Effectiveness of Different Approaches to Disseminating Traveler Information on Travel Time Reliability (2013) / Chapter Skim
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Pages 132-145
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From page 132... ...
132 The measurement of travel time reliability is an emerging practice. However, a few measures appear to have technical merit and are easily understood by nontechnical audiences.
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133 terms that the transportation profession uses to describe the travel time reliability of a transportation system. The initial list, shown in Table 11.1, was drawn primarily from the FHWA Travel Time Reliability information brochure (Texas A&M Transportation Institute with Cambridge Systematics, Inc.
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From page 134... ...
134 trip time or worst-case scenario rather than the 95th percentile time that was intended. Arrival Time Alternate terms for arrival time -- the time that a traveler arrives at his or her destination after a trip -- were not tested because the phrase is commonly used.
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135 • Cushion; • Departure window; • Extra time; • Leeway; and • Recommended cushion. Of the tested terms, extra time was preferred by the most participants in the computer survey, followed by departure window; in the open-ended survey, recommended cushion, added time, and extra time all performed well.
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From page 136... ...
136 Of the tested terms, recommended departure time was preferred most frequently by survey participants, followed by suggested departure time and estimated departure time; 95th percentile departure time was the least preferred. Recommended Route A recommended route in the context of travel time reliability is defined as the route between two points calculated by a traveler information system that would ensure an on-time arrival for a given level of risk tolerance.
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137 planning websites that were reviewed during focus group preparation and survey development often indicated trend information graphically (if they indicated it at all)
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138 the related terminologies. The team developed these phrases using the general guidance for DMS message development provided in the Manual on Uniform Traffic Control Devices (MUTCD)
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139 Table 11.3. Travel Time Reliability Lexicon for 95th Percentile Technical Term 95th Percentile Definition The point on a travel time frequency distribution at which 95% of the trips made would be arrive at or less than the identified time Usage To describe the longest time a driver can expect a trip to take Recommendation Alternate Phrase Wording Context/Additional Information Information Technology Platforms Web Mobile Web Text Mobile Application Dynamic Message Sign Best Majority of the time "The majority of the time, your trip will take X minutes or less." 3 3 3a 3a X MAJORITY OF TIME TRIP TO [DESTINATION]
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From page 140... ...
140 Table 11.4. Travel Time Reliability Lexicon for Arrival Time Technical Term Arrival Time Definition The time at which a traveler would arrive after a trip Usage To tell the driver when he/she can expect to arrive at his/her destination Recommendation Alternate Phrase Wording Context/Additional Information Information Technology Platforms Web Mobile Web Text Mobile Application Dynamic Message Sign Best Arrive by "Arrive by X:XX a.m./p.m." 3 3 3 3 X ARRIVE BY X:XX AM/PM 3 3 3 3 3a,b Adequate Arrive at "Arrive at X:XX a.m./p.m." 3 3 3 3 X ARRIVE AT X:XX AM/PM 3 3 3 3 3a,b What time do you want to get there?
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141 Table 11.5. Travel Time Reliability Lexicon for Average Travel Time Technical Term Average Travel Time Definition An average of historical travel times calculated over a specified time interval for a specified trip or roadway segment Usage To describe the typical travel time a driver can expect a trip will take Recommendation Alternate Phrase Wording Context/Additional Information Information Technology Platforms Web Mobile Web Text Mobile Application Dynamic Message Sign Best Estimated travel time "Estimated travel time is X minutes." 3 3 3a 3a X "It is estimated that your trip will take X minutes." 3 3 3a 3a X EST THAT TRIP TO [DESTINATION]
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From page 142... ...
142 Table 11.6. Travel Time Reliability Lexicon for Buffer Time Technical Term Buffer Time Definition The average travel time multiplied by the buffer index Usage To describe how much extra time a driver should plan for a trip he/she wishes to take Recommendation Alternate Phrase Wording Context/Additional Information Information Technology Platforms Web Mobile Web Text Mobile Application Dynamic Message Sign Best Extra time "Extra time for trip is X minutes." 3 3 3a 3a X EXTRA TIME TO [DESTINATION]
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143 Table 11.8. Travel Time Reliability Lexicon for Recommended Departure Time Technical Term Recommended Departure Time Definition A time of departure calculated by a traveler information system that would ensure an on-time arrival for a given level of risk tolerance.
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144 Table 11.9. Travel Time Reliability Lexicon for Recommended Route Technical Term Recommended Route Definition A route between two points calculated by a traveler information system that would ensure an on-time arrival for a given level of risk tolerance Usage To describe the route a driver should take for a planned trip to ensure he/she arrives on time to his/her destination Recommendation Alternate Phrase Wording Context/Additional Information Information Technology Platforms Web Mobile Web Text Mobile Application Dynamic Message Sign Best Best route "Best route is via [facility]
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From page 145... ...
145 Table 11.10. Travel Time Reliability Lexicon for Reliability Technical Term Reliability Definition Consistency or dependability in travel times between two points, as measured from day to day or across different times of day Usage To describe the variability of travel times to drivers so they can plan their trip with more robust information Recommendation Alternate Phrase Wording Context/Additional Information Information Technology Platforms Web Mobile Web Text Mobile Application Dynamic Message Sign Best Predictable "Most predictable trip" 3 3 3 3 X Adequate Reliable "Most reliable trip" 3 3 3 3 X Consistent "Most consistent trip" 3 3 3 3 X Vary "Trip varies." 3 3 3 3 X Avoid Differ Preference shown for other terms na na na na na Fluctuate Change Go up or down Increase or decrease Deviate Note: 3 = suitable for this message; X = not recommended for this message; na = not applicable.
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