Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Report
trucks determine when they can travel. Similarly, work schedules define when travelers must
leave home on the way to work, which provides for different levels of exposure to routinely
congested time periods. It is unclear at this time whether freight mover reliability should be
reported differently than passenger traveler reliability for the same roads. Table 3.3 provides
example performance measures for roadway users (both passenger travelers and freight movers)
as well as for agencies.
Table 3.3 Example Performance Measures for Roadway Users and Agencies
Stakeholder
Performance
related to
Performance Measure
Mean Travel Time
Roadway Users:
Passenger
Travelers
Freight Movers
Travel Time
(point to point)
95th Percentile Travel Time
80th Percentile Travel Time
Percentage center line miles for
which real time travel information
is available, and the accuracy of
that data
Percentage of roadway mile for
which disruption data are available
Percentage of all disruptions for
which a forecast of the effects of
that disruption is available
Performance Measure
depends mainly on
Demand, capacity
Disruption occurrence, disruption
nature, effectiveness of incident
response
Disruption occurrence, disruption
nature, effectiveness of incident
response
Agency
Congestion (on a
specific roadway
segment)
Mean, 80 th , 95 th Percentile Travel
Times for defined roadway
segments
Percentages of time and/or trips
during which a segment operates
lower than an “on-time” standard
adopted by the roadway agency
Traffic volume operating on a
segment at specified times of day,
days of the week, and times of
year
Percentage center line miles for
which real time travel information
is available, and the accuracy of
that data
Percentage of roadway mile for
which disruption data are available
Percentage of all disruptions for
which a forecast of the effects of
that disruption is available
Demand, capacity
“On-time” standards:
Rural: Free-flow speed
Urban: “Speed at maximum
vehicular throughput” (~45mph) or
a slower standard, if heavy
congestion.
Travel demand
Effectiveness of operational
decisions and other management
actions and policy decisions
Disruption Management
The second category of performance measures describes the number and nature of disruptions
that occur on the roadway system and the management actions being taken in response to those
disruptions. These measures are used to:
• Define the nature and significance of the sources of congestion or traffic disruptions;
• Monitor the level of effort and the nature of effort committed in responding to the sources
of congestion; and
• Monitor the impacts of managing disruptions.
GOALS AND PERFORMANCE TARGETS Page 28