## 2 Literature Review  
### Schedule Risk Analysis (SRA)  
Construction projects are not exempted from risk in that they are initiated in a complex and dynamic environment associated with high risk and uncertainty which is compounded by time [8] and resource constraints. Risk is defined as \"an uncertain event or condition that, if it occurs, has a positive or a negative effect on project objectives\" [9]. Risk management is an indispensable component of construction project management. [PERSON] et al. [8]stated that risk analysis is an important aspect of risk management that allows project practitioners to quantify and analyze the risk that may impact the performance of a project in terms of time, cost quality, and safety. Equally, [PERSON] and [PERSON] [12] affirmed that risk management is crucial to construction activities in reducing losses and maximizing profits. Additionally, [PERSON] [13] stressed the need to integrate risk management into the organization's culture as a safety measure against unforeseen events that might negatively impact organizational goals and project outcomes. SRA is a method used for analyzing the risk and uncertainty peculiar to the schedule baseline. [PERSON] and [PERSON] [14] stipulated that SRA is conducted to assess the variability of the activity durations and to estimate the probability of completing the project within the project time. Furthermore, to analyze risk several models, tools and techniques have been developed by practitioners and researchers [8; 15; 16]. The program evaluation and review technique (PERT) was the early SRA tool developed and used by the U.S. Department of the Navy in weapon system management [8]. Likewise, [PERSON] et al. [15] developed an SRA model called the evaluating risk in construction-schedule (ERIC-S) model for construction schedule risk analysis by determining the optimistic and pessimistic activity durations of schedule based on the project characteristics. Another SRA tool developed by [16] is the correlated schedule risk analysis model (CSRAM) use for evaluating the correlation between activity durations and risk factors to establish the degree of uncertainty in the schedule. Most of the aforementioned models are either CPM or PERT based model with their drawbacks. @Risk, Crystal ball, primavera risk analysis R8.x, etc. are the popular risk analysis software developed based on statistical method and Monte Carlo simulation. However, these tools have their limitations. @Risk for example can only deal with the risk and uncertainty that is related to scheduled activity durations but cannot resolve the issues that are related to resource conflict of resource-constrained projects. However, the software is still not affordable to most small-scale companies in the developing countries, especially when coupled with the time and cost required for the software training. Therefore, it is imperative to develop an alternative SRA tool that is simple, easy-to-use, and affordable to small-scale firms. Triangular Probability Distribution  
One of the objectives of this study is to develop an SRA model with the aid of a simple and accessible tool. Microsoft (MS) Excel is an application program accessible to all Microsoft Office users. MS Excel is a simple but powerful tool that is used as a platform upon which many commercial risk analysis software are built. This is due to various functions embedded in the spreadsheet, which can be used to perform different mathematical computations, statistical analysis, simulation, etc. Usually, to conduct SRA in MS excel, different statistical probability distributions such as normal, beta, lognormal distributions, etc. are employed to generate stochastic activity durations. However, past studies have confirmed that triangular distribution is the most acceptable for SRA. [PERSON] [17] reported in a study, that the statisticians recommended triangular distribution as the best alternative to beta distribution because beta distribution maximum-likelihood parameters are not explicit enough. Similarly, [PERSON] et al.