Guide for the Preservation of Highway Tunnel Systems (2015)

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40 6.1 Use of the Metric in Prioritization The process outlined in Chapter 5 uses a simple metric that provides the basis for comparison of numerous alternatives to establish present and future priorities and for comparison of pres­ ervation actions in a single tunnel versus all tunnels in a certain region or over the entire tunnel system. The metric uses the combination of three scores into one MOE and allows each alter­ native activity to be weighted against the others and the priorities to be established. This process is represented visually in Appendix C: Highway Tunnel Preservation Prioritization Flowchart. The methodology presented in Chapter 5 provides guidance to a tunnel owner for setting pri­ orities. However, prioritization and programming for the next 5 or 10 years requires consideration of many other factors. Sometimes, lower­priority activities will be performed sooner because of their relatively low cost and ability to fit within the remaining available budget. Essentially, the projects that represent low­hanging fruit and can be accomplished easily might warrant higher priority. Another factor that might influence priorities is the impact on the traveling public. Activities that require tunnel lane closures for an extended period may be given priority by grouping them with other activities within the same tunnel that can be accomplished during the same closure. There are many factors that go into an owner’s ultimate decision on priorities, but the MOE methodology presented in Chapter 5 provides a first pass that can assist an owner in making these decisions. Table 6­1 shows the priorities for each improvement based on the calculated MOE. The owner should review the prioritized list and then assign its own priorities to the list of projects. Ultimately, it is the user’s prioritization that will be used in the funding and staffing analyses presented in Chapter 7. For the selected preservation actions provided, the owner assigned new priorities in the user­ defined priority column in Table 6­1. The owner chose to rate repairing the active leak in the ceiling, repairing the CO system, and upgrading the ventilation system as 1, 2, and 3, respectively, because of the agency’s decision to focus on safety as described in Section 5.2.1 and because the ceiling removal is more costly and could be combined with installation of flood gates in the future. For the full list of Agency X’s preservation actions and prioritization, refer to Appendix D. 6.2 Use of the Metric for Evaluation of Alternatives Inherent in the metric is the ability to evaluate various alternatives for a specific tunnel pres­ ervation action. Similar to the process of prioritizing multiple preservation actions, the MOE score can be used when evaluating these alternatives. This type of analysis considers alternatives that are used to select a single preservation action. Examples of this include lighting replacement, C H A P T E R 6 Prioritization of Preservation Actions

Prioritization of Preservation Actions 41 fire alarm upgrades, supervisory control and data acquisition (SCADA) systems, and different methods of wall repair. Two examples are presented in the following sections to highlight the use of the MOE in evaluating alternatives. 6.2.1 Lighting Replacement Comparison Table 6­2 compares three lamp options for replacing the existing tunnel lighting system. High­pressure sodium (HPS), induction lighting, and LED fixtures are considered. Note that the no­build option is not included. The reason for this will be explained in the discussion of cost­effectiveness. Since the table compares options for the same overall preservation action (i.e., replacing the lighting), the LOS scores will not vary much. The ratings, although subjective, are nearly the same for many of the categories, with minor variances. In this case, reliability, safety, and security are uniform across all three options as they are not affected by the light fixture chosen. However, the whiter light emanating from the induction and LED lamps may be perceived to provide better quality of service than the yellow tint of the HPS, as reflected in a higher rating. Also, the life expectancy of an LED lamp is longer than the others, and the lamps require less maintenance. Similarly, LED and induction lighting use less energy and are therefore more environmentally friendly if carbon footprint is compared. The CE scores shown in Table 6­3 are the result of the differences between the various options. The initial cost to upgrade or replace the system, the annual energy savings, and the annual reduction in maintenance costs can vary significantly. The changes in annual energy and main­ tenance costs are compared to the existing system, which inherently considers the no­build option. Thus, it is not necessary to consider the no­build option as one of the alternatives as long as the costs are evaluated relative to the existing system. Levels of Service LOS Score Cost- Effectiveness Score Risk- Based Urgency Score Measure of Effectiveness Score Calculated Priority User- Defined Priority Weights 35% 20% 45% 100% Preservation Action Tunnel # Ventilation upgrade to meet NFPA 502 1 66.0 1.9 80.0 59.5 4 3 Install new LED lights 1 78.0 2.4 30.0 41.3 6 5 CO system – repair to operating condition 2 63.2 100.0 70.0 73.6 3 2 Repair active leak in ceiling 4 89.0 100.0 70.0 82.7 1 1 Remove existing concrete tunnel ceiling 6 85.4 2.3 100.0 75.4 2 4 Install flood gates 6 66.0 2.8 60.0 50.7 5 6 Table 6-1. Prioritization of preservation actions.

42 Guide for the Preservation of Highway Tunnel Systems Levels of Service Reliability Safety Security Preservation Quality ofService Environment LOS Score (Eq. 5-1) Weights 20% 40% 5% 18% 15% 2% Preservation Action Tunnel # Replace lighting system with HPS lamps 1 4 3 2 3 3 2 62.6 Replace lighting system with induction lamps 1 4 3 2 4 5 3 72.6 Replace lighting system with LED lamps 1 4 3 2 5 5 3 76.2 Table 6-2. Level-of-service score for lighting replacement. Pr es er va tio n A ct io n Tu nn el # C ap ita l C os t ( $) A ge nc y O ve rs ig ht C os t ( $) A nn ua l C ha ng e i n C os ts ($ ) PV o f L C C ($ ) R em ai ni ng L ife D ue to P A A D T (x 10 00 ) A LC C ($ ) (E q. 5-5 ) A nn ua l C os t p er D ai ly V eh ic le ($ ) C E Sc or e ( Eq . 5 -6) Replace lighting system with HPS lamps 1 3,090,000 123,600 –2,500 3,170,067 25 40 182,050 4.55 2.2 Replace lighting system with induction lamps 1 3,120,000 124,800 40,000 3,941,326 25 40 226,342 5.66 1.8 Replace lighting system with LED lamps 1 3,400,000 136,000 -68,500 2,516,893 20 40 169,175 4.23 2.4 Table 6-3. Cost-effectiveness score for lighting replacement. Since the comparison is of various lighting systems, the RBU score in Table 6­4 is the same for each. The remaining life of the existing lighting system, the original service life, and the existing condition are all the same and are not relevant to the fixture type chosen since these factors apply to the existing lighting system. If the required system, in this case the lighting, needs to be replaced or upgraded, then each alternative will have the same RBU score. The MOE score in Table 6­5 combines the three scores from the previous example with alter­ native preservation actions. In this case, there is little variability in the LOS and CE scores and no variability in the RBU score. Therefore, the MOE scores are similar. Replacing the current lighting system with LED lights yields the highest LOS and CE scores and, therefore, the highest MOE score. The induction system lamps are prioritized second due to their greater impact on the LOS score, which the agency has placed greater weight on than the CE score.

Prioritization of Preservation Actions 43 While the use of the metric for lighting replacement alternatives compared three similar types of preservation actions, the metric can also be used to evaluate repairing or replacing tunnel systems or structural components, as highlighted in the example in the next section. 6.2.2 Ceiling Improvement—Repair Versus Replacement The previous example compared the use of varying materials to accomplish one improvement in the tunnel—a lighting upgrade. An agency often has to decide whether to continue to maintain an existing asset, replace it, or eliminate it altogether if possible. It may be necessary to bundle two or more preservation actions when comparing them using the MOE since one action is predicated on another. In this example, the agency evaluates whether to repair an existing tunnel ceiling or remove it altogether. Because the tunnel ceiling cannot typically be removed without modification of the ventilation system, it might make more sense to evaluate a combination of ceiling and ventilation improvements in one preservation action to facilitate comparison. For the purpose of the example provided in this section, however, assume that the ceiling removal is independent of the ventilation improvement. Table 6­6 shows that removal of the ceiling more closely achieves the goals of the agency than repairing the existing ceiling. While repairs may solve problems associated with deteriorated and Pr es er va tio n A ct io n Tu nn el # R em ai ni ng L ife Th eo re tic al S er vi ce Li fe % L ife E xp en de d C on di tio n (1 to 4) R eg ul at or y C om pl ia nc e I ss ue ? R isk o f U np la nn ed Ev en t P ro ba bi lit y (1 to 3) R BU R at in g (1 to 10 ) R BU S co re Replace lighting system with HPS lamps 1 5 20 75 1 N 1 3 30.0 Replace lighting system with induction lamps 1 5 20 75 1 N 1 3 30.0 Replace lighting system with LED lamps 1 5 20 75 1 N 1 3 30.0 Table 6-4. Risk-based urgency score for lighting replacement. Levels of Service LOS Score Cost- Effectiveness Score Risk- Based Urgency Score Measure of Effectiveness Score Calculated Priority Weights 35% 20% 45% 100% Preservation Action Tunnel # Replace lighting system with HPS lamps 1 62.6 2.2 30.0 35.8 3 Replace lighting system with induction lamps 1 72.6 1.8 30.0 39.3 2 Replace lighting system with LED lamps 1 76.2 2.4 30.0 40.6 1 Table 6-5. Measure of effectiveness score and calculated priority for lighting replacement.

44 Guide for the Preservation of Highway Tunnel Systems spalling concrete for a period of time, the agency has experienced situations where the repair eventually failed as well. These failures resulted in unsafe conditions and caused the agency to close the tunnel to make repairs. For these reasons, the owner assigned lower ratings to the repair option. Furthermore, the repair will likely require future maintenance and repair, whereas removal of the ceiling eliminates the problem entirely. Thus, a lower score for preservation was also assigned. The cost­effectiveness of the two options, as shown in Table 6­7, is based on the LCC for each since the ADT value is the same for each option. In this case, the option to repair the ceiling is more cost­effective than the ceiling removal option due to the high initial cost of removal. Since the current condition of the ceiling warrants significant repairs, and these repairs would need to be repeated in future years, the ceiling repair option receives a moderately low CE score. Because the RBU is based on the existing asset, in this case the existing ceiling, the RBU scores are the same for both alternatives (see Table 6­8). Levels of Service Reliability Safety Security Preservation Quality of Service Environment LOS Score (Eq. 5-1)Weights 20% 40% 5% 18% 15% 2% Preservation Action Tunnel # Repair ceiling 6 3 3 N/A 2 3 N/A 52.2 Remove ceiling 6 4 4 N/A 4 5 N/A 77.4 Table 6-6. Level-of-service score for ceiling study. Pr es er va tio n A ct io n Tu nn el # C ap ita l C os t ( $) A ge nc y O ve rs ig ht C os t ( $) A nn ua l C ha ng e i n C os ts ($ ) PV o f L C C ($ ) R em ai ni ng L ife d ue to P A A D T (x 10 00 ) A LC C ($ ) (E q. 5-5 ) A nn ua l C os t p er D ai ly V eh ic le ($ ) C E Sc or e ( Eq . 5 -6) Repair ceiling 6 140,000 5,600 12,000 454,357 50 75 17,659 0.24 42.5 Remove ceiling 6 8,000,000 800,000 –20,000 8,285,405 50 75 322,016 4.29 2.3 Table 6-7. Cost-effectiveness score for ceiling study. Pr es er va tio n A ct io n Tu nn el # R em ai ni ng L ife Th eo re tic al S er vi ce Li fe % L ife E xp en de d C on di tio n (1 to 4) R eg ul at or y C om pl ia nc e I ss ue ? R isk o f U np la nn ed Ev en t P ro ba bi lit y (1 to 3) R BU R at in g (1 to 10 ) R BU S co re Repair ceiling 6 0 50 100 3 N Low 10 100 Remove ceiling 6 0 50 100 3 N Low 10 100 Table 6-8. Risk-based urgency score for ceiling study.

Prioritization of Preservation Actions 45 Although the ceiling removal option receives a low CE score, Agency X weighted cost­effectiveness as only 20% due to its high priority on safety and emphasis on minimizing risk (see Table 6­9). Therefore, the ceiling removal option receives a higher MOE score due to its moderately high impact on the agency’s LOS. The ceiling repair option will not solve the current issue in Tunnel 6 and will lead to additional costly repairs in the future. These repairs are not only a cost issue, they also affect the overall preservation of the tunnel, quality of service, safety, and the reliability of the tunnel’s operation. Table 6-9. Measure of effectiveness score and calculated priority for ceiling study. Levels of Service LOS Score Cost- Effectiveness Score Risk- Based Urgency Score Measure of Effectiveness Score Calculated PriorityWeights 35% 20% 45% 100% Preservation Action Tunnel # Repair ceiling 6 52.2 42.5 100 71.8 2 Remove ceiling 6 77.4 2.3 100 72.6 1