L02 – Establishing Monitoring Programs for Travel Time Reliability SHRP 2 Joint Technical Coordinating Committee Meeting Irvine, CA - April 8, 2010
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L02 – Establishing Monitoring Programs
for Travel Time Reliability
SHRP 2 Joint Technical Coordinating Committee Meeting
Irvine, CA - April 8, 2010
April 8, 2010 SHRP2 L02 2
Purpose and Deliverables
• Guidebook
– Travel time reliability
monitoring system
– Design, build, integrate,
operate, maintain
• System prototype
• Efficacy assessment
– How well the guidebook
and system work
– Real-world network and
data (primary)
– Simulation (if needed)
April 8, 2010 SHRP2 L02 3
Research Team
Ralph Hessian
April 8, 2010 SHRP2 L02 4
In the midst of other SHRP2 projects
L02 – Establishing
Travel Time
Monitoring Systems
L13 – Archive for
Reliability and
Related Data
L11 – Evaluating
Alternative Operations
Strategies to Improve
Travel Time Reliability
L17 – A Framework
for Improving Travel
Time Reliability
L14 – Traveler
Information and
Travel Time
Reliability
L05 – Incorporating
Reliability Performance
Measures into the
Transportation Planning
and Programming
Processes
L03 – Analytic
Procedures for
Determining the
Impacts of Reliability
Mitigation Strategies
April 8, 2010 SHRP2 L02 5
Guiding Principles
• Be clear and action oriented
• Use field-based case studies as much as possible
• Employ a long-term vision
• Learn from operational agencies during development
• Focus on origin-destination travel times
• Stress the use of probe vehicles
• Develop clear, concise, and robust metrics tailored for
all users
April 8, 2010 SHRP2 L02 6
Phase I - Finished
System Design Needs: Define user and functional
requirements for travel time reliability monitoring
systems
– Task 1: Inventory and Assess Existing Traffic Monitoring
Systems
– Task 2: Identify User Needs
– Task 3: Characterize User Needs
– Task 4: Define Functional Requirements
– Task 5: Phase I Interim Report
April 8, 2010 SHRP2 L02 7
Phase II – About to Start
System Design Completion and Guidebook Preparation
– Task 6: Develop Sampling and Data Acquisition Plans
– Task 7: Design a Monitoring System
– Task 8: Assess the Design Trade-offs for Real-time versus Archived Travel
Time Data Collection Systems
– Task 9: Phase II Report – Including a Draft of the Guidebook
April 8, 2010 SHRP2 L02 8
Phase III – In the Future
Validate Monitoring Programs
– Task 10: Program Validation
• Subtask 10.1: Module Development
• Subtask 10.2: Module Integration
• Subtask 10.3: Site selection (Five sites)
• Subtask 10.4: Validate Systems
• Subtask 10.5: Analyze Results
• Subtask 10.6: Summarize Results
• Subtask 10.7: Update Guidebook
– Task 11: Final Report
April 8, 2010 SHRP2 L02 9
Task 1 – Inventory and Assess Existing
Traffic Monitoring Systems
• Findings based on the 25 largest metropolitan areas
• Nearly every major metropolitan area has travel time monitoring and
reporting capabilities
• Many areas are served by several information providers, public and private
• A few providers report travel time reliability information to travelers
• Several providers contrast current travel times and delays with averages
• Behind-the-scenes data processing firms are striving to determine how to
report and use travel time reliability information
April 8, 2010 SHRP2 L02 10
Be
st
Pra
cti
ce E
xam
ple
s
April 8, 2010 SHRP2 L02 11
Source: GMC Website
April 8, 2010 SHRP2 L02 12
April 8, 2010 SHRP2 L02 13
Task 2/3 – User Needs• A few agencies are reporting reliability measures
• Clearly communicating travel time reliability information is a challenge
• Many agencies strive to use reliability measures in decision-making
• But how they use the information varies widely:
– planning and programming, user cost assessment, performance assessment
• Reliability measures are used internally to monitor and manage:
– peak hour congestion, work zones, incidents, and special events
• Agencies must understand what users value and what they will listen to and
comprehend
• Most common communication channels are:
– media outlets, 511, other internet tools (websites, email distribution lists, twitter)
• Average travel time is reported most often and is the easiest metric to communicate
• Most agencies are unsure about using private sector information
• Agencies need to share information and resources to do an effective monitoring job
• Communication tools need to be constantly updated to ensure user confidence
April 8, 2010 SHRP2 L02 14
Task 2/3 – Passenger MetricsBroad
Classification by
Trip Purpose
Detailed Classification by
Trip Purpose
Importance / Severity of
Reliability
Primary User Information Need
Recommended Reliability
Measure
Daily, Constrained Trips
Work High Delay during heaviest traffic days. Planning Time Index Pick-up & Drop-off
Children High
Daily, Unconstrained Trips
Shopping Low Additional time necessary to generally arrive on time. Buffer Index
Return home High-Medium
Occasional, Constrained Trips
Appointments High Travel time during peak period versus off-peak period. Travel Time Index
Leisure Medium-Low
Occasional, Unconstrained Trips
Leisure Low Additional time necessary to generally arrive on time.
Buffer Index
Source: Adapted from SHRP 2 Project L11 Technical Memorandum 1, Exhibits 2 and 4
April 8, 2010 SHRP2 L02 15
Freight
Metrics
Source: Adapted from SHRP 2 Project L11 Technical Memorandum 1, Exhibit 3
April 8, 2010 SHRP2 L02 16
Category Key Questions Key Takeaway Points
Relative Amount of
Information
Received
1. Data Collection
Practices and
Travel Time
Measurement
Tools
Do you currently use travel time reliability as a performance measure for
your system? If so, how do you measure it? Where, when, and for what
facilities, areas, corridors, or OD pairs do you measure it?
What information is gathered to monitor travel time reliability?
How do you obtain travel time information?
Are the travel time reliability results archived and/or reported?
Many new and emerging data collection technologies exist, but agencies are still using
inductive loops as the most common source for travel time and speed data.
Quality control and management of tools and data is very time intensive and takes
more resources than most agencies have available.
Partnerships with other public and private agencies are vital when it comes to
assembling the resources necessary to accurately record and archive data.
Medium
2. Communication
to Users
What information is presented to the users of your system and how is it
presented?
In the future, what reliability information can you envision being
delivered to system users and in what forms?
Do you provide pre-trip information to users on system conditions? If so,
what media is this communicated through?
A few agencies are experimenting with reporting reliability measures. Overall, most
users seem more interested in knowing travel times rather than travel time variance.
Reliability measures seem to be more useful when communicating pre-trip information.
Users are demanding travel time information on alternate routes.
Providing travel time or arrival information causes users to perceive the system as
reliable.
With all of the technology available, agencies need to better understand the most
effective and efficient means by which to communicate reliability information.
High
3. Business
Processes and
Future
Monitoring Plans
To what extent do you incorporate information about travel time
reliability into day-to-day operations?
Do you have quantitative or qualitative goals with respect to reliability?
What are the challenges you face with setting reliability goals?
Are there gaps in the travel time information you use that need filling?
Are there other deficiencies that need improvement?
Using reliability measures is a goal of many agencies, but the way they are used
varies. Examples are planning and programming, user cost assessments,
performance assessments.
Need to develop reliability initiatives at the national level and encourage partnerships
at the local level to more easily reach goals established by initiatives.
Few agencies monitor reliability on roadways other than freeways.
High
4. Performance
Measures
What travel time reliability performance measures or indices do you
monitor? Are these measures archived, tracked, or analyzed in any
way?
Under what system conditions do you monitor travel time reliability
(relating to the seven factors influencing reliability)?
What spatial and temporal levels of detail do you capture in your existing
monitoring system and would you prefer more or less detail?
Understanding the “why” behind the variability is important for agencies to mitigate the
problem behind the variability.
Agencies would like more guidance on evaluating performance measures on a
network level.
Need to identify measures most clearly portrayed to the public and that are not facility
or mode specific.
Medium
5. Education and
Outreach
What resources do you most commonly use to educate your
organization on travel time reliability monitoring practices?
Does your organization provide public information programs to educate
users on how to use travel time reliability monitoring resources?
Do users generally feel the system is reliable and, if so, why? If not,
what do you think could be implemented to change their perception?
The traveling public is intuitively aware of reliability concepts, but this intuition must be
enhanced with educational tools that are marketable and easily accessible to the
public.
It is important to share information among agencies to advance the research and
implementation of reliability programs.
Effective outreach strategies must be centered on what users perceive and value and
what they will listen to and comprehend in regard to reliability reporting.
The guidebook ought to: 1) compile best practices, 2) provide specific examples, 3)
provide guidance on reporting reliability for all user types, and 4) address integration
with the private sector.
Low
Task 2/3 – Key Take-Away Points
April 8, 2010 SHRP2 L02 17
Task 4- System Vision
Use Cases for:
• Passenger travelers
• Freight movers
• Policy makers
• Roadway system managers
• Transit system managers
April 8, 2010 SHRP2 L02 18
Information Service
Provider
Other
Transportation
Management
Systems
Transportation
System Data
Collection
Subsystems
Transportation
Management
SystemOther
Transportation
Management
Systems
Information Service
Provider
RTIP Focus
Area
Traveling
Public
Information Service
Provider
Other
Transportation
Management
Systems
Transportation
System Data
Collection
Subsystems
Transportation
Management
SystemOther
Transportation
Management
Systems
Information Service
Provider
RTIP Focus
Area
Traveling
Public
Dual-use:
• Real-time
• Off-line
RTIP Guidelines:
Real-Time System
Management
Information Program
Real-Time System Archived Data System
Network Surveillance
Traffic Probe Surveillance
Weather Information Processing and Distribution
Maintenance and Construction Activity Coordination
ISP Based Trip Planning and Route Guidance
Broadcast Traveler Information ITS Data Warehouse
Interactive Traveler Information ITS Virtual Data Warehouse
Dynamic Route Guidance -
April 8, 2010 SHRP2 L02 19
Task 4 - System Capabilities
• Address both person and freight trips
• Support computation and estimation of travel time reliability
• Support prediction algorithms for both real-time and static (e.g. planning)
applications
• Impute data for facilities and areas where data are not available
• Support aggregation of localized travel time reliability to corridors, subsystems,
and systems
• Monitor long- and short-term changes in the reliability of roadway systems,
and compare the findings with peer systems
• Be able to check for equipment failures in real-time
• Be compatible with existing (legacy) systems.
• Receive data from existing and future sensing technologies
• Disseminate travel time reliability information to users.
• Use public and private sources of data as appropriate.
April 8, 2010 SHRP2 L02 20
Task 4 – System Capabilities (cont)
• Serve the traffic monitoring needs of the public and, to the extent
practical, the private sector.
• Store travel time and other data concerning reliability in a standard-
compliant data base
• Use appropriate telecommunication technologies
April 8, 2010 SHRP2 L02 21
User Type Use Case Index Use Case Description
Travelers
Constrained Trips
T1
A user wants to find out, in advance, what time to
leave for a trip and what route to take in order to arrive
at a destination on time.
T2
A user wants to find out, immediately before a trip,
what time to leave and what route to take in order to
arrive at a destination on time.
T3
A user wants to determine the time or extra time
needed for a trip in order to arrive on-time a certain
percentage of the time.
T4
A user wants to calculate the expected travel time and
buffer time for a congestion-inducing event (as defined by the seven sources of unreliability).
T5
A user wants to determine en-route whether an
alternate route would increase the likelihood of an on-
time arrival or minimize the travel time.
Unconstrained Trips
T6 A user wants to know what time of day to make a trip
in order to generally arrive on time.
T7 A user wants to know how much extra time to add on
to a trip to generally arrive on time.
Use Cases – The Building Block
April 8, 2010 SHRP2 L02 22
Use Case ProcessingUse Case T3: A user wants to determine the time or extra time needed for a trip in order
to arrive on-time a certain percentage of the time.
Purpose: Different users making different constrained trips may have varying ideas
on acceptable risks of arriving late that is not necessarily the 5 percent risk captured by the planning time metric. This capability would allow travelers to select the
percentage of time that they need to arrive on-time to find the route that best
accommodates this threshold.
Steps:
1. User selects an origin.
2. User selects a destination.
3. User selects from a list of percentage thresholds of how often they want to
arrive on-time (example: 75%, 85%, 95%).
4. User selects the day(s) of the week.
5. User selects the time period.
Results:
A map of the route with the lowest travel time for the selected threshold.
The route’s average travel time, selected percentile travel time, and buffer time corresponding with that percentile travel time.
An option to view the average travel times and percentile travel times of alternate routes.
Spatial Aggregation: Origin-Destination Pair
Metrics:
Buffer Time
Percentile Travel Time
Average Travel Time
April 8, 2010 SHRP2 L02 23
Data Needs
Travel Time Input
Fre
e-F
low
Med
ian
95th
Per
centi
le
Def
ined
Per
centi
le
Max
imum
Curr
ent
Aver
age
Traveler Freight Mover
T1 T2 T3 T4 T5 T6 T6 F1 F2 F3 F4 F5 F6 F7
Tra
vel
Tim
e M
etri
c
Planning Time X O-D O-D R R O-D O-D O-D O-D R O-D O-D O-D
Planning Time Index X X
Buffer Time X X O-D R R
Buffer Index X X
Travel Time Index X X
Average Travel Time X X O-D O-D O-D O-D R O-D O-D O-D O-D O-D
Percentile Travel Time X O-D
Maximum Travel Time X R
Current Travel Time X R
Free-Flow Travel Time X
Conges
tion S
ourc
e
All Combined X X X X X X X X X X X X X
Incidents
X
Weather X
Construction
X
Special Events X
Traffic Control
Fluctuations in Demand
Inadequate Capacity
Example for travelers and freight movers
R= Travel Time Metric aggregated to Route
O-D = Travel Time Metric for Origin-Destination Pair
April 8, 2010 SHRP2 L02 24
Data Sources
April 8, 2010 SHRP2 L02 25
AV
I S
en
so
rs in
Ho
us
ton
April 8, 2010 SHRP2 L02 26
Data Issues
• Traffic data collection (infrastructure, vehicle, private)
• Other data/sources (incidents, weather, other)
• Storage
• Validation (infrastructure, vehicle)
• Imputation
• Computation
• Assembly (routes, corridors, areas, etc.)
• Causal analyses
– Incidents, weather, construction, special events, traffic control,
fluctuations in demand, inadequate base capacity
April 8, 2010 SHRP2 L02 27
Report Generation
April 8, 2010 SHRP2 L02 28
April 8, 2010 SHRP2 L02 29
Mo
nth
ly T
rav
el C
on
dit
ion
s
April 8, 2010 SHRP2 L02 30
April 8, 2010 SHRP2 L02 31
System Integration
Mobile Communications
Remote Traveler Support
Traffic Management
Emergency Management
Commercial Vehicle
Administration
Maintenance & Construction Management
Transit Management
Fleet & Freight
Management
Archived Data Management
Vehicle
Emergency Vehicle
Commercial Vehicle
Transit Vehicle
Maintenance & Construction
Vehicle
Roadway
Security Monitoring
Toll Collection
Parking Management
Commercial Vehicle CheckVehicles Field
Travelers Centers
Travel Time Reliability Monitoring
Emissions Management
Toll Administration
Fixed Point-Fixed Point Communications
Information Service Provider
Personal Information
Access
Mobile Communications
Remote Traveler Support
Traffic Management
Emergency Management
Commercial Vehicle
Administration
Maintenance & Construction Management
Transit Management
Fleet & Freight
Management
Archived Data Management
Vehicle
Emergency Vehicle
Commercial Vehicle
Transit Vehicle
Maintenance & Construction
Vehicle
Roadway
Security Monitoring
Toll Collection
Parking Management
Commercial Vehicle CheckVehicles Field
Travelers Centers
Travel Time Reliability Monitoring
Emissions Management
Toll Administration
Fixed Point-Fixed Point Communications
Information Service Provider
Personal Information
Access
April 8, 2010 SHRP2 L02 32
Questions / Thank you
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