Idaho Administrative Code › Title IDAPA 39 - Transportation, Department of › Rule 39.03.04 - RULES GOVERNING SPECIAL PERMITS - OVERWEIGHT NON-REDUCIBLE › Section 39.03.04.300 - MAXIMUM OVERWEIGHT LEVELS FOR ANNUAL OVERWEIGHT/OVERSIZE PERMITS

Current through August 31, 2023
01.
Allowable Gross Vehicle
			 Weight
. The gross vehicle weight allowable by overweight permit is
			 subject to the seasonal stability of the roadway and the capacity of the
			 structures on the route of travel. For the purpose of issuing special permits,
			 seven (7) levels of overweight are established, based on the weight formula of
			 W = 500((LN/N-1) + 12N + 36) and routes for carrying the various levels of
			 overweight are designated by color coding. The Weight Formula ("W") is the
			 maximum weight in pounds (to the nearest five hundred (500) pounds) carried on
			 any group of two (2) or more consecutive axles. "L" is the distance in feet
			 between the extremes of any group of two (2) or more consecutive axles, "N" is
			 the number of axles under consideration. The load factor based on the most
			 critical bridge on the highway route will also be used in determining allowable
			 weights. (3-31-22)
a. Red Routes - The red
			 routes contain posted bridges and require approval or analysis from the
			 Department. A vehicle configuration may be issued an annual overweight/oversize
			 permit for travel on red routes only, upon completion of an analysis verifying
			 the requested weights are acceptable. The annual permit will be issued for a
			 specific vehicle configuration, operating on a specific route, at specific
			 weights. All information will be listed on the annual permit and will be
			 subject to revocation at such time the vehicle configuration changes (such as
			 axle spacings), the approved weights change, or a bridge rating changes. Annual
			 permits issued for red routes will be in addition to the annual permit required
			 for other routes. (3-31-22)
b.
			 Yellow Routes - The yellow overweight level is based on a single axle loading
			 of twenty-two thousand five hundred (22,500) pounds, a tandem axle loading of
			 thirty-eight thousand (38,000) pounds, and a tridem axle loading of forty-eight
			 thousand (48,000) pounds or the equivalent loading as determined by spacings
			 and number of axles and computed by applying the formula W = 560 ((LN/N-1) +
			 12N + 36). (3-31-22)
c. Orange
			 Routes - Orange overweight level is based on a single axle loading of
			 twenty-four thousand (24,000) pounds, a tandem axle loading of forty-one
			 thousand (41,000) pounds, and a tridem axle loading of fifty-one thousand five
			 hundred (51,500) pounds or the equivalent loading as determined by spacings and
			 number of axles and computed by applying the formula W = 600 ((LN/N-1) + 12N +
			 36). (3-31-22)
d. Green Routes -
			 The green overweight level is based on a single axle loading of twenty-five
			 thousand five hundred (25,500) pounds, a tandem axle loading of forty-three
			 thousand five hundred (43,500) pounds, and a tridem axle loading of fifty-four
			 thousand five hundred (54,500) pounds or the equivalent loading as determined
			 by spacings and number of axles and computed by applying the formula W = 640
			 ((LN/N-1) + 12N + 36). (3-31-22)
e.
			 Blue Routes - Blue overweight level is based on a single axle loading of
			 twenty-seven thousand (27,000) pounds, a tandem axle loading of forty-six
			 thousand (46,000) pounds, and a tridem axle loading of fifty-seven thousand
			 five hundred (57,500) pounds or the equivalent loading as determined by
			 spacings and number of axles and computed by applying the formula W = 675
			 ((LN/N-1) + 12N + 36). (3-31-22)
f.
			 Purple Routes - The purple overweight level is based on a single axle loading
			 of thirty thousand (30,000) pounds, a tandem axle loading of fifty-one thousand
			 five hundred (51,500) pounds, and a tridem axle loading of sixty-four thousand
			 five hundred (64,500) pounds or the equivalent loading as determined by
			 spacings and number of axles and computed by applying the formula W = 755
			 ((LN/N-1) + 12N + 36). (3-31-22)
g.
			 Black Routes - The black overweight level is based on a single axle loading of
			 thirty-three thousand (33,000), pounds a tandem axle loading of fifty-six
			 thousand (56,000) pounds, and a tridem axle loading of seventy thousand five
			 hundred (70,500) pounds or the equivalent loading as determined by spacings and
			 number of axles and computed by applying the formula W = 825 ((LN/N-1) + 12N +
			 36). (3-31-22)