Driver heat becomes an operational safety issue

Around 1,500 Arriva North London bus drivers took further industrial action in August amid concerns about excessive temperatures inside vehicle cabs.

Drivers and their union have argued that existing cooling arrangements are inadequate during extreme summer temperatures.

Whatever the eventual industrial outcome, the dispute raises a broader fleet-safety question.

Commercial fleets increasingly measure speed, harsh braking, fatigue, distraction, seatbelt use and mobile-phone use. But temperature, hydration and heat stress receive significantly less attention.

As extreme weather becomes a more regular operational challenge, that may change.