[Federal Register Volume 59, Number 193 (Thursday, October 6, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-24747]


[[Page Unknown]]

[Federal Register: October 6, 1994]


_______________________________________________________________________

Part V





Department of Transportation





_______________________________________________________________________



Federal Highway Administration



_______________________________________________________________________




Truck Size and Weight; Vehicle Size and Weight Limits in Metric Units; 
Notice
DEPARTMENT OF TRANSPORTATION

Federal Highway Administration
[FHWA Docket No. 94-20]

 
Truck Size and Weight; Vehicle Size and Weight Limits in Metric 
Units

AGENCY: Federal Highway Administration (FHWA), DOT.

ACTION: Notice of interpretation; opportunity for comments.

-----------------------------------------------------------------------

SUMMARY: The FHWA has initiated a phased 5-year plan to convert its 
activities and business operations to the Metric System of Measurements 
as required by the 1988 amendments to the Metric Conversion Act of 
1975. Details of the FHWA metric conversion policy and plan were 
published in the Federal Register on June 11, 1992 (57 FR 24843). The 
plan calls for the conversion to be completed by September 30, 1996. 
FHWA regulations currently specify vehicle size and weight limits and 
certain distances in English units. This notice converts the most 
commonly used of these units to their metric equivalents and provides 
guidance for the public to make similar conversions.

DATES: Comments on this interpretation should be submitted by January 
4, 1995.

ADDRESSES: Submit written, signed comments to the FHWA Docket No. 94-
20, Room 4232, HCC-10, Office of Chief Counsel, Federal Highway 
Administration, 400 Seventh Street SW., Washington, DC 20590. All 
comments received will be available for examination at the above 
address from 8:30 a.m. to 3:30 p.m., e.t., Monday through Friday, 
except Federal holidays. Those desiring notification of receipt of 
comments must include a self-addressed, stamped postcard.

FOR FURTHER INFORMATION CONTACT: Mr. Thomas Klimek, Office of Motor 
Carrier Information Management, (202) 366-2212 or Mr. Charles Medalen, 
Office of the Chief Counsel, (202) 366-1354, Federal Highway 
Administration, Department of Transportation, 400 Seventh Street SW., 
Washington, DC 20590. Office hours are from 7:45 a.m. to 4:15 p.m., 
e.t., Monday through Friday, except Federal holidays.

SUPPLEMENTARY INFORMATION: The English unit values for Federal size 
(length and width) and weight limits are set by law (49 U.S.C. app. 
2311, 2316 and 23 U.S.C. 127, respectively). The conversion of these 
values to metric equivalents is not intended to change the law. 
However, public acceptance of the metric system will be considerably 
delayed unless regulatory limits are reasonably easy to use, remember, 
and enforce.
    The Congress enacted the current single-axle, tandem-axle, and 
gross weight limits--20,000, 34,000, and 80,000 pounds, respectively--
for economic and engineering reasons, but it obviously chose round 
numbers to promote compliance and ease of enforcement. That policy is 
also embodied in the Bridge Formula, where calculated weights must be 
rounded to the nearest 500 pounds [23 U.S.C. 127(a)], producing a 
weight table with increments of exactly 500 or 1,000 pounds. In other 
words, the legal limit could be nearly 250 pounds higher or lower than 
the figure generated by the formula. The Congress balanced its interest 
in establishing precise and accurate weight limits with the need to 
make a complex proposal more workable. Similarly, the FHWA believes 
that some compromises are necessary to reconcile the statutory mandates 
to enforce size and weight limits denominated in English units with the 
goal to promote conversion of all measurements to the metric system.
    Consider, for example, the maximum weight for a tandem axle, 34,000 
pounds. The precise metric equivalent is 15,422.4 kilograms. Converting 
to a fractional value is obviously impractical, and the nearest whole 
kilogram is an awkward number also. One kilogram represents 65 ten- 
thousandths of 1 percent (.0065 percent) of 15,422 kilograms. In an 
industry where scales are considered acceptable if they are accurate to 
within 0.2 percent, 1 kilogram has little meaning. Similarly, a 48-foot 
trailer is 14.6304 meters long. Enforcement officers are not in a 
position to measure ten-thousandths of a meter, but all Metric devices 
for measuring length are calibrated in hundredths of a meter.
    With this in mind, the FHWA has decided, for purposes of enforcing 
Federal weight law, to allow the rounding of weight values up or down 
to the nearest whole number of kilograms evenly divisible by 10; this 
gives a margin of error of about 5 kilograms. In the example above, the 
15,422.4 kilogram tandem-axle limit would, therefore, be rounded down 
to 15,420 kilograms. Five kilograms, just over 11 pounds, are well 
within the 0.1 percent margin of error allowed by the National 
Institute of Standards and Technology for a new certified truck scale. 
Such a scale could have a margin of error of 20 pounds when weighing a 
20,000-pound single axle, 34 pounds when weighing a 34,000-pound tandem 
axle, and proportionally more for heavier loads. The FHWA believes that 
this conversion standard will ease the transition to the metric system 
while ensuring that the weight standards established by the Congress 
are enforced. We anticipate that implementation of this conversion 
standard will have no effect on current loading and enforcement 
practices, as no change in current weight regulations is intended.
    The FHWA also will allow the measurement of dimensional values to 
the nearest one-hundreth of a meter. A 48-foot trailer, therefore, 
would be 14.63 meters long. Since dimensions do not fluctuate like 
vehicle weights, the FHWA anticipates fewer problems in enforcing these 
limits. The rule establishing a vehicle width of 2.6 meters as the 
legal equivalent of 102 inches, 23 CFR 658.15(a) remains unchanged.
    The metric weight table (appendix A) yields values more precise 
than those resulting from the rounding method described in this notice. 
For example, the table shows that a three-axle vehicle with a 32-foot 
(or 9.75 meter) wheelbase has a gross weight limit of 27,216 kilograms; 
States may round this figure to 27,220 kilograms. The values in the 
table have not been rounded, however, because the FHWA will not require 
States to further round Federal weight standards if they choose not to 
do so. The metric values in the table represent the conversion of 
English units which have already been rounded one time as discussed 
earlier.
    This notice supersedes the FHWA's previous policy. In a May 16, 
1994, letter to the Florida Department of Transportation, which was 
transmitted to the other States, the Associate Administrator for Motor 
Carriers announced that the Agency intended ``to use as precise 
conversions as possible to determine the metric equivalent to the 
English unit.'' After further consideration, the FHWA has determined 
that the rounding methods described above are consistent with the 
requirements of Federal law and will reduce the difficulties inherent 
in switching from English to metric units.
    With regard to terminology, the FHWA is aware that the correct 
technical equivalent for an English ``weight'' limit would be a metric 
``mass'' limit. However, because of its historic and widespread use, 
the term ``weight limits,'' when referring to commercial motor 
vehicles, will be retained for the present time.
    The FHWA will use the following conversion factors, as established 
by the American Society for Testing and Materials (ASTM) in its 
Standard ASTM E380, ``Standard Practice for Use of the SI International 
System of Units,'' to arrive at metric equivalent measurements: 

------------------------------------------------------------------------
               Weight                      Distance and dimensions      
------------------------------------------------------------------------
1 pound = 0.4536 kilograms.........  1 mile = 1.609 kilometers.         
1 Metric ton = 2,205 pounds........  1 foot = 0.3048 meters.            
1 Metric ton = 1,000 kilograms.....  1 inch = 25.4 millimeters.         
------------------------------------------------------------------------

Conversion and Rounding

    When converting mixed size or weight units, e.g., feet and inches, 
to the metric equivalent, reduce the measurement to the smaller unit 
before converting to metric and rounding. For example, 10 feet, 3 
inches equals 123 inches; 123 inches multiplied by 25.4 millimeter/inch 
equals 3,124.2 millimeters; round to 3120 millimeters or 3.12 meters.

Converting Part 658 to Metric Measurements

    The metric equivalent of every English unit of measurement which is 
used in 23 CFR part 658 and which applies in all States is provided in 
the following table:

                    Conversions of Weight Quantities                    
------------------------------------------------------------------------
                                                             Metric     
                       Quantity                            equivalent   
------------------------------------------------------------------------
1 lb..................................................  0.4536 kg.      
1,000 lbs.............................................  450 kg.         
20,000 lbs............................................  9,070 kg.       
34,000 lbs............................................  15,420 kg.      
80,000 lbs............................................  36,290 kg.      
------------------------------------------------------------------------


                 Conversions of Dimensional Quantities                  
------------------------------------------------------------------------
                    Quantity                         Metric equivalent  
------------------------------------------------------------------------
3 inches.........................................  76 millimeters.      
27 inches........................................  0.69 meters.         
3 feet...........................................  0.91 meters.         
40 inches........................................  1.02 meters.         
4 feet...........................................  1.22 meters.         
96 inches........................................  2.44 meters.         
102 inches.......................................  2.6 meters.*         
108 inches.......................................  2.74 meters.         
12 feet..........................................  3.66 meters.         
28 feet..........................................  8.53 meters.         
28.5 feet........................................  8.69 meters.         
34 feet..........................................  10.36 meters.        
36 feet..........................................  10.97 meters.        
41 feet..........................................  12.5 meters.         
45 feet..........................................  13.72 meters.        
48 feet..........................................  14.63 meters.        
60 feet..........................................  18.29 meters.        
65 feet..........................................  19.81 meters.        
75 feet..........................................  22.86 meters.        
------------------------------------------------------------------------
*An exception to the standard conversion process established by 23 CFR  
  658.15(a).                                                            


                           Other conversions                            
------------------------------------------------------------------------
                                                             Metric     
                       Quantity                            equivalent   
------------------------------------------------------------------------
1 mile................................................  1.61 km.        
500 pounds per inch...................................  8930 kg/m.      
------------------------------------------------------------------------

Metric Equivalent of the Federal Bridge Formula

    The Federal Bridge Formula found in 23 U.S.C. 127 is an integral 
part of the limits placed on vehicle weight. The Bridge Formula in 
English units is as follows:

TN06OC94.013

W=The maximum weight in pounds that can be carried on a group of two or 
more axles to the nearest 500 pounds.
L=The distance in feet between the outer axles of any two or more 
consecutive axles.
N=The number of axles being considered.

    Because the statute requires the use of English units to calculate 
Bridge Formula limits, a metric formula is not really possible. 
However, appendix A reproduces in English and the equivalent metric 
units the weight table generated by the Bridge Formula. The values in 
this table reflect the FHWA's policy of rounding down when calculated 
weights fall exactly halfway between 500-pound increments. Because the 
Bridge Formula is designed to protect the highway infrastructure, the 
agency has determined that this conservative policy is consistent with 
the statutory mandate.
    Congress decided to adopt the metric system nearly 20 years ago. A 
notice of proposed rulemaking would serve no purpose since conversion 
to that standard is the policy of the United States. There may be 
errors in the data published in this notice, however, and the FHWA has 
therefore established a docket to receive technical comments on these 
provisions. The interpretations will be corrected as necessary, and in 
case of omissions, consideration will be given to additional 
interpretations.

(Sec. 123, Pub. L. 95-599, 92 Stat. 2701; 23 U.S.C. 127, 141, and 
315; 49 U.S.C. 31111-31114; and 49 CFR 1.48.

    Issued on: September 30, 1994.
Rodney E. Slater,
Federal Highway Administrator.

TN06OC94.014


                    Appendix A--Permissible Gross Loads for Vehicles in Regular Operation\1\                    
                                                                                                                
 Distance in feet (L) (column 1) and meters (m) (column                                                         
     2) between extremes of any group of 2 or more        Maximum load in pounds (lb) and kilograms (kg) carried
                   consecutive axles                          on any group of 2 or more consecutive axles\2\    
                                                                                                                


                                                                                                                                                        
                                                                         Axles                3 Axles               4 Axles               5 Axles       
                       Column 1                        Column 2  ---------------------------------------------------------------------------------------
                                                                      lb         kg         lb         kg         lb         kg         lb         kg   
4....................................................       1.22     34,000     15,422  .........  .........  .........  .........  .........  .........
5....................................................       1.52     34,000     15,422  .........  .........  .........  .........  .........  .........
6....................................................       1.83     34,000     15,422  .........  .........  .........  .........  .........  .........
7....................................................       2.13     34,000     15,422  .........  .........  .........  .........  .........  .........
8....................................................       2.44     34,000     15,422     34,000     15,422  .........  .........  .........  .........
8.01.................................................       2.44     38,000     17,237     42,000     19,051  .........  .........  .........  .........
9....................................................       2.74     39,000     17,690     42,500     19,278  .........  .........  .........  .........
10...................................................       3.05     40,000     18,144     43,500     19,732  .........  .........  .........  .........
11...................................................       3.35  .........  .........     44,000     19,958  .........  .........  .........  .........
12...................................................       3.66  .........  .........     45,000     20,412     50,000     22,680  .........  .........
13...................................................       3.96  .........  .........     45,500     20,639     50,500     22,907  .........  .........
14...................................................       4.27  .........  .........     46,500     21,092     51,500     23,360  .........  .........
15...................................................       4.57  .........  .........     47,000     21,319     52,000     23,587  .........  .........
16...................................................       4.88  .........  .........     48,000     21,773     52,500     23,814     58,000     26,309
17...................................................       5.18  .........  .........     48,500     22,000     53,500     24,268     58,500     26,536
18...................................................       5.49  .........  .........     49,500     22,453     54,000     24,494     59,000     26,762
19...................................................       5.79  .........  .........     50,000     22,680     54,500     24,721     60,000     27,216
20...................................................       6.10  .........  .........     51,000     23,134     55,500     25,175     60,500     27,443
21...................................................       6.40  .........  .........     51,500     23,360     56,000     25,402     61,000     27,670
22...................................................       6.71  .........  .........     52,500     23,814     56,500     25,628     61,500     27,896
23...................................................       7.01  .........  .........     53,000     24,041     57,500     26,082     62,500     28,350
24...................................................       7.32  .........  .........     54,000     24,494     58,000     26,309     63,000     28,577
25...................................................       7.62  .........  .........     54,500     24,721     58,500     26,536     63,500     28,804
26...................................................       7.92  .........  .........     55,500     25,175     59,500     26,989     64,000     29,030
27...................................................       8.23  .........  .........     56,000     25,402     60,000     27,216     65,000     29,484
28...................................................       8.53  .........  .........     57,000     25,855     60,500     27,443     65,500     29,711
29...................................................       8.84  .........  .........     57,500     26,082     61,500     27,896     66,000     29,938
30...................................................       9.14  .........  .........     58,500     26,536     62,000     28,123     66,500     30,164
31...................................................       9.45  .........  .........     59,000     26,762     62,500     28,350     67,500     30,618
32...................................................       9.75  .........  .........     60,000     27,216     63,500     28,804     68,000     30,845
33...................................................      10.06  .........  .........  .........  .........     64,000     29,030     68,500     31,072
34...................................................      10.36  .........  .........  .........  .........     64,500     29,257     69,000     31,298
35...................................................      10.67  .........  .........  .........  .........     65,500     29,711     70,000     31,752
36...................................................      10.97  .........  .........  .........  .........     66,000     29,938     70,500     31,979
37...................................................      11.28  .........  .........  .........  .........     66,500     30,164     71,000     32,206
38...................................................      11.58  .........  .........  .........  .........     67,500     30,618     71,500     32,432
39...................................................      11.89  .........  .........  .........  .........     68,000     30,845     72,500     32,886
40...................................................      12.19  .........  .........  .........  .........     68,500     31,072     73,000     33,113
41...................................................      12.50  .........  .........  .........  .........     69,500     31,525     73,500     33,340
42...................................................      12.80  .........  .........  .........  .........     70,000     31,752     74,000     33,566
43...................................................      13.11  .........  .........  .........  .........     70,500     31,979     75,000     34,020
44...................................................      13.41  .........  .........  .........  .........     71,500     32,432     75,500     34,247
45...................................................      13.72  .........  .........  .........  .........     72,000     32,659     76,000     34,474
46...................................................      14.02  .........  .........  .........  .........     72,500     32,886     76,500     34,700
47...................................................      14.33  .........  .........  .........  .........     73,500     33,340     77,500     35,154
48...................................................      14.63  .........  .........  .........  .........     74,000     33,566     78,000     35,381
49...................................................      14.94  .........  .........  .........  .........     74,500     33,793     78,500     35,608
50...................................................      15.24  .........  .........  .........  .........     75,500     34,247     79,000     35,834
51...................................................      15.54  .........  .........  .........  .........     76,000     34,474     80,000     36,288
52...................................................      15.85  .........  .........  .........  .........     76,500     34,700     80,500     36,515
53...................................................      16.15  .........  .........  .........  .........     77,500     35,154     81,000     36,742
54...................................................      16.46  .........  .........  .........  .........     78,000     35,381     81,500     36,968
55...................................................      16.76  .........  .........  .........  .........     78,500     35,608     82,500     37,422
56...................................................      17.07  .........  .........  .........  .........     79,500     36,061     83,000     37,649
57...................................................      17.37  .........  .........  .........  .........     80,000     36,288     83,500     37,876
58...................................................      17.68  .........  .........  .........  .........  .........  .........     84,000     38,102
59...................................................      17.98  .........  .........  .........  .........  .........  .........     85,000     38,556
60...................................................      18.29  .........  .........  .........  .........  .........  .........     85,500    38,783 


--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                        6 Axles               7 Axles               8 Axles               9 Axles       
                       Column 1                        Column 2  ---------------------------------------------------------------------------------------
                                                                      lb         kg         lb         kg         lb         kg         lb         kg   
--------------------------------------------------------------------------------------------------------------------------------------------------------
61...................................................      18.59     90,500     41,051     95,500     43,319    101,000     45,814    106,500     48,308
62...................................................      18.90     91,000     41,278     96,000     43,546    101,500     46,040    107,000     48,535
63...................................................      19.20     92,000     41,731     96,500     43,772    102,000     46,267    107,500     48,762
64...................................................      19.51     92,500     41,958     97,500     44,226    102,500     46,494    108,000     48,989
65...................................................      19.81     93,000     42,185     98,000     44,453    103,000     46,721    108,500     49,216
66...................................................      20.12     93,500     42,412     98,500     44,680    103,500     46,948    109,000     49,442
67...................................................      20.42     94,000     42,638     99,000     44,906    104,500     47,401    109,500     49,669
68...................................................      20.73     95,000     43,092     99,500     45,133    105,000     47,628    110,000     49,896
69...................................................      21.03     95,500     43,319    100,000     45,360    105,500     47,855    111,000     50,350
70...................................................      21.34     96,000     43,546    101,000     45,814    106,000     48,082    111,500     50,576
71...................................................      21.64     96,500     43,772    101,500     46,040    106,500     48,308    112,000     50,803
72...................................................      21.95     97,000     43,999    102,000     46,267    107,000     48,535    112,500     51,030
73...................................................      22.25     98,000     44,453    102,500     46,494    107,500     48,762    113,000     51,257
74...................................................      22.56     98,500     44,680    103,000     46,721    108,500     49,216    113,500     51,484
75...................................................      22.86     99,000     44,906    103,500     46,948    109,000     49,442    114,000     51,710
76...................................................      23.16     99,500     45,133    104,500     47,401    109,500     49,669    114,500     51,937
77...................................................      23.47    100,000     45,360    105,000     47,628    110,000     49,896    115,500     52,391
78...................................................      23.77    101,000     45,814    105,500     47,855    110,500     50,123    116,000     52,618
79...................................................      24.08    101,500     46,040    106,000     48,082    111,000     50,350    116,500     52,844
80...................................................      24.38    102,000     46,267    106,500     48,308    111,500     50,576    117,000     53,071
81...................................................      24.69    102,500     46,494    107,000     48,535    112,500     51,030    117,500     53,298
82...................................................      24.99    103,000     46,721    108,000     48,989    113,000     51,257    118,000     53,525
83...................................................      25.30    104,000     47,174    108,500     49,216    113,500     51,484    118,500     53,752
84...................................................      25.60    104,500     47,401    109,000     49,442    114,000     51,710    119,000     53,978
85...................................................      25.91    105,000     47,628    109,500     49,669    114,500     51,937    120,000     54,432
86...................................................      26.21    105,500     47,855    110,000     49,896    115,000     52,164    120,500     54,659
87...................................................      26.52    106,000     48,082    110,500     50,123    115,500     52,391    121,000     54,886
88...................................................      26.82    107,000     48,535    111,500     50,576    116,500     52,844    121,500     55,112
89...................................................      27.13    107,500     48,762    112,000     50,803    117,000     53,071    122,000     55,339
90...................................................      27.43    108,000     48,989    112,500     51,030    117,500     53,298    122,500     55,566
91...................................................      27.74    108,500     49,216    113,000     51,257    118,000     53,525    123,000     55,793
92...................................................      28.04    109,000     49,442    113,500     51,484    118,500     53,752    123,500     56,020
93...................................................      28.35    110,000     49,896    114,000     51,710    119,000     53,978    124,500     56,473
94...................................................      28.65    110,500     50,123    115,000     52,164    119,500     54,205    125,000     56,700
95...................................................      28.96    111,000     50,350    115,500     52,391    120,500     54,659    125,500     56,927
96...................................................      29.26    111,500     50,576    116,000     52,617    121,000     54,886    126,000     57,154
97...................................................      29.57    112,000     50,803    116,500     52,844    121,500     55,112    126,500     57,380
98...................................................      29.87    113,000     51,257    117,000     53,071    122,000     55,339    127,000     57,607
99...................................................      30.18    113,500     51,484    117,500     53,298    122,500     55,566    127,500     57,834
100..................................................      30.48    114,000     51,710    118,500     53,752    123,000     55,793    128,000     58,061
101..................................................      30.78    114,500     51,937    119,000     53,978    123,500     56,020    129,000     58,514
102..................................................      31.09    115,000     52,164    119,500     54,205    124,500     56,473    129,500     58,741
103..................................................      31.39    116,000     52,618    120,000     54,432    125,000     56,700    130,000     58,968
104..................................................      31.70    116,500     52,844    120,500     54,659    125,500     56,927    130,500     59,195
105..................................................      32.00    117,000     53,071    121,000     54,886    126,000     57,154    131,000     59,422
106..................................................      32.31    117,500     53,298    122,000     55,339    126,500     57,380    131,500     59,648
107..................................................      32.61    118,000     53,525    122,500     55,566    127,000     57,607    132,000     59,875
108..................................................      32.92    119,000     53,978    123,000     55,793    127,500     57,834    132,500     60,102
109..................................................      33.22    119,500     54,205    123,500     56,020    128,500     58,288    133,500     60,556
110..................................................      33.53    120,000     54,432    124,000     56,246    129,000     58,514    134,000     60,782
111..................................................      33.83    120,500     54,659    124,500     56,473    129,500     58,741    134,500     61,009
112..................................................      34.14    121,000     54,886    125,500     56,927    130,000     58,968    135,000     61,236
113..................................................      34.44    122,000     55,339    126,000     57,154    130,500     59,195    135,500     61,463
114..................................................      34.75    122,500     55,566    126,500     57,380    131,000     59,422    136,000     61,690
115..................................................      35.05    123,000     55,793    127,000     57,607    131,500     59,648    136,500     61,916
116..................................................      35.36    123,500     56,020    127,500     57,834    132,500     60,102    137,000     62,143
117..................................................      35.66    124,000     56,246    128,000     58,061    133,000     60,329    138,000     62,597
118..................................................      35.97    125,000     56,700    129,000     58,514    133,500     60,556    138,500     62,824
119..................................................      36.27    125,500     56,927    129,500     58,741    134,000     60,782    139,000     63,050
120..................................................      36.58    126,000     57,154    130,000     58,968    134,500     61,009    139,500     63,277
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\The permissible loads are computed to the nearest 500 pounds as required by statute.                                                                 
\2\The following loaded vehicle must not operate over H15-44 bridges: 3-S2 (5-axle) with wheelbase less than 38 feet (11.58 meters); 2-S1-2 (5-axle)    
  with wheelbase less than 45 feet (13.72 meters); 3-3 (6-axle) with wheelbase less than 45 feet; and 7-, 8-, and 9-axle vehicles regardless of         
  wheelbase.                                                                                                                                            

[FR Doc. 94-24747 Filed 10-5-94; 8:45 am]
BILLING CODE 4910-22-P