a) Deviations. Deviations of design alignment from centerline of
existing foundations shall not exceed the allowable structural eccentricities.
Deviations of 1 inch or less can generally be achieved.
b) Offset Closures. Offset closures (i.e. the perpendicular
distance from the surveyed curve tangent to the design curve tangent, at the
design PT) must be 0.2 inch or less. For sketches see Application Manual for
Portal Crane Track Design or TRACKS Users Manual.
c) Tangent Closures. Tangent closures at the midpoint of the two
partial curves making up a horseshoe curve must not be overlapping. (Tangent
closure and horseshoe curves are described in detail in the Application Manual
for Portal Crane Track Design and the TRACKS Users Manual.) Overlapping
tangent closures indicate that the two partial curves have no common point of
d) Required Float. Required crane float shall not exceed the
allowable float for any crane that will traverse the track.
e) Design Gage. Design gage between rails shall be used as a
check of field placement of track.
f) Physical Obstructions. Physical obstructions must be checked
before allowing a new crane on the track.
Rail Construction Requirements. Prior to any portal crane track
curve construction, all float requirements of portal cranes traversing the
design curve must be satisfied. Working drawings showing adequate information
for rail fabrication shall be prepared. These drawings should be formal,
scaled layouts of the track alignment and should contain the following design
information as a minimum:
PC, PT and PI locations
For each segment
Tangent offsets to segment PCC points
Stations of PCC's