Travel Time Reliability Study - TTAC - Hampton Roads• Travel time reliability is defined as how...
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HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY Presented by: Keith Nichols, PE Transportation Technical Advisory Committee Meeting Agenda Item #14 June 5, 2013
Transcript of Travel Time Reliability Study - TTAC - Hampton Roads• Travel time reliability is defined as how...
HAMPTON ROADS
REGIONAL
TRAVEL TIME
RELIABILITY STUDY
Presented by:
Keith Nichols, PETransportation Technical Advisory Committee MeetingAgenda Item #14June 5, 2013
• HRTPO staff has analyzed congestion in Hampton Roads through various efforts.
INTRODUCTION
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 2
• However, average congestion levels don’t tell the whole story.
INTRODUCTION
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 3
Eastbound Hampton Roads Bridge-Tunnel Approach4:30 pm, Monday 4/1/13 (left) and Tuesday 4/2/13 (right)Source: VDOT.
• Travel time reliability is defined as how much travel times vary from day to day over the course of time.
• Since the level of consistency and dependability in travel times is important for so many roadway users, analyzing both typical congestion levels and travel time reliability are important.
TRAVEL TIME RELIABILITY
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 4
Free-Flow Travel Time = 11.5 minutes
DELAY AND TRAVEL TIME RELIABILITY TERMS
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 5
VDOT
Distribution of Trips by Travel Time
Average Travel Time = 15.9 minutes 95th percentile Travel Time = 22.7 minutes
Image source: FHWA.
DELAY AND TRAVEL TIME RELIABILITY TERMS
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 6
VDOT
Travel Time Index
Travel Time Index = Average Travel Time / Free-Flow Travel Time
= 15.9 minutes / 11.5 minutes
= 1.38
Index used to describe typical congestion levels by comparing average travel conditions during a particular time of day with free-flow conditions.
DELAY AND TRAVEL TIME RELIABILITY TERMS
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 7
VDOT
Buffer Time
Buffer Time = 95th percentile Travel Time - Average Travel Time
= 22.7 minutes - 15.9 minutes
= 6.8 minutes
Measure used to describe the extra time that travelers must add to their average travel time to ensure they will arrive on-time 95% of the time.
DELAY AND TRAVEL TIME RELIABILITY TERMS
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 8
VDOT
Buffer Index
Buffer Index = Buffer Time / Average Travel Time
= 6.8 minutes / 15.9 minutes
= 0.43
Index used to measure travel time reliability relative to average conditions, and compare the reliability of various roadways.
DELAY AND TRAVEL TIME RELIABILITY TERMS
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 9
VDOT
Planning Time
Planning Time = 95th percentile Travel Time
= 22.7 minutes
Measure that includes boththe average travel time and the buffer time to measure the total amount of time that travelers must budget to ensure they will arrive on-time 95% of the time.
DELAY AND TRAVEL TIME RELIABILITY TERMS
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 10
VDOT
Planning Time Index
Planning Time Index = Planning Time / Free-flow Travel Time
= 22.7 minutes / 11.5 minutes
= 1.97
Index used to measure congestion and reliability by comparing travel times during some of the most congested conditions with free-flow conditions.
• New technologies have been created in recent years that collect travel time and speed data on a continuous basis, allowing for the calculation of travel time reliability measures.
• Using INRIX data, HRTPO staff was able to determine 2012 weekday AM and PM Peak Period buffer indices and planning time indices for most CMP roadways in Hampton Roads.
TRAVEL TIME RELIABILITY
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 11
BUFFER INDEX – PM PEAK PERIOD
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 12
VDOT
BUFFER INDEX – PM PEAK PERIOD
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 13
VDOT
PLANNING TIME INDEX – PM PEAK PERIOD
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 14
VDOT
PLANNING TIME INDEX – PM PEAK PERIOD
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 15
VDOT
• Incorporate travel time reliability data into the Project Prioritization Process.
• Incorporate this data into the Congestion Management Process.
NEXT STEPS
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 16
• The draft version of the “Hampton Roads Regional Travel Time Reliability Study” will be open for public review until June 19th.
• Approval of the final document is expected at the July TTAC and TPO Board meetings.
DRAFT REPORT
HAMPTON ROADS REGIONAL TRAVEL TIME RELIABILITY STUDY 17
HAMPTON ROADS
REGIONAL
TRAVEL TIME
RELIABILITY STUDY
Presented by:
Keith Nichols, PETransportation Technical Advisory Committee MeetingAgenda Item #14June 5, 2013
