CT224-2

• Consistency is the most important single rule in highway
• AASTHO is the American Association of State Highway and Transportation Officials
• AASHTO publications includes: 1. Transportation Materials Specifications and Tests. 2. Specifications for highway bridges

  3. Geometric deign standards.

  4. Numerous policy statements and guides.
• Roads and Highways is defined as strips of land that have been cleared and further improved for the movement of people and goods.
• Road has somewhat broader application in usage while generally used to describe a public thoroughfare. It can also refer to railways.
• Highway is The term was first used in England to describe a public road built by digging ditches on both sides and heaping up the earth in the middle creating a way higher than the adjacent land. Highway now connotes, a higher state of development than road. but the words are almost interchangeable.
• Expressway is a divided arterial highway for through traffic with full or partial control or access and generally provided with grade separation at major intersections.
• Freeway is au expressway with full control of access"
• Control of Access is a condition where the rights of owners or occupants of adjoining land or other persons access to light, air or view in connection with a highway is fully or partially

  controlled by public authority.
• Full Control of Access - The authority to control access is exercised to give preference to through traffic by providing access connections to selected public roads only. Crossing at grade or direct private driveway connections is not permitted.
• Partial Control of Access - The authority to control access is exercised to give preference to through traffic. Although in addition to access connestions with selected public roads, there may be some crossings at grade and some private driveway connections allowed.
• Through Street or Through Highway - Every Highway or portion thereof on which vehicular traffic is given preferential right of way, and at the entrance
• Parkway is an arterial highway for non-commercial traffic, with full or partial control of access usually located within a park or ribbon park-like development.
• Arterial Street is an arterial route that carries traffic to the nearest access point or through traffic.
• Collector Street form smaller mesh grid pattern where passengers are pick up from service streets and carried to the arterials.
• Local Road is defined as street or road primarily for access
• Highway Capacity is defined as the manimum number of vehicles that are reasonably expected to pass a given point over a given period of time usually expressed as vehicles per hour.
• The speed determined for design and correlation of the physical feature of a highway that influence vehicles operation'
• Basic Design Features refers to the tightness and super elevation of curves, the sight distance, and grade
• The cross section of a typical highway has latitude of variables to consider such as:

  1. The volume of traffic. 2. Character of the traffic. 3. Speed of the traffic.
  2. 4. Characteristics of motor vehicles and of the driver
• Two Lane Rural Highways, a 7.20 meters wide sur- face is required for safe clearance between commercial vehicles and is recommended in highways.
• Collector Roadway, 6.00 meters wide surface is acceptable only for low volume traffic including few trucks traveling thereon.
• Local Rural Roadway, the minimum surface width is 4.80 meters for a 30 km / hr. design speed.
• Urbair Roadway, the minimum design width is 3.60 meters although 3.00 meters is allowed where space is limited.
• Road shoulder or verge is defined as that portion of the roadway between the edge of the traffic lane and the edge of the ditch, gutter, curb or side slope.
• A continuous narrow white line strip at the edge of the roadway that separates the shoulder, serves as guide to drivers during bad weather and poor visibilrty conditions.
• Width is defined as "extending from the edge of the surfacing to the point where shoulder slope intersect the side slope. "
• The cross slope is provided in all tangent sections of the roadway.
• The number of lanes in a segment of the highway is deter- mined from the estimated traffic volume for the design year
• For Narrow Median, there are four means of reducing cross median accidents: 1. Provide deterring devices. 2. Provide non-traversable energy absorbing barriers' 3. Provide non-traversable rigid barriers. 4. Provide G.M. barriers.
• Deterring Devices. - Two sets of double strip painted on the existing pavement, raised diagonal bars, low curbing and shallow ditches.
• Non-Traversable Energy Absorbing Devices- The line chain link fence I meter high supported by steel post augmented by cables at the bottom and midpoint. Non-traversable rigid barriers are metal guard rail.
• G.M. Barriers. A high non mountain sloped face concrete barriers called New Jersey.
• Grade line is defined as the longitudinal profile of the high- way as a measure how the centerline of the highway rises and fall.
• All vertical curves should not be shorter than the established minimum over crests.
• The stopping sight distance is defined as the longest distance that a driver could see the top of an object
• The passing sight distance is the longest distance that a driver can see the top of an oncoming vehicle where the driver's eye level
• Road alignment should be consistent
• Arc Definitions - The degree of curve is the central angle subtended by a 30 meters arc of the curve.
• Chord Definitions - The degree of curve is the central angle subtended by 50 meters chord.