View
241
Download
1
Category
Tags:
Preview:
DESCRIPTION
AITPM presentation
Citation preview
Value of Time of Carshare Users in SydneyRevealed Preference Study of GPS Data
Dr. V.V. Dixit | John Trieu | Sisi Jian | Xun Li
2
Introduction – Why Study Value of Time?
• Economic cost of congestion– $3.9 billion to Sydney in 2005
(BITRE, 2007)
3
This Study – Value of Time in Sydney
• Goal– Value of time for motorists in Sydney
• Why?– Important consideration in Congestion Charging
schemes– Important input to Cost-Benefit Analysis of
transport projects• Economic “benefit” of travel time savings
• How?– Revealed preference study of GPS data– Data provided by carshare program in Sydney
4
Value of Travel Time Savings (1)
• Value of Time– Not directly measurable– Minimum travel time, regardless of mode and
route
5
Value of Travel Time Savings (2)
• Need to consider the “Value of Travel Time Savings”
6
What is a Revealed Preference study?
• Collection of raw data (e.g. GPS logs)• Convert data to trips• Determine relationships between trip
decisions and factors influencing choices
• The preferences of drivers are “Revealed”– Preferences are not explicitly “Stated” by drivers
7
Past Studies
• Different locations = Different characteristics– Los Angeles– Brisbane
• Stated Preference = Controlled Experiment(Hensher, Greene and Li, 2011)– Artificial environment
8
Delineating Trips – Overview
• GPS Logs = Data Points– Need trips
• Trip Identification – Trip Ends– (1) Time between GPS data points– (2) Time with zero movement– (3) Significant changes in direction
9
Delineating Trips – (1) Time between GPS data points
• Large amount of time (e.g. 2 Days)– Trip has ended
• Cut-off = 20 minutes– Timeout of in-car GPS units
10
Delineating Trips – (2) Time with zero movement
• Based upon maximum signal cycle time in Sydney – 150 seconds during peak periods
11
Delineating Trips – (3) Significant changes in direction
• U-turns• Turns greater than 90 degrees– Sensitivity testing undertaken on the
change in heading– No change in number of trips identified
12
This Study
• Focal Point– Toll Road versus Untolled Alternative– Can isolate value of time• Explicit cost for toll road• Stochastic travel time saving
13
Study Area (1) – M2 vs Epping Road
14
Study Area (2) – M4 vs Parramatta Road
• Used as a “control” for the study– Equivalent to “no treatment” scenario in
experiments
15
This Study
• Other variables / covariates– Age / Experience– Preferred Travel Mode– Car Ownership
16
Modelling – Value of Expected Travel Time Savings
• Regression Modelling– Binary Logit Model
Choice of Motorway or Arterial• Value of Expected Travel Time Savings (VETTS)– $9.63 / hour
• Comparison VETTS– Los Angeles, USA: $21.46 / hour– Brisbane, Australia: $17.60 / hour
17
Modelling – Value of Expected Travel Time Savings
• Value of Expected Travel Time Savings (VETTS)– $9.63 / hour
• VETTS result is more than 50% less than in other cities
• Reason for difference– VETTS identified is specific to Carshare Users– Carshare Users are suspected of having lower
VETTS compared to average motorist• Cannot be used as a representative sample group
18
Further Studies
• Risk aversion– Travel times are stochastic– Need to include risk parameter• Model including risk parameter is ongoing
– Risk models considered:• Constant Absolute Risk Aversion (CARA)• Constant Relative Risk Aversion (CRRA)
• Ongoing / Not yet finalised
19
Questions?
Recommended