Evaluation of safety performance indicators for construction projects: A review study

Contractorchr('39')s safety performance assessment provides an opportunity for managers and decision-makers to choose contractors based on safety principles as an effective factor. The construction industry creates a complex working environment due to the use of complex devices and equipment, modern construction methods, temporary organizational structures, and the multidisciplinary and multitasked aspects of the project workforce. Construction projects are performed by contractors in many countries, and the accident rate is very high in this industry. Therefore, the safety of the workplace in the construction industry needs considerable attention. In the construction industry, completing a high-quality project with the minimum time and cost is a priority, and safety is a secondary concern. The lack of motivation to promote a safety culture at the organization and project level has weakened the safety performance and made construction one of the most dangerous industries in the world. It is possible to improve the safety standards of contracting organizations with continuous monitoring and reviewing of their safety performance. To achieve this goal, safety performance measurement methods must be available. To achieve the safety objectives of the safety management system, organizations require a rational framework for assessing safety performance to measure the effectiveness of the organization in preventing accidents over time. The goal of measuring the safety performance is to provide a feedback mechanism to accelerate improvement. The effectiveness of the feedback mechanism is directly dependent on the use of appropriate information resources. Safety performance is one of the most important concerns of project managers, because poor safety increases project failures and affects other key performance indicators. For example, the unsafe work environment reduces the quality of work and causes extra time and costs. This study was conducted to evaluate the contractorchr('39')s safety performance indicators.

In this study, the articles published in the Science Direct database from the beginning of 2005 to the end of 2017 on measuring the safety performance of construction projects were reviewed. Articles with the term "safety performance" and "construction" in the title, abstract, or keywords were selected. A total of 145 articles were found in the first search, and after a closer look at the title and abstracts of articles, 54 articles related to the purpose of the study were examined. These 54 selected articles were categorized based on various criteria such as the title of the article, year of publication, journal name, authorchr('39')s country, and methods. In general, the safety performance indicators were divided into three groups of methods, including lagging indicators, leading indicators, and other methods, and each of these groups includes subgroups.

From the review of 54 articles, it was found that two indicators of incident rate (29 articles) and accident rate (19 articles) were studied in the majority of articles. These two were followed by studies on the near miss rates, safety culture, risk assessment, unsafe conditions, experience modification rating, and safety costs for safety performance measurement, respectively. Most articles in the field of safety performance of contractors were published in the Journal of Safety Science and originated from the USA and China. Below, each lagging and leading indicator is summarized.Lagging indicators: Accident rateAccident rate is most commonly used in assessing safety performance, simply calculated by having the number of accident. It can be used to compare performance. The accident rate can be calculated for a month to several years with the following formula:Accident rate = (number of accidents / number of employees) ×106 Incident rateAccording to some authors, incidents include accidents, near misses, unsafe acts, and unsafe conditions. In fact, the word incident can refer to any situation where there is a lack of safety. The methods for calculating incident rate vary from country to country. Typically, the rate of incident is calculated as follows: Incident rate = (number of incidents / number of employees) ×106Incident and accident rate have certain advantages for assessing the safety performance; for instance, information about them is relatively easy to collect and understand, they are suitable indicators for comparison, and they prove useful in the identification of trends over time. Near missNear miss is defined as an unplanned event that has the potential to cause damage, injury, or illness, but does not cause any specific damage and does not come with a direct cost. In fact, a near miss is a warning for the occurrence of accidents. By controlling and recording near misses, it is possible to measure the current safety performance, and by investigating near misses and their causes, organizations can prevent accidents and improve safety performance. It is not easy to identify near misses, and some of the factors preventing employees from reporting near misses include fear of being blamed, accepting a risk because such events are considered part of the work, lack of feedback on how the reported information has been used, and the perception that data collection is difficult and time-consuming. Experience modification rateExperience modification rating is a method used by companies in the United States to measure the safety performance of firms based on the company’s injury and illness claims for over the past three years. The basic formula for experience modification rating is:EMR = actual claims / expected claimsThis formula is adjusted according to company size and the frequency and severity of injuries. The actual losses of accidents and injuries result in workers’ compensation claims, and the expected losses are based on the experience of claims for a particular work classification. Companies are ranked based on the experience modification rate. The average score for an experience modification rate is 1, with higher scores indicating the payment of more insurance premium, and lower rates indicating a lower premium.The formula of experience modification rate is relatively complex and, in practice, different methods are used to calculate it. This formula is not a suitable method for calculating the safety performance of all types of companies. The experience modification rate is based on the performance of the past three years and is, therefore, not appropriate for measuring the current safety performance.Leading indicators:Leading indicators provide early warning signals for potential failures and continuous control of safety in the work processes. These indicators primarily and often focus at the level and analysis of small units such as individual behavior, so that work processes and behaviors can be improved before an accident occurs. Leading indicators based on the type of selected criteria can predict future safety performance and prevent future accidents. Risk assessmentRisk assessment is a fundamental principle in safety management. For the effective prevention of accidents, their causes should be identified with risk assessment. In construction projects, risk assessment can be the identification of hazards in the design phase of construction before they can lead to an accident. To do this, the first step is to identify the main stages of the construction process and then to identify the risks associated with each step. To determine the hazards, one can use the information on incidents and accidents occurring in similar projects. Behavior-based safetyBehavior-based safety is a measure of performance evaluation that is measured by different methods, including the use of checklists. Checklists evaluate different behaviors such as the use of personal protection equipment, housekeeping, hot work, scaffolding, and access to heights. The four basic steps in behavior-based safety include identifying, observing, intervening, and review (or follow-up observation) and monitoring. After the interventions, behaviors are observed and grouped as safe and unsafe behaviors. Then, the raw data are converted into a score, so that the numbers of safe behaviors multiply 100 and divided by all observed behaviors. In most leading indicators, data collection is performed manually. The observation and control of construction sites are time-consuming for safety authorities. The inspectorschr('39') errors are also involved in the results and reports. Safety cultureTo assess the safety culture of an organization, there are a variety of qualitative methods such as observation, and quantitative methods such as surveys, each being useful for assessing culture. However, quantitative methods, in particular, surveys of individuals’ responses, are often more practical in terms of time and cost-effectiveness. As a result, surveys and questionnaires are widely used in assessing the safety culture in various industries. Different studies use parameters, management commitment, supervisory environment, supportive environment, communication and feedback, work pressure, personal perception of risk, workerschr('39') involvement, training and competency, safety rules and procedures, and assessment of work hazards to evaluate the safety culture.

One cannot claim that a certain indicator of safety performance measurement is better than another; the choice of indicators depends on the objective of safety performance measurement and the available sources of information. The use of safety performance measurement methods depends on the time and location of their use. At the project level, the use of leading indicators causes the current safety performance of the project measurable, so that its results can be used to improve performance. For example, incidents and accidents can be prevented by improving the behavior and safety culture. Nevertheless, for companies that choose a contractor for their own projects, using indicators such as accident rate, incident rates, and experience modification rate will be very useful because these indicators show the outcomes of contractor safety performance. This paper can serve as a useful source of information for employers and managers of construction projects to evaluate the safety performance of contractors in this field.