Description
To allow widening and narrowing of surface grade and road crowns, only one
of the two lines defining the surface grade or crown, is shifted when adding a
horizontal shift. This behaviour is useful for small changes to the original
design, for example to bus stops or emergency bays.
a
b
c
Road_017
a
Centreline
b
Original line of the design
c
Line with horizontal parabolic
shift
Horizontal shift
For surface grades and crowns, the horizontal shift is added to the line that is
defined as the reference line. To maintain the original surface grade/crown
ratio the line is shifted along the surface grade/crown.
a
e
b
d
c
+
Road_018
a
Surface grade to shift
b
Reference line of the surface
grade
c
Second line of the surface
grade
d
Positive horizontal shift
e
Position of the shifted refer-
ence line
Vertical shift
The vertical component of the shift for a surface grade or crown is applied to
all lines.
a
e
b
d
c
Road_019
a
Surface grade to shift
b
Right line of the surface grade
c
Left line of the surface grade
d
Negative vertical shift
e
Shifted surface grade
Horizontal shifts are always perpendicular to the centreline.
Rail_013
a
b
d
c
Plan view
a
Reference line
b
Point to stake
c
Stake height difference
d
Stake offset
Shift for surface
grade and road
crowns
Horizontal alignment
with constant hori-
zontal shift
684
Roads - General
