Hand line construction in forests

Forest fires that can be controlled with hand tools spread relatively slowly, and provided crews work in a safe manner from a secure anchor point near the back of the fire and burn-out their fireline progressively as they go they should never have any need for fire shelters. In any case if the speed of the fire is such that the crew cannot walk to burnt ground or away from the fire they will not have time to build an adequate clearing to deploy their shelters. Once intensities exceed this limit it is obvious from spot fire behaviour that a change in fuel type, topography or weather conditions will be needed before suppression can be successful. When suppression is carried out on the flanks of fires or on backing fires on slopes the fire management and crew leaders must always assess the likely head fire behaviour up-slope and plan strategies to ensure crews work safely.

During fireline construction with hand tools, most heat experienced by firefighters is metabolic heat from their bodily exertions. Firefighter clothing should be light and designed to dissipate bodily heat while providing protection from low levels of radiant heat from the fire, sparks and abrasions (Budd et al. 1997). This clothing is not compatible with that required for withstanding high levels of radiant heat or entrapment. Firefighters constructing hand line self-pace themselves to work at elevated deep-body temperatures and small increases in environmental temperatures (from radiation or hot gases) may cause dizziness and collapse (Budd et al. 1997). Thus training of firefighters should emphasise that:

• only relatively low-intensity fires can be controlled directly or indirectly by known techniques;
• systematic fireline construction from an anchor-point must always allow firefighters rapid egress to a cool safe area at all times to protect against heat exhaustion let alone avoid entrapment; and,
• the crew leader must recognise the known situations where fire behaviour changes can occur rapidly with little warning.

Fire management teams must keep line firefighters fully informed about potential changes in fire weather and fire behaviour and be prepared to withdraw firefighters from the fireside well before these changes occur.