3.4 Risk, hazard and control
Risk assessment
Good safety management depends on risk assessments and controls designed to reduce exposure to danger. Risk control is based on the management maxim: if you can measure it, you can manage it. Risk assessment involves predicting, estimating, observing and reviewing. Your ability to accurately carry out risk assessments relies on practical experience in the field and writing it up so that other people understand. You must use your experience to predict, protect and avoid exposure to danger for less experienced workers and for workers whose safety you are responsible for engaged in other parts of the project.
Risk assessment operates on similar principles to safety assessment of the whole site but this time the focus is at the level of the individual project or contract, and the risks identified relate to each step of the construction process carried out by each worker. Attention to detail is key to good risk assessment.
Definitions
- A hazard is something that has the potential to cause harm.
- A risk is the likelihood of the potential hazard being released and causing damage or injury.
- A control is a recommended or prescribed way of carrying out the work that, if followed, should reduce the risk.
Section 3.3 identified the hazards of access management, the various operations that need to be carried out on site that have the potential to cause harm. This section concentrates on the evaluation of the risk involved, and how to quantify the level of risk and apply controls that reduce the risk, by either reducing the frequency of an accident happening or reducing the potential severity if there is an accident.
It is good practice for risk assessments to be carried out twice: by the client as part of preparing the pre-tender health and safety plan and other contract documents after visiting the site and designing the work; and by the contractor or team leader as part of their bid to carry out the construction work and submitted with the safety method statement. It is the responsibility of both the client and the contractor to compile risk assessments before any task is undertaken, to submit these to the planning supervisor and to receive their approval before work commences. It is the responsibility of the planning supervisor to ensure that the risk assessments are comprehensive, and that everyone working on the site is fully aware of the safe procedures for work.
Evaluating risk
Risk is a combination of two factors: likelihood and severity. A simple task such as moving boulders to form a crossdrain may hold a high likelihood of the worker trapping a finger. The severity of the injury depends on the size of the stone and its momentum when the finger is trapped. To reduce this moderate risk (frequency: likely + severity: slightly harmful) to a tolerable risk involves applying controls: two people manoeuvring larger stones; never rolling a stone into a hole if there is someone working in there; and using a pinch bar to butt stones together. This simple process of identifying the risk, assessing its severity, applying a control and considering whether that control is sufficient to reduce the event to a tolerable risk is what risk assessment is all about.
There are several ways of calculating risk and evaluating severity, all of which use different scales to estimate the frequency with which events will happen and the severity if they do. The system described here is loosely based on the BSI 8800 Safety Management System: Risk Assessment Method. It uses a simple matrix to read off the risk level, based on your own estimation of frequency and severity. Read off the risk classification from the matrix, for each task to be undertaken.
| Slightly harmful | Harmful | Extremely harmful | |
|---|---|---|---|
| Highly unlikely | Trivial risk | Tolerable risk | Moderate risk |
| Unlikely | Tolerable risk | Moderate risk | Substantial risk |
| Likely | Moderate risk | Substantial risk | Intolerable risk |
The five scales of risk identified from the matrix are:
- Trivial – no action required.
- Tolerable – additional controls are required if possible. Situations where a tolerable risk may become moderate or substantial should be avoided; for instance, in wet weather, when tired or when work is being carried out in a rush.
- Moderate – this risk must be reduced to a tolerable level as soon as possible. The resources required should not be excessive. Work should not commence on site until you are confident that risks can be reduced to a tolerable level. Moderate risks may be tolerable in good conditions but more risky in poor conditions on site; these tasks should be carefully timed and stopped if conditions deteriorate.
- Substantial – work should not start until these measures have been reduced to a tolerable level. Production methods may need more resources. When work is in progress, it must be stopped until the risk is reduced to tolerable. Substantial risks are unlikely to be tolerable, even in good conditions, and therefore a different approach will be needed, whatever the situation.
- Intolerable – work must not be carried out. If the resources are not available to reduce the risk to tolerable, the work should not be undertaken. It is often necessary to look around for a new solution or an alternative way of carrying out this work. If intolerable risk activities are taking place on site, they must be stopped immediately and preventative measures taken to stop them recurring, such as removing equipment from the site or restricting access to parts of the site.
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The aim of risk management is to reduce all risks to the lowest level possible, i.e. tolerable or trivial levels of risk. Moderate risk activities are often tolerable if they are carried out in good conditions, in good weather, with a strong team and where additional help is at hand. Conversely, tolerable risk tasks can become substantial risk tasks if they are carried out by one person alone on site – the potential frequency of occurrence may be the same, but the seriousness of the consequences are much greater.
Substantial and intolerable risk activities usually require that an alternative is found. This may involve redesigning the path, finding a new method of moving materials, carrying out the work at a different time of year, or looking for an entirely different solution. It is usually not possible to reduce substantial or intolerable risks just by providing better safety techniques. It normally requires changes to other parts of the project inputs and outputs. In reality, most high-risk project activities are avoidable and alternative solutions can be found; the majority of management effort goes into reducing moderate risks to tolerable levels.
Risk assessment is undertaken out of a belief in uncertainty. It is possible, but not certain, that the risks you have identified will take place. As the damage is potential, but the outcome uncertain, it is wise to use the precautionary principle. If you are unsure of the risk of an activity, do not carry it out until you have the information you need to accurately estimate its impact. The precautionary principle is also important, because ‘prevention’ often takes less time and uses less resources than ‘cure’, and failure to take preventative action may result in long-term damage that is very expensive to put right later on.
Hazard control
For each hazard identified, a risk classification is calculated from the matrix. This risk is managed by applying a range of control methods. For tasks that come up frequently on many path sites, a series of generic risk assessments has been prepared for the following tasks and hazards:
- manual handling
- use of hand tools
- use of power tools – pneumatic and electric
- use of power tools – engine driven
- use of plant – hand driven
- use of plant – excavation
- use of plant – ride on transport
- site conditions – slopes and steep ground
- site conditions – elevation
- site conditions – weather
- site conditions – remoteness
- site conditions – flora and fauna
- working over or near water
- excavations – ditches alongside paths
- excavations – cross-path ditches
- excavations – borrow pits
- fire
- waste handling and removal
- use of helicopters
- aerial cableways
- lone working
- work alongside a road or railway
- tree felling and brush clearing
- demolition
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For each of these tasks a generic risk assessment describes how to work safely in a way that ensures that work is carried out effectively and the risk is reduced to a tolerable level.
As a manager, you must contemplate how these generic risk assessments will apply to the particular task under way on the site you are managing. It is usually necessary to adapt the generic controls to suit conditions on the site, or highlight particular parts of each risk assessment that are relevant. For most sites, there are also tasks that do not fall within this list, and for which no standard risk control is available. For each risk assessment you prepare, make up an additional sheet that provides specific detail on how the general assessments are applied on this site, highlighting the most important features for workers to be aware of.
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As well as adapting the existing controls, it is frequently necessary to come up with a new procedure or solution for an unusual working situation. For instance, on the Craig to Diabeg path, block stones from a nearby scree slope had to be removed to the work site in bags with strops by helicopter. The risks and the controls necessary to carry this out safely were significantly different from the standard way of moving aggregate used elsewhere on the site. A risk assessment was developed specifically for this work.
Review your performance: learn from experience
Risk assessment is all about prediction and avoidance. It is therefore an essential part of risk assessment to review the actual experience of safety on site and identify whether the risks were as predicted. This experience can be used in future projects to control risk better. Risk assessment needs to be an active process. It is not sufficient to wait until an accident happens before changing your risk assessment or controls. A short review involving the planning supervisor, the client and the contractor should be carried out during or at the end of each project. Your safety review should include:
- ‘near misses’ and any accidents – the events that caused it, the response once it happened and the lessons to be learned to stop it recurring;
- tasks that were unforeseen and had to be carried out unplanned;
- the effectiveness of the risk controls – are procedures difficult or cumbersome and therefore abandoned or avoided by workers? It may be possible to come up with a simpler but equally safe solution that can be used on the next project.
Larger footpath clients and contractors will meet annually with their teams to review health and safety. This is a good opportunity to consider the effectiveness of current risk assessments, and spot any that need to be changed. The techniques of path work are changing, and numerous risk assessments will be needed, or old ones amended to take this into account. For instance, there has been a move towards using small-tracked excavators to carry out borrow-pit digging and material grading, often on sites not using excavators to dig and lay the path itself. Ten years ago this work would have been carried out manually, and the use of machines is speeding up work and taking some of the drudgery out of material digging. This has long-term health benefits for path workers, but more short-term hazards on site. Risk assessment has been revised to ensure that these pits are situated well away from the path line, that there is a safe operating zone around them, and that the power carriers coming to collect materials do not enter that zone until the operator signals.
Finally, it should be remembered that risk assessments are good for managing easily identified and shorter-term ‘event’ hazards. They are less effective at detecting less visible, long-term and ‘background’ hazards. For instance, risk assessment of a new site may very easily identify poor path condition that is a hazard to users. However, the gradual, continuing erosion of the site will increase the risk over time, but this may not be noticed by a manager who is unfamiliar with the condition of the site. Similarly, risk assessment may help avoid intolerable risk to workers digging a borrow pit, but it might not predict the long-term impact of several years’ excavation work that results in inflamed or arthritic joints for site workers. Remember, risk assessment is the best approach for hazard control, but it is not the whole solution for safety management. Be on the look out for long-term, slow-changing or less visible impacts that also need to be managed and reduced.