Project Research Scope
Background Statement
The US Population is aging and Florida has one of the oldest state populations with about 18 percent over the age of 65. In some Florida counties 22 percent or greater of the population is 65+ years old. With the aging of the baby boomers, we face a growing challenge to design safer road and street environments for Florida’s citizens. For traffic control devices to function effectively they must be legible soon enough that the user can safely take appropriate action. That is, both perceptual (legibility) and cognitive (decision) factors can affect driver/pedestrian behavior. Usually, the relevant actions to be taken involve decisions about braking, stopping, accelerating, and lane changing for drivers, and the decision to enter and navigate an intersection for pedestrians. This research topic relies on human factors principles and methodologies which are critical to being able to fulfill the implementation of traffic control countermeasures outlined in the Department’s Safe Mobility for Life Program business plan.
In FY 06/07 the Department funded a human factors research project with Florida State University’s Department of Psychology where both field and lab studies were conducted at the Traffic Engineering Research Laboratory on Springhill Road. This proposed topic is a continuation of this project and will include the following human factors studies to assist the Department in making effective policy decisions, especially with respect to older drivers and pedestrians where national research is limited.
Task 1. Effective word order for message signs.
Informal observation and predictions from human factors frameworks about effective warnings (Wogalter & Laughery, 2006) suggest that word order can be critical in promoting rapid compliance. Informally, we have observed that a “left lane closed ahead” warning initially had people moving into the left lane! This task will investigate the most efficient wording patterns for message signs used to convey relevant actions and alerts for motorists. Currently, the MUTCD states that, for single phase messages, “the top line should present the problem, the center line should present the location or distance ahead, and the bottom line should present the recommended driver action” (§6F.55). However, various FHWA standard messages report an action, and then distance. This task will explore both message formats to ascertain which is more effective. Additionally, the information presentation of both Silver and Amber alerts will be assessed using the same layout designs. This study will be conducted as a lab study using computer displays to assess decision-making by drivers varying in age. Results of this task can be used to improve traffic flow and response, particularly for older drivers.
First, we will explore word messages for DMS and PCMS signs taking advantage of eye-tracking equipment here in the psychology department for a pilot study to provide detailed information about sign reading dynamics. Then we will conduct a laboratory study with 20 younger, middle-aged, and older drivers using both the current guidelines for information placement and the reverse ordering and probe driver comprehension of the action to be taken. Comprehension will be assessed from the driver’s accuracy and response time to questions about sign content.
Task 2. Role of headlight beam setting on sign perception by older drivers.
This task builds from a task in the previous project, the Intersection and Pedestrian Safety Research Project (BD543-17), comparing the use of fluorescent yellow vs. standard yellow sheeting on sign conspicuity for aging drivers. In that task, drivers were allowed to choose whether to use their headlights on low or high beam. The research demonstrated a trend of low beam superiority for fluorescent sheeting and high beam superiority for standard sheeting that requires a follow-up to the previous study before policy decisions can be made on the Department’s use of fluorescent yellow sheeting on warning signs.
We will conduct a field study with 20 younger, middle-aged, and older drivers. In this task, each participant will approach a target sign in their vehicle until they can verify (match) the identity of the sign as shown to them on a computer screen at the start of a trial. For half the trials the sign will match and for half it will be mismatched. Half the time the participants will approach signs using their high beams and half with their low beams activated. The variables of distance to sign at the time of judgment and the accuracy of judgment will be assessed. The stimuli will consist of a set of ten, 36 inch by 36 inch symbolic warning signs. The signs included will be as follows: speed zone ahead (W3-5), stop ahead (W3-1), yield ahead (W3-2), right lane ends (W4-2R), and signal ahead (W3-3). The 5 standard signs will use grade 7 retroreflective sheeting, while the 5 fluorescent signs will use grade 9 diamond retroreflective sheeting. This task will be conducted at the Broadmoor Estates area at 4745 Jackson Bluff Rd during evening hours.
Task 3. Efficacy of pedestal traffic signals.
Traffic Engineering and Operations staff have asked whether traffic signals could have significantly increased conspicuity by the addition of pedestal signals that are within the view of the driver as they approach and enter the intersection. In this task we propose to investigate such benefits by completing both lab and field studies contrasting typical signalized intersections with pedestal signals and examining comprehension accuracy and speed. We will conduct the field study at the TERL facility after completion of proposed facilities construction.
We will conduct both lab and field studies with 20 younger, middle-aged, and older drivers. We propose to pilot test using eye-tracking techniques to assess the areas of fixation of participants in pedestal and non-pedestal intersections for the lab study. In the lab task, participants will view images on a computer screen. For half of the images normal intersections will be shown, for the remaining half, augmented images of intersections will be shown with a pedestal traffic signal for left turning lanes. The variables,speed and accuracy of judgment, will be assessed. In the field task, participants will half of the time drive through an intersection without a pedestal traffic signal and half of the time with a pedestal traffic signal. The variables assessed will be accuracy of judgment and distance of judgment.
Internally illuminated street name signs have been proposed as a way to improve performance in night driving situations particularly for older adults. The goal of this task is to assess the size of the advantage for lighted versus reflective signs in order to assess cost-benefit functions. This study will assist in making good fiscal and environmental (green) decision making by both local and state governments when choosing sign types without compromising visibility. This task will be conducted as a field trial on the TERL facility at night after completion of proposed facilities construction. In addition to determining the size of any advantage of internally illuminated signs versus reflective signs, and if an advantage exists for LED lit signs versus fluorescent lit signs.
Twenty younger, middle-aged, and older drivers will be asked to approach the two sign types --illuminated, reflective -- to determine if the sign matches a target displayed on a computer screen. Depending on illuminated sign frame availability from FDOT, we will also examine the factor of type of illuminated lighting: fluorescent or LED. Street names will be chosen from the set used in our prior project. Half the time the sign will match and half mismatch. Driver distance to the sign at the time of decision making and their accuracy in decision making will be assessed.
Task 5. Effectiveness of Pedestrian Confirmation Button vs. no confirmation.
One issue with pedestrian crossing devices is the general lack of confirmation feedback from a crossing device. Pedestrians may often press the crosswalk signal buttons a number of times in an effort to ensure the traffic computer’s acknowledgement of their desire to cross. We will test various forms of confirmation feedback from approved devices provided to us by FDOT. Additionally, we will test for any advantages that feedback may provide above no feedback confirmation from the pedestrian device. We will conduct this task as a field study at the TERL facility after completion of proposed facilities construction.
Initially, we will conduct pilot observational studies around the Leon County area to look at the patterns of usage for confirmation and non-confirmation pedestrian device buttons. This study is intended to be naturalistic and will have no experimental manipulation but the data on frequencies of behaviors will be used to guide the specific design of the lab and field studies.
We will then conduct a field study with twenty younger, middle-aged, and older pedestrians who will be asked to activate a crosswalk signal in daytime/lab conditions and cross an intersection (in field conditions). Their behavior will be recorded for confirmation feedback and non-confirmation feedback crosswalk signals. The number of button presses and type of crossing behavior exhibited (e.g., premature crossings) will be recorded to assess the efficacy of type of feedback.
Task 6. Character size efficacy for Dynamic Message signs.
Traffic Engineering and Operations staff have asked about the effectiveness of 16.8” character size boxes for LED-based DMS signs. Sign manufacturers have argued that because of “blooming” effects, the effective character size for a 16.8” character is equivalent to that of an 18” character size. Apparently, there are no empirical tests of this phenomenon, and whether, for instance, it holds for younger and older viewers. In this task we propose to investigate this assumption in a field study that asks younger, middle-aged, and older drivers to match and comprehend standard message sets, on the 16.8” character size set during both day and night conditions. We will try to determine if fusion effects vary for younger to older drivers in a way that affects legibility distance. We will approach this task with an initial pilot testing before full experimental testing. We will conduct this task as a field study during day and night conditions at the TERL facility after completion of proposed facilities construction.
We will conduct a field test with 20 younger, middle-aged, and older drivers. Due to the size, lack of portability, possible availability, and surrounding logistics, the use of full dynamic message signs will not likely occur. Instead we propose to use either a mock-up row of 10 characters at 16.8” character height, a smaller version of the DMS provided by manufacturers, or the entire device itself with the aid of the TERL facility. The accuracy of judgment and distance of judgment will be the assessed variables.