The terms fall arrest and fall restraint often get used interchangeably. This gets you in trouble during site briefings and when you’re putting in equipment orders.
The main goal of a restraint system is to eliminate the risk of reaching a fall hazard. This is done by shortening the length of the lanyard to ensure that the lanyard does not allow the user to reach the hazard. Because the lanyard is never long enough to allow the user to reach the edge of the hazard, there is no fall to be arrested. Restraint systems work great for tasks performed on flat roofs, at the edges of fall hazards that are not approached, and on tasks that allow the working area to be at a safe distance from a drop.
Fall arrest systems are designed with the understanding that the user will be at risk of falling. Because of this, the fall arrest system is designed and constructed to arrest a fall that the user may take. This type of system is used when the work must be performed at the edge of a fall hazard, such as on sloped roofs or when the leading edge of a construction operation is being worked on. This type of system uses a lanyard that has an inertia reel or a shock absorber, and fall arrest systems are designed to ensure that a fall is safely decelerated before a user is injured.
They start from fundamentally different perspectives, and knowing which is the right one is often difficult. A lanyard designed for fall restraint positioned where fall arrest is actually required provides no allowance for the distance a fall would take to decelerate, because fall restraint does not arrest a fall. Fitting full fall arrest equipment where full restraint would be acceptable is not dangerous for the same reason, but often results in a much larger and heavier connecting device than the task actually required, and there is a carry cost in how willingly a worker would wear the device for a full day.
The confusion occurs much earlier in the purchasing stage than in task performance. A box of lanyards is purchased under the assumption that all lanyards are the same, and either fall restraint or fall arrest is irrelevant, and whoever is to connect the equipment that morning pulls out the first one grabbed. It is not easy to tell the two apart from some distance, and the distinction is often lost until the critical moment reveals otherwise.
The first step in identifying the necessary equipment for a job is the following question: Are they able to reach the fall hazard while connected? If all the components (the lanyard, the anchor, the work zone, etc.) sufficiently keep someone away from the working edge, then restraint is probably the best option. If there’s any scenario where the person can reach a fall hazard, then the lanyard needs to provide fall arrest. Restricting the working lanyard and leaving the employee’s movements to the planned limits is not the right option.
The Work at Height Regulations 2005 are strict about using these terms, and the job should clearly state which option is being used and the justification for the choice rather than leaving the lanyard in the box to make that call by default. This is a five minute conversation of picking the right option and is the goal for the equipment. Getting this wrong is found out at the most unfortunate time.
In an absolute sense, fall clearance numbers are more meaningless than principles, but the consequences for dealing in numbers are much more severe. Fall arrest systems need to have sufficient vertical space beneath the anchor point to account for the height of the person, lanyard length, and the absorber’s extension, as well as the person coming to a complete stop when the system activates. This is not the case for fall restraint systems because there is no fall. On paper, these two systems are completely interchangeable. In reality, treating a restraint system as if it has fall arrest clearance is how a system that on paper looks acceptable actually turns out to be longer than it needed to be.