where switching to the congested flow regime becomes possible.
In other words, if high traffic volumes aren’t present, those behaviors don’t have that consequence, and moreover, if high traffic volumes are present, the free-flow regime is such an unstable equilibrium that some kind of event (even one as minor as a driver briefly tapping their brakes) triggering a shift away from it and to the congested regime is inevitable. It’s the volume that’s the essential condition, not the behavior.