pdf - Coordinates

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Mileage stakeout: setover of ‘0’
means current position is on the
center line of the railway. Go forward
or back along the center line, when
the mileage shows the same as the
calculated mileage of the pile, current
position is the right position.
Survey profi le: along the center line of
railway, survey the topographic points
(such as ridge, wire, and canal).
Using RTK system
in this process
The design of railway is quite simple and
fast. Railway-design software is quite
advanced when designing a railway. For
example to design a 40km long railway
line, we only need the coordinates of
intersection, distance between points
of intersection, easement curve length,
circular curve length and pile mileage. The
main work is to arrange these elements
in certain order and build a road fi le,
and could be fi nished in 2 minutes.
30 | Coordinates October 2009
User-defi ned feature function. The function
of user-defi ned features makes the inside
and outside work much simpler. When
surveying the profi le, if there is some
topography point (such as the scarp), one
needs to record the name and attributes of
this point in a notebook, and then input this
points details into the computer once back
in the offi ce. But, with Railway-design
software, the engineer can input attributes
directly in the fi eld and save time.
Transect
Transect refl ects the topography
situation on both sides of the railway.
After confi rming the position of
a pile, measure the topographic
points along the transect direction
to record the transect condition.
There are many advantages of using RTK.
Graphic is intuitionistic: when
measuring transect, the departure
distance from midline can be seen
directly in the controller. It is more
accurate than traditional visual method.
Auto name: when measuring the
profi le, the system names the fi rst point
as d1, the second point as d2, etc.
Add point: If the designed pile is
on a bridge, transect of this pile
cannot be measured. In this situation,
‘Add point’ function is used. Add
pile before or behind this pile, and
measure transect of added pile.
To improve working effi ciency and reduce
measurement mistakes caused by operation
misplay, a lot of work can be done indoors:
like making fi le for site calibration, making
line fi le, making stakeout fi le, etc.
RTK is applied in the railway industry
quite early. It is widely used in the
design and other aspects of railway
construction. With the use of RTK GPS
system, the working effi ciency of railway
construction is signifi cantly improved.