Progress measurement is cardinal for effective project delivery. It assesses the physical amount of completed work within budgeted cost and manpower performance at a specified stage of the project. Effective progress measure ment facilitates progress monitoring, an inevitability for identifying early warning signs and confirmation of structured work proceeding. Different progress measuring methods are available and used for construction projects. They range from the traditional to the contemporary ones like three-dimensional and four-dimensional models. This paper examines current progress measurement methods used in the Ghanaian construction industry. Eight commonly employed methods were identified from the literature and rated by sixty-two construction professionals, practicing with tier one construction firms and construction consultancy services. Relative Important Index ranking and Mann-Whitney U test statistics were used to rank and check the consistency of survey responses. Cost Ratio ranked the highest, followed by Su pervisor’s Opinion and Unit s Completed. The fourth-ranked method was Time Ratio, then Incremental Milestone before Start-Finish. Weighted/Equivalent Unit s was at the penultimate with Earned Value Analysis ranked the lowest. The study will not only underscore the relevance of the current project progress measurement practices and provoke prolific debates on their merits, but will also serve as a precursor for critical evaluation of the methods with the view to identify ing barriers militating against realistic progress assessment of construction works.
The proper focus and speed of construction cannot be economically attained by compulsion, but require careful and adequate planning and control. Under the unsteady, unpredictable and highly competitive construction business environment, progress and performance measurement are very critical for all categories of construction organizations, including clients, architects, quantity surveyors, engineering and contractors [
One critical job specification of the project manager is to monitor and track work progress against the planned targeted schedule within accepted scope and cost. Effective project progress monitoring should identify early warning signs and also confirm whether the work is proceeding in a considered manner to avoid incessant pressure at the eleventh hour. Progress measurement is a critical component of successful project control in the project delivery caboodle. It is highly unlikely that a project will conform to plan, and all schedules during the construction phase, so the project manager must recognize this and be in a constant reactive mode to realign it back on track. Consequently, for any construction project to be delivered on time, within budget and at a specified quality, accurate progress measurement is crucial. Progress, according to Jung and Kang [
There are several conventional and other emerging contemporary methods of measuring the progress of construction projects. According to Rahimian et al. [
Contemporary progress measuring techniques use three-dimensional and four-dimensional (3D/4D) models and rely on Barcodes, Laser Detection and Ranging (LADAR), Video and Audio Technologies, Radio Frequency Identification (RFID) and Global Positioning System (GPS) for automatic data collection and visualization and real-time presentation of results. Golparvar-Fard et al. [
The eight traditional methods of measuring work progress are discussed below.
This progress measurement method is normally used for work packages whose scope can further be segregated into fairly standardized units of work such that each unit requires roughly the same level of effort to complete. Suited for repetitive tasks where each actual compact of iteration can easily be measured against the planned [
The emphasis of this method is on the commencing and ending points of the tasks with no consideration of the intermediate activities. It is best adaptable to small tasks with short durations. The construction manager or coordinator may assign two or three levels for the activity or work sections or the entire project. Not started will be 0%, progressing but not completed (an arbitrary amount) says 45% or 60% and completed will be 100%. Alternatively, the 0/100% (start/finish) could be applied to tasks of very high value, 20/80 for high-value tasks and 50/50 for very short tasks [
This is the most biased method which is mostly used where no other method will be appropriate to be applied. The supervisor simply makes a judgement on the percentage of work completed. As a subjective approach, it should be reserved for only minor tasks where other options cannot be used. This method depends solely on the experience and opinion of the supervisor [
A preferred method for project management contracts, the Cost is usually applicable to construction activities which do not have discrete deliverables and tend to occur over a relatively long period of time [
Another favorite method for project management contracts, the Time Ratio is also apposite for tasks such as contract administration and project management. It is estimated on the basis of time (work-hours) accomplished on a project rather than on the actual production [
Applicable to projects which involve subtasks or steps which must be carried out in sequence so that the completion of incremental tasks can be observed. Each stage or step of a given project is assigned a “weight” that is approximately equivalent to its percentage share of effort in the task of the project. Milestones can be considered as an important means of tracking progress as they are substantially tied to activities on the schedule. This method seems simple but highly dependent on the experience of the supervisor who assigns or estimates the weights or milestones [
This method is a combination of units completed and incremental milestone. It is used for projects of relatively long durations, when the work package scopes, include multiple subtasks of non-standardized units of work that overlap such that the other methods cannot work well. The cardinal point here is to accumulate the weighted value which is eventually denominated into the value of the units of specific tasks. Ideal for activity level progress measurement due to its level of objectivity, but relies on past experience of the project manager to assign weights [
Earned Value Analysis is a system employed to determine the actual or physical progress of the project and it incorporates scope, time and cost [
The professionals’ assessment of their familiarity and application of construction project progress measurement techniques in Ghana was undertaken through literature review and survey strategy. Data collected were analyzed quantitatively, using descriptive and inferential statistics [
A total of sixty-two sets of questionnaires (87%), comprising 36 (84%) Contractors and 26 (93%) Consultants, were retrieved and used in the analysis.
Variable | Characteristics | Frequency | Percentage |
---|---|---|---|
Firm | Construction Firms | 36 | 58.1 |
Consultancy Services | 26 | 41.9 | |
Total | 62 | 100.0 | |
Position in Firm | Senior staff | 33 | 53.2 |
Junior staff | 2 | 3.2 | |
Management | 27 | 43.5 | |
Total | 62 | 100.0 | |
Working Experience | 1 - 5 years | 1 | 1.6 |
6 - 10 years | 13 | 21.0 | |
11 - 15 years | 12 | 19.4 | |
16 - 20 years | 21 | 33.9 | |
Above 20 years | 15 | 24.2 | |
Total | 62 | 100.0 | |
Knowledge in Construction Project Progress Measurement | Intermediate | 3 | 4.8 |
Adequate | 27 | 43.5 | |
Advanced | 32 | 51.6 | |
Total | 62 | 100.0 |
in the averages of the ranks across the two groups (contractors and consultants). The non-parametric or distribution-free alternative is used because no assumptions about the parameters (such as shape and variance) of the population are made, instead, the mean ranks are used.
The eight (8) common methods of construction progress measurement which were identified from the literature include Units Completed, Cost Ratio, Time Ratio and Start-Finish. The rest are Supervisor’s opinion, Incremental Milestone, Weighted or Equivalent Units and Earned Value Analysis. These were tested on construction professionals to determine their familiarity and level of application. The Relative Importance Index (RII) was calculated for the eight methods of project progress measurement based on their mean scores. The rankings are presented in
Method | N | Sum | Mean | Standard Deviation | RII | Ranking |
---|---|---|---|---|---|---|
Cost Ratio | 62 | 300 | 4.84 | 0.549 | 96.8 | 1 |
Supervisor’s Opinion | 62 | 280 | 4.52 | 0.954 | 90.3 | 2 |
Units Completed | 62 | 246 | 3.97 | 0.829 | 79.4 | 3 |
Time Ratio | 62 | 221 | 3.56 | 1.140 | 71.3 | 4 |
Incremental Milestone | 62 | 198 | 3.19 | 1.006 | 63.9 | 5 |
Start-Finish | 62 | 174 | 2.81 | 1.353 | 56.1 | 6 |
Weighted/Equivalent Units | 62 | 102 | 1.65 | 0.630 | 32.9 | 7 |
Eared Value Analysis | 62 | 99 | 1.60 | 0.858 | 31.9 | 8 |
Mann-Whitney U-test, a non-parametric alternative to the t-test, was used to compare differences between the two independent data sets (Contractors and Consultants) for the given dependent variable (e.g. Cost Ratio or Units Completed). As the data were skewed and participants’ numbers were small, the choice of this technique, which requires no assumptions about the parameters of the population, is appropriate [
These positions have been collaborated in
Method | Category of Respondents | N | Mean Rank | Sum of Ranks |
---|---|---|---|---|
Units Completed | Contractors | 36 | 35.58 | 1281 |
Consultants | 26 | 25.85 | 672 | |
Total | 62 | |||
Incremental Milestone | Contractors | 36 | 23.42 | 843 |
Consultants | 26 | 42.69 | 1110 | |
Total | 62 | |||
Start-Finish | Contractors | 36 | 28.74 | 1034.5 |
Consultants | 26 | 35.33 | 918.5 | |
Total | 62 | |||
Supervisor’s Opinion | Contractors | 36 | 37.86 | 1363 |
Consultants | 26 | 22.69 | 590 | |
Total | 62 | |||
Cost Ratio | Contractors | 36 | 31.86 | 1147 |
Consultants | 26 | 31 | 806 | |
Total | 62 | |||
Time Ratio | Contractors | 36 | 40.14 | 1445 |
Consultants | 26 | 19.54 | 508 | |
Total | 62 | |||
Earned Value Analysis | Contractors | 36 | 27.67 | 996 |
Consultants | 26 | 36.81 | 957 | |
Total | 62 | |||
Weighted/Equivalent Units Completed | Contractors | 36 | 34.67 | 1248 |
Consultants | 26 | 27.12 | 705 | |
Total | 62 |
Method | Mann-Whitney U | Wilcoxon W | Z | Asymptotic Significance (2-tailed) |
---|---|---|---|---|
Units Completed | 321 | 672 | −2.251 | 0.024 |
Incremental Milestone | 177 | 843 | −4.334 | 0.000 |
Start-Finish | 368.5 | 1034.5 | −1.459 | 0.145 |
Supervisor’s Opinion | 239 | 590 | −4.168 | 0.000 |
Cost Ratio | 455 | 806 | −0.362 | 0.718 |
Time Ratio | 157 | 508 | −4.597 | 0.000 |
Eared Value Analysis | 330 | 996 | −2.227 | 0.026 |
Weighted/Equivalent Units | 354 | 705 | −1.847 | 0.065 |
a. Grouping Variable: Category of respondents (Contractors and Consultants).
The association between the two variables (contractors and consultants) is statistically significant if asymptotic significance (2 sides) is less than 0.05 (for a 95% confidence level). It can be deduced from
The Cost Ratio method was ranked premium of the eight common project progress measurement methods (
The Units Completed, Time ratio and Incremental Milestone methods were ranked from third to fifth. A minor difference between the ratings of the groups in relation to the Units Completed method, as evident in the high Mann-Whitney U value of 321 and the close mean ranks of 35.58 and 25.85, means the contractors have just a slight preference. There are great differences in the responses of the 2 groups to the other two methods. Contractors apply the Time Ratio frequently than the Consultants and the reverse holds for the Incremental Milestone. Units Completed method is simple and objective for activity level measurement but concentrates on the quantity at the expense of cost and time. The Time Ratio also has limitations similar to the Cost Ratio. It is affected by inclement weather and extension of time thereby altering the actual duration and cost of an activity. The Start-Finish and Weighted/Equivalent Units methods, were lowly ranked, implying they are not commonly used. Their high Mann-Whitney U values are indicative that both groups rated them relatively alike. Their low rankings can partly be explained as unfamiliarity of practitioners with these techniques. Finally, with a mean score of only 1.6 and RII of 31.9, the Earned Value Analysis is the least method used by the construction professionals in assessing project progress. The high value of 330 for the Mann-Whitney U, coupled with the close mean ranks of 27.67 and 36.81 shows that both Contractors and Consultants agreed to rarely employ the method. It is unexpected that such an objective technique which gives early indications on project performance should be least appreciated by Ghanaian construction professionals. Probable negative perceptions affecting this method are the large scope of data required and unacquaintance of professionals.
Eight project progress measurement techniques practised in the Construction Industry of Ghana were identified and tested to determine their frequency and consistency of use. These methods were sourced from literature and ranked by RII and non-parametric Mann-Whitney U test statistics. The Cost Ratio method of construction progress measurement is the preferred choice of construction professionals in Ghana. This system involves the assessment of the actual cost of work executed as a percentage of the total budgeted cost. Its popularity can be attributable to its quick and simple applicability but could be misleading in instances where the cost incurred does not match time or quality of work. The next two favourite methods are Supervisor’s Opinion, and Units Completed. Contractors slightly rated them higher than the Consultants but the high ranking of Supervisor’s Opinion, in particular, suggest that subjectivity is rooted in progress measurement. Reliability and limitations of such subjective methods which do not integrate all key performance/progress indicators (cost, time and work scope) into the measurement are not the focus of this paper. Current work is about predominant project measurement methods of construction professionals. Time Ratio, Incremental Milestone and Start-Finish ranked between fourth and sixth. Contractors proportionately use the Time Ratio more than the Consultants possible due to its simplicity but delays and even fast pace work delivery can make the system unreliable. Consultants rated Incremental Milestone higher than consultants but both had a level of consensus on the Start-Finish method. These methods are also subjective and rely on the experience of the project manager. Weighted/Equivalent Units was the penultimately ranked ahead of Earned Value Analysis. Their low rankings suggest the unfamiliarity of construction professionals but not necessary undependability of the methods. In fact, the lowest ranked is the only technique which factors time, cost as well as quantity of work into the measurement.
This work identified and ranked the common construction project progress measurement methods. Merits of the methods, the critical factors that drive the process of progress measurement and critical barriers militating against a realistic assessment of construction progress will be considered in future studies. The scope was limited to conventional methods which are contingent upon computer-assisted tool formats of 2-dimensioned drawings, bar charts, schedules and photo logs, critical path network and reports. Contemporary progress measuring methods of 3D/4D models with automatic data collection and visualization and real-time presentation of results (such as LADAR, RFID, GPS and Video and Audio technologies) have not been covered in this study.
The authors are grateful to the Ghana Institution of Surveyors (GhIS) and the Association of Building and Civil Engineering Contractors of Ghana (ABCECG) for facilitating the data collection for this paper.
The authors declare no conflicts of interest regarding the publication of this paper.
Danku, J.C., Agyekum, K. and Asare, F.T. (2020) Professionals’ Perceptions on Construction Progress Measurement Methods Used in Ghana. World Journal of Engineering and Technology, 8, 145-158. https://doi.org/10.4236/wjet.2020.82012