Vertical Curve Calculator

Design vertical curves (sag and crest) for roads — grade difference, curve length, minimum radius — free road design tool

Input Parameters

Incoming Grade g1 (%)

Outgoing Grade g2 (%)

VPI Station

VPI Elevation (m)

Curve Length Method

Curve Length L (m)

Results

Curve Type

Crest

Grade Change A (%)

5.00%

K Value

40.00

Curve Length L (m)

200.00

BVC

Sta: 400.00

Elev: 147.000 m

EVC

Sta: 600.00

Elev: 148.000 m

High Point

Station: 520.00 | Elevation: 148.800 m

Elevations Along Curve

Station	x (m)	Tangent Elev (m)	Curve Elev (m)	Offset (m)
400.00	0.00	147.000	147.000	0.0000
420.00	20.00	147.600	147.550	-0.0500
440.00	40.00	148.200	148.000	-0.2000
460.00	60.00	148.800	148.350	-0.4500
480.00	80.00	149.400	148.600	-0.8000
500.00	100.00	150.000	148.750	-1.2500
520.00	120.00	150.600	148.800	-1.8000
540.00	140.00	151.200	148.750	-2.4500
560.00	160.00	151.800	148.600	-3.2000
580.00	180.00	152.400	148.350	-4.0500
600.00	200.00	153.000	148.000	-5.0000

Min Curve Length by Design Speed

Speed (km/h)	K	Min L (m)	Check
20	3	15.00	OK
30	6	30.00	OK
40	11	55.00	OK
50	17	85.00	OK
60	28	140.00	OK
70	40	200.00	OK
80	55	275.00	NG
100	100	500.00	NG
120	160	800.00	NG