|(Excerpts from National Institute of Standards & Technology Handbook 44 as amended by Oregon Administrative Rules Chapter 603, Division 27.)
UR.3.3. single-draft vehicle weighing
A vehicle or a coupled vehicle combination shall be commercially weighed on a vehicle scale only as a single draft. That is, the total weight of such a vehicle or combination shall not be determined by adding together the results obtained by separately and not simultaneously weighing each end of such vehicle or individual elements of such coupled combination. However
(a) The weight of a coupled combination may be determined by uncoupling the various elements (tractor, semitrailer, trailer), weighing each unit separately as a single draft, and adding together the results.
(b) The weight of a vehicle or coupled-vehicle combination may be determined by adding together the weights obtained while all individual elements are resting simultaneously on more than one scale platform.
(c) The requirements of this rule apply only to new or used vehicle scales installed after August 13, 1975.
UR.5. multiple-draft vehicle weighing
A vehicle scale installed and in use for weighing highway vehicles prior to August 13, 1975 may, at its then existing location, continue to be used for commercially weighing a highway vehicle or a coupled highway vehicle in multiple-draft rather than a single draft if
(a) the vendor and vendee to the weighing transaction or an agent of either with written authority to consent to the transaction, agree in writing to a multiple-draft weight determination and provide written disclosure of the multiple-draft weight determination or the information of third parties to the weighing transaction, in a manner prescribed by the Department.
(b) at least one of the approaches to such a scale is straight, level and in the same plane as the scale platform and the weight determination is made using that approach.
(c) The vehicle weight is limited or distributed on the scale platform so as not to exceed the manufacturer's rated sectional capacity for such a scale.