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136 Table 65. Countermeasure 24: Waterborne patrols. Deploy mobile, boat-based patrols to monitor boat traffic Countermeasure Description over an underwater tunnel crossing. Types/Components Mobile boat based. Use Use for water crossings only. Category Measures for an elevated threat level. Provides an active presence to the waters above a tunnel. Strengths Particularly useful in protecting tunnels under navigable waterways. May not be able to stop a suicide attacker intent on Weaknesses scuttling the boat. Rough Cost of Implementation Low--less than $1 million per tunnel. Operation and Maintenance High--boats require specialized maintenance. High--personnel on patrol boats require specialized training to operate boat, board, or other vessels and to Training Requirements conduct interdiction activities. These personnel are likely drawn from law enforcement and must be authorized to conduct waterborne searches. Life Expectancy Short-term duration to match escalated threat level. Comments Table 66. Countermeasure 25: Ship-tracking protocols. Establishment of restrictions for any vessel transiting the Countermeasure Description waterway above a tunnel footprint. This action may require the coordination of nearby docks and water users. Types/Components Water areas above tunnel footprint. Use Use for water crossings only. Category Measures for an elevated threat level. Provides a standard-use pattern for vessels to transit the Strengths area above the tunnel. The restrictions should prevent vessels from stopping or staging above the tunnel. May hamper shipping patterns in area. Also, spotlights Weaknesses vulnerable location. Rough Cost of Implementation Low--less than $1 million per tunnel. Operation and Maintenance High--boats require specialized maintenance. Training Requirements Medium--a high level of coordination must occur. Life Expectancy Continual use of restrictions. Comments ability to be deployed at different locations based on chang- The C/B/R measure requires a capital investment, special- ing threat levels. However, these detectors require increased ized handling of the machinery, and training for those oper- maintenance. ating the systems. Countermeasure 27: C/B/R Detectors--Mobile 5.4.3 Recommended Permanent Enhancements C/B/R detectors provide a means to detect C/B/R materi- als before they enter the tunnel environment. The C/B/R Countermeasure 28: Explosive Detectors--Fixed detectors can be located on mobile units for easy deployment. The C/B/R detectors may use the current technologies avail- Mechanical devices with the intent of detecting explosives able and may contain sensors to detect individual materials. within the tunnel environment may be fixed and installed at See Table 68. tunnel perimeters and entrances. See Table 69.

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137 Table 67. Countermeasure 26: Explosive detectors--mobile. Implementation of fixed or mobile explosive detection Countermeasure Description devices in and around the tunnel area. Fixed and mounted inside tunnel structure or mobile and Types/Components moved by mechanical means. Use At tunnel portals or inside traffic areas. Category Measures for an elevated threat level. Provides a measure of detection to find explosives in the Strengths tunnel. Detection devices may be impaired by the harsh Weaknesses environment of most tunnels. The systems may be impacted by dirt, grime, and poor air quality. Low--less than $1 million per mobile unit. Rough Cost of Implementation Medium--between $1 and $3 million per fixed unit. Operation and Maintenance High--units require specialized maintenance. Training Requirements Medium--supplemental training is required. Life Expectancy 510 years. New technology with increasing reliability is continually Comments being researched and designed. Improvements to reliability and durability are in the future. Table 68. Countermeasure 27: C/B/R detectors--mobile. Install sensors at tunnel portals to provide notification of Countermeasure Description C/B/R material entering the tunnel. The detectors provide a means to detect and interdict the material. Types/Components Chemical; biological; radiological. Use Located at portals. Category Measures for an elevated threat level. Provides a measure of detection and interdiction of C/B/R Strengths material. Weaknesses Current technology is imperfect. Rough Cost of Implementation Low--less than $1 million per tunnel. High--machinery and detectors require specialized Operation and Maintenance maintenance and handling. Medium--technicians or personnel operating the detectors Training Requirements require specialized training. Life Expectancy 510 years. Comments The fixed explosive detector typically consists of a Countermeasure 29: C/B/R Detectors--Fixed mechanical device that extracts air samples and, using a C/B/R detectors provide a means to detect C/B/R materi- variety of means, tests them for explosive residue. Some als before they enter the tunnel environment. The C/B/R models are capable of performing the test immediately, and detectors can be permanently installed. The C/B/R detectors others rely on a technician removing the sample and con- may use the current technologies available and may contain ducting the detection test in another location. The fixed sensors to detect individual materials. See Table 70. detector relies on the extraction of air samples that are clean The C/B/R measure requires a capital investment, special- enough to be tested. Impurities that may contaminate the ized handling of the machinery, and training for those oper- air sample must be low to allow a true measure of explosive ating the systems. residue to be detected. Foul air or clogged intake lines can alter the integrity of the explosive detection test. Fixed detectors are designed to mechanically emulate the chemi- Countermeasure 30: Redundant Ventilation Systems cal sensing abilities of a dog. Explosive detectors are not guaranteed to prevent the entry of explosives, and this tech- To ensure an adequate supply of fresh air to the tunnel nology is continually being reworked. and the exhaust of contaminated, foul, or smoke-filled air

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138 Table 69. Countermeasure 28: Explosive detectors--fixed. Implementation of fixed or mobile explosive detection Countermeasure Description devices in and around the tunnel area. Fixed and mounted inside tunnel structure or mobile and Types/Components moved by mechanical means. Use At tunnel portals or inside traffic areas. Category Measures for an elevated threat level. Provides a measure of detection to find explosives in the Strengths tunnel. Detection devices may be impaired by the harsh Weaknesses environment of most tunnels. The systems may be impacted by dirt, grime, and poor air quality. Low--less than $1 million per mobile unit. Rough Cost of Implementation Medium--between $1 million and $3 million per fixed unit. Operation and Maintenance High--units require specialized maintenance. Training Requirements Medium--supplemental training is required. Life Expectancy 510 years. New technology with increasing reliability is continually Comments being researched and designed. Improvements to reliability and durability are in the future. Table 70. Countermeasure 29: C/B/R detectors--fixed. Install sensors at tunnel portals to provide notification of Countermeasure Description C/B/R material entering the tunnel. The detectors provide a means to detect and interdict the material. Types/Components Chemical; biological; radiological. Use Located at portals. Category Permanent enhancements. Provide a measure of detection and interdiction of C/B/R Strengths material. Weaknesses Current technology is imperfect. Rough Cost of Implementation Low--less than $1 million per tunnel. High--machinery and detectors require specialized Operation and Maintenance maintenance and handling. Medium--technicians or personnel operating the detectors Training Requirements require specialized training. Life Expectancy 510 years. Comments during an incident, the tunnel owner or operator may wish A redundant ventilation system requires a significant capital to install a redundant ventilation system. The system may investment by the tunnel owner or operator. The effectiveness be designed and built to supply air to and/or exhaust air of the redundant system relies on a commitment to maintain- from specific critical areas, evacuation shelters, and path- ing the system and testing its functionality at regular intervals. ways or to ventilate air throughout the entire tunnel struc- ture. The redundant system may be designed to operate Countermeasure 31: Interior Liner Steel Plates independently of the main ventilation system, with a dif- or Panels ferent power source and air source. Both systems will be controlled from a control station located outside the tun- The thickness of the steel plates or energy-absorbing steel nel. The system may provide pressurized stairwells and panels will depend on the specific tunnel construction type, evacuation zones dictated by local code or installed as part the construction materials (concrete, brick, etc.), the sur- of original design for newer assets. Existing structures or rounding soil or earth geology, the groundwater conditions, systems may sometimes be used to reduce the cost of instal- the size of the IED or fire being considered, and the proxim- lation. See Table 71. ity of the hazard or threat to the liner. See Figure 15.

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139 Table 71. Countermeasure 30: Redundant ventilation systems. Establishment of redundant ventilation to be used to Countermeasure Description supply fresh air and remove impure air in an emergency condition if the main ventilation system is not available. Supply fans (blowers); exhaust fans; ducts; dampers; Types/Components louvers; power source; backup power source. Installation to provide redundancy to critical tunnel areas, Use including evacuation routes. Strengths Provides redundancy to airflow systems. Weaknesses Requires high level of maintenance. High--over $10 million per tunnel. Cost depends on tunnel Rough Cost of Implementation length, ventilation system type, and scope of redundant system. Operation and Maintenance High--system must be kept in constant state of readiness. Training Requirements None. Life Expectancy 2025 years. Comments Constructability issues include the following: Countermeasure 32: Interior Liner Concrete Panels The thickness of the precast or cast-in-place concrete pan- Interior clearances for installation of steel plates or energy- els will depend on the specific tunnel construction type, the absorbing panels. construction materials (concrete, brick, etc.), the surround- Work hours (weekdays, nighttime, and weekends); ing earth geology, the groundwater conditions, the size of the required track outages or highway lane closures. IED or fire being considered, and the proximity of the hazard Limited number of crews per shift due to space constraints. or threat to the liner. See Figure 16. Access to tunnel (personnel, equipment and material). Constructability issues include the following: Contractor staging area outside of tunnel. Work trains for rail tunnels; portable platforms for high- Interior clearances for installation of concrete panels. way tunnels. Work hours (weekdays, nighttime, and weekends); Protection services for contractors (i.e., flagging); safety required track outages or highway lane closures. training for employees. Limited number of crews per shift due to space constraints. Access to tunnel (personnel, equipment, and material). Contractor staging area outside of tunnel. Figure 15. Interior liner steel plates or panels. Figure 16. Interior liner concrete panels.

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140 Work trains for rail tunnels; portable platforms for high- Countermeasure 34: Interior Liner Bolting way tunnels. or Tie-Backs Protection services for contractors (i.e., flagging); safety Another method of strengthening the tunnel liner is to use training for employees. bolting or tie-backs with wire mesh and to apply shotcrete over it. The suitability of this method depends greatly on the Countermeasure 33: Interior Concrete or Chemical surrounding geology. For example, this method is very effec- Grouting tive for strong to medium rock types, but not for medium to weak rock types. See Figure 18. To provide more strength for existing tunnels within the Constructability issues include the following: zone influenced by the hazard or threat of explosion or fire, and to overcome problems associated with these hazards and Interior clearances for installation of bolting or tie-backs, threats, a variety of protective systems can be applied. These wire mesh, and shotcrete. protective systems include ground treatment measures such as Work hours (weekdays, nighttime, and weekends); cement-rich concrete and chemical grouting, which enable the required track outages or highway lane closures. tunnel liners to withstand higher forces. However, grouting Limited number of crews per shift due to space constraints. mechanisms are difficult to verify and site-specific geotechni- Access to tunnel (personnel, equipment, and material). cal information varies from project to project. See Figure 17. Contractor staging area outside of tunnel. Constructability issues include the following: Work trains for rail tunnels; portable platforms for high- way tunnels. Work hours (weekdays, nighttime, and weekends); Protection services for contractors (i.e., flagging); safety required track outages or highway lane closures. training for employees. Limited number of crews per shift due to space constraints. Access to tunnel (personnel, equipment, and material). Contractor staging area outside of tunnel. Countermeasure 35: Exterior (Ground) Concrete Work trains for rail tunnels; portable platforms for high- or Chemical Grouting way tunnels. Protection services for contractors (i.e., flagging); safety Grouting mechanisms are difficult to verify, and site- training for employees. specific geotechnical information varies from project to Figure 17. Interior concrete or chemical grouting.

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141 Figure 18. Interior liner bolting or tie-backs. project. To provide more strength for existing tunnels Constructability issues include the following: within the zone influenced by the hazard or threat of explo- sion or fire, and to overcome problems associated with these Material is delivered via barge and lowered by cranes. hazards and threats, a variety of protective systems can be Environmental issues require permits and approval from applied. These protective systems include ground treatment responsible agencies. measures (such as cement-rich concrete and chemical Coordination with water traffic authorities is required. grouting), which enable the tunnel liners to withstand All work is conducted outside of the tunnel. higher forces. See Figure 19. Constructability issues include the following: Countermeasure 37: Precast Concrete Slab All work is conducted outside of the tunnel. over Tunnel The interior of the tunnel must be monitored by employ- ees or expert contractors to ensure that the grouting Similar to rip-rap, the precast concrete slab is laid on the process is not negatively impacting the tunnel. bottom of a water body, such as a river bed or stream, to pro- Depending on the land use above, tect the tunnel below from threats such as large IEDs or Permits may be required from the agency owning the explosive containers dropped from a passing ship. The land of the grout injection sites, thickness of the slab should depend on the size of the IED Coordination with other agencies may be required, being considered and the amount of cover over the tunnel. Utility relocation and coordination may be required, However, the ground geology and the structural capacity and/or of the tunnel may limit the amount of weight that can Work hours may depend solely on the contractor's be added and, thus, must be taken into consideration. See schedule. Figure 21. Constructability issues include the following: Material is delivered via barge and lowered by cranes. The Countermeasure 36: Rip-Rap over Tunnel size of the concrete segments depends on the capacity of Rip-rap can consist of stones, blocks of concrete, or other the crane. similar material. It is laid on the bottom of a water body, such Environmental issues require permits and approval from as a river bed or stream, to protect the tunnel below from responsible agencies. threats such as large IEDs or explosive containers dropped Coordination with water traffic authorities is required. from a passing ship. See Figure 20. All work is conducted outside of the tunnel.

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142 Figure 19. Exterior (ground) concrete or chemical grouting. Countermeasure 38: Interior Roof Steel Plates Limited number of crews per shift due to space constraints. Access to tunnel (personnel, equipment, and material). Interior roof steel plates are appropriate only for flat- Contractor staging area outside of tunnel. topped, cut-and-cover tunnels. The thickness of the steel Work trains for rail tunnels; portable platforms for high- plates will depend on the available clearances, the tunnel con- way tunnels. struction materials (concrete or brick), the depth of cover Protection services for contractors (i.e., flagging); safety over the tunnel, the surrounding soil or earth geology, the training for employees. groundwater conditions, the size of the IED or fire being con- sidered, and the proximity of the hazard or threat to the liner. See Figure 22. Constructability issues include the following: Countermeasure 39: Interior Roof Concrete Panels Interior roof concrete panels are appropriate only for flat- Interior clearances for installation of steel plates. topped, cut-and-cover tunnels. The thickness of the concrete Work hours (weekdays, nighttime, and weekends); panels will depend on the available clearances, the tunnel required track outages or highway lane closures. construction materials (concrete or brick), the depth of cover

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143 Figure 20. Rip-rap over tunnel. over the tunnel, the surrounding soil or earth geology, the Protection services for contractors (i.e., flagging); safety groundwater conditions, the size of the IED or fire being con- training for employees. sidered, and the proximity of the hazard or threat to the liner. See Figure 23. Constructability issues include the following: Countermeasure 40: Exterior Roof Steel Plates Interior clearances for installation of concrete panels. Exterior roof steel plates are appropriate only for flat- Work hours (weekdays, nighttime, and weekends); topped, cut-and-cover tunnels. The thickness of the steel required track outages or highway lane closures. plates will depend on the tunnel construction materials Limited number of crews per shift due to space constraints. (concrete or brick), the depth of cover over the tunnel, Access to tunnel (personnel, equipment, and material). the surrounding soil or earth geology, the groundwater Contractor staging area outside of tunnel. conditions, the size of the IED or fire being considered, Work trains for rail tunnels; portable platforms for high- and the proximity of the hazard or threat to the liner. See way tunnels. Figure 24.

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144 Figure 21. Precast concrete slab over tunnel. Constructability issues include the following: tunnel. However, the ground geology and the structural capacity of the tunnel may limit the amount of weight that All work is conducted outside of the tunnel. can be added and, thus, must be taken into consideration. See Depending on the land use above, Figure 25. Permits may be required, Constructability issues include the following: Coordination with other agencies may be required, Utility relocation and coordination may be required, All work is conducted outside of the tunnel. and/or Depending on the land use above, Work hours may depend solely on the contractor's Permits may be required, schedule. Coordination with other agencies may be required, Utility relocation and coordination may be required, Countermeasure 41: Exterior Roof Concrete Panels and/or The thickness of the concrete panels will depend on the size Work hours may depend solely on the contractor's of the IED being considered and the amount of cover over the schedule.

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145 Figure 22. Interior roof steel plates. Figure 23. Interior roof concrete panels. Countermeasure 42: Bollards to Control Access There must be sufficient property (width and depth) to accommodate the bollards. Bollards are typically constructed around the outside perimeter or across the front entrances of stations or buildings Depending on who owns the property, in order to protect the buildings and occupants from vehicles, Permits may be required, including those that may be carrying IEDs. The bollards are Coordination with other agencies may be required, designed to withstand the force of a speeding van or truck. Utility relocation and coordination may be required, Depending on the application, bollards can be permanent or and/or removable. See Figure 26. Work hours may depend solely on the contractor's Constructability issues include the following: schedule.

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146 Figure 24. Exterior roof steel plates. Figure 25. Exterior roof concrete panels. Figure 26. Bollards to control access.

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147 Figure 27. Fencing to control access. Countermeasure 43: Fencing to Control Access to the columns. The concrete increases the fire resistance of the column. If additional fire resistance is desired, the concrete can Fencing is built around the perimeter of a building or facil- be mixed with polypropylene fibers. See Figure 28. ity to keep intruders from entering. There are many different Constructability issues include the following: types of fencing. See Figure 27. Constructability issues include the following: Interior clearances for installation of concrete encasement. Coordination of passengers or other users if area is occupied. There must be sufficient property to accommodate the fencing. Depending on who owns the property, Countermeasure 45: RFP Wrapping of Columns Permits may be required, Coordination with other agencies may be required, Reinforced fiber protection (RFP) systems are used for Utility relocation and coordination may be required, blast hardening and mitigation for circular reinforced con- and/or crete columns that support stations and air-rights structures. Work hours may depend solely on the contractor's The RFP wrapping provides strength and ductility to mini- schedule. mize damage; prevent collapse; and enhance blast perform- ance of columns, beams, walls, and ceiling slabs. If fire Countermeasure 44: Concrete Encasement of Columns Existing support columns can be strengthened by adding concrete encasements around the steel. This measure can be done for all columns or selected columns. The thickness of the encasement will depend on the size of the IED or fire being Figure 28. Concrete considered and the relative proximity of the hazard or threat encasement of columns.

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148 Figure 29. RFP wrapping of columns. Figure 31. Redundant columns or walls. resistance is an issue, there are composite systems on the mar- ket that allow the addition of a spray-applied coating on top Constructability issues include the following: of the RFP system to increase the fire rating. See Figure 29. Constructability issues include the following: The facility must have sufficient space to accommodate the additional columns and/or walls. Minor interior clearances for installation of RFP wrapping. Applicable fire and life-safety (i.e., egress) codes must be Coordination of passengers or other users if area is occupied. considered if new walls are constructed. Coordination of passengers or other users if area is occupied. Countermeasure 46: Steel Jacketing of Columns Countermeasure 48: Floodgates Steel jackets can be installed around existing support columns. The steel jacket can be designed based on the size of Flooding in a tunnel can be extremely dangerous and the IED or fire being considered and on the relative proxim- damaging. This is particularly true if an underwater tunnel ity of the hazard or threat to the columns. See Figure 30. is interconnected with other tunnels and/or passenger Constructability issues include the following: stations because the water has the potential to travel farther, cause more destruction, and interrupt tunnel operations. Minor interior clearances for installation of steel jackets. To lessen the potential for extensive flooding from situa- Coordination of passengers or other users if area is occupied. tions such as these, floodgates are sometimes installed. See Figure 32. Countermeasure 47: Redundant Columns or Walls Constructability issues include the following: In some cases, such as a particularly vulnerable air-rights Significant vertical clearances for installation of floodgates. structure or transit station, it may be deemed necessary to Extensive tunnel utility relocation. build additional support columns or walls. This measure Work hours (weekdays, nighttime, and weekends); would, of course, increase the support capacity in the event of required track outages or highway lane closures. an explosive or large fire. To justify this level of effort, the haz- Limited number of crews per shift due to space constraints. ard or threat scenarios should be examined closely to deter- Access to tunnel (personnel, equipment, and material). mine the size of the IED or fire to be considered as well as the Contractor staging area outside of tunnel. proximity of the hazard or threat to the existing and new Work trains or portable platforms; protection services for columns and walls. See Figure 31. contractors (i.e., flagging); safety training for employees. Countermeasure 49: Barrier Walls Barrier walls are sometimes constructed on the water side of a tunnel portal to create a stand-off distance and protect the portal from waterborne hazards and threats, such as off- course ships or ships carrying explosives. See Figure 33. Constructability issues include the following: Environmental issues require permits and approval from Figure 30. Steel responsible agencies. jacketing of columns. Coordination with water traffic authorities.