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Perpendicular distance of all vehicles going in the same direction
The standard (default) value is 4 meters and is taken from Madsen et al. (1986). This is shown in Figure
31. This parameter specifies the perpendicular distance (i.e. a distance measured along a line at right
angles to the line of travel of the radioactive materials shipment) between the radioactive materials
shipment and other traffic lanes, in meters. This is an average perpendicular distance between the
shipment centerline and the centerline of adjacent passing vehicles. This value is based on the median
value for all Interstate and secondary-road lane widths.
Minimum number of rail classification stops
This applies to rail mode only and specifies the minimum number of railcar classifications per trip. The
standard (default) value is 2 since there are at least two inspections per trip – one at the beginning and one
at the end of each trip (Wooden 1986). When the origin of a rail shipment is very different from its
destination, it may be useful to change the value to 1. The collective dose to railyard workers at a 30-hour
classification stop has been integrated into RADTRAN, and is multiplied by this number to give the dose
to these workers at classification stops. The dose is the weighted sum of the doses for all close-proximity
railyard worker groups, and is calculated primarily with a line-source model, though a point-source model
is used when appropriate. For general freight, dose is calculated with the modifying factors b1 through b7,
which have units of person-hr/km and are derived from Wooden (1987) as described in Appendix B of the
RADTRAN 5 Technical Manual (Neuhauser, et al, 2000). This is shown in Figure 32.
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