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21st Century Operations Using 21st Century Technologies
Table of Contents

Approaches to Presenting External Factors with Operations Performance Measures

CHAPTER 1. INTRODUCTION

Transportation agencies that wish to effectively manage system performance should understand the nature and extent of this influence of external factors on system performance. Understanding the nature and extent of external factors helps in several elements of performance management, particularly in communication and target setting. This project identified key external factors that can impact performance, and developed recommendations for including external factors in performance reporting.

This report discusses general research associated with performance measures and elements of a performance management framework.  This report was not intended to address the specific requirements associated with the FHWA rule that established national measures for system performance and other associated requirements, including specific target setting, data collection/reporting, and other general reporting requirements.  That final rule ["National Performance Management Measures; Assessing Performance of the National Highway System, Freight Movement on the Interstate System, and Congestion Mitigation and Air Quality Improvement Program": Docket No. FHWA-2013-0054, RIN 2125-AF54, Federal Register - Vol. 82, No. 11, Pg. 5970 - January 18, 2017] can be found at: https://www.gpo.gov/fdsys/pkg/FR-2017-01-18/pdf/2017-00681.pdf.

FACTORS IMPACTING SYSTEM PERFORMANCE

Transportation system performance (e.g., poor mobility and travel time reliability) can be impacted by one or more key contributing factors:

  • Travel demand exceeds physical capacity (e.g., bottlenecks).
  • Traffic crashes and unplanned incidents (e.g., vehicle breakdown).
  • Construction and work zones.
  • Bad weather.
  • Poor traffic signal timing.
  • Special events (e.g., athletic events, festivals, etc.).

Most efforts to improve transportation system performance focus on addressing, improving, or better managing one or more of these key contributing factors.

WHAT ARE EXTERNAL FACTORS?

External factors (also called exogenous factors) are those influences that affect transportation system performance but are typically outside the control (at least operationally) of transportation agencies. Common examples of external factors include fuel prices, economic conditions, and employment levels.

WHY SHOULD YOU CARE?

By definition, external factors are typically outside the control of transportation agencies, but still influence transportation system performance. Therefore, transportation agencies that wish to effectively manage system performance should understand the nature and extent of this influence of external factors on system performance. Understanding the influence of external factors helps in several elements of performance management, particularly in communication and target setting.

PROJECT OBJECTIVES AND APPROACH

The project objectives were to:

  1. Use statistical analysis to identify key external factors that can influence system performance.
  2. Based on the statistical analysis and best practices in visual display, provide recommendations for including external factors in performance reporting.

This approach—using statistical analysis to identify key external factors, then providing recommendations for presenting external factors in performance reporting—is described in more detail in the following chapters and the appendix.

OVERVIEW OF REPORT

This report documents the research conducted in the following sections:

  • Chapter 1. Introduction: Introduces the concept of external factors and why they are important.
  • Chapter 2. Analysis of External Factors: Summarizes the conduct and results of a statistical analysis used to identify key external factors that were most strongly correlated with operations performance measures.
  • Chapter 3. Recommendations for Presenting External Factors: Provides recommendations for presenting relevant external factors with operations performance measures.
  • Appendix: Documents a state-of-the-practice review and statistical analysis conducted to identify key external factors that influenced performance measures in FHWA's Urban Congestion Report. The Appendix also summarizes best practices for visual displays of external factors and performance reporting.

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