10.4 Factors Affecting Acceptable Gap Distances Many factors influence acceptable gap distance. When making assumptions about acceptable gap distance, it is important for designers to keep in mind issues summarized in Table 10.2 Table 10.2 Factors that Influence...
9.2 Perceptual and Physical Elements to Support Rural-Urban Transitions When motorists driving at a high speed enter an area with lower speed limits, they tend to underestimate their speed and not adjust it downward enough. The design of transition zones needs to...
8.2 Task Analysis of Lane Changes on Tangent Sections In areas where lane changes are likely (e.g., interchanges, entrance and exit ramps, merge/weave sections) avoid incorporating design features that require motorists to read signs or engage in complex decision...
7.6 Preview Sight Distance and Grade Perception at Vertical Curves Preview sight distance measures the motorist sight distance required under the assumption they base their behaviors on a preview of the road surface and other cues that lie downstream. The concept...
5.12 Influence of Speed on Sight Distance When operating speeds are much faster than design speed, increasing sight distance to account for higher vehicle speeds can be a good option. Table 5.8 summarizes how different aspects of a road’s design influences operating...
5.10 Determining Passing Sight Distance Passing sight distance is the length of roadway downstream a motorist must be able to see to safely complete a passing maneuver. Safe completion means the motorist does not cut off the vehicles they are passing before they meet...
