Solving a Hunter Valley dust mystery – with maths

Tracking dust

Statisticians have revealed the surprising source of dust that plagues townships beside a Hunter Valley rail line delivering coal to Newcastle’s busy port.

Airborne dust increases as trains pass. But it wasn’t clear exactly how—for example, whether the dust was escaping uncovered coal wagons or coming from the diesel engines pulling the wagons. The answer was surprising.

Mathematicians from the ARC Centre of Excellence for Mathematical and Statistical Frontiers correlated air-pollution data against information on passing trains and weather conditions.

Professor Louise Ryan from the University of Technology, Sydney and other Centre analysts built a complex, fine-tuned model of interdependent factors.

They found that airborne dust increased by the same amount whether passing coal trains were empty or full, and the dust increased the same amount when heavy freight trains passed as when coal trains passed. Shorter passenger trains didn’t increase dust by same amount and it wasn’t related to the number of diesel locomotives.

The most likely explanation, they found, was that the measured increase in airborne dust as trains passed was being caused by vibrations and turbulence from the trains’ passing throwing up dust from the tracks and the ground.

This information will enable policymakers and train operators to focus their efforts to reduce dust.

Read about more work from the Centre here.