Lean Scheduling for Safety: Development of a Time-Dependent Risk Level Model

Rafael Sacks1, Ophir Rozenfeld2 & Yehiel Rosenfeld3

1Senior Lecturer, Faculty of Civil and Env. Eng., 840 Rabin Building, Technion—Israel Institute of Technology, Haifa 32000, Israel, Phone +972-4-8293190, Fax +972-4-8293190, cvsacks@technion.ac.il
2Senior Lecturer, Faculty of Civil and Env. Eng., 840 Rabin Building, Technion—Israel Institute of Technology, Haifa 32000, Israel, Phone +972-4-8293190, Fax +972-4-8293190, cvsacks@technion.ac.il
3Associate Professor, Faculty of Civil and Env. Eng., Technion—Israel Institute of Technology, Haifa 32000, Israel, roseny@technion.ac.il

Abstract

This paper presents ongoing research toward a conceptual model to support an advanced proactive safety management approach that is efficient not only in terms of the resources it requires, but also in terms of its impact on construction process flow. The model is based on the understanding that the risk levels to which workers are exposed, change through time. Accident risk levels are dependent on human factors, physical hazards, environmental factors and organizational/business factors. Many of these are time-dependent and their values can be derived from construction schedules (at various levels of detail, from the master schedule down to the weekly work plan). The model enables forecasting of risk levels for work teams and individual workers as a function of time. Forecasts will be available at different levels of planning windows. In implementation, the model will enable two main enhancements to project planning. First, in planning activities, the safety level resulting from combinations of activities planned to be performed simultaneously can be evaluated and manipulated (lowered, or peaks avoided) by safety-conscious scheduling. In many instances process flow can be enhanced if accident prevention measures can be made redundant by avoiding particular combinations of simultaneous activities. For example, an acceptable impact on overall risk level may be added as a consideration for releasing work for execution in a Last Planner meeting. Second, the activities and effort of those responsible for site safety can be ‘pulled’ by peaks of high risk levels. The goal is a dynamic, ‘lean’ level of effort invested in safety management, eliminating the ‘wasted’ effort inherent in standard practice, where a steady and uniform investment of accident prevention effort is applied throughout the project duration.

Keywords

Hazard, Risk level, Safety

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Reference

Sacks, R. , Rozenfeld, O. & Rosenfeld, Y. 2005, 'Lean Scheduling for Safety: Development of a Time-Dependent Risk Level Model' In:, 13th Annual Conference of the International Group for Lean Construction. Sydney, Australia, 19-21 Jul 2005. pp 513-520

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