Cover Image

Not for Sale



View/Hide Left Panel
Click for next page ( 24


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 23
CHAPTER 4 Performance Measures for Rural DRT The research underlying this TCRP project identified more than 60 different performance measures that have been used to evaluate DRT service, with 16 or so measures used more com- monly. But one does not need a litany of measures to capture the important aspects of DRT per- formance, and six measures have been selected as the key measures for the Guidebook, given that one of the objectives of the project was to select a limited number of measures. 4.1 Key Performance Measures for Assessing Rural DRT The six measures selected for the Guidebook for assessing rural DRT performance are identified in Table 4-1 and discussed in this section. Depending on the results of those measures, a rural DRT system may need to delve deeper into certain aspects of its operations, examining more detailed data and assessing additional measures to address questions or questionable performance. Importantly, rural DRT systems must consider the extent to which their mission influences their day-to-day performance. When a rural system is tasked with serving the needs of riders who are transit-dependent, its DRT service will often include lengthy trips for critical purposes with limited opportunity for shared-riding. Its performance measures will then reflect lower produc- tivity and higher cost per passenger trip than might otherwise be the case. Passenger Trips per Vehicle-Hour Passenger trips per vehicle-hour measures the productivity of a DRT system. Many consider productivity to be the most important single measure of DRT performance, assessing the system's effectiveness. As a performance measure, productivity captures the ability of the DRT system to schedule and serve passenger trips with similar origins, destinations, productivity = total passenger trips and time parameters, using the least number of in-service vehicles and hours. total vehicle-hours This is the essence of shared-ride, public DRT service. However, there are various important factors that affect the ability of a DRT system to be productive: the size of the service area; the distribution of residential areas and destination areas; and the patterns of riders' trips, including the extent of group trips. Particularly for rural DRT systems, large service areas with dispersed trip patterns make it harder to effectively schedule two or more riders on the same vehicle; this will result in a lower productivity. The extent to which the rural DRT system serves pre-scheduled group trips will also impact productivity, such as group trips to the senior center or other frequented desti- nation. If there are limited group trips--that is, few opportunities to schedule riders on the same 23

OCR for page 23
24 Guidebook for Rural Demand-Response Transportation: Measuring, Assessing, and Improving Performance Table 4-1. Six key DRT performance measures selected for Guidebook. 1. Passenger Trips per Vehicle-Hour 2. Operating Cost per Vehicle-Hour 3. Operating Cost per Vehicle-Mile 4. Operating Cost per Passenger Trip 5. Safety Incidents per 100,000 Vehicle-Miles 6. On-Time Performance vehicle at the same time for travel to a common destination--this will also mean a lower pro- ductivity. Other factors that impact productivity include the level of no-shows and late cancellations, scheduling efficiency, dispatcher skills, and ability to schedule trips in real-time, vehicle opera- tor experience and familiarly with the service area and their passengers' trip-making patterns, and the operating environment including the roadway network and geographic barriers that impact that network. The type of DRT service--particularly whether it functions as ADA paratransit--also affects productivity because ADA regulations have effective limits on the flexibility that a DRT system has to maximize shared riding. This also may mean a lower productivity. Some of these are exam- ples of uncontrollable factors affecting the performance of DRT systems. Such factors impacting DRT performance are discussed in more detail in Chapter 5. From a DRT performance perspective, the emphasis on productivity stems in great part from the fact that small changes in productivity can be very cost effective. Larger changes can be even more cost effective. The productivity measure can be calculated with either revenue-hours or vehicle-hours in the denominator. For this Guidebook on rural DRT, the measure uses vehicle-hours, in keeping with one of the project's objectives to use NTD data definitions. To the extent that vehicle-hours are generally fixed, at least in the short run, while revenue- hours occur only during passenger service, using vehicle-hours to measure productivity may provide a better indication of how well vehicle resources are being used over the course of a day, week, or month (5). However, in the guidebook for urban DRT (TCRP Report 124), the productivity measure uses revenue-hours as the denominator. Direct comparisons, then, between productivity data included in TCRP Report 124 and that included in this Guidebook for rural systems are not valid since deadhead time is included in the measure for rural DRT systems. In some cases, deadhead can be a significant proportion of vehicle-hours. For those rural DRT systems that collect revenue-hours data, productivity can be calculated using revenue-hours. Use of revenue-hours for measuring productivity has generally been used for demand-response transportation where revenue-hour data are available. Revenue-hours are typically used for measuring fixed-route productivity as well. Moreover, since revenue-hours are less than vehicle-hours, the productivity figure will be higher when revenue-hours are used as the numerator in the measure--passenger trips--is divided by a smaller number. Productivity is sometimes measured as passenger trips per mile. Given the low passenger vol- umes on DRT relative to mileage, this ratio usually results in a number less than 1. Such resulting numbers are not particularly logical given that an actual passenger trip is not less than 1; passenger trips per hour is an easier number to visualize.

OCR for page 23
Performance Measures for Rural DRT 25 Performance Considerations If a rural DRT system has a lower performance on passenger trips per vehicle-hour than desired, it should look to various possible reasons, only some of which the system can affect: A large service area, where passenger trips are lengthy; Low density of passengers within the service area; System policies that allow riders to travel to destinations beyond the primary service area, for example, service to a distant medical facility; Significant deadhead time, related to service area size and long-distance trips; Service policies and scheduling practices that facilitate individualized trip-making ("one-to- one" trips rather than "few-to-one" or "many-to-one" trips); Limited dispatch control that lacks the tools to manage service operations and respond to changes on a real-time basis; High rates of no-shows and late cancellations; Scheduled vehicle-hours that are not aligned with ridership demand; and Less-than-reliable vehicles, with excess breakdowns, requiring replacement service to be deployed. Operating Cost per Vehicle-Hour Operating cost per hour is a key cost efficiency measure, assessing the financial resources needed to produce a unit of service, defined for this measure as an hour of service. What does it cost the DRT system to put service on the street? This measure, however, does not evaluate use of the DRT service; because of this, it should be assessed in conjunction with the measure passenger trips per vehicle-hour or other ridership use measures. Similarly to the productivity measure, practices vary as to whether the mea- sure uses revenue-hours or vehicle-hours in the denominator. Since the produc- operating cost per vehicle-hour = tivity measure has used vehicle-hours, this measure also used vehicle-hours. total operating cost total vehicle-hours Performance Considerations The elements in this measure are (1) the DRT operating costs, with the major components of costs related to staff labor and vehicle operations and their maintenance and (2) the amount of DRT service provided as measured by vehicle-hours. For a rural DRT sys- tem, deadhead time may have a significant impact on operating costs if large amounts of time are needed to travel to and from pick-up and drop-off locations at the start and end of passen- ger service. There are various reasons that a DRT system's performance on operating cost per vehicle-hour may not meet objectives, including Costs for labor, particularly vehicle operators, since these compose the largest share of tran- sit staff; Costs for maintenance from an older fleet, from problem vehicles, from accidents, and from fuel costs; High costs for administration or other overhead; High proportion of paid hours for vehicle operators related to vehicle-hours of service-- that is, a significant proportion of operator payhours that is attributed for cost items other than providing passenger service (e.g., administrative efforts); High fringe benefits costs for items such as vacation, sick leave, family leave, and med- ical benefits;

OCR for page 23
26 Guidebook for Rural Demand-Response Transportation: Measuring, Assessing, and Improving Performance Costs for significant amounts of deadhead time because of service-area size and/or long- distance trips; and Inefficient number of vehicle-hours, resulting from a poor service design or from schedul- ing practices. Labor is a major cost center. For the transit industry in general, labor including fringe bene- fits may account for up to 70% to 80% of total operating costs, with the majority of employees working in vehicle operations and vehicle maintenance. The labor rates paid to vehicle opera- tors and mechanics are somewhat controllable, but will depend on the local job market and wages paid for similar positions at competing organizations. For some DRT systems, the rates may be influenced by a labor contract. Maintenance is an important functional cost center. Based on NTD data for the transit indus- try in general, vehicle maintenance may account for up to 20% of operating expenses. DRT man- agement has some control over this factor, but costs will also depend on the type of vehicles, their age, and the vehicles' operating conditions--the latter of which is influenced by service-area characteristics and weather. Operating Cost per Vehicle-Mile Operating cost per mile is another service efficiency measure often used for performance assess- ments, either in addition to or instead of operating cost per hour. While cost per hour is often the more important measure because the largest proportion of costs (wages and salaries) is paid on an hourly basis, the measure operating cost per vehicle-mile is included for rural DRT sys- tems since rural systems with limited data reporting practices are more likely to report vehicle-mile data than vehicle-hour data. operating cost per vehicle-mile = As a cost efficiency measure, operating cost per vehicle-mile assesses the total operating cost total financial resources needed for the rural system to produce "vehicle-miles." vehicle-hours Similarly to the related measure, operating cost per vehicle-hour, this mea- sure does not evaluate the use of those vehicle-miles, so the measure should be assessed along with measures of DRT utilization. Performance Considerations Factors that influence the operating cost per vehicle-mile measure for DRT include the oper- ating costs as well as number of miles operated, which is influenced by the average speed of ser- vice and deadhead requirements, among other factors. Reasons that a rural DRT system may have a relatively high operating cost per vehicle-mile include some of the same as listed above for the measure operating cost per vehicle-hour: Relatively high operating costs stemming from high costs for labor, maintenance, and/or administration; Costs for significant amount of deadhead miles because of service-area size and/or long- distance trips; and Low average operating speed, which could result from a number of factors, including excess dwell times at riders' pick-up and drop-off locations or other factors which slow down service--for example, weather-related factors such as fog or poor road conditions. While the primary cost factor is the hourly operating cost, the measure cost per vehicle- mile is impacted because the costs are spread over a smaller number of miles. For urban DRT systems, high operating cost per vehicle-mile may result in part from excess traffic congestion, which slows down average operating speed, but this is less a factor in rural areas.

OCR for page 23
Performance Measures for Rural DRT 27 Operating Cost per Passenger Trip Operating cost per passenger trip is a critical cost-effectiveness measure. It combines elements of the first two measures--operating cost per vehicle-hour operating cost per passenger trip = and passenger trips per vehicle-hour, relating productivity to the hourly oper- total operating cost total ating cost. passenger trips As a composite measure, a DRT system may have low operating costs but if productivity is also low, the operating cost per passenger trip may be relatively high. Conversely, a DRT system may have a relatively high cost on a vehicle- hour basis, but if its productivity is high, the cost per passenger trip may be low. Performance Considerations A key element of this measure is productivity. Efforts to improve the cost per passenger trip measure should first focus on increasing the number of passenger trips served within given resources. Reasons that a DRT system might show high operating cost per passenger trip include: High operating costs: Costs for labor, particularly vehicle operators; Costs for maintenance from an older fleet, from problem vehicles, from accidents, and from fuel costs, and High administrative costs. Low productivity: Large service area where passenger trips are lengthy; Low density of passengers within the service area; System policies that allow riders to travel to destinations beyond the primary service area; Significant deadhead time related to service-area size and long-distance trips; Service policies and scheduling practices that facilitate individualized trip-making ("one-to-one" trips rather than "few-to-one" or "many-to-one" trips); Limited dispatch control that lacks the tools to manage service operations and respond to changes on a real-time basis; High rates of no-shows and late cancellations; and Scheduled vehicle-hours that are not aligned with ridership demand. Safety Incidents per 100,000 Vehicle-Miles Safety needs to be a primary concern for all transit systems, including DRT. Rural DRT sys- tems should track and monitor their safety record and make adjustments as needed to ensure safe operations. As a performance measure, the safety incident rate can be seen as one that incor- porates an assessment of both service operations as well as passenger service quality. The safety of the DRT system may not be an attribute that passengers consider each day that they ride the DRT system, but safety is a dimension of customer service quality. Calculation Given the different ways the DRT systems define and measure safety and their accident rates, it was determined that the Guidebook use the NTD definitions to assess safety. As described in Chapter 3, these are very specific definitions. The performance measure uses the sum of NTD safety incidents, which is a required Rural NTD data element, divided by 100,000 vehicle-miles. The measure compares the raw number of

OCR for page 23
28 Guidebook for Rural Demand-Response Transportation: Measuring, Assessing, and Improving Performance NTD safety incidents with the miles traveled by the system, which places the raw number into the perspective of miles traveled by the system. However, since the reporting thresholds for NTD safety incidents are rela- tively high (e.g., for a property damage incident, the reporting threshold is $25,000 worth of damage), rural systems should monitor safety incidents of all safety incidents per 100,000 vehicle- types and distinguish between preventable and non-preventable accidents, miles = [(NTD reportable safety without regard to a pre-determined dollar threshold. When assessing this more incidents) (total vehicle-miles)] detailed safety data, comparisons over time for the individual rural system will x 100,000 likely be more meaningful than comparisons to peer systems since individual system definitions of accidents and preventable versus non-preventable vary. Performance Considerations A DRT system's performance on safety can be improved by ensuring that vehicle operators are well trained, vehicles are well maintained, and operating policies and procedures support safe operations day to day. Lower than expected or desired performance on safety may result from a variety of reasons: Limited vehicle operator training and/or retraining; Inexperienced vehicle operators; Vehicle issues such as the vehicle type or design and their condition; Scheduling practices that result in a system speed that forces vehicle operators to rush, which then increases opportunities for accidents; Environmental factors such as bad weather; and The system's commitment to safety and efforts to communicate that commitment to all its employees. On-Time Performance On-time performance is an important measure of service quality from a on-time performance = DRT rider's perspective. On-time performance measures the reliability of the (total on-time trips, including system: does the vehicle arrive for the pick-up when it was promised? While no-shows) this measure may get more attention at urban DRT systems that operate ADA (total completed trips + no-shows + paratransit, it is important for all DRT systems. Rural systems should routinely missed trips) monitor and assess their on-time performance. On-time performance may also be important at the drop-off end. In fact, timeliness at the destination end may be more important for riders with time- sensitive trips such as to work or medical appointments. DRT systems should consider assessing on-time performance at the drop-off end for time-sensitive trips, those with a pre-determined "appointment" time. This would be a separate assessment since only those trips with an appointment time would be included for this assessment. However, even if a DRT system sched- ules a rider's trip to ensure timeliness at the destination, the system needs to give the rider a pick-up time (or time window) so that the rider can be ready when the vehicle arrives. As discussed in the last chapter, the definition of "on-time trips" varies among DRT systems. Data collection also varies although most rural systems use vehicle operator-reported data from operators' manifests. Calculation On-time performance can be calculated based on data for all trips (which may require more data processing time unless the system has MDTs) or on a sample of trips. For a rural system that