Determining Average Available Workdays for Roadway Construction Projects Using Long-Term Weather Data—A Case Study for Alabama

Construction project durations specified on contracts are influenced by adverse weather conditions such as rainfall and low temperatures. This study aimed to develop an efficient method for determining monthly Average Available Workdays (AAWDs) for roadway construction projects using historical long-term (ten years or more) local weather data. A survey was conducted to understand the status of current practices using weather information for contract time determination by transportation agencies. Excel spreadsheet tools with Visual Basic for Applications (VBA) programs were developed to process the downloaded long-term weather data with two different formats. Instead of manually processing the short-term (e.g., one–three years) weather data, VBA programs efficiently count for weekends, legal holidays, and adverse weather days as non-workdays each month over the years with weather data (>10 years) and then determine the monthly available workdays (AWDs) and AAWDs. This method was verified using daily records from five completed roadway construction projects. Many contractor-claimed non-workdays due to other factors, not weather-related, that contributed to substantially longer project duration affect the comparison of AWDs determined from nearby weather stations using the developed VBA tools. The method and VBA tools developed were applied to 88 weather stations (10–122 years, average 42 years of data) to determine AAWDs in Alabama, USA, as a case study. Monthly AAWDs in Alabama were grouped into three climate zones: North Region, Central Regions, and South Regions with 185, 193, and 200 AAWDs per year, respectively, with more workdays (17–19 days) in warmer months and fewer (9–11 days) in colder months. The determined AAWDs help both DOTs and construction contractors determine/propose reasonable construction project durations and resolve the construction delay issues. The method and VBA tools can be revised/updated by other DOTs and construction companies for different definitions and thresholds on non-workdays and then efficiently determine AWDs and AAWDs using long-term local weather data.