Description of the project
It’s required to design divided level terrain highway in Suburban Environment with design speed 60 km/hr, with 10% truck movement, 5% Percent of Busses and no recreational cars. and the angular average daily traffic (AADT) equals 13000(Veh/day) With a groth rate of 1.5% for the next 15 years . PHF = 0.75,
LOS =D
Population doesn't consist Primerly of comuters.
Methodology Description
First: from given data it could be able to measure the number of lanes attained the level observer.
Second: design the horizontal curve by measure the radius ( R ) and supper elevation value (q) and spotting the curve on the map.
Third: Draw the curvature of the design road and draw the supper elevation for the edges of the road.
Finally: design the vertical curve, by estimate the reduced level of the road each 20m, then assume the gradient and spot the vertical curve.
Geometric Design Parameters
Geometric design parameters can be categorized as follows:
Horizontal Alignment
Vertical Alignment
First
Horizontal Alignment
Horizontal alignment, which comprises a series of intersecting tangents and circular curves (with or without transition curves) is a most important feature affecting the safety, efficiency and cost of road. Several studies have indicated that highway curves exhibit higher accident rates than tangent sections, and that the accident rate increases as the radius of curvature is decreased. Generally, vehicle operating speeds decreases as the overall horizontal curvature increases; thus road user costs are affected by bendiness of a road. Also speeds on individual curves are lowered as their radii are reduced, while construction costs usually increase as radii increase (especially in hilly terrain).
Horizontal alignment can be classified into three groups as follows :
1. Straight Line.
2. Circular Curve.
3. Transitional Curve.
second
Verticle Alignment
A vertical curve provides a smooth transition between successive tangent gradients in the road profile. When the algebraic difference of the two gradients is positive the curve is called a crest or summit curve; when the difference is negative it is called a sag or valley curve.
As a motorist, traverses a vertical curve a radial force acts on the vehicle and tries to force it away from the centre of curvature and this may give the driver a feeling of discomfort; in extreme cases, as at hump-backed bridges, vehicles traveling at high speed may leave the carriageway.
The discomfort experienced by the motorist is minimized by restricting the gradients (which reduces the force) and by using a type and length of vertical curve which allow the radial force to be experienced gradually and uniformly. Sight distance requirements also aided by the use of long vertical curves on both crest and sag curves.
Circular, elliptical and parabolic curves can all be satisfactorily used in venial curve design. In practice, however, the tendency is to use the simple parabola, primarily because of the ease with which it can be laid out as well as enabling a comfortable transition from one gradient to another. Vertical curves of this type are not necessary when the total grade change from one tangent to the other does not exceed 0.5 percent.
It’s required to design divided level terrain highway in Suburban Environment with design speed 60 km/hr, with 10% truck movement, 5% Percent of Busses and no recreational cars. and the angular average daily traffic (AADT) equals 13000(Veh/day) With a groth rate of 1.5% for the next 15 years . PHF = 0.75,
LOS =D
Population doesn't consist Primerly of comuters.
Methodology Description
First: from given data it could be able to measure the number of lanes attained the level observer.
Second: design the horizontal curve by measure the radius ( R ) and supper elevation value (q) and spotting the curve on the map.
Third: Draw the curvature of the design road and draw the supper elevation for the edges of the road.
Finally: design the vertical curve, by estimate the reduced level of the road each 20m, then assume the gradient and spot the vertical curve.
Geometric Design Parameters
Geometric design parameters can be categorized as follows:
Horizontal Alignment
Vertical Alignment
First
Horizontal Alignment
Horizontal alignment, which comprises a series of intersecting tangents and circular curves (with or without transition curves) is a most important feature affecting the safety, efficiency and cost of road. Several studies have indicated that highway curves exhibit higher accident rates than tangent sections, and that the accident rate increases as the radius of curvature is decreased. Generally, vehicle operating speeds decreases as the overall horizontal curvature increases; thus road user costs are affected by bendiness of a road. Also speeds on individual curves are lowered as their radii are reduced, while construction costs usually increase as radii increase (especially in hilly terrain).
Horizontal alignment can be classified into three groups as follows :
1. Straight Line.
2. Circular Curve.
3. Transitional Curve.
second
Verticle Alignment
A vertical curve provides a smooth transition between successive tangent gradients in the road profile. When the algebraic difference of the two gradients is positive the curve is called a crest or summit curve; when the difference is negative it is called a sag or valley curve.
As a motorist, traverses a vertical curve a radial force acts on the vehicle and tries to force it away from the centre of curvature and this may give the driver a feeling of discomfort; in extreme cases, as at hump-backed bridges, vehicles traveling at high speed may leave the carriageway.
The discomfort experienced by the motorist is minimized by restricting the gradients (which reduces the force) and by using a type and length of vertical curve which allow the radial force to be experienced gradually and uniformly. Sight distance requirements also aided by the use of long vertical curves on both crest and sag curves.
Circular, elliptical and parabolic curves can all be satisfactorily used in venial curve design. In practice, however, the tendency is to use the simple parabola, primarily because of the ease with which it can be laid out as well as enabling a comfortable transition from one gradient to another. Vertical curves of this type are not necessary when the total grade change from one tangent to the other does not exceed 0.5 percent.
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