CHEC flags heat risk in Saudi desert

China Harbour Engineering Company (CHEC) has implemented a four-color flag warning system at the Sedra Infrastructure Project in Riyadh, Saudi Arabia, where summer temperatures can exceed 50 C and heatstroke poses severe risks to a multinational workforce facing language barriers.

At the project's start in May 2023, the team relied on standard thermometers that measure only air temperature and ignore solar radiation and humidity, leading to inaccurate heat-risk assessments. The team then deployed a five-in-one environmental sensor that collects temperature, humidity, and solar radiation data every 30 minutes and calculates heat stress indexes for quantified monitoring.

Drawing on the local tradition of using flags for signaling in desert environments, the team developed a visual warning system that requires no translation: green (caution, 32-41 C, 45 minutes work/15 minutes rest), yellow (heightened caution), orange (danger), and red (extreme danger, work suspension above 54 C).

The project conducts mandatory heatstroke training for new hires and monthly all-staff emergency drills based on the "Golden 3-5-10 Rescue Protocol": initial cooling within 3 minutes, medical intervention within five minutes, and hospital transport within 10 minutes. In July 2025, the project received the Owner's 10 Million Safe Work Hours milestone certificate.

Two workers test the temperature of the site. [Photo provided to chinadaily.com.cn]