Hot temperatures are unpleasant, and occasionally dangerous to work in for the average human, but extreme temperatures also have an important impact on rail networks.
The basic danger that extreme temperatures pose to rails is thermal expansion. Put simply: during hot weather, the steel rails expand, and they contract in the cold. This happens in all directions but are most noticeable in the direction of the rail.
Steel expands by about 11 mm per kilometre per one degree of warming. This can sound inconsequential but consider how long some of the rails are in Australia. The rail line from Darwin to Alice Springs is 1420 kilometres long, meaning a one-degree temperature change changes the length of that track by 16.2 metres.
Another challenge that occurs is rails through the Australian deserts must contend with wild temperature extremes. Clear desert skies often mean days are very warm, but nights are bitterly cold. Alice Springs for example has been as hot as 46°C and as cold as –7.5°C at contrasting times of year.
Steel, being a metal, is a great conductor of heat, and is more susceptible to temperature changes than the air. On the hottest days, rails can exceed 65 degrees in full sunlight. Going back to the Darwin to Alice Springs rail line, a temperature range of 75 degrees along the entire track can mean the track is 1.2 kilometres longer on a hot day versus a cold night.
Fortunately, the change from heavy concrete sleepers anchoring the track to the ground instead of the traditional wooden sleepers basically eliminates the overall movement cause by thermal expansion. These sleepers prevent the track from expanding along the entire length of the track, only allowing it to expand in the gap between sleepers. That transforms the expansion from 1.2 kilometres to just 7 thousandths of 1 millimetre.
That said, extreme temperatures do put stress on the rail network. It is common for speed restrictions to be enforced to minimise the stain on the rails, that can deteriorate and even break from the constant expansion and contraction.
DTN APAC supplies world-class temperature forecasts up to 14 days in advance to give business the most amount of warning when extreme temperatures are upcoming.
Image: 14-day temperature forecast for Port Hedland from a Weatherzone Dashboard
In real time, our dashboards can also supply alerts when the temperature exceeds your customised thresholds, so there is no wasted time in enforcing or retracting speed limits due to temperatures. To find out more about Weatherzone’s services, please email us at apac.sales@dtn.com.
