TRACK STRESSING AND EXPANSION

WHEN laid, track in the

UK is pre-stressed to 27°C allowing it to function within a temperature range of -10 and 35°C.

In hotter countries, that range is different. In Spain for example, where there was at least one recent heat-related derailment, the stress range is from 0-45°C, while in Saudi Arabia it is 10-55°C.

Network Rail has said it is neither practical nor cost effective to restress track for higher temperatures during the year, simply because of the rarity of extremely hot days, but says it is keeping a watching brief on the situation.

Track laid in concrete slab will provide even greater stability than concrete sleepers, but the costs compared to ballasted track are around four times higher.