Atlanta Metro ventilation rehabilitation 18 Feb 2016

Operational and fire-life safety ventilation systems on the underground sections of the mass rapid transit system of Atlanta, Georgia, are to be fully overhauled and upgraded via a six year design-built contract awarded to Archer Western Construction with WSP | Parsons Brinckerhoff as the lead designer.

Fig 1. Plan of the Atlanta Metro system

The $198.5 million contract for the Metropolitan Atlanta Rapid Transit Authority (MARTA) will involve restoring the existing system in 16 tunnel segments of the system to a state of good repair through a combination of repair, rehabilitation or replacement of ventilation equipment.

The current ventilation system covers approximately nine miles (14.5km) of subway tunnel and underground rail stations, representing about one-fifth of the rail system's total footprint (Fig 1). The deepest station on the system is the Peachtree Center Station located some 120ft (36m) beneath downtown Atlanta in hard gneiss rock. No tunnel lining was installed in this station or in the adjacent tunnels, the rock itself providing the architectural finish.

The aging ventilation system of fans and dampers that control and direct air flow during normal rail operations and in emergency situations require renovation and renewal as a priority to maintain optimal functionality and good repair.

As the lead designer, services by WSP | Parsons Brinckerhoff will include evaluation of the existing system requirements and projected temperature ranges of a potential fire together with preparing design and performance criteria for ventilation equipment, overseeing the factory testing of the manufactured equipment, and the acceptance and commissioning of the installed system.

No lining required for the Peachtree Centre Station in the hard gneiss rock

The WSP | Parsons Brinckerhoff team will perform electrical system studies, egress analyses and tunnel fan scenarios for remote monitoring and control of the ventilation system, and will also prepare sustainability plans, conduct training and compile operations and maintenance manuals to help ensure that MARTA has the proper tools to manage and maintain the tunnel ventilation system long-term.

Construction of the MARTA heavy rail system began in 1975 with services on the first line commencing in June 1979. The system now has 48 miles (77km) of route with 38 rail stations located on four service lines and comprising a combination of elevated, ground-level, and underground alignment. It is the eighth largest rapid transit system in the United States, by ridership.