Contractor prequalification model for lean project delivery

Abstract

Wastage rates in the construction industry are relatively high and this affects the cost, time, safety and quality of construction projects. These wastes occur at all stages of the construction development starting from the inception stage and carrying through the design, construction and operation stages. One of the management approaches that is being used to eliminate or reduce wastes is Lean Construction. This approach is designed to eliminate wastes and improve value of construction projects. The method is adopted through application of Lean Construction tools when delivering projects. For this to be achieved, the key stakeholders involved in the project must understand the details of Lean Construction tools and how are they applied through all the project stages. One of the key stakeholders that influences the success or failure of implementing Lean Construction tools is the contractor. Thus, it is very important for the team responsible for contractor prequalification and selection to use the right factors when selecting contractors, in order to achieve a successful implementation of Lean Construction tools when delivering a Lean project. The aim of this research is to investigate contractor selection factors during pre-qualification stage of Lean projects.

The objectives of this research include:

1. Reviewing the history of Lean Production and Lean Construction.

2. Reviewing the existing contractor pre-qualification approaches and evaluating their suitability for prequalifying contractors for Lean projects.

3. Describing the principles and benefits of Lean Construction to introduce a new model for contractor evaluation factors for Lean projects.

4. Improving the performance of construction projects through facilitating a more comprehensive implementation of Lean principles starting from prequalification stage.

5. Describing various types of lean construction wastes and investigating challenges facing implementation of Lean Construction tools.

Achieving these objectives will provide useful information on factors to consider when selecting a contractor for a lean project.

The study is conducted using a combination of qualitative and quantitative research approaches. This methodology is appropriately chosen to address the aim and objectives of the research and to comprehensively answer research questions. The research presents the outcomes of three phases, the first phase aims at identifying the main factors that could be used as indication of a contractor's ability to deliver Lean project, the second phase utilizes an AHP model to rank these factors based on their relative importance, and the third and final phase builds a scoring system to evaluate the contractor's ability against each of the identified criteria. The model can be used by any client to evaluate the contractors during pre-qualification stage, the outcome of this model will rank the contractors from the highest lean practitioner to the lowest based on the total weighted score. The built AHP model is flexible and can be fine-tuned by each user (client) to produce the weighted factors that accurately model the client's priorities, to evaluate the model and to show how it works. To validate the model, a questionnaire was designed and distributed among different international construction contractors. This questionnaire asked contractors basic questions about their company and the submittals from each contractor are then evaluated from technical directors, general managers and construction experts. The results of the contractors' submittal evaluations indicated that the contractor with highest weighted score was the contractor that had the most experience applying Lean principles. These results were validated through providing a case study from the contractor with highest score. The results indicated that the developed model can identify the contractors with more experience in applying Lean as the more qualified candidates for delivering Lean projects.