Technical Specifications and Requirements

In order to comply with the Concessionaire Agreement requirements for the Cut & Cover, Cross –passages and Tunnel Sections, the Fire Protection had to meet NFPA-502 edition 2008. Chapter 7 applies: Road Tunnels - Section 7.3 Protection of Structural Elements

Section 7.3.1:

Regardless of tunnel length, all primary structural concrete and steel elements shall be protected in accordance with this standard in order to:
  • maintain life safety and provide a tenable environment
  • mitigate structural damage and prevent progressive structural collapse
  • minimize economic impact

Section 7.3.2 defines the thermal design exposure to the concrete lining:

The structure shall be capable of withstanding the Rijkswaterstaat (RWS) time-temperature curve that is acceptable to the AHJ.

Section 7.3.3: defines the thermal failure criteria of the load bearing structures:

After a 120-minute period of fire exposure, the following failure criteria shall be satisfied:
  • tunnels with Cast in–situ concrete structural elements shall be protected such that:
    • the temperature of the concrete surface does not exceed 380°C (783°F).
    • the temperature of the steel reinforcement within the concrete [assuming a minimum cover of 25mm (1in.) does not exceed 250°C (482°F).
  • tunnels with concrete structural elements shall be designed or protected such that explosive spalling is prevented.

Section 7.3.4: defines material properties of passive fire protection materials that are used for protection of structural linings. 

This aim, amongst others reasons, to prevent that such materials do not become a hazard in itself when exposed to fire.
Structural fire protection material where provided, shall satisfy the following performance criteria:
  • the material shall be noncombustible in accordance with ASTM E 136 or equivalent international recognized standard.
  • the material shall have a minimum melting temperature of 1350°C. (2462°F).
  • it shall not produce toxic smoke or fumes under fire exposure in accordance with ASTM E 84 or equal international standard.

It shall meet the fire protection requirements with less than 5 percent humidity by weight and also when full saturated with water, in accordance with the approved time-temperature curve tested in accordance with RWS Fire Test Procedure 1998-CVB-R1161 (Rev.1).

RWS curve 120 minutes