Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Report
using real-time traffic data from Atlanta and Seattle. The fundamental objective of project L03 was
to develop predictive relationships between highway improvements and travel-time reliability. An
overall finding from the LO3 research was that all forms of improvements, including capacity
expansions, affect both average congestion and reliability in a positive way (i.e., average
congestion is reduced and reliability is improved). The following are other key findings of the
SHRP2 LO3 study:
• Traditional capacity projects significantly improve reliability, not only capacity.
• Demand management strategies such as congestion pricing will lead to improvements in
reliability.
• Accounting for traffic volume as a factor of available capacity can provide valuable input
for efficiently allocating operations strategies, particularly incident management.
The SHRP2 - LO3 study documents the fact that travel-time reliability is largely influenced by the
degree to which recurring congestion occurs. That is, on a congested roadway segment, travel
quickly becomes unreliable when nonrecurring events occur (such as incidents, inclement weather,
crashes, or special events). Conversely, when a road segment is uncongested, travel time can often
remain stable - even when nonrecurring events occur due to the ability of the roadway to "absorb"
these events.
CLASSIFICATION OF STRATEGIES AND TREATMENTS TO IMPROVE
TRAVEL-TIME RELIABILITY
This section introduces the organizational structure of strategies and treatments that can be applied
to improve travel-time reliability. For the purposes of this report, the following definitions apply:
• Strategy: A group of related activities that might include different ITS technologies,
operational improvements, and management techniques that are aimed at achieving an
improvement in travel-time reliability (e.g., improve incident response).
• Treatment: A specific activity or action that i8mprove travel-time reliability (e.g., GPS
technology to measure the variation in travel times). The application of one or more
treatments composes a strategy.
These strategies and treatments were identified through a literature review of other SHRP2
projects listed as follows:
•
SHRP 2 L03: Analytic Procedures for Determining the Impacts of Reliability Mitigation
Strategies (3)
•
SHRP 2 L06: Institutional Architectures to Advance Operational Strategies (4)
• SHRP 2 L07: Evaluation of Cost-Effectiveness of Highway Design Features (5) , and
•
SHRP 2 C05: Understanding the Contribution of Operations, Technology, and Design to
(6, 7)
Meeting Highway Capacity Needs
Additionally, FHWA publications and international research documents were also reviewed. These
sources are listed in the References portion at the end of this chapter.
Classification of Strategies
Based on their general focus area, the strategies are grouped into six major categories as follows:
• Agency Management, Organization, and Resource Allocation
• Information Collection and Dissemination
• Vehicle Technologies
• Incident and Special Event Management
OPERATIONS STRATEGIES AND TREATMENTS TO IMPROVE TRAVEL-TIME RELIABILITY Page 63