Three types of calculator given below check by scrolling
Note: In below calculator,
1)we assumed plain and rolling terrain for which emax=0.07, fmax=0.15
2)we assumed mixed traffic for which f=o, x=75%
Superelevation
Raising outer edge of road with respect to inner edge is termed as superelevation. when vehicle is moving on curve road, then centrifugal force is try to push the vehicle away from the road. Thats why superelevation is provide to counteract the centrifugal force. Superelevation is calculated by different formulas as below
Superelevation formula
1) e = Bv2/gR
e = superelevation
B = width of road in meter
v=speed of vehicle in m/s
g= acceleration due to gravity
R= radius of horizontal curve
2) e+f = v2/127R
e =rate of superelevation in per meter
v=speed of vehicle in km/hr
R= radius of horizontal curve in meter
f= coefficient of friction
For mixed traffic the f=0, velocity is taken 75%
e = (0.75V)2/127R = V2/225R
you can design superelevation by using the last calculator.
Design procedure of superelevation
We are designing the superelevation for mixed traffic conditions for that we take velocity, 75% of design speed and lateral friction to zero.
Take the value of emax and fmax according to ground terrains. For example, if terrain is plain and rolling then emax = 0.07 and fmax= 0.15, emax and fmax value depend on terrain types.
emax = 0.07, fmax = 0.15
step 1) calculate the superelevation
e = (0.75V)2/127R = V2/225R
emax = 0.07
if e ≤ emax provide superelevation e.
if e > emax , go for next step
step 2) check for friction
take e = emax
emax = 0.07
e+f = v2/127R
emax+f = v2/127R
f = (v2/127R) - emax
fmax = 0.15
if f ≤ fmax then provide superelevation emax
f > fmax go for next step
step 3) check for limiting speed Va
Take e = emax = 0.07
f = fmax = 0.15
e+f = v2/127R
emax+fmax= Va2/127R
if Va ≥ V provide superelevation emax
Va < V provide superelevation emax and speed limit (Va) board on road.
How to design superelevation
Q. Design rate of superelevation for mixed traffic for horizontal road of radius of curve is 500m, speed is 150 km/hr and terrain is plain and rolling.
=>
R = 500m
V = 150 km/hr
For mixed traffic
We take f = 0 and speed of vehicle is taken as 75%
for plain and rolling terrain
emax = 0.07, fmax= 0.15
step 1) e = (0.75V)2/127R = V2/225R
e = 1502 / (225 × 500) = 0.2 per meter
emax = 0.07
e > emax , go for next step
step 2) check for friction
take e = emax
e+f = v2/127R
emax+f = v2/127R
0.07 + f = 1502 / (127 × 500)
f = 0.28, fmax = 0.15
f > fmax go for next step
step 3) check for limiting speed Va
Take e = emax
f = fmax
e+f = v2/127R
emax+fmax= v2/127R
0.07 + 0.15 = Va2 / (127 × 500)
Va = 118.19 km/hr
V = 150 km/hr
Va < V
For speed limit board on road of 118 km/hr