Accelerating the development of the road network.
State of Qatar developed a comprehensive programme called "Doha Expressways" to improve the country's road network, particularly in and near its capital, Doha. The whole programme included nine projects (or "Groups"), each divided further into between one and four highway projects.
Context
"Group 8a" is located in Central Doha and consisted of widening existing urban or suburban roads. Egis was appointed as the Supervision Consultant for Al Rayyan Road Upgrade Project Contracts 1 and 2.
Al Rayyan is the third-largest municipality in the State of Qatar with an estimated population of over 600,000 with a mixture of commercial and residential areas.
Al Rayyan Road is an arterial road that provides connectivity to Education City and Dukhan to the west and Doha to the east; and its upgrade will ease the traffic flow to Al Bustan North and South.
The Al Rayyan Road Upgrade Project Contracts 1 and 2 involved the upgrade of 8.4 km of Al Rayyan Road from west of Olympic Intersection, to east of Bani Hajer roundabout, doubling the lane capacity of Al Rayyan Road from two to four lanes, as well as providing service roads.
A congested urban environment
As the project commenced, the client was aware that the works were to take place in an already congested urban setting. Traffic flow and private access in all areas of Al Rayyan had to be maintained at all times. This included Shemal Road, where three lanes of traffic had to remain open at all times whilst constructing the new flyover crossing them. 68km of concrete barrier were used to suit the needs of the diversion roads.
Sixteen VVVIP’s had residences adjacent to or located on the proposed right of way. Extensive land expropriation and the demolition of over 120 buildings had to be executed before a large portion of the construction proper could commence. All 16 of the VVVIP’s properties were affected.
A risk of construction conflicts
Three Qrail stations are positioned within the P007 C02 right of way with the rail tunnel running below the road tunnel on what is now Al Sabah Corridor. Additionally, a new micro-tunnel was constructed along Al Rayyan to R6 junction. Without careful co-ordination and sequencing of work, there was a risk of construction clashes with potentially devasting consequences.
High presence of underground gas
The geotechnical report indicated an extremely high concentration of H2S ground gas in the location of the R5 underpass. Special construction techniques were needed to safely excavate and construct the work.
Dealing with ground water
Ground water and underground cavities could be found on the alignment of the R6 tunnel, the extent of which was difficult to determine as Qrail were already in the process of de-watering when P007 C02 construction started. When Qrail completed its construction and stopped de-watering, this coincided with the deepest part of tunnel excavation, and ground water increased to 1000l/s. This led to us setting up a temporary pump station and redesigning the tunnel’s attenuation tanks.
