Effectiveness of Different Approaches to Disseminating Traveler Information on Travel Time Reliability (2013) / Chapter Skim
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49 C H a P T e r 7 The usability portion of this project ultimately consisted of three research activities: a multiple-choice survey conducted on a laptop computer, an open-ended survey, and a computerbased experiment intended to simulate daily trips. Each research activity produced different types of data that were analyzed separately and, where applicable, in comparison with one another.
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50 • An open-ended survey was added to further clarify comprehension of and preferences for various terms. • Questions were included in the computer-based survey and in the open-ended survey to elicit more potential lexicon terms.
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51 • Texas DOT TransGuide, San Antonio; • 511 Travel Info, San Francisco; • San Diego Transportation, California; • Washington State DOT; • FlightStats; and • FlightCaster. The website reviews examined the formats of the home page or the primary traffic information page, the labeling of any links or buttons and banners for accessing information about historical travel time information, the mechanism and labeling for trip information input by the user, and the format and terminology used for the output information.
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52 image, including the option to look back and forth between the image and the on-screen question. Paper Prototyping of Web Page Examples Used in Survey A human factor usability research technique called paper prototyping was used to develop the simulated websites displayed during the survey.
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53 Research Method Participant Demographics Researchers surveyed a total of 300 participants. Each person was asked the following demographic and driving questions: • Gender; • Age; • Education; • How often participant drove on freeways on weekdays between 6 a.m.
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54 be an indication that those people misunderstood that the question was asking about additional travel time above the average and instead answered by choosing the category representing their total trip time. Experimental Design and Procedure The survey was developed using the survey software SuperLab.
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55 Each question featured a different underlined term and asked participants to choose which of the four described trips the term best described: • Question 1: Whose trip is the most reliable? • Question 2: Whose trip is the most predictable?
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56 the preliminary demographics questions. This figure shows predictable travel times are more important for those with inflexible work start times than they are for those with more flexible work schedules.
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57 Question 6 asked "If you click on the Current Trip button, what do you think you'll get? " Response options for this question were as follows: • It will take me to a webpage that will allow me to enter information about a trip I want to take right now.
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58 would be getting information about a trip they were about to take at that moment. And there were 9% who responded that "the website does not know what day or time it is." These three questions taken together offer different ways to assess drivers' understanding of the real-time nature of a website such as this.
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59 • The website will tell me how long my trip will take for the date/time I enter. • The website will show me if there are any accidents or construction on my trip right now.
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60 • Get trip; • Submit; • GO; and • OK. As seen in Table 7.11, the most frequently selected terms were predict trip (28%)
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61 Planner site. They were then presented with the following information: This page in the binder shows the map of the Forest City area.
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62 projected trip times and the variability of those times. The research team used many of those terms as answer options in Questions 15 through 28.
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63 convey the opposite. If the worst-case travel time is reported as 25 min, then the trip will nearly always take less than 25 min.
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64 by some researchers as an index and by others as an actual time representing the sum of some central tendency or freeflow condition plus some buffer time. Question 19 asked about terms that could be used for buffer time, which FHWA defines as the extra time, or time cushion, that travelers add to their average travel time.
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65 Comparison of the results for all versions of Question 19 are shown in Table 7.15 and in Figure 7.5. Regardless of the term used, a majority of participants chose to leave earlier than the departure time provided by the fictional website.
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66 preferred that term over the alternatives. Across all versions, recommended departure time received most of the shifts in preference: 40% to 45% of people preferred the term to the one they saw in their own version of the survey.
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67 would like the worst case to be presented, and they would make adjustments on the basis of their individual risk tolerance. Questions 24–26: Travel Time Variability Terminology Questions 24 through 26 explored additional terms and phrases that could be used to express travel time variability.
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68 modifier specifying that the trip time could be less than the 95th percentile time was not mentioned) : • It is 95% reliable that your travel time will be 45 minutes.
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69 of participants selected it -- which is troubling. Because 95th percentile is such a critical and common performance metric for reliability calculations, travel information designers and providers need to be sensitive to this finding.
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70 • For output screens, the term best route was preferred as a map title or output section header (Question 14)
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