The construction sector is one of the most dangerous industrial sectors. Struck-by object or equipment is one of the main causes of fatal accidents on construction sites. Although many regulations have been designed for struck-by accidents, these accidents are still causing many injuries and fatalities. According to the U.S. Bureau of Labor Statistic, the struck-by accidents has led to 112 deaths on construction site in 2018. The application of real-time location systems (RTLS) on construction sites provides new possibilities in construction safety management. Previous researchers have proposed using RTLS to track the location of workers and equipment on construction sites to improve construction safety. However, the previous methods have some limitations (e.g. cabling problems, positioning quality). Furthermore, providing effective safety alerts to workers within dangerous proximity to equipment has not been addressed in previous research. This research aims to develop a method for providing near real-time proximity alerts to workers on construction sites using Bluetooth Low Energy (BLE) RTLS based on angle of arrival (AOA). This RTLS can provide acceptable accuracy coupled with large coverage without the need of timing cables. Also, with the support of two-way communications between the tags and sensors, it is possible to provide vibro-tactile alerts to the workers using wristbands. In addition, alerts representing different cases of proximities and speeding were defined. The prototype system has the following features: (1) less cabling by using wireless technologies for data transmission, (2) less false alerts by generating the alerts to specific entities based on the micro-schedule of activities, (3) easily perceived alerts. Tests were conducted on a construction site of an electric substation to test the accuracy of the RTLS and the performance of the prototype system. The test results indicated that the prototype system is capable of detecting proximities and generating timely alerts to the involved entities
