Transportation Lap Civil Engineering Project mainly deals with geometric design of highways which include dimensions of highways, curves in design, paths for bicycles, and parking facilities , lengths of vertical curves or radii of circular curves are determined to assure that the minimum stopping sight distance is provided to highway users for the design speed of the highway. The fundamental objective of geometric design is to produce a smooth-ﬂowing and safe highway facility, an objective that only can be achieved by providing a consistent design standard that satisﬁes the characteristics of the driver and the vehicles. that use the road.
There are many problems faces the transportation Palestine, such as process of execution , occupation and cost. Palestinian projects of transportation are supported by government donor countries.
Project Description :
The main object of our project is design a new highway connecting A with B, started from (A) with elevation 520m to point (B) with 493.9m elevation , with total length 2750 m and scale map (1:2000).
Our project contains 2 horizontal and 3 vertical curves .
First , we selected the design speed with suitable slope . then We started with straight line , then we draw the horizontal curve with appropriate radius taking the min raduis as a limit and length of the curve with factor of safety . then we set the stations (50 m) on the plan . Then we draw the elevations of the stations on the profile which represents natural ground elevations .
The main required from this project is to design the horizontal curves and determine its stations, design vertical curves and determine its station, determine the cut and fill in cross section.
We designed this highway by passing through many stages, included in :-
Center line and tangents:-
we started from point A and make a tangent until we reach point B.
The maximum grade (slope) of this tangent is 7%,
where : ∆h:- is the difference in elevation between the two station.
d:- is the distance between the two station.
We must keep the stream line of the center line parallel to contour lines to decrease the slope and the magnitude of cut and fill.
The center line of the highway must not pass through forests and population area.
There are four types of horizontal curves :-
simple, compound, reversed, and spiral , and we use the simple circular curve in our design.
We have in this project two horizontal curves, we must use a comfortable radius for the curve, takind Rmin as a limit , we can do that by using the equation of ().
Because we need to keep the safety and efficiency of the highway, We can use R > Rmin. if we, then we calculate the angle of intersection (∆), and we use it to calculate (T), (L)..
Then we determine the point of curvature (PC) and the point tangency (PT) form the point of intersection (PI), then we erect a perpendicular line from (PC) and (PT) with length equal to (R), theintersection point is the center of the curve, then by using dividers draw the horizontal curve.
To make the profile for this highway we find the station and elevation for each 50m, we start from point A, we find the elevation from the elevation of the contour line, we continue chaining until we reach point B.
Then we sketch the longitudinal section (profile) by using AutoCAD or EXCEL (we use autacad), we plot a graph between station (m) on X-axis with horizontal scale (1:2000), and elevation(m) on Y-axis with vertical scale (1:200)
After we draw the profile we make a suitable grades
( From To ) , then we can determine the cut and fill areas and volumes.
After we sketch the grades, we designed the vertical curve at the intersection of the two grades, the vertical curve is a parabolic curve, in this project we have three vertical curves, one of them is crest and two are sag, we must use a suitable length for the curves, we can do that by using the equation of .
K= 96 for sag , 84 for crest curve.