Units of information on dynamic message signs: a speed pattern analysis

Abstract

A single unit of information is an answer to any anticipated question a motorist may ask. Such questions include: "What happened? Where? What do I do?" This study, a first of its kind, analyzes the optimum number of units of information Dynamic Message Signs (DMSs) should display to influence driver speeding behavior. A 155-mi 2 virtual road network of the Baltimore-Washington Parkway (MD-295) in Maryland was developed for use with a mediumfidelity driving simulator, and 65 participants took part in the study. Six scenarios featured DMSs displaying 2-7 units of information, interchangeably, and a total of 296 simulation sessions were conducted. Mean speeds are calculated over five different phases: the initial speed area, visible area, readable area, lost legibility area and post DMS area. Analysis of variance (ANOVA) and post-hoc analysis showed that participants tend to accelerate as soon as they lose sight of the DMS displaying 2-3 units of information and continue to do so after they pass the DMS. An ordinary least squares (OLS) regression analysis reveals that participants older than 55 slow down the most when they encounter DMSs with 6-7 units of information. Participants in the age group of 26-35 tend to increase speeds, especially when a DMS displays 2-4 units of information. This suggests that the comprehension time is low when there are fewer units of information on a DMS. Too little information may be unclear or ambiguous whereas too much may be hard to comprehend and cause drivers to slow down.

Cognitive Load Variability from Road Characteristics Should Influence a Safety Requirement for Vehicle Stopping Sight Distance

“…As studied in Kolisetty et al (2006), a variable message was associated with a decrease in driver speed by about 10% (1-6 miles per hour) when displayed in advance of adverse weather warnings. Additional work conducted by Banerjee et al (2019) supports the idea that the speed decrease occurred because of the number of bits processed by the driver.…”

“…To effectively measure a driver's field of view in terms of information (bits) it is necessary to consider a "visual information theory" which heretofore has not been developed. Prior work has applied the information theory of Fitts's law and Hick-Hyman law to investigate touch-screen HMIs (Large et al, 2018) or traffic signage (Banerjee et al, 2019), but not on other external information (road geometry, traffic volume, pedestrians, signage, and others) that would influence driver reaction times. To constrain the definition of information, as it applies to this paper, it is considered the content that reduces uncertainty of a driver's risk to unexpectedly stop the vehicle.…”

Visual Perception and Understanding of Variable Message Signs: The Influence of the Drivers’ Age and Message Layout

“…According to the paper by [15], reading times are affected by the length of the message, and messages too long or complicated may lead some drivers to slow down dangerously to read them. In this regard, the paper by [16] analyzed through a medium-fidelity driving simulator the optimum number of units of information VMS should display to influence driver speeding behavior. Their results suggest that, on the one hand, the comprehension time is low when there are fewer units of information, and on the other hand, too little information may be unclear or ambiguous, whereas too much may be hard to understand and cause drivers to slow down.…”

Comprehensive Analysis of Dynamic Message Sign Impact on Driver Behavior: A Random Forest Approach

“…Over the past couple of decades, numerous attempts have been made by researchers to understand the influence of various design, traffic, and environmental factors on driving behavior [1][2][3][4][5][6][7]. Efforts have also been made to develop accurate model(s) of drivers' behavioral response(s) to these factors [8][9][10][11][12]. The understanding and analysis of driving behavior is vital to the provision of safe driving environments [13][14][15], as such knowledge is necessary for the development of effective tools designed to influence driver's decisions, speed selection, and route choice, and by so doing enhance driving experience and safety.…”