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Effectiveness of Disseminating Traveler Information on Travel Time Reliability: Implement Plan and Survey Results Report

CHAPTER 6. WEST AND NORTH HOUSTON TRANSPORTATION STUDY

The following sections describe in detail the various recruiting rounds of study in Houston.

STUDY SITE DEPLOYMENT TIMELINE

As previously discussed, several rounds of data collection were conducted in Houston (i.e., Rounds 1 and 2 in West Houston, and Round 3 in North Houston). The following sections provide an overview of the recruitment and participation timeline for each round.

West Houston, Round 1

Invitation postcards were sent to potential participants in the Houston area on April 3, 2015. The baseline survey was opened on April 6. Qualifying participants were notified by email on April 17, invited to download the smartphone application, and given instructions for recording trips and completing trip diary questions. Phase 1 of the travel study began on April 22. On May 6, Phase 1 participants who had completed at least three recorded trips were invited to continue to Phase 2. Phase 2 concluded on May 24, and participants who had completed at least four trips during Phase 2 were invited on May 27 to take the exit survey. Incentives were distributed by email on June 8 to participants who had completed all steps of the study. Table 7 illustrates the timeline for Round 1 of the West Houston Transportation Study.

Table 7. Timeline of activities for Round 1 of the West Houston Transportation Study.
West Houston (Texas) Transportation Study Weekly Timeline of Activities (Date)
April 2015 May 2015 June 2015
Recruitment postcards mailed 3rdgray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell
Potential participants begin taking baseline survey Empty cell 6thgray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell
Reminder postcards mailed Empty cell 7thgray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell
Participants assigned to treatment groups Empty cell Empty cell 16thgray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell
Phase 1 "Welcome" email sent Empty cell Empty cell 17thgray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell
West Houston Phase 1 Empty cell Empty cell Empty cell 22ndgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell
West Houston Phase 1 reminder email sent Empty cell Empty cell Empty cell Empty cell 29thgray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell
Phase 2 "Welcome" email sent Empty cell Empty cell Empty cell Empty cell Empty cell 6thgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period Empty cell Empty cell Empty cell
West Houston Phase 2 Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell 13thgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period Empty cell Empty cell
Exit survey invitation sent Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell 27thgray shaded cell: activity took place during this period Empty cell Empty cell
Exit survey reminder sent Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell 1stgray shaded cell: activity took place during this period Empty cell
Incentive distribution Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell 8thgray shaded cell: activity took place during this period

West Houston, Round 2

The second round of the West Houston Transportation Study targeted participants who had completed the baseline survey in Round 1 but had not proceeded to Phase 1. The intent was to encourage participants who had invested a nominal amount of time in the study to continue forward into the next phase; additionally, inviting participants who had already been recruited was expected to be a low-cost way to encourage additional completions. Directed email messages were sent to the participants to encourage participation. Table 8 illustrates the timeline for Round 2 of the West Houston Transportation Study.

Table 8. Timeline of activities for Round 2 of the West Houston Transportation Study.
West Houston (Texas) Round 2 Weekly Timeline of Activities (Date)
June 2015 July 2015 August 2015
West Houston Round 2 Phase 1 30thgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell
Phase 2 "Welcome" email sent Empty cell Empty cell 15thgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell
West Houston Round 2 Phase 2 Empty cell Empty cell 15thgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period Empty cell Empty cell
Exit survey invitation sent Empty cell Empty cell Empty cell Empty cell Empty cell 3rdgray shaded cell: activity took place during this period Empty cell Empty cell
Exit survey reminder sent Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell 10thgray shaded cell: activity took place during this period Empty cell
Incentive distribution Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell 17thgray shaded cell: activity took place during this period

North Houston, Round 3

A third round of subject recruitment and site deployment in Houston was initiated to continue to increase participation to reach the target subject number. The study corridor was changed to IH-45 north from downtown Houston to Conroe. The study team thought that the likely subject pool had been exhausted for the Katy freeway corridor, thus the shift to a different corridor. The IH-45 north corridor is similar to the Katy Freeway corridor in that the travel time reliability was readily available and the interstate freeway has a tolled alternative for a considerable length of the corridor. Recruitment efforts began in September 2015, and participants were invited to the baseline survey beginning October 5. Following baseline completion, participants were invited to Phase 1 in weekly batches. Batching participants was more efficient for administration and smartphone application activation efforts, while still allowing recruitment to continue. It also allowed the first participants to begin Phase 1 soon after enrollment without waiting until all potential participants had finished. Similarly, participants began and completed Phase 2 and the exit survey in batches. Table 9 illustrates the timeline for Round 3 of data collection in Houston.

Table 9. Timeline of activities for Round 3 of the North Houston Transportation Study.
North Houston (Texas) Round 3 Weekly Timeline of Activities (Date)
October 2015 November 2015 December 2015 January 2016
Outreach recruitment & prescreening 3rdgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell
Baseline survey 5thgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell
North Houston Round 2 Phase 1 Empty cell Empty cell Empty cell 26thgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period Empty cell Empty cell Empty cell Empty cell Empty cell
North Houston Round 2 Phase 2 Empty cell Empty cell Empty cell Empty cell Empty cell 10thgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period Empty cell Empty cell
Exit survey Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell 24thgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period
Incentive distribution Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell Empty cell 14thgray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period gray shaded cell: activity took place during this period

PARTICIPANT SELECTION AND ASSIGNMENT

The following sections provide a summary of the participation recruitment, selection, and assignment for the Houston study.

West Houston, Round 1

For West Houston, the study area was defined as the Katy Freeway (I-10) and Westpark Tollway between Grand Parkway in Katy, Texas, and downtown Houston. As shown in the map and table on the following pages, the geographic sample frame included twenty-two zip code areas adjacent to and between the Katy Freeway and Westpark Tollway, and between Katy (just west of Grand Parkway) and the western segment of I-610 (the West Loop Freeway). Zip codes inside the West Loop Freeway were not included because it was assumed that residents closer to downtown were less likely to regularly drive on a significant portion of either freeway, particularly in the direction with the most frequent congestion (inbound towards downtown in the morning, outbound away from downtown in the evening).

A sample of 35,800 addresses (approximately 10 percent of the addresses in the selected area) was randomly selected, proportional to the population across the entire area. As previously discussed, this quantity of invitations was determined based on initial predictions about response rates and retention rates throughout the study. The sample included all types of residential mailing addresses (single-family houses, apartments, post office boxes, etc.), but excluded "seasonal and vacant" addresses. A list of the zip codes used for the invitations is provided in Table 10, while a map illustrating the locations of these zip codes in the region is shown in Figure 25. Recruitment materials used to collect participants for West Houston are provided in Appendix P.

Table 10. Houston sample zip codes.
Zip Code Estimated Number of Households Percent
77094 2,890 0.8
77493 7,090 1.9
77043 7,830 2.1
77407 9,076 2.5
77056 9,288 2.5
77079 11,891 3.3
77055 14,255 3.9
77024 14,275 3.9
77080 14,993 4.1
77081 15,460 4.2
77042 16,838 4.6
77072 16,915 4.6
77063 17,527 4.8
77082 19,124 5.2
77057 19,708 5.4
77083 19,976 5.5
77494 20,042 5.5
77036 22,890 6.3
77450 23,249 6.4
77077 23,644 6.5
77449 26,855 7.4
77084 31,310 8.6
Total 365,126 100

Figure 25. This figure shows a map of the zip codes within the West Houston Transportation Study region. They are color-coded (i.e., degree of darkness) to signify population counts.

Figure 25. Map. Houston sample zip codes geography.

West Houston, Round 2

In Round 2, participants who had been invited to participate in Round 1 but had not participated at that time were re-invited. In an attempt to address potential privacy concerns of participants, Round 2 eliminated the phone application requirement, providing a website-based alternative for logging information about trips. The information collected with the website-based alternative was identical to that for the phone application and did not impact the accuracy nor amount of the data collected.

North Houston, Round 3

Participants were recruited in a variety of ways, including postings on the Texas A&M Transportation Institute (TTI) website and TTI social media channels, a link on the Houston TranStar® website, and posting of flyers at community college campuses in the corridor. These additional recruiting notifications are included in Appendix Q.

BASELINE SURVEY RESULTS

Table 11 through Table 16 summarize the results of the baseline survey for the Houston area for all three rounds. Note that all tables include only valid responses, and do not include any responses from participants who were screened out due to infrequent corridor use or lack of a smartphone. Some tables include fewer than 100 percent of qualified participants if the question was skipped by certain participants (for example, participants who reported "never" using the Travel Time Reliability [TTR] information resources in Phase 2 skipped questions about TTR information ratings and satisfaction and instead were asked why they did not use the information). The total number of baseline responses provided in each round in Houston are shown in Table 11.

Table 11. Number of baseline completions by round, Houston.
Data Collection Round Count Percent
Rounds 1 & 2 (Spring/Summer 2015)4* 623 68.8
Round 3 (Fall 2015) 282 31.2
Total Baseline Participants 905 100

4*Rounds 1 & 2 in West Houston completed the baseline at the same time. [Return to 4*]

Table 12 and Table 13 summarize how often participants reported typically driving on the main freeway and tollway, respectively, in the study corridor. The majority of participants drive more frequently on the freeway than they do the tollway (note that all participants were asked about their travel behavior on both facilities, and therefore each person reported on travel frequency in the study corridor twice (once for each road).

Table 12. Number of weekdays typically driven on primary freeway (Katy Freeway or North Freeway) in study area, Houston.
Number of Weekdays Typically Driven on Primary Freeway in Study Area5* Count Percent
5 weekdays/week 584 64.5
4 weekdays/week 98 10.8
3 weekdays/week 113 12.5
2 weekdays/week 30 3.3
1 weekday/week 21 2.3
Weekends only 27 3.0
Less than weekly 27 3.0
Never* 5 0.6
Total Baseline Participants 905 100

5* Participants who traveled less than 3 days/week on the primary freeway were required to travel at least three days/week on the tollway to qualify. [Return to 5*]


Table 13. Number of weekdays typically driven on parallel tollway (Westpark Tollway or Hardy Tollway) in study area, Houston.
Number of Weekdays Typically Driven on Parallel Tollway in Study Area6* Count Percent
5 weekdays/week 172 19.0
4 weekdays/week 50 5.5
3 weekdays/week 74 8.2
2 weekdays/week 76 8.4
1 weekday/week 70 7.7
Weekends only 47 5.2
Less than weekly 281 31.0
Never 135 14.9
Total Baseline Participants 905 100

6* Participants who traveled less than 3 days/week on the tollway were required to travel at least three days/week on the primary freeway to qualify. [Return to 6*]

Table 14 summarizes the age groups of participants who completed the baseline survey. The majority were between 25 and 55 years old, which is expected given the requirements of the study (regular highway users and smartphone owners).

Table 14. Respondent age, Houston.
Respondent Age Count Percent
18-24 34 3.8
25-34 243 26.9
35-44 247 27.3
45-54 192 21.2
55-64 134 14.8
65-74 46 5.1
75-84 8 0.9
85 or older 1 0.1
Total Baseline Participants 905 100

Table 15 summarizes participants' baseline use of informational sources (prior to being provided the TTR information). Given that participants were required to use smartphones in the study, it is not surprising that a large majority of them already used apps on a regular basis.

Table 15. Types of information sources used at least one day per week, Houston.
Types of Information Sources7* For Familiar Trips: Count For Familiar Trips: Percent For Unfamiliar Trips: Count For Unfamiliar Trips: Percent
Websites 491 54.3 433 47.8
Smartphone apps 670 74.0 579 64.0
Telephone numbers8* 102 11.3 80 8.8
TV 326 36.0 177 19.6
Radio 479 52.9 273 30.2
Built-in GPS device 144 15.9 140 15.5
Portable GPS device 100 11.0 105 11.6
Other sources 31 3.4 30 3.3
Total Baseline Participants 905 -- 905 --

7* Participants could report using multiple sources. [Return to 7*]
8* Generalized question about telephone information use; may or may not include existing 511 services
where applicable or other local services (e.g., a state or city toll-free information number). [Return to 8*]

Table 16 summarizes participants' baseline tendencies for behavioral change; specifically, participants were asked how often they made different kinds of changes to their travel plans based on traveler information that they used. Almost all participants change their routes or start their trips earlier at least some of the time, but fewer reported starting later or canceling their trips, and only a very small percentage reported switching to transit.

Table 16. Types of travel behavior changes made "sometimes" or "frequently" due to traveler information, Houston.
Types of Travel Changes9* For Familiar Trips: Count For Familiar Trips: Percent For Unfamiliar Trips: Count For Unfamiliar Trips: Percent
Start trip earlier 838 94.1 823 92.2
Start trip later 583 65.4 559 62.6
Make minor route changes 849 95.3 819 91.7
Change to toll road 741 83.2 730 81.7
Completely change route 695 78.0 683 76.5
Change to public transit 75 8.4 60 6.7
Cancel or postpone trip 335 37.6 360 40.3
Telecommute 177 19.9 96 10.8
Total participants answering 891 -- 893 --

9* Participants could report multiple changes; some participants skipped these questions because they "never" used traveler information. [Return to 9*]

EXIT SURVEY RESULTS

Table 17 through Table 20 summarize the results of the exit survey in Houston for all rounds of data collection. The total number of exit survey responses collected in each round in Houston are shown in Table 17.

Table 17. Number of exit responses by round, Houston.
Data Collection Round Count Percent
Round 1 (Spring 2015) 107 27.6
Round 2 (Summer 2015) 27 7.0
Round 3 (Fall 2015) 253 65.4
Total Exit Participants 387 100

Table 18 summarizes the proportion of participants assigned to each treatment group. As previously noted, prior to Phase 1 the study team assigned participants to treatment groups of approximately equal sizes. This distribution remained roughly equal through the end of the study.

Table 18. Exit responses by treatment group, Houston.
Treatment Group Count Percent
Web, Lexicon A 58 15.0
Web, Lexicon B 69 17.8
App, Lexicon A 67 17.3
App, Lexicon B 63 16.3
511, Lexicon A 64 16.5
511, Lexicon B 66 17.1
Total Exit Participants 387 100

Table 19 and Table 20 summarize some of the participant perceptions towards the TTR information that was provided to them during the study. Approximately two thirds of participants felt that it was clear and easy to understand, and a little more than half felt that it was reliable. Similarly, about a half of participants reported feeling satisfied with the information they were provided. As previously discussed, the exit survey measured participant perceptions of their activities, information use, and information satisfaction during Phase 2, rather than objectively observed behaviors or outcomes. The questions included attitudinal statements designed to measure participants' satisfaction with various aspects of the TTR information, as shown in the tables below.

Table 19. Travel time reliability information ratings ("somewhat agreed", "agreed", or "strongly agreed"), Houston.
TTR Ratings Statement10* Count Percent
The Transportation Study Resource was easy to understand 217 67.4
The Transportation Study Resource was reliable 181 56.2
Transportation Study Resource did NOT reduce the amount of travel time I plan for my trips 227 70.5
Overall, the Transportation Study Resource was useful 160 49.7
The Transportation Study Resource helped me reduce my travel time 77 23.9
The Transportation Study Resource helped me avoid congestion 101 31.4
The Transportation Study Resource reduced the stress of my trip 77 23.9
The Transportation Study Resource helped me plan my trips 124 38.5
Total participants answering 322 --

10* Participants could agree with multiple statements; some participants skipped these questions because they "never" used TTR information. [Return to 10*]


Table 20. Travel time reliability lexicon satisfaction ("somewhat satisfied", "satisfied", or "very satisfied"), Houston.
TTR Lexicon Category11* Count Percent
Estimated/approximate travel time 174 54.0
Extra time/recommended cushion 159 49.4
Recommended/suggested departure time 157 48.8
Total travel time estimate for most/majority of the time 165 51.2
Total participants answering 322 --

11* Participants could agree with multiple statements; some participants skipped these questions because they "never" used TTR information. [Return to 11*]

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