Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Report
Table 5.2 Mediocre Scenario Effects on Sources of Congestion
Source of Congestion
Traffic Incidents
Weather
Work
Zones/Construction
Fluctuations in Demand/
Special Events
Traffic-control Devices/
Signal Timing
Bottlenecks
Effects of Scenario Drivers
• Improvements in in-vehicle detection and control technology, along with reductions in
vehicle size, will lead to fewer crashes and reductions in severity related to:
o Congestion
o Run-off the Road Crashes
o Weather Management
o Incident Management
• Increase frequency of rare events such as tornados, heavy rain and snow storms,
flooding, etc., will cause service interruptions and decrease travel-time reliability
• Technological advancements will allow for better system integration and weather
management
• Work zones will become more common because of both infrastructure failures and
infrastructure maintenance and renewal activities
• Stresses on the aging electrical grid will lead to failures and the need for street and lane
closure for utility repairs
• Many jurisdictions will use ITS technologies and more comprehensive analyses to
minimize delays in work zones, but the overall outcome will be decreased travel-time
reliability
• Increasing variations in day to day travel demand will result from growing population and
relaxation of economic constraints on travel
• Better information dissemination will result in peak spreading which may improve
reliability
• Application of ITS technologies to help plan and manage special events will improve
network reliability
• Available technologies will be deployed to interconnect TCDs and make them more
adaptable/available to more locations. Surveillance technologies and speed smoothing
(variable speed limits) will contribute to increase network reliability
• More effective use of responsive technologies to monitor network performance and
condition will contribute to enhanced flow management. These and other technologies
will enable collection, analysis, and dissemination of detailed performance and condition
data that will support better decision by system owners, operators, and users to make the
trips smoother and more reliable
• Some maintenance and renewal funding will be available to address bottlenecks
(persistent capacity limitations)
• Less funding for infrastructure will retard the pace of resolution of such problems
ALTERNATIVE FUTURE 3: THE PESSIMISTIC SCENARIO
The driving variables—climate change, the economy, and energy—will be in a range that does not
support economic growth due to, among other influences, more-frequent rare events and increasing
energy prices. In particular, it is assumed that the “drivers” of change result in worst-case
outcomes, such as an increasing rate of climate change, a worsening of economic conditions, and
increasing energy prices.
This scenario focuses on the effect of exogenous variables on travel costs and provides the basis
for an overall assessment. In this scenario, the demand for reliable transportation will increase
because of policies/goals focused on 1) reducing fuel consumption, 2) decreasing greenhouse gas
emissions, and 3) supporting economic growth. With the high value of travel cost, delays become a
much stronger economic constraint and thus strategies aimed at reducing delays and travel
variability become an important component of state and regional transportation strategies to
improve system performance. Large-scale applications of technology, financial tools, and
institutional arrangements will be needed to support this focus on system reliability.
ALTERNATIVE FUTURES Page 57