Tunnel Business Magazine

AUG 2018

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Page 25 of 43

TUNNELINGONLINE.COM 2 6 TBM: TUNNEL BUSINESS MAGAZINE // AUGUST 2018 The Elizabeth River Tunnel project, locate - folk and Portsmouth, Virginia, included the develop- ment, design, construction, finance and operation of a new two-lane unidirectional immersed tunnel adjac unnel under the Elizabeth River unnel will re- lieve congestion and improve safety by eliminating bi-directional traf unnel. unnel, the project included the rehabilita and Downtown Tunnels. The Virginia Department of Transportation (VDOT) awarded the project under a P3 delivery method to Elizabeth River Concessionaire (ERC), which is responsible for all aspects of the project (design, build, finance, operate, and maintain). ERC will perform tolling, operations, and maintenance activi- ties for a 58-year period. With input provided by local police, fire, ambulance and first responders, the design enables enhanced emergency response and evacuation readiness. State- of-the-art safety features in the new tunnel includes a separate escape corridor, longitudinal ventilation, deluge system, fire sensors, fire alarms, motorist aid phone system, fire protection of the structural lining and video monitors for traveler safety meeting History of Existing Tunnels The unnel (Highway 58) opened T olk and Portsmouth and consists of a single bidi- rectional tunnel with transverse ventilation beneath the main channel of the Elizabeth River. Since the opening of the tunnel the population in the area has increased by 70% and average daily traffic has in- creased from 8,400 vehicles to 31,194 vehicles per day. NFPA-502 Fire Protection Case Histories: Elizabeth River Tunnel and the Hugh L. Carey Tunnel F ire and life safety systems for transportation tunnels are of paramount concern. The results of a tunnel fire can be catastrophic if the facility is not properly equippe only can a fire result in loss of life, but also significant eco- nomic ramifications. Today, tunnel owners r tional Fire Protection Associa- A) Standard 502 to provide guidance when building or rehab- A 502 provides fire protection and fire life safety re- quirements for limited access highways, road tunnels, bridges, elevated highways, depressed highways, and roadways that are located beneath air-right structures. To illustrate fire and life safety considerations, this paper explores two recent projects involving tunnels, the construction of the Elizabeth River Tunnels in Virginia, and the rehabilitation of the Hugh L. Carey T art of the fire and life safety scope for these tun- nels was to protect the tunnel structur A 502 standard, pre- venting explosive spalling and progressive collapse of the tunnel lining during a 2-hour Rijkswaterstaat (RWS) fire event. Key p A 502 edition 2011 include: Section 7.3.1: Regardless of tunnel length, acceptable means shall be included within the design of the tunnel to protect all primary structural concrete and steel elements in accordance with this stan- dard in order to: 1. te structural damage and prevent progressive structural collapse 2. conomic impact due to tunnel closure Section 7.3.2: The structure shall be capable of withstanding the RWS time/temperature curve or other recognized standard time/tempera- ture curve that is acceptable to the authority having jurisdiction (AHJ), following an engineering analysis. Section 7.3.3: During a 120-minute period of fire exposure, the fol- lowing failure criteria shall be satisfied: 1. Tunnels with concrete structural elements shall be designed or protected such that explosive spalling is prevented. 2. Steel or cast-iron tunnel structural elements shall be protected such that the lining temperature shall not exceed 300 C (572 F). Section 7.3.4: Structural fire protection material, where provided, shall satisfy the following performance criteria: 1. Tunnels with cast in situ concrete structural elements protected such that: a. The temperature of the concrete surface does not exceed 380 C (716 F). b. The temperature of the steel reinforcement within the con- crete [assuming a minimum cover of 25 mm (1 in.)] does not exceed 250 C (482 F). 2. The material shall be noncombustible in accordanc E 136 or equivalent international recognized standard. 3. The material shall have a minimum melting temperature of 1,350 C. (2,462 F). 4. The material shall meet the fire protection requirements with less than 5 percent humidity by weight and when fully satu- rated with water, in accordance with the approved time/tem- perature curve. Elizabeth River Tunnel

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