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3. Recommendations and Implementation Strategy

Team members identified a number of underground transportation system initiatives or practices that varied from those in the Unites States in some respect. The team recommended that nine of these initiatives or practices be further considered for possible implementation in the United States.

Little was discovered related to the threat from terrorism to underground structures, perhaps because of the confidential nature of this information or the lack of perceived need for such measures. The scan team learned that the Europeans consider response and safety measures already in place for crashes and other incidents to also be applicable for many terrorist actions.

The nine initiatives and practices the scan team identified are described below. Included are the team's assessment of the benefits of each initiative or practice and the planned implementation strategy.

3.1. Develop Universal, Consistent, and More Effective Visual, Audible, and Tactile Signs for Escape Routes

The scan team noted that the signs Europeans use to indicate emergency escape routes are consistent and uniform from country to country. Emergency escape routes are indicated by a sign showing a white-colored running figure on a green background. Other signs that indicate the direction (and in tunnels, the distance in meters) to the nearest emergency exits are similarly indicated by a white figure on a green background, as used in European buildings and airports. See Figure 13 for examples. All SOS stations in the tunnels were identified by the color orange. This widespread uniformity promotes understanding by all people, and helps assure that in the event of an emergency, any confusion related to the location of the emergency exit will be minimized. In addition, the team learned that the use of sound that emanates from the sign, such as a sound alternating with a simple verbal message (e.g., " Exit Here" ), when combined with visual (and, where possible, tactile) cues, makes the sign much more effective.

The U.S tunnel engineering community relies on NFPA 130, Standard for Fixed Guideway Transit and Passenger Rail Systems, and NFPA 502, Standard for Road Tunnels, Bridges, and Other Limited Access Highways, for fire protection and fire life safety design standards. These standards should be reviewed and revised as necessary to incorporate the most current technology and results of recent human response studies on identifying and designing escape portals, escape routes, and cross passages.

Implementing this practice will provide the benefits of reducing the time it takes for motorists to get to a safe location during the initial stages of a tunnel emergency and improving the efficiency of the evacuation process.

The implementation strategy includes promoting the use of easy-to-recognize multisensory signs that are uniform and consistent, and providing input and assistance for inclusion of these signs in tunnel design manuals and standards.

3.2. Develop AASHTO Guidelines for Existing and New Tunnels

Single-source guidelines for planning, designing, constructing, maintaining, and inspecting roads and bridges have been in place for many years. NFPA has developed standards for safety in highway tunnels and passenger rail tunnels. APTA has general safety standards and guidelines for passenger rail operations and maintenance, with incorporation of some of the NFPA guidelines by reference. However, AASHTO does not have standards or guidelines specifically for highway or passenger and freight rail tunnels. Recently, the AASHTO Subcommittee on Bridges and Structures created a new committee, the Technical Committee on Tunnels (T-20), to help address this problem. T-20 should take the lead in developing AASHTO standards and guidelines for existing and new tunnels, working with NFPA, APTA, FHWA, and the appropriate TRB committees on standards and guidelines for highway and passenger and freight rail tunnels. T-20 should consider tunnel safety measures such as the Mont Blanc Tunnel emergency pullout area and variable message sign showing maximum speed limit and required vehicle spacing, as shown in figure 19, as well as refuge room requirements, as shown in figure 20.

Implementing this initiative will provide the benefits of creating a single-source AASHTO reference for use by tunnel engineers and operators. This reference will facilitate the use of consistent criteria in U.S. tunnels.

The implementation strategy includes review of the ongoing FHWA Tunnel Design Manual project, and coordination with AASHTO, FHWA, NFPA, APTA, and TRB on standards and guidelines for highway tunnels and passenger and freight rail tunnels.

3.3. Conduct Research and Develop Guidelines on Tunnel Emergency Management that Includes Human Factors

Tunnel design solutions may not anticipate human behavior, and consistently predicting the way people will behave in an incident is not easy. During emergency situations, human behavior is even harder to predict as the stress of the situation replaces intellect with curiosity, fear, or even panic. During a tunnel emergency, people often must be their own first rescuers and must react correctly within a few minutes to survive. Tunnel emergency management scenarios and procedures must take human behavior into account to be fully effective in saving lives. The European experience in human factor design provides a good basis for the United States to discover and include more effective measures for tunnel planning, design, and emergency response.

Implementing this initiative will provide improved emergency response plans to enable response teams to better handle situations, thereby mitigating the consequences of an incident. Its implementation will also improve the ability of planners and designers to address security and safety issues in tunnel design, and improve the ability of tunnel owner-agencies to provide training and guidance to the public on how to respond when an incident occurs in a tunnel.

The implementation strategy includes working through the AASHTO HSCOBS Technical Committee for Tunnels (T-20) to fund and develop guidance for tunnel emergency management. Part of this effort will be to reach out to academia to perform studies on human response in tunnel incidents. The work done by the Europeans (PIARC Working Group 3) in this area can be used to promote the importance of human response studies in the United States.

3.4. Develop Education for Motorist Response to Tunnel Incidents

During an emergency situation, most people do not immediately know what to do to save themselves and others. Motorists are their own first rescuers, and European studies indicate that self-rescue may be the best first response for a tunnel incident. For this to be an effective strategy, it is important to educate the public about the importance of reacting quickly and correctly to a tunnel incident, such as a fire.

Road crashes are the consequence of one or more faults in a complex system involving drivers, vehicles, the road, and its surroundings. Nevertheless, the major factor in road crashes is human error, so efforts to increase the level of road safety must be aimed primarily at preventing these human errors. The main benefit of this initiative is to avoid loss of lives by making motorists aware of safety features in U.S. tunnels and how to react properly in case of an incident in a tunnel. Also, proper education will help motorists avoid human errors that can lead to incidents.

The implementation strategy includes working with AASHTO, NFPA, the American Automobile Association (AAA), and TRB on outreach, including preparing brochures, articles, and presentations for conferences, schools, and other venues. Other efforts under consideration are development of television and radio public announcements, a video for professional drivers, and a pilot tunnel safety program with the States.

3.5. Evaluate Effectiveness of Automatic Incident Detection Systems and Intelligent Video for Tunnels

The scan team learned of sophisticated software that, using a computer system interfacing with ordinary video surveillance cameras, automatically detects, tracks, and records incidents. As it does so, it signals the operator to observe the event in question and take the appropriate action. This concept can also be applied to detect other activities and incidents in areas besides tunnels, from terrorist activities to crashes, vandalism and other crimes, fires, and vehicle breakdowns.

Widespread public use of CCTV is not as readily accepted in the United States as in other countries because of privacy concerns. However, people are entitled to security, and the implementation of this technology in the United States is expected to provide the benefits of defining the usefulness of the technology and, if practical, encouraging its adoption by tunnel operators and engineers in their tunnel operations. The goal is to decrease the time it takes to detect an incident and respond to it.

The implementation strategy includes outreach to describe the technological capabilities now available and to explain the safety benefits and possibilities of using this technology.

3.6. Develop Tunnel Facility Design Criteria to Promote Optimal Driver Performance and Response to Incidents

Europeans found that innovative tunnel design that includes improved geometry or more pleasing visual appearance will enhance driver safety, performance, and traffic operation. For example, the full-size model of one section of the twin roadway tube for the A-86 motorway in Paris, shown in Figure 9, demonstrates the effectiveness of good lighting and painting to improve motorist safety. It is a particularly important consideration for a tunnel roadway section designed with limited headroom. Tunnel designers should evaluate the materials and design details used to reduce risks to ensure that they do not pose other unacceptable hazards. For example, paint used to enhance the visual experience should not produce toxic fumes or accelerate fire.

Implementing this practice will provide tunnel designers, owners, and operators with guidelines for tunnels that will ultimately result in improved tunnel safety.

The implementation strategy includes conducting an internal U.S. tunnel scan, and working with AASHTO T-20, FHWA, NFPA, and TRB to develop standards and guidelines for road tunnel emergency response management.

3.7. Investigate One-Button Systems to Initiate Emergency Response and Automated Sensor Systems to Determine Response

The European scan revealed that one of the most important considerations in responding to an incident is to take action immediately. For this to be effective, the operator must initiate several actions simultaneously. An example of how this immediate action is accomplished is the " press one button" solution that initiates several critical actions without giving the operator the chance to omit an important step or perform an action out of order. On the Mont Blanc Tunnel operations center control panel shown in Figure 18, operators can initiate several actions by moving a yellow line over the area where a fire incident is indicated on a computer screen. This " one-button" action reduces the need for time-consuming emergency decisions about ventilation control and operational procedures.

The Europeans observed that tunnel operations personnel have difficulty keeping up with events like tunnel fires, and they believe that an automatic system using devices like opacity sensors can be helpful in determining the correct response. A closed-loop data collection and analysis system that takes atmospheric conditions, tunnel air speed, and smoke density into account may best control fans and vents.

Implementing this technology will provide the benefits of reducing the time required to start tunnel ventilation and traffic control systems and reducing the need for an operator to make subjective decisions on emergency operations.

The implementation strategy includes reaching out to planners of new or upcoming major tunnel projects, describing through presentations and training efforts the technological capabilities now available, and promoting the potential safety benefits from using this technology.

3.8. Use Risk-Management Approach to Tunnel Safety Inspection and Maintenance

The scan team learned that some organizations use a risk-based schedule for safety inspection and maintenance. Through knowledge of the systems and the structure gained from intelligent monitoring and analysis of the collected data, the owner can use a risk-based approach to schedule the time and frequency of inspections and establish priorities. It makes more sense to inspect less critical or more durable portions of the system on a less frequent basis, and concentrate inspection efforts on the more critical or more fragile components. A risk-based assessment of the condition of facilities also can be used to make optimal decisions on the scope and timing of facility maintenance or rehabilitation. This method offers a statistical process to manage the tunnel assets.

Implementing this practice will help tunnel operators establish risk-based maintenance and safety inspection procedures to help maximize their resources without compromising safety to the public.

The implementation strategy includes promoting the use of tunnel management systems, and working with AASHTO and FHWA to establish guidelines for conducting and reporting tunnel safety inspections on a routine basis.

3.9. Implement Light-Emitting Diode Lighting for Safe Vehicle Distance and Edge Delineation in Tunnels

The scan team noted that in several European tunnels, LED lights were installed along the edge of the tunnel at regular intervals of about 10 to 20 m (33 to 66 ft) to clearly identify the edge of the roadway (see Figure 14). These lights were either white or a highly visible yellow color. In some tunnels, blue lights were spaced among these edge-delineation lights at 150-m (490-ft) intervals. See Figure 15 for examples. Motorists are instructed through formal (for truck and bus drivers) and informal driver education to keep a safe distance between them and the vehicle in front, and that distance is indicated by the spacing of the blue lights. This visual cue is more reliable than asking motorists to establish distance between vehicles using speed-based guidelines (i.e., maintain one car length spacing for every 16 km/h (10 mi/h) of speed). The LED markers are also less susceptible to loss of visibility because of road grime and smoke during a tunnel fire.

Implementing this technology will provide the benefit of increasing driver awareness of the roadway/tunnel limits, thus increasing safety. While driving in tunnels, motorists typically and unconsciously move away from the edge of the tunnel and crowd the centerline. In bidirectional tunnels, this means opposing vehicles pass dangerously close to one another. Also, following too closely is an endemic problem on our Nation's highways, but the risks increase significantly when vehicles follow too closely in tunnels. Using blue LED lights at a given spacing will make it easier for drivers to gauge the distance to the vehicle in front and help them maintain safe spacing. Future guidelines should include recommending to designers that white or yellow LED lights be established as roadway edge delineation and blue LED lights be established at the recommended following distance, which will vary with the tunnel design, traffic count, and speed limit.

The implementation strategy includes working with AASHTO and FHWA on outreach to tunnel owners to advocate installing such devices and to drivers to educate them on what the LED lights mean and how to use them to gauge the lateral location of a vehicle in its lane and the distance between vehicles. This training could be incorporated into driver education.

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Page last modified on November 7, 2014
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