CECC481 Highway Terms and Surveying Terms

Highway Terms

• Asphalt – a dark brown to black cement-like material in which the predominant constituents are bitumen that occurs naturally or is obtained through petroleum processing.
• Base – the top surface of a road structure. It is also the component of the road structure which receives the traffic laod and transfers it to the subgrade.
• Base coat – it is a plaster coat or coats applied prior to application of the finish coat.
• Collector Street – is a type of street which serves internal traffic movements within an area and connects this area with major arterials.
• Expressway – a divided arterial highway for through traffic with full or partial control of access and generally with grade separation at intersections.
• Freeway – is an expressway with full control access.
• Hardness – the hardness of asphalt cement is obtained by conducting a penetration test.
• Highway – a general term denoting a public way for purposes of vehicular travel, including the entire area within the right of way.
• Interchange – is a system of interconnecting roadways in conjunction with one or more highway separations providing for the interchange of traffic between two or more intersecting highways, usually without at-grade crossing of through and major turning movements.
• Intersection – is an area/section where two or more roads come together.
• Overpass – when the major highway is taken above by raising its profile above the general ground level by embankment and an overbridge across another highway.
• Pavement – is the layered structure placed over a soil sub-grade for forming a road.
• Prime coat – is the single application of liquid bituminous material to a previously prepared and untreated road base, such as earth, gravel, stabilized soil, or water-bound macadam base courses.
• Road bed – is the graded portion of a highway within the top and side slopes, prepared as a foundation for the pavement structures and shoulders.
• Seal coat – a very thin surface treatment of bituminous material which is applied as a final step in the construction of certain bituminous wearing surfaces of roads.
• Sub-base – is the part of the road structure which is immediately above the subgrade and composed of stone boulders or superior soil.
• Subgrade – is the layer of natural soil over which the pavement of a road is laid.
• Tack coat – is the single initial application of bituminous material to an existing bituminous, Portland cement concrete, or block surface or based.
• Underpass – when the major highway is taken by depressing it below the ground level to cross another road by means of an underbridge.
• Wearing course – is the layer in a road pavement which provides resistance to wear and tear due to traffic.

Surveying Terms

• Contour lines - is an imaginary level line that connects points of equal elevation. This is also the most common method of representing the topography of an area.
• Foresight reading - is taken on a rod held on a point whose elevation is to be determined.
• Form lines – are used in the maps intended for purposes of navigation to show peaks and hilltops along the cost lines. Form lines resemble contours, but are not drawn with the same degree of accuracy.
• Hachures – are a series of short lines drawn in the direction of the slope. It gives a general impression of the configuration of the ground, but they do not give the actual elevations of the ground surface.
• Height of the Instrument - In stadia surveying, it is required to determine the elevation of the line of sight.
• Pace – is defined as the length of a step in walking. It may be measured from heel to heel or from toe to toe.
• Pacing – consists of counting the number of steps or paces in a required distance.
• Photogrammetry – is the science of mapping out a big tract of land and consist in taking overlapping photographs from an airplane flown at adequate altitudes.
• Planimeter - An instrument or device used to determine the area of any irregular figure plotted on a map that is drawn to scale.
• Saddle - refers to a geographical feature where two adjacent hilltops or ridges slope downward on both sides, creating a low point or dip between them. This low point resembles the shape of a saddle, hence the term.
• Stadia Method – provides a rapid means of determining distances. The equipment for stadia measurement consists of a telescope with two horizontal hairs called stadia hairs and a graduated rod called a stadia rod.
• Tachymetry (or tacheometry) – is another procedure of obtaining horizontal distances. It is based on the optical geometry of the instruments employed and is an indirect method of measurement.
• Taping – is the method of measuring or laying out horizontal distances by stretching a calibrated tape between two points and reading the distance indicated on the tape.
• Thalwegs - It refers to the line of lowest elevation within a valley or watercourse, which typically represents the path of a river or stream's current.
• Transit rule – is the correction to be applied to the latitude or departure of any course is to be the total error of latitude or departure as the length of the course is to the length of the traverse is one way of balancing a traverse.
• Zenith – a point where the vertical produce upward, pierces the celestial sphere.