Effectiveness of Safety and Public Service Announcement Messages on Dynamic Message Signs

Chapter 1. Introduction

The number of transportation agencies that use DMS to provide traffic information to motorists has increased dramatically over the past four decades. According to the USDOT’s 2010 deployment survey, almost 90 percent of freeway agencies and approximately 20 percent of arterial agencies reported using DMS to disseminate traveler information. This growing trend of DMS deployment is a reflection of the public interest in more information about travel conditions and the importance of traveler information for transportation system operations.

Although extensive research has been conducted on traffic-related messages (see Dudek 1992; 1997; and 2006 for examples),[1] policies regarding the display and type of non-traffic-related messages vary greatly among states and, in some cases, are nonexistent. Therefore, it is unclear how effective these non-traffic-related messages are in modifying driver or travel behavior. It is also unclear whether these messages are acceptable to motorists and whether they have a positive or negative impact on their driving behavior (Tay and deBarros, 2010).[2]

The purpose of this study is to identify how safety and PSA messages influence driver behavior. The findings from the study will help the USDOT, Transportation Management Centers Pooled Fund Study (TMC PFS) members, and state agencies and local transportation partners identify and implement the necessary improvements and changes to DMS technologies and safety and PSA messaging strategies in order to better support the public’s travel and safety needs.

The effectiveness of the messages is based on two primary factors:

• Usefulness of the information disseminated.
• Motorists’ ability to understand and willingness to use the information.

The survey distributed to respondents did not define the terms “usefulness” or “effectiveness.” However, the survey was built under the assumption that most respondents spoke English and had an 8th grade education level. Therefore, it was assumed that a common interpretation in this context would be implied by all participants. Usefulness encompasses the practical and functional application of PSAs on DMS. Effectiveness is the perception that DMS would deliver safety and PSA messages such that a driver’s behavior would be positively impacted.

Four urban areas in the United States were selected as study sites—Chicago, IL; Houston, TX; Orlando, FL; and Philadelphia, PA. Surveys were designed to specifically address the types of safety and PSA messages for each respective city. The goal was to collect approximately 500 survey responses per city. In total, 2,088 responses were received.