17.6 Effects of Roadway Factors on Speed Geometric, environmental, and traffic-related variables all influence driving speed under free-flow conditions on tangents. Drivers of free-flowing vehicles can select speeds based on their level of comfort and the appearance...
17.4 Speed Perception and Driving Speed Motorists can misperceive the speed at which they are traveling. Although speedometers indicate vehicle speed, often motorists rely on external cues (e.g., engine noise, vibrations, visual sensations elicited through highway...
17.2 Behavioral Framework for Speeding Factors related to the motorist, vehicle, road, and environment influence speeds at which motorists drive. Figure 17.1 reviews factors designers should focus on to select countermeasures that mitigate speeding. It is critical to...
16.8 Design Consistency in Rural Driving Motorists make fewer errors when they encounter geometric features that are consistent with their expectations. Inconsistent designs or facility operations violate driver expectations. Expectations for downstream road segments...
16.4 Countermeasures for Pavement/Shoulder Drop-Offs Shoulder drop-offs are present where the pavement surface and roadside surface differ in height (from a fraction of an inch to several inches). Height differences typically result from rutting erosion, excessive...
16.2 Passing Lanes The addition of passing lanes on two-lane roads can improve traffic operations and minimize motorist frustration by giving faster-moving vehicles a designated lane in which to bypass slower traffic. Table 16.1 lists design parameters for passing...
