1. Updated Service Measure for Freeway Facilities
HCQS Performance Measures Subcommittee
Doug McLeod, Florida DOT
Rich Margiotta, Cambridge Systematics
June 3, 2015

2. Background : Why Are We Doing This?
Current facility service measure is density unless one freeway segment is in LOS F, then the whole facility is assigned LOS F
All performance measurement activity uses travel time-based measures – HCM needs to be compatible
This is an opportunity for the HCM to provide guidance
Travelers experience the entire trip, not isolated pieces
Using travel time makes it conceptually consistent with Urban Streets
Addresses the long-standing “LOS F Problem” where all LOS F conditions are assigned the same grade, regardless of severity
Current service measure definition is still useful
Density still applies up to a point (need to determine that point)
Segment LOS provides a helpful diagnostic on the source of the problem

3. Issues to be Addressed
Need a service measure for both the Traditional (single input) and Reliability methods
As always, picking the LOS boundaries requires consensus and judgement
Measures need to be related to the travel time distribution and, to the extent possible, based on those commonly used for performance measurement

4. Many Potential PMs Are Available4

5. Selection of a PM as a Service Measure
Mean Travel Time Index could be used for both Traditional and Reliability methods…
… But the mean from the Traditional method will not be same as the Reliability method
Reliability mean has variability “baked in”
Would require 2 different LOS scales
Use the mean for Traditional and a Reliability PM for the Reliability method?
80th or 95th percentile TTI most commonly used in performance measurement

6. Do We Really Want to Define a Service Measure?
Defining the LOS ranges is contentious and should be based on research
Possible upcoming FDOT project
By moving LOS ranges into the current F region, the E/F boundary that defines failure is no longer relevant
Which is fine because this a facility, not a segment
Same as Urban Streets service measure

7. Do We Really Want to Define a Service Measure (cont.)?
If HCM does not define a service measure, the profession still needs guidance
E.g., What are good, bad, and ugly values for the PTI?
HCM could provide guidance on how locals should determine their own service standards
HCM is then “standard test method” rather than a hard standard
HCM could still recommend ranges for reporting purposes without assigning LOS grades
Would allow national comparisons
Agencies still free to set their own standards

8. Discussion of Options
Do we want an updated service measure or just guidance on how to: (1) report congestion and reliability and (2) set agency-specific performance standards?
If we pursue an updated service measure:
What performance measure(s) makes sense to use for the Traditional and Reliability Methods?
Discontinuity in LOS grades if current method is maintained?
Under what conditions would it apply?
Is the Subcommittee comfortable with eventually recommending LOS ranges for the selected measure?
What information does the Subcommittee need in order to make an informed decision on LOS ranges?

9. Motion
The Performance Measures Subcommittee recommends that the current service measure definition for freeway facilities be replaced with a travel time-based definition
Optional add-on: …when facilities reach a certain threshold of performance.