National Academies Press: OpenBook

Minutes Matter: A Bus Transit Service Reliability Guidebook (2020)

Chapter: Chapter 2 - Addressing Bus Transit Reliability

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Suggested Citation:"Chapter 2 - Addressing Bus Transit Reliability." National Academies of Sciences, Engineering, and Medicine. 2020. Minutes Matter: A Bus Transit Service Reliability Guidebook. Washington, DC: The National Academies Press. doi: 10.17226/25727.
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Suggested Citation:"Chapter 2 - Addressing Bus Transit Reliability." National Academies of Sciences, Engineering, and Medicine. 2020. Minutes Matter: A Bus Transit Service Reliability Guidebook. Washington, DC: The National Academies Press. doi: 10.17226/25727.
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Suggested Citation:"Chapter 2 - Addressing Bus Transit Reliability." National Academies of Sciences, Engineering, and Medicine. 2020. Minutes Matter: A Bus Transit Service Reliability Guidebook. Washington, DC: The National Academies Press. doi: 10.17226/25727.
×
Page 11
Page 12
Suggested Citation:"Chapter 2 - Addressing Bus Transit Reliability." National Academies of Sciences, Engineering, and Medicine. 2020. Minutes Matter: A Bus Transit Service Reliability Guidebook. Washington, DC: The National Academies Press. doi: 10.17226/25727.
×
Page 12
Page 13
Suggested Citation:"Chapter 2 - Addressing Bus Transit Reliability." National Academies of Sciences, Engineering, and Medicine. 2020. Minutes Matter: A Bus Transit Service Reliability Guidebook. Washington, DC: The National Academies Press. doi: 10.17226/25727.
×
Page 13
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Suggested Citation:"Chapter 2 - Addressing Bus Transit Reliability." National Academies of Sciences, Engineering, and Medicine. 2020. Minutes Matter: A Bus Transit Service Reliability Guidebook. Washington, DC: The National Academies Press. doi: 10.17226/25727.
×
Page 14
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Suggested Citation:"Chapter 2 - Addressing Bus Transit Reliability." National Academies of Sciences, Engineering, and Medicine. 2020. Minutes Matter: A Bus Transit Service Reliability Guidebook. Washington, DC: The National Academies Press. doi: 10.17226/25727.
×
Page 15

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9 This chapter presents the three major perspectives on transit reliability, defines transit reliability, describes the elements of an effective reliability measurement system, and proposes an outline of reliability management system that is discussed in detail in the remainder of the guidebook. 2.1 Reliability Points of View Bus service reliability is a key quality-of-service issue for passengers; an important driver of bus operations costs for transit agencies; and a health, safety, morale, and job satisfaction issue for bus operators. Each of these groups has a unique perspective on reliability. Figure 2.1 illus- trates these perspectives and a subsequent process for addressing unreliability. 2.1.1 Customer From the passenger point of view, unreliable service means that customers must allow extra time for trips to make sure they arrive at their destinations by a particular time—lost time that could otherwise have been used more productively. A typical rule of thumb is that passengers perceive wait time as being twice as onerous as in-vehicle time. In contrast, automobile travelers value travel time unreliability (i.e., unexpected delay) at approximately the same level that they value travel time; transit service may be at a competitive disadvantage with the automobile with respect to unreliable travel times. The experience of waiting also has impacts beyond time usage and perceptions. In the act of waiting, passengers may face health and safety impacts. They may experience unsafe feelings while waiting on quiet street corners, especially after dark. Inclement weather could expose a waiting passenger to rain, hot sun, or cold. Finally, impacts could also be monetary if passengers seek other modes of transportation when a service is extremely or repeatedly late. Measures of reliability that are passenger focused, such as wait time consistency, travel time variability, and perceptions of wait time, are critical to the rider experience and can potentially influence rider behavior. These measures should include both the actual experience and percep- tions of the experience. Passengers are fundamentally concerned about when the bus operates rather than the cause of a delay. Their perspective is critical to ensuring a service is used and therefore successful. 2.1.2 Agency From the transit agency point of view, travel time variability affects a route’s cycle time and, ultimately, operating cost. Poor reliability (or unreliability) can increase labor costs. In a best-case scenario, reduced cycle time resulting from reduced travel time variability allows a bus to be C H A P T E R 2 Addressing Bus Transit Reliability

10 Minutes Matter: A Bus Transit Service Reliability Guidebook removed from a route while maintaining scheduled headways. Conversely, if reliability issues are not addressed, a transit agency may eventually need to add buses to a route (increasing costs) or decrease bus frequency. The impacts of unreliable service on an agency can also go beyond the costs and immediate service impacts. An agency with chronic reliability issues will earn a bad reputation in the community even among non-riders, which affects community support in bond referenda and the agency’s ability to implement new services and physical measures that might improve its reliability. Agency measures of reliability such as on-time performance and headway adherence relate to planning and scheduling. The agency level is where underlying causes of unreliability will be assessed so that appropriate strategies can be undertaken. The agency level will have the broadest range of measures since there could be actions that the agency takes internally, on a larger trans- portation systems level or in relation to how it manages a contracted bus operator, that would require different measures. These measures will require an understanding of external factors that could affect the reliability of the transit service. The agency level is also where most treatments to improve reliability will be championed even if external parties are involved in completing the projects. Declines in Travel Time Reliability Route Cycle Time - Increases time - Increases variability Route Operating Cost - Increased labor costs - Add buses to a route Lower Transit Agency Reputation Operator Health - Stress - Fatigue - Lack of personal recovery time Operator and Passenger Safety - Potential for crashes - Negative interactions with passengers Current Customer Behavior - Budgeting extra time for trip - Health and safety impacts (comfort) - Monetary impacts (other modes of last-minute transportation) Future Customer Behavior - Choice riders turn to other modes - Decreased desire to use transit Customer Point of View Agency Point of View Operator Point of View Issues with Morale and Retention Decreased Satisfaction and Ridership Addressing and Improving Reliability Continuous Performance Monitoring Diagnose Underlying Causes of Unreliability Select and Implement Strategies for Improvement Improvements in Travel Time Reliability Figure 2.1. Addressing bus transit reliability.

Addressing Bus Transit Reliability 11 2.1.3 Operator From the bus operator point of view, unreliable service can lead to adverse effects on operator health and safety. When services are irregular, an operator may become stressed due to the tight schedule, may become fatigued over time, and may have fewer opportunities for personal recovery time to use restroom and break facilities. This can have negative impacts on operators’ morale and job satisfaction, possibly causing impacts to operators’ personal health, and may even result in them leaving the agency. Continuation of poor operating conditions may increase the potential for crashes and intensify negative interactions between operators and passengers. These poor operating conditions may result in lost time, directly affecting operator availability and, ultimately, further declines in service reliability. Operator measures of reliability relate to transit operations and the operators that perform them, including operator conditions (such as relief time) and mechanical issues (such as time between vehicle breakdowns). In this case, demonstrating regulatory/contractual compliance is typically the starting point, and any incentives to improve punctuality are likely to have more impact than the ease or relevance of the performance measure. 2.2 Why Does Reliability Matter? Transportation system users need consistent daily travel times to enable them to plan their daily activities. Frequent users of a facility can become accustomed to the typical travel time, but their continuing concern is punctuality, or the deviations from the expected travel time. A journey to work (travel time) that takes 20 minutes one day and 40 minutes another day takes an average of 30 minutes, but the individual making this trip would either have to plan for the 40-minute trip or plan for 30 minutes and be late on certain days. The consequences of being late repeatedly could mean anywhere from daycare fines to the loss of a job. An often-heard analogy with travel time reliability is that if you put one foot in a bucket of freezing cold water and one foot in a bucket of boiling hot water, on average you feel great. In the world of transportation, the average travel time is not adequate to define reliability. One must work at the margins to understand the variation in that travel time and how it affects system users. To understand the effects such variability has on transportation customers, performance measures must not only take typical travel times into account, but also the deviation from those typical travel times. The inclusion of travel time reliability in planning and operations analysis is becoming a critical element of understanding the customer perspective. Some travel behavior studies have even suggested that reliability in travel is more important than travel time [1] [2]. 2.2.1 Defining Reliability It helps to begin the discussion of reliability by defining it. Many different definitions of bus service reliability have emerged in the literature over the years, mostly revolving around consis- tency in service and lack of variability in performance. For further definitions of reliability in the literature, the final report can be consulted. To determine how reliability is defined by transit agencies today, agencies operating fixed- route bus service were asked via the online survey to define fixed-route bus service reliability. Of the 86 agencies for which the question was applicable and answered, 81 percent had a defini- tion that included either on-time performance or schedule adherence. The next most popular definitions were missed trips, mentioned by 7 percent of responding agencies, and road calls or breakdowns, mentioned by 4 percent of responding agencies.

12 Minutes Matter: A Bus Transit Service Reliability Guidebook Of those agencies reporting use of alternative measures of reliability such as on-time perfor- mance, four mentioned headway adherence, two mentioned wait time, and two mentioned running time or travel time consistency. The focus on the customer was apparent by the four agencies that mentioned customer satisfaction or complaints as part of their definition and one agency that included overcrowding. Two agencies mentioned safety, either generically or specifi- cally through crashes or incidents. For the purposes of this guidebook, definitions from the literature and surveys were used, as was the need to accommodate both schedule-based and headway-based service. Reliability was defined as having three components: • Short and consistent wait times, • Consistent on-time arrivals at destinations, and • Consistent travel times. 2.2.2 Perceptions of Reliability Reliability and the perception of reliability are closely related, but they are not the same. While reliability can be measured rather precisely, the perception of reliability is difficult to quantify. Perceived reliability is subjective, in that it varies from person to person, and perhaps even from day to day for an individual. While from the operator perspective, objective measures of on-time performance and miles traveled between breakdowns may be the primary concerns with regard to reliability, perceived reliability is what matters most to the customer. The perceived and actual reliability of service affects passenger choices, such as the time passengers will plan to arrive at the transit stop or whether to take the trip at all. Researchers have found that reliability has a major impact on customers’ perceived quality of service [3], punctuality is a highly valued characteristic of transportation systems, and unreliability is especially costly when public transit is the chosen mode [1]. Researchers have also found evidence of a strong risk aversion when it comes to uncertainty in the reliability of public transport. Rietveld et al. specifically calculated the relationship between an “uncertainty minute” (one spent waiting, not knowing when a transit vehicle would arrive) and a “certainty minute” spent inside a transit vehicle that is proceeding along its route. In this study, the weight of an “uncertainty minute” was estimated to be 2.4 times the weight of a “certain” in-vehicle minute [2]. Service reliability is an important factor in transit users’ perceived travel time [5]. On-time performance positively affects riders and ridership due to less waiting, decreased travel times, fewer missed connections, more on-time arrivals, and reduced uncertainty [6]. Although the exact value has varied by study, it is generally estimated that wait times are weighted at twice that of in-vehicle travel times. The key aspect of perceived reliability in relation to the measurement of reliability is that perception matters greatly to rider satisfaction and, in the longer term, to ridership itself. This means that bus reliability is a key component of providing good service. However, this also means that in addition to measuring reliability itself, agencies should periodically inquire about customers’ perceptions of reliability through surveys. Watkins et al. developed a method to measure actual versus perceived wait times that is useful for agencies to consider when assessing system changes such as real-time information that are meant to address perceived reliability rather than actual improvements to the service [7]. Although most of the treatments discussed in this guidebook were designed to improve actual transit reliability, several were also targeted specifically toward perceptions of reliability. A study of perceived and actual wait times [7] found that for riders without real-time information, perceived wait time was greater than measured wait time, but having real-time information brought perceived wait time in line with actual wait time. In addition, mobile real-time infor- mation users in the study were observed to wait almost 2 minutes less than those arriving using

Addressing Bus Transit Reliability 13 traditional schedule information (which, when aggregated over 100,000 riders per week, adds up to a considerable time savings). Studies in Chicago [8] and New York [9] found ridership increases of about 2 percent on routes with real-time information. 2.2.3 Importance of Reliability in Customer Satisfaction Although the need for consistency in travel time is true for any mode of transportation, transit reliability is critical to the operation and attraction of public transportation services. As compared to the use of automobiles or even bicycling and walking, with transit services, riders are putting their trips into someone else’s hands, thereby giving up control over when the vehicle arrives to pick them up or drop them off. Riders stand at a corner scanning the horizon for an approaching bus, wondering when or if it will come. On another day, they time their arrival exactly to the scheduled minute, only to see that the early running bus just passed their stop and they have another 30 minutes (or longer) to wait. If transit agencies hope to retain riders and increase ridership, they need to allow riders to maintain some control over their trips by providing them with reliable services. Customer satisfaction surveys consistently list reliability as one of the most important aspects of transit service. The authors of this study conducted a review of several transit agency annual and biannual surveys that asked about the importance of various components of transit service. The review showed that on-time performance, one key measure of reliability, was frequently listed by customers as the most important measure. 2.2.4 Operational Efficiencies Although serving customers well is critical for a transit agency, reliability from the operator perspective also affects the cost-effectiveness of operations. As a vehicle becomes delayed, a customer can face an unexpected wait time and become late for an appointment, and those delays can also cause in-vehicle crowding. As crowding occurs, passengers become more uncomfortable, and boarding and alighting time can increase, which can cause further delays, eventually resulting in bus bunching. Furthermore, schedule recovery time can be affected, propagating unreliable service. 2.2.5 Changing Face of Transportation Reliability has always been a key component of public transportation, but with the current unprecedented evolution in transportation services, transit reliability has taken on an even greater level of importance. The past half decade has seen the introduction of a new type of transportation service in the form of ride sourcing by mobility service providers (also called transportation network companies) such as Lyft and Uber. These services allow users to easily call for a vehicle to pick them up with minimal wait time and accurate Global Positioning System (GPS) information to track vehicle location and arrival time. Although the services generally cost more than transit, their convenience provides fierce competition. Many in the transit industry see the services as complementary to traditional rail and bus services, but the level of informa- tion and reliability of travel time provided raises the expectation for transit services to provide real-time information about arrivals and on-time service. Similarly, as society moves toward the world of automated vehicles, the role that transit plays in the transportation system will naturally evolve. One of the benefits of transit is the ability to let someone else drive, thus eliminating stress and freeing up time during travel for other activities. For these reasons, transit reliability is becoming even more critical as the competition for riders increases and the expectations for level of service escalate.

14 Minutes Matter: A Bus Transit Service Reliability Guidebook 2.3 Developing an Effective Reliability Improvement Program An effective reliability measurement system will have a number of key characteristics. The desired qualities for a measurement system have been addressed frequently in the literature, and the final report addresses these studies in further detail. Many themes are repeated throughout the literature about characteristics of reliability perfor- mance measurement. First, measures must be easy to understand and interpret. Measures must be standardizable and allow consistent comparison across geography, modal technology, and periods (short versus long, historic versus future, time of day). Measures must rely on accurate and complete data with cost-effective means to collect the necessary data. Measures must take into account the target user, including some customer-centric measures and some operational measures. Measures must relate to an agency’s goals and objectives. Finally, in relation to the later stages of addressing reliability, measures must allow an agency to determine the major causes of delay (often referred to as “problem diagnostics”) and the effects of improvements (allowing comparison to after implementation of treatments). These characteristics are taken into account in the suggested development steps of a bus service reliability improvement program. The process of addressing reliability has evolved immensely in the past few decades. More data are now available than ever before, and some agencies are beginning to make use of these data to monitor and evaluate reliability performance. However, best practices in this regard are in their infancy. Therefore, in the overview that follows as well as in the following chapters, this guidebook outlines an ideal process that takes the current availability of data into account in three major stages. The process is explained step by step in Chapter 3. Following is an overview of the three major stages. 2.3.1 Performance Monitoring Continuous monitoring of reliability is critical for identifying corridors and periods where performance has been compromised. Therefore, Chapter 4 provides several potential measures that could be used to gauge reliability, along with acceptable ranges in and standards for those measures to understand what would be considered poor, average, or good performance. The measures include those that are customer-centric, agency-centric, and operator-centric to ensure that all perspectives of reliability are addressed. 2.3.2 Problem Diagnostics The basic measures of reliability used by most agencies only identify that a problem with performance exists. Therefore, the next critical stage, described in Chapter 5, is identifying the source of the problem to begin to determine how it should be addressed. In the problem diagnostics stage, more specific measures are used to identify root causes. As an example, an agency may notice that its on-time performance (its chosen measure to monitor performance) on a particular route is consistently bad in the PM peak hour. A more detailed analysis might include breaking the performance into individual runs and stops so that a specific location and time might be identified. If it is a problem on that run every day, buffer time could be added to the schedule for a quick fix. However, it may be found that congestion only occurs a few times per month. By drilling down further, the agency could separate out dwell time and travel time reliability and find that a large number of people are boarding after particular events. This could invoke an entirely different set of possible treatments. Travel time reliability is influenced by a number of causes, some controlled by the transit agency, some partially controlled by the transit agency, and still others beyond the agency’s

Addressing Bus Transit Reliability 15 control [6]. Causes controlled by the agency include operator and vehicle availability, break- downs, recovery and break time, and length of routes. Causes partially controlled by the agency include operator skill and behavior, delays from merging into traffic, incidents and events, and variable passenger delay. Causes outside of the agency’s control include congestion, signal delays, and weather. 2.3.3 Improvement Strategy Selection The final stage, described in Chapter 6, is to identify strategies to improve reliability. An entire chapter of the guidebook is devoted to the range of strategies available, from operational and physical treatments to technology and policy measures. Selection of a strategy or strategies to address a reliability problem will depend on the particular problem being addressed (as identified in the previous stage). In addition, however, the strategy will also depend on the agency’s ability to work with partners and to use available capital and operating funds. After an improvement is implemented, the effect on reliability must be monitored, which brings the process back to the initial stage of performance monitoring.

Next: Chapter 3 - Developing a Bus Service Reliability Improvement Program »
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Transit reliability is critical to the operation and attractiveness of public transportation services. With the current unprecedented evolution in transportation services, including new competition from mobility service providers such as Uber and Lyft, improving transit reliability has taken on an even greater level of importance.

The TRB Transit Cooperative Research Program's TCRP Research Report 215: Minutes Matter: A Bus Transit Service Reliability Guidebook details eight steps that a transit agency can undertake to develop and maintain a Reliability Improvement Program.

There is also a Power Point presentation that provides an overview of the project accompanying the report and a supplemental report, TCRP Web-Only Document 72: Developing a Guide to Bus Transit Service Reliability.

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