Highway Design and Safety Parameters

The process of planning and designing the physical layout of a highway, including elements like curves, slopes, and sight distances.

The banking of a road on a curve to counteract the centrifugal force experienced by vehicles, ensuring they don't slide outwards.

The process of moving earth to create or modify the terrain to accommodate a highway or railway, including excavation and embankment.

A slice through a highway or railway, showing its width, lanes, shoulders, and other features.

The volume, character, and speed of traffic, as well as vehicle characteristics and driver behavior.

Wider pavements generally reduce accidents, with significant reductions observed between narrow (<5.5 m) and wider (7.2 m) pavements.

Wider shoulders with a width of 2.7 to 3.0 meters are associated with notably lower accident rates compared to narrower shoulders.

Used to determine the volume of earth that needs to be either removed (cut) or added (fill) to build a highway or railway.

A formula used to calculate the volume of a solid that has a varying cross-section, like a trench.

A correction applied to the volume calculated by the Prismoidal Formula to account for the difference between the true volume and the volume calculated.

To determine the volume of earth that needs to be moved or filled during a construction project.

A method used to calculate the volume of earthworks by calculating the areas of the cross-sections at the ends of a section and then averaging them.

It takes into account the areas at the beginning, end, and midpoint of a section to calculate a more accurate volume.

The angle of the sides of a cut or fill, expressed as a ratio.

The horizontal distance across the bottom of a cut or fill.

The area of a slice taken perpendicular to the length of the earthwork.

The minimum distance required for a vehicle traveling at design speed to safely stop without hitting an obstacle.

The vertical distance from the road surface to the driver's eye level.

The vertical distance from the road surface to the top of the object (like a sign or a car).

The time it takes a driver to perceive an obstacle, react, and apply the brakes.

The time it takes a driver to realize they need to stop after seeing an obstacle.

The time it takes a driver to physically press the brake pedal after recognizing the need to stop.

The factors influencing the stopping sight distance, including driver reaction time, vehicle speed, brake efficiency, road friction, and road slope.

The driver's ability to slow down the vehicle safely while maintaining control.

The rate at which a vehicle slows down, measured in meters per second squared (m/s²).

The value representing how much friction exists between the road surface and the vehicle's tires.

The time it takes a driver to perceive a hazard and react by applying the brakes.

The distance covered by a vehicle after the brakes are applied until it comes to a complete stop.

SSD = (Reaction Time x Velocity) + (Velocity² / [2 x Gravity x (Friction ± Gradient)])

To determine if the vehicle will hit the wall, calculate the SSD using the given information and compare it to the distance to the wall.

The minimum distance required for a vehicle to safely stop before hitting an obstacle. It's calculated considering factors like initial speed, driver reaction time, and road conditions.

The slope of the road at the beginning of a vertical curve. It's expressed as a percentage, indicating the change in elevation over a given distance.

The slope of the road at the end of a vertical curve. Like the initial grade, it's expressed as a percentage and indicates the change in elevation over a given distance.

The minimum clear distance needed for a vehicle to safely overtake another vehicle on a two-lane road. It's calculated considering factors like vehicle speeds, passing time, and oncoming traffic.

The distance a vehicle travels during the initial phase of overtaking, while accelerating and moving to the left lane.

The distance a vehicle travels while it's fully occupying the left lane and passing the slower vehicle.

The distance required between passing vehicles and oncoming traffic for safety.

The distance an approaching vehicle travels during the overtaking maneuver, while maintaining its lane.

The minimum distance a driver needs to see in each quadrant of an intersection to safely maneuver their vehicle.

The triangular area in each quadrant of an intersection that must be free of obstructions to ensure adequate visibility.

A curved section of road that connects two grades with different slopes, ensuring smooth transitions.

The maximum speed a vehicle can safely travel on a road segment based on its geometric design.

The height of the driver's eye above the road surface.

The height of an object on the road that needs to be visible to the driver.

The steepness of a road expressed as a percentage.