Horizontal Alignment ( Free PDF )


  • Distance
  •  (side block
  •  Distance
  •  Other parts
  •  Transition- Current- Completed
  •  Circular lines
  •  Larger line width
  •  Two-way/two-lane high-level intersection
  •  (changes in central profile (C.L.).
  •  Internal profile migration (I.E).
  •  Circulation related to external identity (O. E).
  •  Junction Divided HWY
  •  (variable between centerline, median width <4.5 m.
  •  Perimeter around median margin, median width 4. 5′ 12m.
  • Turns as separate pavement, center width > 12m.
  •  Fresh water
  •  Widened lanes (pavement widening)
  •  The width of the coating varies from 0 to m 2; the maximum value in the range of 0.6 to 1.20 m is most commonly used. The required values ​​are calculated according to the following formula,
  •  No spiral
  •  Circular lines
  •  SPECS no longer uses loops
  •  Spirals have complex geometry
  •  Request further research
  •  If used, the height transition must be completely spiral
  •  Length of spiral
  •  How do I prepare a simple line?


The horizontal road connection consists of a series of horizontal elements (straight road sections), roundabouts and crossings. It shows the proposed location of the road relative to existing land and adjacent land. In addition to vertical alignment (points and vertical lines) and road alignment (roads, edges, roads, medians, slopes, ditches, pavements), horizontal alignment (tangents and lines) contribute to providing a three-dimensional road structure. This course focuses on the geometric design of horizontal connections on modern roads. The content is intended as a guide, not a rule or rule. Once you complete the course you will be familiar with horizontal road design. The aim of the course is to provide engineers and designers with an in-depth understanding of the principles that should be taken into account in design integration. Topics covered include:  Approvals for Far View Block Intersections  Cross Mountain Views Elevation Radius Degrees  Horizontal Lines Mixed Intersections  Alignment of Horizontal and Vertical Lines Policy Concerning Geometric Design of Roads and Streets (also known as the “Green Book”) published American Highway and Prepared by the Association of Transportation Officials (AASHTO), it is considered the leading guide to the design of American highways. In this course, Chapter 3 (Section 3.3 Horizontal Alignment) will be used only for the basic principles of geometric geometry. Horizontal intersection is a series of horizontal segments (straight road sections), curves, and transitions used in road geometry. A map showing the location of the proposed road in relation to the existing terrain and adjacent terrain. The primary goal of geometric road design is to combine these factors to provide a speed that is compatible with the road’s function and location. The safety, quality of work and cost of the project can be affected by the combination of horizontal and vertical components. DESIGN SPEED AASHTO defines design speed as “the maximum safe speed that can be maintained on a given road under conditions sufficiently favorable to be determined by the design of the road.” It is a common way to control horizontal alignment in a road design that can meet or exceed the legal speed limit. Service level is directly related to the speed of work. The must meet the driver’s requirements and be compatible with the company’s operating procedures. Choosing the right speed is a very important decision that should be made early in the planning and design process. This pace needs to balance safety, mobility and efficiency with environmental quality, economy, aesthetics and social and political consequences. Path design (radius, height, view distance, etc.) affects drawing speed, as do other non-speed related features. Therefore, any change in the design can affect many ways. The design of rural roads should be as long as possible to provide the best possible level of safety and efficiency. Data has shown that drivers perform better at speeds above the normal speed limit. On some city streets (residential streets, school zones, etc.) lower speeds may be better. For residential applications, technical vehicle stabilization has proven to be the best choice. Designers must consider high-speed connections (pedestrians, sidewalks, parking lots, etc.) on urban arteries for safety reasons.

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