Guidebook for Measuring Performance of Automated People Mover Systems at Airports (2012)

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20 Research of several industry documents shows that current performance measurement of both airport and non-airport APMs is primarily focused on traditional measures of op- erating system performance (i.e., reliability, maintainability, and availability). Other APM performance measures related to economic efficiency, comfort, and convenience, among others, have received significantly less attention in the lit- erature, if any at all. Some of these measures are applied in other industries, however, and have been considered in the development of the performance measures set forth in this guidebook. 4.1 Historical Performance Measurement of APM Systems at Airports The documented methods of system performance mea- surement for airport APMs can be broadly divided into two classes: applied methods and theoretical methods. These clas- sifications are described in the following subsections. 4.1.1 Applied Methods In general, there are four applied methods used in air- port APM performance measurement: the System De- pendability Method, the Contract Service Dependability Method, the System Service Availability Method, and the Paris Airport Authority Method. These methods are pri- marily distinguished from one another by the number of factors measured, grace period durations, whether credit is allowed for partial service operations during failures, and whether capacity is a consideration in any of the measures. The methods and characteristics of each are summarized in Table 1. Each of the applied methods is described in detail in the following. 4.1.1.1 System Dependability Method The classical measurement of performance for systems in general, as well as in the APM industry, is the System Depend- ability Method, as presented in ASCE 21-05, American Society of Civil Engineers, Automated People Mover Standards— Part 1, Chapter 4. This method incorporates three measures of overall system performance: reliability, or mean time be- tween failure (MTBF); maintainability, or mean time to restore (MTTR); and availability (the ratio of MTBF to the sum of MTBF and MTTR). This method allows for the consideration of grace periods for downtime incurred as a result of an inci- dent or failure, and it also allows for downtime credit during partial service operations. Capacity is not considered as part of this method. 4.1.1.2 Contract Service Dependability Method The Contract Service Dependability Method was developed by U.S. consulting firm JKH Mobility and has been imple- mented at some APM systems. The method is very similar to the System Dependability Method in that it incorporates the same three performance measures: reliability, maintain- ability, and availability (RAM). While the older literature revealed that this method previously relied on three sets of the RAM measures (one set called “absolute” RAM, one called “design/operational” RAM, and another called “contract ser- vice” RAM), it has today generally evolved into two measure sets—one RAM set where all failures are taken into account and where failures that are considered exceptions are not taken into account. This method generally allows for a grace period of 3 min or less for downtime resulting from incidents/failures. Concerning the method’s treatment of partial service credit and capacity considerations, most of the examples of this method revealed that these are not incorporated as part of the method. There were two exceptions, however. The first C h a p t e r 4 Performance Measurement of APM Systems at Airports: The Current Situation

21 is the method as applied to the pinched-loop APM system at Chicago’s O’Hare International Airport. There, the system has the capability to operate around many types of failures because its numerous switches and routing combinations, as well as its bidirectional capability, provide a high degree of flexibility in maintaining service during failures. As such, partial service credit is allowed, and system capacity is con- sidered only so far as to make the calculation of the credit. The formula is complicated by the fact that various train lengths may be operating at the same time, which forces the consideration of both transportation capacity and headway as well as a corresponding set of specific rules. This is not so in the case of the Paris Airport Authority Method that will be discussed later. The second exception is the method as applied to the dual- lane shuttle APM at Orlando International Airport. Although capacity is normally not considered in this exception at all, a type of partial service credit is allowed in one specific case— during a failure of the scheduled single train/lane operation when the standby train/lane is undergoing maintenance and is unavailable. 4.1.1.3 System Service Availability Method The System Service Availability Method has been advocated and used by U.S. consulting firm Lea+Elliott since 1994. As a result, it is in wide usage at airport APMs worldwide. The method is distinguished from the other methods by measures that record the performance of subsystems that are most likely to affect passengers. Because the other methods con- centrate only on performance as affected by interruptions to system service (i.e., train stoppages), other failures that affect passenger service without interrupting system service are not captured. For example, station platform door failures that deny passengers access to the vehicles affect passenger service and may not be reflected in the measures of the other meth- ods. This method incorporates measures of service mode avail- ability, fleet availability, station platform door availability, and system service availability. The additional availability measures related to fleet and station platform doors ensure that all fail- ures affecting passengers (not just those that interrupt service) are reflected in the overall service availability measure. The System Service Availability Method also tracks the number of service mode failures, or downtime events, which allows measures of service mode reliability and maintainabil- ity to be easily made. These two measures, along with the four availability measures described previously, make up the six measures unique to this method. This method allows an equivalent of one headway dura- tion or less for a grace period for both incidents/failures and schedule transitions. It also allows for the consideration of downtime credit for partial service operations provided dur- ing failures, and it considers capacity as part of its normal measure set rather than during partial service credit only. 4.1.1.4 Paris Airport Authority Method The Paris Airport Authority (Aeroports de Paris) Method is a variation on the System Dependability Method discussed pre- viously. It was introduced by Aeroports de Paris and ALONEX for Line 1 of the APM system at Roissy Charles-de-Gaulle (CDG) Airport. Unlike the other methods, it calculates con- Table 1. APM performance measurement, applied methods. Method/Measures No. ofMeasures Grace Period Partial Service Credit Capacity Considered System Dependability Method Reliability Maintainability Availability 3 yes optional no Contract Service Dependability Method Contract service reliability Contract service maintainability Contract service availability 3 3 min no* no* System Service Availability Method Service mode reliability Service mode maintainability Service mode availability Fleet availability Station platform door availability System service availability 6 1 head- way yes yes Paris Airport Authority Method Contract service availability 1 no yes yes** *In most cases of the literature reviewed. **During degraded mode operations.

22 tracted service availability on the basis of service unavailabil- ity, and in so doing, eliminates from the calculation any need to consider grace periods or the downtime exclusions common to the other methods. (The other methods are similar in that they exclude the consideration of downtime caused by exter- nal sources, such as passenger-induced delays, interruptions caused by intrusions of unauthorized persons or objects, and other external sources beyond the control of the system or operating entity.) Working from the perspective of service unavailability, the goal of this method is to take into account the transporta- tion capacity of the system during periods of degraded mode operations. Providing the ability to earn this partial service credit, and tying the contracted service availability to pay- ment, is an incentive to the operator to provide the best possible transportation capacity during failures. Although the path to calculating the contracted service availability number is different, the partial service credit incentive concept is very similar to the approach used for the Chicago O’Hare APM discussed previously. One significant difference is that whereas the Chicago APM must deal with a specific approach due to its variable-length trains, the CDG APM system does not (it has fixed-length trains). Both of these APM systems, Roissy Charles-de-Gaulle and Chicago O’Hare, are supplied by the same APM system supplier, which may explain some of the similarities in the methods. 4.1.2 Theoretical Methods The literature review and analysis have also revealed that APM performance measurement has been studied and re- ported on theoretically. Three papers in particular have been presented in this area. 4.1.2.1 Airport APM Performance Measurement: Network Configuration and Service Availability The first paper, “Airport APM Performance Measurement: Network Configuration and Service Availability,” was pre- sented in 2007 at the 11th International ASCE APM Confer- ence in Vienna. It was written by Wayne D. Cottrell, Associate Professor at California State Polytechnic University, and Yuko J. Nakanishi, President of Nakanishi Research and Consult- ing, LLC. This paper examines service availability and reliability and how they are affected by airport automated people mover (AAPM) network configurations and other system parameters. The paper affirms the importance of availability and reliability measurements in the APM industry. The paper suggests that detailed measures of headway regu- larity would be useful in an empirical study of AAPM reliabil- ity performance. Measures that are set forth include headway adherence, service regularity, headway ratio, headway regu- larity index, and headway deviation. The ultimate conclusion is that network configuration affects the reliability and availability of airport APMs, albeit in a limited way due to the limited variety of airport APM networks. Other system parameters such as consist size and the number of in-service trains also affect reliability and availability. 4.1.2.2 Defining and Measuring Service Availability for Complex Transportation Networks The second paper, “Defining and Measuring Service Avail- ability for Complex Transportation Networks,” was presented in 1996 at the International Conference on Personal Rapid Transit (PRT) and Other Emerging Transportation Systems in Minneapolis. It was written by Charles P. Elms, now retired from Lea+Elliott. The paper first defines measures of service availability in current use and analyzes exact and approximation methods for data collection and computation. It then postulates and explores classical and new definitions of service availability applicable for complex networks such as PRT. Insight is pro- vided for choosing a suitable definition based on the type of transportation network. The methodology in the paper is based on the classi- cal approach of service mode availability [MTBF/(MTBF + MTTR)], and adjusts for fleet availability and station platform door availability. Ultimately, the methodology outlined in the paper aligns with the System Service Availability Method discussed previously. 4.1.2.3 RAM: Reliability, Availability and Maintainability of APM Systems The third paper, “RAM: Reliability, Availability and Main- tainability of Automated People Movers,” was presented in 1989 by John K. Howell at the Second International Conference on APMs in Miami. This paper discusses in detail reliability theory in particu- lar, as well as the factors that influence reliability (MTBF), maintainability (MTTR), and availability in an APM system. It also describes approaches to specifying contract service requirements based on classical definitions of MTBF, MTTR, and availability. The paper ends with a discussion of RAM monitoring and accountability. The methodology in the paper is generally based on the classical approach of availability [MTBF/(MTBF + MTTR)] and aligns with the Contract Service Availability Method dis- cussed previously.

23 4.2 Characteristics of Effective Performance Measurement Systems for APM Systems at Airports Performance measurement is a type of assessment. It is the ongoing monitoring and reporting of system or pro- gram accomplishments, particularly of progress toward pre-established goals. A key aspect of a successful performance measurement system is that it is composed of a balanced set of a few vital measures. For example, performance measurement of airport APM systems has historically focused on a system availability measurement, often including reliability and maintainability. This is no surprise because these are also the core measures for many other engineered systems composed of numerous, technically complex subsystems designed to work together seamlessly and efficiently as a whole. APM suppliers use these measures in their system designs, and owners use the measures to verify that the technology in which they have invested heavily is performing satisfactorily. It is a natural progres- sion, then, that these same measures be used during the ongoing operation and maintenance of the system after its construction and as the basis for payment to companies con- tracted to provide operations and/or maintenance services of these systems. While the limited number of these core mea- sures satisfies the “few vital measures” aspect of a successful performance measurement system, they may not be well bal- anced in the absence of measures that look at the performance of other vital areas of an airport APM system (such as safety), the economic efficiency of the system or O&M service provider, or the quality of service perceived by airport APM passengers, for example. Besides making up a balanced set of a few vital measures, other aspects of effective performance measurement systems for airport APM systems include that: • The measurement system be cost effective to implement and sustain, • The system be reviewed on a semi-regular basis to ensure that the measures are still appropriate, • Reporting or posting of the measures avoids oversaturation in order to maintain relevance and minimize the desensi- tizing effect over the long term, and • The system contain measures that: – Are meaningful; – Describe how well the goals and objectives are being met; – Are simple, understandable, logical, and repeatable; – Show a trend; – Are unambiguously defined; – Allow for economical data collection; and – Are timely and sensitive. Historically, airport APM performance measurement has been meaningful to owners, APM system suppliers, and O&M service providers, but not always reflective or meaningful from the passengers’ perspective. As such, “meaningful” is further clarified to mean “meaningful, but representative from all views.” Similarly, the core availability, reliability, and maintainabil- ity measures discussed previously have sometimes not been simple since there can be onerous rules, problems collecting data, or interpretational issues. Therefore, this guidebook strives to improve airport APM performance measures in this area to make them more simplistic and straightforward, where possible. In short, performance measurement focuses on whether a system or program has achieved its objectives, expressed as measurable performance standards. Because of its ongoing na- ture, it can serve as an early warning system to management, as a vehicle for improving accountability to the public, as a method to document accomplishments, and as a way to compare similar programs and systems, such as other airport APM systems.