The evaluation and selection of contractors prior to the award of a construction contract is a vital part of the construction process. Procedures related to the pre-qualification of potential bidders and the assessment of bids submitted by pre-qualified contractors are normally performed by a client’s representative and ultimately lead to the selection of a contractor for the project.

The qualification and bid-assessment processes require the development of sufficient and suitable criteria. Project complexity and developer requirements have greatly expanded in the last two decades. This expansion has led to an increased use of alternative forms of project delivery systems. Conversely, the qualification and bid evaluation processes, which involve the quantification and the assessment of criteria, have remained unchanged.

Applying a decision-making tool such as the AHP to contractor selection and qualification can be particularly useful to ensure that a project is successful because selecting a qualified and capable contractor to complete any project increases the likelihood of a timely delivery of results that are within the allocated budget and of acceptable quality.

The model used in this study was developed based on two questions, which included all of the questions for level 1 of the hierarchy shown in Figure 1. Level 2 of the hierarchy was not part of the questionnaire due to confidentiality reasons.

The questionnaire was distributed to subject matter experts in the fields of contract procurement and project management from various departments at Saudi Aramco including the contracting department, the project management team (PMT) and the project management office department (PMOD). Table 1 shows the types of questions used for data collection.

Interviews and meetings were conducted with various groups of individuals involved in the contract procurement process and project management including senior project engineers, project managers, contract advisors, and project controllers. Based on previous information, we developed a questionnaire to collect the required data. The AHP model was formulated after the data were gathered from all of the questionnaire responses.

Given the dimensions and the merits of the problem, the model was developed to select the most appropriate

contractor for the project.

Questionnaires were used for data collection to prioritize the criteria and rate the relative importance of each criterion used in the AHP model. The survey was distributed to subject matter experts in the fields of project management, contract procurement and contractor evaluation. Contractors play critical roles in the success of any project, particularly in construction; therefore, selecting the most qualified primary contractor to complete the project is critical to the project’s success. A pre-determined set of qualifying criteria are used to eliminate undesirable contractors from the bidding process, thus ensuring that the project is completed within the allocated budget, on schedule, safely, and to a desired level of quality. The following criteria were used for contractor qualification.

Table 2 is an example in which all of the criteria were applied to three potential bidders interested in the project. As mentioned previously, the example was used only to demonstrate the application of certain criteria to various alternatives. As discussed previously, the names of all of the bidders have been withheld, and the information provided on all of the bidders was hypothetical; the information is listed to demonstrate the application of the method to actual cases.

The average Level 1 scores for the six criteria based on a survey is shown in Table 3. The weight of each criterion at the same level was calculated as follows:

Level 1:

• Calculate the total for each column in the comparison matrix;

• Divide each score by the sum of its column to form a new matrix; and

• Calculate the average of each row in the new matrix to obtain the priority vector weights of each criterion. Table 4 shows the new matrix after the weights were calculated.

The “Average” column above shows the average values of the normalization matrix and is called the priority vector. The priority vector is usually determined by averaging the row entries in the normalization matrix.

Table 5 shows the pair wise comparison and normalization matrices for each criterion.

The consistency ratio for each criterion at the same level was calculated as follows:

Level 1:

• Multiply the “Weight” column by the Level-1 matrix in Table 6, and then obtain a new matrix, which is shown in Table 7;

• Find the sum of each row, as shown in Table 8;

• Divide the “Sum” column by the “Weight” column to find the average of that column (λ_max), as shown in Table 9;

• Find the average of the column that was obtained in the previous step;

• Calculate the consistency index using the following formula:

where n = 6 represents the number of factors and λ_max is the average of the sum column;

• Find the consistency ratio using the following formula:

where RI = 1.41.

Averaging these results yields:

The consistency index, CI, for two terms is as follows:

The consistency ratio, CR, is CI/RI, where RI = 1.24 for the six criteria:

The value of the consistency ratio CR is less than 0.10, which is well within the acceptable range.

The overall priorities were determined by multiplying the priority vectors of the criteria by the priorities for each alternative decision for each objective.

Based on Table 10 and Table 11, the best contractor was Bidder#1.