Disseminating Traveler Information on Travel Time Reliability
CHAPTER 5. FINAL REMARKS
The field study was beneficial in better refining the information originally developed as part of the Strategic Highway Research Program 2 (SHRP2) L14 research project. However, only one survey question resulted in statistically significant differences between the Lexicon terminologies. Overall, the particular Lexicon terminologies tested performed similarly. The biggest finding of the field study was that dissemination of Travel Time Reliability (TTR) information via the 511 information channel was less preferred than via the Web or App access channels. In a few instances, the App access demonstrated superior responses over both the Web and 511 access.
However, some questions remain unanswered regarding the dissemination of TTR information to travelers across a broad spectrum of delivery platforms. These limitations are discussed below.
WEBSITE / MOBILE APPLICATION DESIGN
The research study assessed the use of the Lexicon in three different dissemination platforms: website, mobile web application, and 511. In all three cases, the information presented was identical across all three platforms. However, the actual user interface of the website and mobile web application was not assessed. User interface best practices should be utilized to develop a website and mobile application that will be easy to use and minimize access time.
GRAPHICAL MESSAGES
Two graphical formats were tested in the original SHRP2 L14 study as alternatives for presenting reliability information to drivers. These two formats were rated by participants as being "more complex" and therefore less easy to use than the same information presented in a text format. However, other graphical formats may prove useful as alternative or supplemental methods for communicating reliability information to drivers. These graphical formats were not tested in this study, so further research is still necessary to assess the potential usefulness and usability of "star" ratings, Harvey Balls, and other graphical formats for conveying reliability information.
AUDITORY MESSAGES
While the research study assessed the use of the Lexicon in a 511 auditory platform, it did not test auditory messages in the vehicle. Auditory messages were included as one format for communicating reliability messages in the original SHRP2 L14 project, but future research should further examine auditory options for both message delivery and, potentially, verbal inputs by system users.
DYNAMIC MESSAGE SIGN MESSAGES
As indicated in the Lexicon tables, sample messages for Dynamic Message Signs (DMSs) are provided. It is important to note that the studies conducted in SHRP2 L14 and in this project did not test these phrases as being displayed on a DMS and as en-route information. Those phrases suggested for display on DMSs were developed by the original SHRP2 L14 research team based on the results discussed for the related terminologies.(3) The team developed these phrases using the general guidance for DMS message development provided in the Manual on Uniform Traffic Control Devices. It is important to note that the formatting of these TTR messages is very different from the standard messages used by state transportation agencies on DMSs. For many of the TTR terms, their use on a DMS would present various challenges to the traveler including:
- Drivers are conditioned to see real-time travel information displayed on DMSs on freeway corridors, and reliability information may confuse them when placed on a DMS.
- Any reliability information displayed on a DMS would need to be relative to the specific location of the sign on the freeway facility, as drivers would have begun their trips from various locations in the region's transportation network.
- Messages providing departure time or buffer time information are not appropriate for DMSs since travelers would need to see these messages prior to starting their trip, not en-route.(3)
