The National Academies Press

Currently Skimming:

Pages 20-49

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 20... ... 19 3 DESCRIPTION OF TOOLS AND METHODS FOR ESTIMATING RELIABILITY Color versions of the figures in this chapter are available online: http://www.trb.org/Main/Blurbs/168856.aspx This chapter summarizes available types of tools and methods that may be used to estimate reliability measures. Chapter 4 provides a comparison of the tools and methods to aid in tool and method selection. Read the entire page →
From page 21... ... 20 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE • Discussion of the general input data required; and • Discussion of the output performance measures and format. The summary section that follows describes the categories of tools and methods and identifies relative strengths and weaknesses of using them. Read the entire page →
From page 22... ... 21 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE incident occurrence, presence of work zones, or other factors influencing nonrecurring congestion. Reliability is then estimated individually for each of the scenarios (typically using one of the methods previously described) Read the entire page →
From page 23... ... 22 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE Several SHRP 2 projects are developing analytic methods for estimating reliability directly, from a variety of resolution scales, from sketch planning to microscopic simulation: • SHRP 2 L03: developed statistically derived reliability equations based on empirical data. Two types of models were developed: "data-poor," which requires only an estimate of recurring delay, and "data-rich," which requires information on demand, capacity, incident characteristics, and weather conditions. Read the entire page →
From page 24... ... 23 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE • SHRP 2 L04: is developing a simulation-based approach to reliability estimation, using a combination of mesoscopic and microscopic models. It fits into the "Simulation or Multiresolution Methods" category. Read the entire page →
From page 25... ... 24 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE 3.2 SKETCH-PLANNING METHODS Overview Sketch-planning methods are designed to provide a quick analysis of reliability using minimum input data. These methods are intended to provide order-of-magnitude estimates of reliability metrics based on assumptions regarding the relationships observed in other areas between reliability metrics and other standard performance metrics (e.g., volume to capacity ratios, mean travel times) Read the entire page →
From page 26... ... 25 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE The overall mean travel time index in Figure 3.2 includes all of the sources of possible variations in travel time (e.g., incidents, weather, special events) , because the measurements were taken over the course of an entire year. Read the entire page →
From page 27... ... 26 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE treatments are those that involve the physical infrastructure of the highway and roadside (e.g., drivable shoulders, runaway truck ramps, and median crossovers) Read the entire page →
From page 28... ... 27 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE Sketch-planning methods generally provide order of magnitude reliability estimation, and as such, are appropriate for conducting assessments of system deficiencies and preliminary screening of alternatives. Sketch-planning methods also can be applied on preferred alternatives to supplement an initial screening process in situations where resources limit the ability to conduct a robust analysis using more complex tools or methods. Read the entire page →
From page 29... ... 28 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE that the analysis is based on the calibrated regional travel model outputs that are generally accepted and widely used in the region for planning efforts, adding credibility to the results and allowing the results to be easily incorporated within the overall planning process. The Florida DOT and the Southeast Michigan Council of Governments ( SEMCOG) Read the entire page →
From page 30... ... 29 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE Figure 3.4. Screenshot of the ITS Deployment Analysis System (IDAS) Read the entire page →
From page 31... ... 30 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE TABLE 3.3. TRAVEL TIME RELIABILITY: RATES FOR 1-H PEAK VEHICLE-HOURS OF INCIDENT DELAY PER VEHICLE-MILE Volume/1-h Level of Service Capacity Number of Lanes 2 3 4+ 0.05 3.44E-08 1.44E-09 4.39E-12 0.1 5.24E-07 4.63E-08 5.82E-10 0.15 2.58E-06 3.53E-07 1.01E-08 0.2 7.99E-06 1.49E-06 7.71E-08 0.25 1.92E-05 4.57E-06 3.72E-07 0.3 3.93E-05 1.14E-05 1.34E-06 0.35 7.20E-05 2.46E-05 3.99E-06 0.4 0.000122 4.81E-05 1.02E-05 0.45 0.000193 8.68E-05 2.34E-05 0.5 0.000293 0.000147 4.93E-05 0.55 0.000426 0.000237 9.65E-05 0.6 0.0006 0.000367 0.000178 0.65 0.000825 0.000548 0.000313 0.7 0.001117 0.000798 0.000528 0.75 0.001511 0.001142 0.00086 0.8 0.002093 0.001637 0.00136 0.85 0.003092 0.002438 0.002115 0.9 0.005095 0.004008 0.003348 0.95 0.009547 0.007712 0.005922 1 0.01986 0.01744 0.01368 agency for the San Francisco Bay Area, has developed relatively simple SAS programming to look up and apply the incident delay measures to data directly from their travel demand model on a link-by-link basis. Read the entire page →
From page 32... ... 31 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE combination with one another (2) Read the entire page →
From page 33... ... 32 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE providing travel times, crash and emission rates, and other impacts that may be needed for a larger analysis. Input Data Input data for model post-processing methods include link-level data that are typically available in most regional travel demand models (or simulation models) Read the entire page →
From page 34... ... 33 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE microsimulation models in terms of complexity, are becoming more prevalent. A multiresolution model can include any two or more of these model resolutions. Read the entire page →
From page 35... ... 34 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE Figure 3.6. Overview of ICM multiresolution analysis approach. Read the entire page →
From page 36... ... 35 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE The use of simulation models in this approach requires that the analysis area be relatively constrained to a small subarea of the regional network, usually a corridor. Expansion of the analysis to a broader region would require significantly more resources. Read the entire page →
From page 37... ... 36 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE data, or default values can be used. Each scenario is then run through the appropriate computational engine, FREEVAL-RL or STREETVAL, for analysis. Read the entire page →
From page 38... ... 37 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE the multiscenario approach. The modeling framework includes a preprocessor, which prepares a set of simulation input files, and a post-processor, which extracts various reliability performance measures from the simulation output. Read the entire page →
From page 39... ... 38 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE Figure 3.9. Proposed simulation modeling framework for reliability (3) Read the entire page →
From page 40... ... 39 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE • Incident logs; • Crash data; • Operational data (e.g., logs of messages displayed on variable message signs, 511 calls or alerts) ; and • Weather data. Read the entire page →
From page 41... ... 40 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE The summary that follows is based on materials developed in SHRP 2 Project L02, Establishing Monitoring Programs for Mobility and Travel Time Reliability, and NCHRP 3-68: Guide to Effective Freeway Performance Measurement (See NCHRP web-only document 97, August 2006) Read the entire page →
From page 42... ... 41 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE Component 3: Data Fidelity Several different geographic and time scales are available for analysis and reporting. Ultimately, the intended audience will determine the geographic scale and level of detail provided in performance measure reports that could range from detailed bottleneck locations to broad regionwide reports. Read the entire page →
From page 43... ... 42 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE traveler information data) Read the entire page →
From page 44... ... 43 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE 1. Determine high-level user requirements for the system (who will use it, what they will use it for, etc.) Read the entire page →
From page 45... ... 44 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE agency priorities and the level of aggregation of the data. Reliability is most commonly applied to facility segments (because of data availability) Read the entire page →
From page 46... ... 45 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE TABLE 3.4. RECOMMENDED MEASURES FOR REPORTING TRAVEL TIME, DELAY, AND RELIABILITY FROM NCHRP REPORT 618 Recommended Performance Measures Congestion Component Addressed Geographic Area Addressed Typical Units Reported Travel Time Measures Travel time Duration Person-minutes/day, person-hours/year Total travel time Duration Person- or vehicle-hours of travel/year Accessibility Extent, intensity Region, subarea Number or percent of "opportunities" (e.g., jobs) Read the entire page →
From page 47... ... 46 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE TABLE 3.5. SHRP 2 RELIABILITY RESEARCH PROJECTS AND HOW THEY CAN BE USED IN THE PLANNING AND PROGRAMMING PROCESS Number Project Title Use in Project L05 Planning and Programming Activities SHRP 2 L01 Integrating Business Processes to Improve Reliability Provides guidance on how internal agency structures and processes can be transformed to focus on transportation operations. Read the entire page →
From page 48... ... 47 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE Number Project Title Use in Project L05 Planning and Programming Activities SHRP 2 L14 Traveler Information and Travel Time Reliability Undertook original research to determine how travelers perceive travel time reliability. The results are very useful for explaining technical analyses that use reliability and can be used to educate the public and decision makers when agencies are explaining such things as performance reports. Read the entire page →
From page 49... ... 48 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE 3.7 REFERENCES 1. Travel Time Reliability Implementation for the Freeway SIS Final Report, Florida Department of Transportation Systems Planning Office, Contract BDK77-931-04, December 31, 2010. Read the entire page →

From page 20...

... 19 3 DESCRIPTION OF TOOLS AND METHODS FOR ESTIMATING RELIABILITY Color versions of the figures in this chapter are available online: http://www.trb.org/Main/Blurbs/168856.aspx This chapter summarizes available types of tools and methods that may be used to estimate reliability measures. Chapter 4 provides a comparison of the tools and methods to aid in tool and method selection.