A wildfire suppression hand line is any fireline which is built with hand tools, such as chainsaws and shovels. The purpose of a fireline is to keep a wildfire from spreading by removing all ignitable material in a wide strip which crosses its path. Most hand lines are built downwind from the main fire, although hand lines are also built to the sides of the fire, where it is not actively burning, to limit its spread. Building these side hand lines is known as cold trailing.
Hand crews are specially trained in the making of hand lines. There are 20 firefighters in each ordinary handcrew. Interagency hotshot crews (IHCs) are a Type 1 handcrew which includes at least 7 full-time career firefighters.
Firelines and saw lines
Every hand line begins from an anchor point, which must be something that the fire cannot burn. A river, lake, or rock outcropping is ideal. It should also be safely ahead of the fire's head, although wildfires often move faster than hand lines can keep up with them. The purpose of the anchor point is to keep the fire from flanking the hand crew.
Once they arrive at the anchor point, the hand crew must clear all ignitable material along the strip right down to the mineral soil. This includes trees, brush, ground vegetation, roots, and even peat.
An alternative to the fireline is the saw line, which removes only wood and brush. The purpose of the saw line is to prevent a ground fire from climbing into the canopy. Handcrews include dedicated sawyers to do the cutting and swampers to remove all cut wood and brush from the saw line.
A couple of experienced members of the hand crew are usually designated as lookouts. They are positioned in a location where they can see most of the fire. It is their job to watch for spot burns and unexpected shifts. They also monitor the weather, including the wind speed and direction.
Building a hand line
There are 3 common methods of building a hand line: the hand-over-hand method, the progressive method, and the 1-lick method. The choice of method usually depends on the situation, the experience of the crew, and the tools available to each member of the crew.
In the hand-over-hand method, the members of the hand crew are spread out a few feet apart in a line along the fireline. Each person is assigned a specific task for clearing the fireline. When he completes it, he goes to the head of the line to start on a new section. Thus, there is a constant leapfrogging of crew members, each moving forwards when his task on his current section of line is complete.
In the progressive method, crew members are spread out in a line along the fireline as in the hand-over-hand method. However, each member of the hand crew performs all parts of the clearing in his section. When all crew members reach the sections which have already been cleared by the crew members ahead of them, the entire crew moves up to the next part of the fireline. This method requires each crew member to have a full complement of cutting and scraping tools.
In the 1-lick method, the crew is spaced out along the width of the fireline, so that each can use a chainsaw safely. Each crew member clears away the fuel in his section, and keeps moving forwards to clear the next part. This is best done with an experienced crew.
Hand crew members may also be assigned to hot spotting or cold trailing. In hot spotting, the crew member tries to cool down or remove hot spots where the wildfire is threatening to get ahead of the hand line. Although cold trailing is always done along the inactive part of a wildfire, it may also serve a double purpose as an emergency zone of safety.
A Type 1 firecrew is expected to clear 496 feet of brush per hour. A Type 2 crew is expected to clear 164 feet of brush per hour.