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42 Table 5.2. Additional recommended comprehensive performance measures for the Interstate Asset Management Framework. Category Asset Type Measure Type Measure Preservation Shoulders Asset Performance Percent functioning as intended Tunnels Asset Performance Percent functioning as intended Culverts/drainage Asset Performance Percent functioning as intended structures Noise barrier walls Asset Performance Percent functioning as intended Retaining walls Asset Performance Percent functioning as intended Overhead sign Asset Performance Percent functioning as intended structures High mast light Asset Performance Percent functioning as intended poles Lighting Asset Performance Percent functioning as intended Median barriers Asset Performance Percent functioning as intended Impact attenuators Asset Performance Percent functioning as intended Surveillance and Asset Performance Percent functioning as intended monitoring equipment Signal and control Asset Performance Percent functioning as intended equipment Rest areas Asset Performance Percent functioning as intended Toll plazas Asset Performance Percent functioning as intended Weigh stations Asset Performance Percent functioning as intended Maintenance depots Asset Performance Percent functioning as intended Pump houses Asset Performance Percent functioning as intended Communication Asset Performance Percent functioning as intended facilities Mobility Winter Maintenance Average time to restore pavement surface Delivery Schedule Adherence Percentage of total projects finished on or before original scheduled contract completion date Cost Control Annual ratio of actual construction cost to bid amount common, but is typically done on an overall basis rather than 5.4 Gap Assessment by system. It is not strictly required that consideration of project delivery be handled in an Interstate Asset Manage- The following are the most significant gaps related to defin- ment Plan if an IHS owner handles this issue separately. ing a set of performance measures for characterizing IHS assets No measures are recommended regarding security or social (or transportation assets in general): impacts, as it is generally not feasible to isolate existing mea- sures to the IHS. However, security and social impacts as well as There is no national standard for accurately characterizing measures of economic impact may be very relevant in charac- structural adequacy of pavement. In the absence of such a terizing the overall importance of a transportation system and measure, it is recommended that agencies use an agency- in justifying investments, particularly large investments in specific index instead or PSR. PSR is reported in the HPMS, additional capacity. but does not consider a full range of pavement distresses. Customer satisfaction measures are not included under the The expected update to the HPMS will add additional assumption that the public is likely to assess the level of satis- measures of pavement condition to the HPMS, and should faction with the transportation system as a whole, rather than facilitate standardization of an overall measure of struc- the IHS specifically. tural adequacy.

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43 Average IRI is recommended as a measure of ride quality. There is a need for standard measures of condition for other This recommendation is based on the fact that IRI is avail- assets beside pavement and bridges. Research is ongoing to able through HPMS data and is the most common measure develop level of service standards for asset management as available for characterizing ride quality. However, there are part of NCHRP Project 20-74(A). In the absence of any significant state-to-state differences in measuring IRI and standard measures for preservation of other assets, percent issues with the measure that complicate use of IRI as a functioning as intended is recommended here. The major standard. shortcoming of this measure is that lacking national stan- There is a need for definitions of a new, standard measures of dards, each IHS owner must define what it means for a given bridge condition and functional adequacy. The existing asset to be classified as functioning as intended. If this mea- measures defined by FHWA include SD/FO classification sure is to be used, further work is needed to define what it and Sufficiency Rating (SR). Of these, SD classification means for different asset types. best measures condition, but is a binary measure (a bridge New measures are needed for characterizing environmental is or is not SD). Ideally, a numeric index would be defined performance. There are few environmental measures that that allows for specifying different levels of urgency for can be both localized to the IHS and used to support the addressing bridge needs. Also, ideally this measure would be asset management process. Also, there is little consistency based on more objective measures of bridge condition than from one IHS owner to another concerning how envi- possible using the current set of bridge condition ratings. FO ronmental data are collected and reported. For instance, classification measures functional adequacy, but is also a measures of emissions are often used for characterizing binary measure, and a number of agencies do not report this environmental impact (e.g., pounds of carbon monoxide measure when discussing bridge conditions either because and/or other pollutants) and these measures can be calcu- they feel it misstates the level of need and/or needs to be lated using systems such as HERS. However, it is not mean- updated to better reflect current functional standards. SR is ingful to report the measures specifically for the IHS in the problematic as it combines structural and functional consid- absence of corresponding data for other systems. Other erations, complicating interpretation of the measure. measures of environmental performance include counts of Various efforts have been undertaken to define alterna- environmental features that are constructed or maintained tive bridge measures, but these have thus far failed to result (e.g., wildlife crossings, culverts/fish passages and other in widespread adoption of new, standardized measures. features), measures of wetland reclamation (e.g., the ratio of Most notably, as described in Chapter 4, most agencies now wetlands reclaimed to that affected), and measures of how collect element-level condition data, and can use this data to well an agency is meeting its environmental commitments. calculate the Health Index developed by California DOT. These measures are meaningful when localized to the IHS, The basic conundrum in recent efforts to develop new but there is no standardization in how they are reported bridge measures is that without improvements in data col- between agencies. lection it is difficult to formulate measures that offer any real There are no standards for characterizing project delivery. improvement upon the existing measures, and changes in AASHTO's report on comparative performance measures data collection needed to yield new measures require wide- between state DOTs (26) discusses this gap and identifies the spread consensus if they are to be standardized between need for one or more standardized delivery measures to states. National leadership is needed to break this logjam. facilitate comparative measurements.