Highway Engineering: Important Definitions

Introduction

In this article you will a few important definitions related to roads. This is article will be updated on regular basis an more of the important definitions will become part of this list. Moreover, you can also download dictionary of civil engineering terminologies.

Roadway cross section

Articulation: As used in this manual, it refers to a machine with a jointed main frame. This assists in steering the machine, allowing it to work in an angled configuration, yet move forward in a straight line.

Ballast: Extra weight added to a machine such as iron weights mounted to the wheels or frame. Liquid material such as a water/ calcium chloride solution placed in the tires can also serve as ballast.

Cross-slope: Definition of road surface shape in which each side slopes in opposite directions from the road center to provide roadway crown for drainage; usually defined in percent, i.e. 4% cross slope.

Crown: That part of roadway shape in which the center of the road is higher than the outer edges of the surface to provide drainage of water from the center of the road surface to curbs or ditches.

Density: The weight of material per unit of volume (generally in pounds per cubic foot or kilograms per cubic meter).

Grader: Any device either self-propelled or mounted on another machine used for final shaping and maintenance of soil or aggregate surfaces. Occasionally, a simple, towed drag-type device is referred to as a grader.

Gravel: A mix of stone, sand and fine-sized particles used as sub-base, base or surfacing on a road. In some regions, it may be defined as aggregate. Gravel may come from natural or quarry sources.

Maintenance: The work done routinely on a road surface, generally no more than light shaping to keep the road smooth, removing slight defects and making sure the crown is maintained to allow water to flow off the driving surface.

Moisture Content: (in percent) Quantity of water contained in a material.

Moldboard: The part of the grader, sometimes called the blade, used to cut, mix, windrow and spread material.

Motor Grader: Any self-propelled machine designed primarily for the final mixing and shaping of soil or surfacing material. Sometimes referred to as a maintainer, patrol, or simply a “blade.”

Optimum Moisture: The percentage of water (by weight) in material that allows it to be compacted to achieve greatest density.

Paved Road: Any road that has a semi-permanent surface placed on it such as asphalt or concrete. Gravel surfaced roads are generally referred to as unpaved roads.

Pit: An area where a natural deposit of stone, sand and/or fine material is removed from the earth.

Rehabilitation: Work performed on the road which extends beyond routine maintenance. Generally this involves loosening of a significant amount of material and changing part of, or much of the geometry of the roadway including fore slopes and ditches.

Quarry: An area where solid stone is removed from the earth generally by ripping, drilling and/or blasting. The stone is then crushed and processed into useable sizes.

Segregation: A problem that arises when the coarse and fine material separates and no longer forms a uniform blend of material.

Windrow: A small conical ridge or long, narrow accumulation of material placed by the grader while performing construction or maintenance operations.