The Orthophotomap for Highway Design.
For highway design a new photoflight at a scale of
4 :.4.000 to 1 : 6 000 will be needed in every case
to obtain the vertical accuracy in a terrain strip
along the centerline necessary for the computation
of earthwork quantities for tendering and also for
the control of payment quantities. The information
content in a large-scale aerial photograph is used
by the highway engineer for design work as well as
for the identification of the property boundaries
for the right-of-way of the highway. A photomap at
the same scale and layout of the planimetric design
map will be of great value in many phases of high-
way work.
Such a "design orthophotomap" mostly consists of
four overlays to be used individually or combined.
They have always the same layout and the accuracy
to ensure a proper fit at all times. A combined
print of four overlays of a highway design map is
shown in Appendix 2.
The four overlays for the highway design are:
i. the planimetric sheet of , the final highway design
with cut and fill, bridges, drainage, interchanges,
cross-sections, maintenance areas, parking lots etc.
2. the topographic sheet of the terrain with height
information shown as contour lines and spot heights,
slope symbols and break lines of the terrain as well
as all objects of interest to the highway engineer
visible from the air. If additionally an orthophoto