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Friday, November 18, 2011

Report on how to design high way on a hilly area


Introduction

Romans was the people who started building long length roads, roads that connected to Europe, who saw the ability to move quickly as essential for both military and civil reasons. The Roman approach to road design is essentially the same as that in current use. The roads were constructed of several different layers, increasing in strength from the bottom. The lowest layer was normally rubble, intermediate layers were made of lime bound concrete and the upper layer was a flag or lime grouted stone slabs. The thickness of the layers was varied according to the local ground conditions.

            Highway designs vary widely and can range from a two-lane road without margins to a multi-lane, grade separated freeway. In law the word highway is often used as a legal term to denote any public road, ranging from freeways to dirt tracks. An interconnected set of highways can be variously referred to as a "highway system", a "highway network" or a "highway transportation system".

            This report consists of a highway which connects two highways A to B, through a declining hilly area, and this area needs to be cut and fill. Consist of a sag curve and crest curve. The minimum gradient through the road is 7%. And the first 50m is 0% and straight.



Speed parameter and route selection

 Route selection

Human beings are natural effort minimizes, notably when it involves moving around. When given the opportunity, they will always try to choose the shortest path to go from one place to another. Transportation, as an economic activity, replicates this process of minimization, notably by trying to minimize the friction of distance between locations. Shorter times and lower costs are looked upon by individuals as well as by multinational corporations. For an individual, it is often only a matter of convenience, but for a corporation it is of strategic importance as a direct monetary cost is involved.

The Road we have designed is 864 meters in length.

 Speed parameter


Speed or velocity, it measure how much of distance a particle or vehicle moves in a period of time. In human there are three thing which influence driver choice of speed; Personal; which means how tired he she is or how occupies he/she is,  Vehicle; the type of vehicle he/she is driving, External; this is things outside the vehicle, like how the road is, how the weather is.
The design speed of this road is 80 Km/H from A to B of 864 meters.


 Design calculations

 Horizontal curvature and alignment

Design speed of road, V =  80 Km/h,                         e = 0.07 Max,              f=0.26
Rmin     =                 V2              .           
                   127 ( emax + fmax)              
Rmin     =                 802              .           
                   127 ( 0.07 + 0.26)                       
Rmin     =       157.5 M



Rate of rotation
   LSD    =       (n.e)     x    VD


                     0.025         3.6
  LSD    =       (0.03 x 0.06)     x    80


                          0.025                  3.6
       LSD    =       80 M




Plan transition length
       LT      =          2/3 x LSD


       LT      =          2/3 x 80


       LT      =          53 M




Chainage at TP leading
       ChTP1             =          130+81 = 160 Tan 52


            =          132.97 M
       ChTP1             =          132.97+145  = 277.97


            =          278 M

Vertical Alignment

Crest curve

A         =          0 – (-7)
            =          7
K = 24,            V =  80 Km/h
Min crest =      7 x 24 = 168 m
Ha       =          912 + 0                        =912
Hb       =          912 – 0.07x 168/2       = 906.12
Hc       =          (912 +906.12)/2          = 909.06
Hd       =          (909.6 + 912)/2           = 910.53
Cha      =          140 – 168/2                 =56 m
Chb     =          140+168/2                   =224 m



   Hp     =          Ha +[(p/100) X] + [ (-A/200L) X2]


          =          912 + 0 - 0.0033


           =          911.99


Table 1 ; Crest curve in every 20 m intervals
Chainge
x
ha
(p/100)
x
A/200L
x2
Hr
56
4
912
0
4
-0.00021
16
912.00
60
24
912
0
24
-0.00021
576
911.88
80
44
912
0
44
-0.00021
1936
911.60
100
64
912
0
64
-0.00021
4096
911.15
120
84
912
0
84
-0.00021
7056
910.53
ok
140
104
912
0
104
-0.00021
10816
909.75
160
124
912
0
124
-0.00021
15376
908.80
180
144
912
0
144
-0.00021
20736
907.68
200
164
912
0
164
-0.00021
26896
906.40
ok

sag curve

A         =          -7 – (3)
            =          -10
sag       =          200 m adopt
Ha       =          865.7  + 0.07x100       = 872.7
Hb       =          865.7  + 0.03x 100      = 868.7
Hc       =          (872.7  +868.7)/2        = 869.92
Hd       =          (869.92+ 865.7 )/2      = 867.92
Cha      =          768 – 200/2                 =668 m
Chb     =          768+200/2                   =868 m
 Chd   =          768



Table 2 ; Crest curve in every 20 m intervals
Chainge
x
ha
(p/100)
x
A/200L
x2
Hr
668
20
872.7
0.07
20
-0.00025
400
871.40
688
40
872.7
0.07
40
-0.00025
1600
870.30
708
60
872.7
0.07
60
-0.00025
3600
869.40
728
80
872.7
0.07
80
-0.00025
6400
868.70
748
100
872.7
0.07
100
-0.00025
10000
868.20
768
120
872.7
0.07
120
-0.00025
14400
867.90
ok
788
140
872.7
0.07
140
-0.00025
19600
867.80
808
160
872.7
0.07
160
-0.00025
25600
867.90
828
180
872.7
0.07
180
-0.00025
32400
868.20
848
200
872.7
0.07
200
-0.00025
40000
868.70
ok
Earth work volume calculation 


From the graph there is around 74 fill in section and 3 cut section.
Cut and fill ratio         =     1 : 24.6

Volume of fill is;
=          74 – 3  = 71 nos
=          71 x 12 x 20
=          17,040 M3 of soil for fill

Volume of cut is;
=          3nos
=          3 x 12 x 20
=          720 Mof soil to be cut

 Reference

[1] Traffic and Highway engineering, Nicholas J garber, lester A Hoel, 3rd edition.
[2] Highway Engineering, Martin Rogers
[3] http://people.hofstra.edu/geotrans/eng/ch2en/meth2en/ch2m2en_2ed.html

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