Performance of Longitudinal Barriers on Curved, Superelevated Roadway Sections (2019) / Chapter Skim
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From page 44... ...
44 Vehicle Dynamics Analysis for Vehicles Leaving the Traveled Way on CSRS 4.1 Background The curvature and surface slope on a roadway are known to effect vehicle dynamics and influence vehicle trajectories, orientation, and speed. On curved sections, the vehicle is more likely to leave the road at a sharper angle and consequently impact the barrier with greater force that could potentially result in higher impact severity.
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45 Such metrics are important for understanding the position of the frontal region of the vehicle relative to the barrier. 4.2 Objective The objective of the research reported in this chapter was to apply vehicle dynamics tools to assess the trajectories of vehicles leaving the traveled way on CSRS.
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46 set of factors and specific parameters associated with them are indicated below: • Barrier type – Concrete barrier [height ≤ 32 in.
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47 the front of the vehicles that represent the engagement point that differentiates between tendencies to override or underride a barrier. Point 1 for the small vehicle is located at a height of 21 in., while Point 2 for the pickup is at a height of 25 in.
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48 reflect exit angles of 20°, 25°, and 30° for the vehicles traveling at 57 mph 62 mph, and 67 mph (90km/h, 100 km/h, and 110 km/h)
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49 Figure 4.5. Vertical surface cross sections analyzed for superelevated curves.
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50 understand the effects as reflected in changes in the vehicle's trajectory (i.e., x-, y-, and z-coordinates, and the roll, pitch and yaw angles)
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V er tic al ( in ) Lateral (ft)
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53 can be used to determine the potential effectiveness for varying barrier systems across all possible lateral positions for a given roadside configuration. Figure 4.11 shows more specific examples of how the plot of maximums and minimums can be applied.
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54 Figure 4.11. Typical barrier interface and effectiveness for given profiles.
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55 Case Parameters Profile Diagram 1 Curvature: 3,050 ft Superelevation: 12% Shoulder Width/Angle: 4 ft/0% Roadside Slope: 12H:1V 2 Curvature: 3,050 ft Superelevation: 12% Shoulder Width/Angle: 4 ft/3% Roadside Slope: 12H:1V 3 Curvature: 3,050 ft Superelevation: 12% Shoulder Width/Angle: 8 ft/6% Roadside Slope: 12H:1V 4 Curvature: 3,050 ft Superelevation: 8% Shoulder Width/Angle: 8 ft/0% Roadside Slope: 12H:1V 5 Curvature: 3,050 ft Superelevation: 8% Shoulder Width/Angle: 8 ft/3% Roadside Slope: 12H:1V 6 Curvature: 3,050 ft Superelevation: 8% Shoulder Width/Angle: 8 ft/6% Roadside Slope: 12H:1V 7 Curvature: 3050 ft Superelevation: 6% Shoulder Width/Angle: 12 ft/0% Roadside Slope: 12H:1V 8 Curvature: 3050 ft Superelevation: 6% Shoulder Width/Angle: 12 ft/3% Roadside Slope: 12H:1V 9 Curvature: 3050 ft Superelevation: 6% Shoulder Width/Angle: 12 ft/6% Roadside Slope: 12H:1V Table 4.1. Sample profile comparisons: NJ concrete barrier.
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Table 4.2. Vehicle interface results for various CSRS and barriers.
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57 – There are cases where the maximum requirement is not met (the "red-bold" values) , indicating that there is increased chance of override due to the CSRS road profile.
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