Guide for the Preservation of Highway Tunnel Systems (2015)

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1 1.1 Why Tunnel Preservation? 1.1.1 Background Highway tunnels play an important role in our nation’s transportation network, providing access through difficult terrain, below waterways, and under other structures. Highway tunnels are often critical links within a region’s transportation system; without them, the remaining roadways would be overburdened, travel would take longer, and routes would be less direct. Maintaining these assets in a state of good repair is paramount to maintaining the viability of the overall transportation network. This maintenance, which includes preservation, must be planned and, more importantly, budgeted for by tunnel owners. As with the nation’s other infrastructure funding, funding for highway tunnel preservation and improvements is limited; multiple agencies and, frequently, multiple departments within an agency, compete for available funding. Overall, available funding is inadequate to maintain the infrastructure. Identifying the specific improvements and preservation needed and planning for these as future expenditures is critical. Once the needs are identified, they must be priori- tized. Tunnels are only one part of a transportation agency’s overall asset inventory, which also includes, for example, roadway pavements, bridges, culverts, signs, and light poles. Tunnel needs have to be weighed against the other asset preservation needs and prioritized based on the entire agency’s goals and objectives. It is common knowledge that many tunnels in the United States are decades old. Approxi- mately 225 highway tunnels in the United States over 300 feet in length are more than 50 years old, and 128 highway tunnels are over 70 years old, as shown in Table 1-1.(1,2) Maintenance of these older facilities can be significant, and major rehabilitation work is often needed. Tunnels more than 25 years old were most likely not designed to current fire and life safety standards, so significant upgrades to their ventilation and electrical systems are needed. Another problem becoming more prevalent is that as existing tunnels age, so does the staff that maintains them. It has been estimated that about 50% of tunnel owners’ personnel will be eligible to retire in the next 10 years.(3) As this occurs, agencies will lose a wealth of historical information, sometimes dating back to the original tunnel construction, including the specific problems that were experienced and the maintenance that was performed through the years. 1.1.2 What Is Tunnel Preservation? Similar to the AASHTO-adopted definition of bridge preservation,(4) tunnel preservation includes actions or strategies that prevent, delay, or reduce deterioration of tunnels or tunnel systems; restore the function of existing tunnels; keep tunnels and their systems in good C H A P T E R 1 Introduction to the Guide

2 Guide for the Preservation of Highway Tunnel Systems condition; and extend their lives. Tunnel preservation may also include preventive maintenance, cyclical preventive maintenance (activities on a predetermined interval), condition-based pre- ventive maintenance, and rehabilitation. Further discussion of definitions for the various types of preservation actions (PAs) for tunnels is presented in Chapter 4. 1.2 Purpose of the Guide Due to funding limitations and an aging infrastructure, tunnel owners are focusing on pre- serving their assets to extend their useful service life. This report, NCHRP Report 816: Guide for the Preservation of Highway Tunnel Systems, provides a tool to assist tunnel owners in making informed decisions, using an asset management process to support their prioritization of highway tunnel preservation actions. Beginning with identifying preservation actions, the guide provides a process for prioritizing needs and developing capital funding and staffing programs to accomplish tunnel preservation goals. Thus, the process outlined in the guide will aid executives in supporting capital funding needs for tunnel improvements as part of their overall transportation system funding, and will help in communicating those needs. As agency staff members who maintain these assets retire, their knowledge and experience need to be transferred to the next generation. There is great need for tunnel preservation docu- mentation of preservation actions and the rationale for when such actions are to be implemented. This guide provides this methodology and also serves as a training tool for new personnel. 1.3 Using an Asset Management Approach for Highway Tunnel Preservation The 2011 AASHTO Transportation Asset Management Guide: A Focus on Implementation provides an effective framework for transportation officials to understand and use in setting up an asset management approach for maintaining and preserving their overall transportation network. The 2011 guide recommends that a comprehensive asset management plan do the following: Tunnel Age Year Constructed Number of Tunnels* 1 to 10 years 2003 to present 6 11 to 20 years 1992 to 2002 17 21 to 30 years 1982 to 1992 36 31 to 40 years 1972 to 1982 21 41 to 50 years 1962 to 1972 57 51 to 60 years 1952 to 1962 56 61 to 70 years 1942 to 1952 41 71 to 80 years 1932 to 1942 64 81 to 90 years 1922 to 1932 34 91 to 100 years 1912 to 1922 6 101 to 110 years 1902 to 1912 7 111 to 120 years 1892 to 1902 10 121 to 130 years 1882 to 1892 6 More than 131 years 1881 and prior 1 *The FHWA in 2003 requested that the highway inventory be limited to tunnels exceeding 300 feet in length. Whereas agencies typically followed this definition, a few tunnels are included in this inventory that are less than 300 feet in length. Table 1-1. Summary of highway tunnel ages.

Introduction to the Guide 3 • Take a network view: A holistic view that considers the entire transportation network as a whole is dependent upon its parts, and, in order to perform, each part needs other parts to function effectively. For example, in an overall highway system that includes tunnels, the performance of both highways and tunnels must be considered for the overall system to function as intended. • Align with strategic directions: The transportation agency’s highest officials must be committed to using a transportation asset management process as part of the organization’s strategic direction in order to achieve policy goals and objectives. • Provide leadership that aligns the agency: Leadership from all parts of the agency (e.g., senior management, planning, operations, and maintenance) should be involved in the asset manage- ment process so that all aspects are considered for making cost-effective decisions that align with the strategic direction. • Communicate with stakeholders: The agency’s use of performance measures to document accomplishments against agency goals and objectives, commonly defined as level-of-service (LOS) standards, is critical for the organization to function with transparency and account- ability, as well as for documenting conditions for obtaining funding streams to improve the agency’s assets. • Make data-driven, informed decisions: An asset management approach requires an agency to have good, historical, readily accessible data on their transportation assets, including their condition, performance, and other characteristics related to the life of the asset and its ability to continue to provide reliable, safe service. Tunnel owners using the approach recommended in this guide will have sufficient knowledge of their tunnel systems from inspections, day-to-day operations, and routine and periodic maintenance activities, such that preservation actions can be readily identified and prioritized. • Integrate agency programs and budgets: The agency must align strategies, plans, programs, and budgets to ensure that the agreed LOSs are delivered to current and future customers in the most cost-effective manner. Using the tools recommended in this guide will be an important step in helping to develop and prioritize capital budgets for accomplishing the preservation actions. • Monitor outcomes: It is absolutely necessary that an agency monitor its performance against stated LOS standards to understand if the outcomes are being reached. • Focus on continued improvement: Continued improvement should become part of any trans- portation agency’s management approach and culture. Inherent in this continued improvement is conducting self-assessments and gap analyses on a regular basis.(5) These concepts are applicable to an asset management approach for highway tunnel preservation as a subset of the transportation system. Chapters in this guide follow general concepts/themes outlined in the 2011 AASHTO Transportation Asset Management Guide through a systematic process identified in Figure 1-1. This flowchart presents an overview of the tunnel preservation asset management process further defined in this guide. The process identifies the following steps to be taken: • The transportation agency assigns committee representatives knowledgeable of its overall transportation system to be members of the agency’s asset management team (AAMT). The AAMT should be a multi-disciplined team with the expertise necessary for evaluating tunnel preservation actions, including structural, electrical, mechanical, lighting, civil, and geo- technical disciplines. • The AAMT is responsible for defining the overall LOSs (goals) that the agency desires to achieve for its overall transportation system, of which highways, bridges, tunnels, culverts, lights, signs, and so forth are elements. • The AAMT establishes the relative importance of each LOS within its agency. Establishment of the agency’s LOS is a key component of its transportation asset management plan, and the

4 Guide for the Preservation of Highway Tunnel Systems identification of LOS priorities with respect to tunnels is a requirement for the tunnel preserva- tion prioritization. • The agency establishes specific performance measures for its transportation system elements based on each LOS to monitor progress in meeting each LOS. • Preservation actions are identified for each tunnel through inspections and testing. • For each preservation action, an LOS score, based on its significance in achieving the LOS, is developed. • To compare alternatives based on cost-effectiveness (CE), life-cycle costs are calculated for each preservation action. Costs for each preservation action should include additional mainte- nance that could be incurred due to delaying of rehabilitating or replacing a system or element, Formation of Agency Asset Management Team (AAMT) Section 1.3 AAMT to Establish Agency Levels of Service (LOSs) and Relative Importance of Each Section 3.2 Develop Tunnel Performance Measures for Each Recommended LOS Category Section 3.3 Summarize Tunnel Preservation Actions Based on Condition Inspections and Regulatory Requirements Chapter 4 Develop LOS Score for Each Tunnel Preservation Action Section 5.2 Develop Cost-Effectiveness (CE) Score for Each Tunnel Preservation Action Section 5.3 Develop Risk-Based Urgency (RBU) Score for Each Tunnel Preservation Action Section 5.4 Determine Weighted Percentage for LOS Score, CE Score, and RBU Score Section 5.5 Calculate Overall Measure of Effectiveness Score for Each Tunnel Preservation Action Section 5.5 Implement Prioritized Tunnel Preservation Actions in Updated Capital Plans Chapter 7 Evaluate Performance Figure 1-1. Highway tunnel preservation asset management flowchart.

Introduction to the Guide 5 as well as the potential savings, such as energy savings resulting from the use of energy-efficient equipment. The average daily traffic (ADT) is another parameter used in determining the cost-effectiveness of a preservation action. • The urgency of the preservation action is evaluated using a risk-based urgency (RBU) score, which considers the condition, remaining life, and risk if the action is not implemented, as well as the need for the preservation action in terms of regulatory compliance. • The combination of three scores (LOS, CE, and RBU) provides the overall measure of effec- tiveness (MOE) score for each preservation action and ultimately provides the basis of the prioritization. • The tunnel owner reviews the prioritization and modifies it as needed, considering the overall system needs and operations, to establish the final priority of preservation actions. • The agency schedules preservation actions based on anticipated funding levels to be received in accordance with the agency’s capital plans or establishes the future capital plan incorporating the desired preservation actions for each year. • The agency establishes staffing needs based on anticipated funding and on the specific needs for the preservation actions to be implemented in a given year. Staffing needed to implement the preservation actions may be procured through external contracts or through the hiring of new agency personnel. 1.4 Overview of the Guide The elements included in each chapter of this guide are summarized in the following. Chapter 1: Introduction to the Guide • Provides the reasons tunnel preservation is needed. • Provides a definition of tunnel preservation. • Describes the purpose of the guide in assisting tunnel owners in implementing preservation actions through the use of an asset management approach. • Summarizes the asset management approach, including a flowchart showing the various steps of the approach. • Outlines each chapter’s contents. Chapter 2: Description of Tunnel Assets • Describes the various complex tunnel systems that are interrelated. • References Appendix A, which includes detailed information on these systems from the 2005 FHWA Highway and Rail Transit Tunnel Inspection Manual(6) and the 2015 FHWA Tunnel Operations, Maintenance, Inspection, and Evaluation Manual (TOMIE Manual)(7) to provide additional details of these systems. • Reviews current tunnel design standards that address recent life safety standards. As rehabili- tation or replacement of systems occurs to preserve older tunnels, many owners are looking to upgrade tunnel systems to improve safety through compliance with the National Fire Protec- tion Association (NFPA) 502 standard.(8) • References Chapter 4, Section 4.3, for examples of types of previously employed preservation actions to upgrade these systems to meet life safety standards. Chapter 3: Establishing the Asset Management Framework • Provides a background on the use of asset management systems for highway agencies. • Recognizes that although tunnels are a subset of an agency’s total transportation system, they provide an important link for the system to remain operational. Most transportation agencies

6 Guide for the Preservation of Highway Tunnel Systems have overall goals and objectives, also known as LOSs, defined for maintaining and improving their transportation assets. In the absence of established LOSs, the transportation agency must establish them for its overall transportation network, of which tunnels are a part. The agency may deem it necessary to develop specific LOSs for its tunnels as a subset of its overall LOSs for the entire transportation system. • Presents a discussion to aid the AAMT in selecting LOSs relative to the overall agency’s goals and objectives. • Provides examples of typical performance measures an agency might consider. Chapter 4: Highway Tunnel Preservation Actions • Defines AASHTO’s tunnel preservation definitions for different types of maintenance (pre- ventive, cyclical preventive, and condition-based preventive), rehabilitation, and replacement actions. • Describes how preservation actions are established by using reliability-based inspection inter- vals from various sources (operational/management staff, staff/consultant inspections, testing agencies). • Provides examples of preservation actions that an owner should consider after receiving results from a recent inspection. • Provides a description of a particular agency’s tunnels, showing both urban and rural tunnels and the associated ADT for each tunnel. • References a catalog of typical preservation actions included in Appendix B to provide guid- ance as to the types of actions that are generally required for various tunnel systems. Chapter 5: Measuring Effectiveness of Preservation Actions • Provides a simple metric that can be used to prioritize preservation actions within a tunnel or across multiple tunnels. • The metric uses three scores: the LOS score, the CE score, and the RBU score. Each score’s calculation is discussed. A weighted combination of these scores results in the overall MOE, which is used to establish priorities. • Additional guidance is provided for incorporating life-cycle cost analysis, present-value costs, and remaining life to evaluate preservation actions. • The LOS score is used by tunnel owners to rate preservation actions to better achieve their overall LOS goals. Owners are knowledgeable about their overall transportation systems and will be expected to set the relative importance of each LOS in the development of the LOS score, reflecting the preservation actions that best accomplish the goals for their overall systems. • Cost-effectiveness is evaluated considering capital cost, life-cycle costs, and the number of users. • The RBU score for a preservation action considers remaining life, condition, regulatory requirements, and the risks of unplanned events such as earthquakes, floods, and fires. • An example is provided to explain the use of the metric to calculate the overall MOE of each preservation action. Chapter 6: Prioritization of Preservation Actions • Using the MOE calculated in Chapter 5, an agency’s tunnel preservation actions can be pri- oritized, regardless of whether the tunnel is in an urban or rural area or whether the improve- ments are for different tunnels or different systems within tunnels. The example developed in Chapter 5 is continued to show the calculated priority.

Introduction to the Guide 7 • Each agency has its own unique set of circumstances—budget limitations, the ability to close the tunnel to perform the work, and so forth—that affect the final prioritization. For this reason, the tunnel owner has the ability to adjust the final prioritization to suit agency needs. • In addition to prioritizing preservation actions for its tunnel systems, an agency may also want to evaluate multiple alternatives for one preservation action. Two examples are provided to show how the metric could be used in this way. Chapter 7: Implementation of Preservation Actions • Describes typical funding sources based on research conducted with tunnel owners as part of this research project. • Presents funding scenarios using both a top-down and a bottom-up approach, as illustrated by the example initiated in Chapter 5. • Using the prioritized list of tunnel preservation actions and the funding year each will occur in, it is possible to develop the staffing needs for the agency for each year. An example is provided. • Presents an example of how various costs (capital, labor, agency oversight, and materials) for each preservation action can be aggregated to support agency funding allocated for particular funding years. • Describes how the metric supports an agency’s ability to communicate tunnel preservation needs to decision makers so that funding streams over a realistic period will be sufficient to keep the tunnel systems in good operating condition. Appendices • Appendix A: Description of Tunnel Types and Systems • Appendix B: Catalog of Preservation Actions • Appendix C: Highway Tunnel Preservation Prioritization Flowchart • Appendix D: Detailed Example