i8 | eyes ahead Resilient concrete posed special challenges. This was due to the Arabian environment, which is awash with hot and dry weather. Other challenges arose due to time-consuming concrete overhauls from ready-mix plants and a frequent use of 200-m long casting lines on-site. Micro silica and fly ash were used as cement replacement in concrete. The micro silica and fly ash served as plasticizer and helped reduce the energy expended and carbon dioxide levels produced by cement manufacturing. To bring this benefit to perspective, it is worth knowing that the project requires about three million m3 of concrete. Special challenges Challenges were part and parcel of the Makkah Haram project. In addition to durability and scale, there were challenges due to the social and religious nature of the project. One of the greatest challenges was the condition imposed by the client for uninterrupted visitor traffic. Despite it being a fast-track, design-build project, construction still had to protect the constant flow of pilgrims at all times. To meet this requirement, a strenuous work schedule of 20-hour work days and 120-hour weeks was enforced. On-site engineers also had to accommodate city regulations requiring closures of the main roads two to three times daily at peak hours, which slowed down materials’ delivery to the site. Rock excavation -all 13.2 million m3 of them- had to be completed while employing controlled blasting and complying with strict noise and vibration limits. And, because of their immediate proximity to the existing Haram, materials and vehicles required careful maneuvering. Behind the scenes: Waste, emergencies and power backup The AWCS employs suction to move the waste from the storage sections in the Haram building to the collection terminal at CUC, some 1,100 m away. A refuse cyclone separator separates the air and the waste bags. The waste is then compacted and locked under negative pressure in a fully sealed container, ready to be transported away. Several devices are in place for emergencies. Two types of sprinklers aid in firefighting, operating as a wet system and a water mist system. Fire extinguishers use an ozone friendly gaseous suppression agent. For smoke evacuation, fire zoning is employed and smoke curtains are positioned every 60 m along the main corridor. For safety and security, access control is provided for doors at important building rooms, offices and electromechanical areas. An automated operation system is provided to monitor and control MV switchgears network using Supervisory Control and Data Acquisition (SCADA) systems. Backup is provided to ensure continuous, uninterrupted performance of all systems. In the event of power shutdown, uninterruptible power supply (UPS) can provide 30% of the lighting power and 100% of the power for safety, security and communication loads. Ease of expandability is central in design, along with flexibility and individuality. Since water is the lifeblood of the pilgrims’ journey, water-proofing measures ensure that the spring water, Zamzam, remains contaminant-free. Throughout the project, rigorous measures of quality were applied. Some are evident, but most are invisible. For example, durability considerations prohibited the use of paint. Instead, white, red and blue aggregates are used to give a permanent, maintenance-free, colorized effect. Structural performance was inspected. Strain gauges are embedded in some rafts to measure deformations. 28