comprehensive truck size and weight study volume 3 chapter 3 · growth rate for rail car miles of...

CHAPTER III

Scenario Descriptions

HPTS

Base Case versus Uniformity

H.R. 551

North American Trade

Longer CombinationVehicles Nationwide

TriplesNationwide

Figure III-1. Illustrative Truck Size and WeightScenarios

Introduction

The outreach processdescribed in Chapter Iidentified a number of trucksize and weight (TS&W)issues of broad interest. Those issues wereincorporated into a set ofillustrative scenarios thatreflected changes in variousFederal TS&W regulations. Potential impacts of thosescenarios were analyzedagainst base case impacts ofmaintaining current FederalTS&W regulations. FigureIII-1 shows the fiveillustrative scenariosanalyzed in this study:• Uniformity• North American Trade• LCVs Nationwide• H.R. 551• Triples Nationwide

The H.R. 551 and TriplesNationwide scenarios aresubsets of the UniformityScenario and the LCVsNationwide Scenariorespectively. They areindented in Figure III-1 toshow this relationship.

In addition, a Base Case wasestablished against which theillustrative scenarios arecompared.

These scenarios should notbe construed as beingindicative of the Departmentof Transportation’s (DOT’s)

disposition toward aparticular TS&W policyoption. Rather, they wereselected to illustrate potentialimpacts across a broad rangeof possible TS&W changes.

This chapter describes theillustrative scenarios indetail. The scenariosaddress a wide range ofissues, and were specified toestimate the upper range ofimpacts that might beexpected from various typesof TS&W policy changes. Under different assumptionsabout the vehicle weights anddimensions that might beallowed under each scenarioor the networks of highwaysthat might be available forcertain vehicles, the estimated impacts might belower.

Base Case

The Base Case provides apoint of reference for thescenario analyses. Itrepresents the motor carrierand rail industries in the year2000, absent any significantchanges in Federal or StateTS&W limits.

Introduction

The Base Case retains allfeatures of current law.Federal size limits [102-inchmaximum vehicle width, 48-foot minimum semitrailerlength limits or longer ifgrandfathered (see Figure III-2), and 28-foot minimumtrailer length limits fordouble-trailer combinations]remain on the InterstateSystem and other highways

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on the NN. Operation ofcommercial motor vehiclecombinations with two ormore cargo-carrying units onthe NN are restricted tolength limits in effect on June1, 1991.

The current Federal weightlimits on Interstate highwaysand bridges [20,000-poundsingle-axle, 34,000-poundtandem-axle, 80,000-poundgross vehicle weight (GVW)cap, and Federal BridgeFormula (FBF)] continue, asdo existing grandfather rights. Operation of LCVs on theInterstate Highway System, isrestricted by State law ineffect as of June 1, 1991.

The analysis year for thestudy is 2000. Projections ofthe truck fleet and truck VMTare based on trends from1994, the base year for boththis study and the 1997Federal Highway CostAllocation (HCA) Study. Based on a review of manystudies, the fleet and VMTwere projected to increase atan annual rate of 2.6 percenta year between 1994 and2000.

The Surface Transportation Assistance Act of 1982mandated minimum semitrailer lengths of 48 feet. However, in those States having semitrailer lengths longerthan 48 feet, these lengths became the (grandfathered)minimum.

Alabama 53'6" Montana 53'0"

Alaska 48'0" Nebraska 53'0"

Arizona 57'6" Nevada 53'0"

Arkansas 53'6" New Hampshire 48'0"

California 48'0" * New Jersey 48'0"

Colorado 57'4" * New Mexico 57'6"

Connecticut 48'0" New York 48'0"

Delaware 53'0" North Carolina 48'0"

District of Columbia 48'0" North Dakota 53'0"

Florida 48'0" Ohio 53'0"

Georgia 48'0" Oklahoma 59'6"

Hawaii 48'0" Oregon 53'0"

Idaho 48'0" Pennsylvania 53'0"

Illinois 53'0" Puerto Rico 48'0"

Indiana 48'6" * Rhode Island 48'6"

Iowa 53'0" South Carolina 48'0"

Kansas 57'6" South Dakota 53'0"

Kentucky 53'0" Tennessee 50'0"

Louisiana 59'6" Texas 59'0"

Maine 48'0" Utah 48'0"

Maryland 48'0" Vermont 48'0"

Massachusetts 48'0" Virginia 48'0"

Michigan 48'0" Washington 48'0"

Minnesota 48'0"" West Virginia 48'0"

Mississippi 53'0" Wisconsin 48'0"

Missouri 53'0" Wyoming 57'4"

* King pin regulation appliesSource: 23CFR 658, Appendix B

Figure III-2. State Semitrailer Lengths on the NN

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Characteristics of the BaseCase commercial vehiclefleet are consistent with thosein the HCA Study. The HCAStudy provides VMT forselected vehicle classesdisaggregated by weightgroup, highway functionalclass, and State.

The rail base case wasprojected to the year 2000using the “International andDomestic Freight Trends”report by DRI/McGraw-Hill

and Reebie Associates. Thisreport projects an annualgrowth rate for rail car milesof 2.2 percent to the year2000. Rail intermodal carmiles were projected to growat 5.5 percent per year.

Scenario Specifications

The number of trucksestimated to be in the truckfleet and the extent of theiruse in 1994 and 2000 areshown in Table III-1 Only

those trucks likely to beimpacted by changes inTS&W limits were explicitlyconsidered in the study. Table III-2 showscharacteristics of how thosevehicles are currently used.

The impact that base year(1994) truck operationswould have on infrastructurecosts (bridge, pavement,roadway geometry), safety,traffic operations, energy andenvironment, shipper costs,

Vehicle Class

Number of Vehicles Vehicle Miles Traveled(in millions)

1994 2000PercentShare of

Truck Fleet1994 2000

PercentShare of

Truck Fleet

3-axle single unit truck 594,197 693,130 24.9 8,322 9,707 7.6

4-axle or more single unit truck 106,162 123,838 4.4 2,480 2,893 2.2

3-axle tractor-semitrailer 101,217 118,069 4.2 2,733 3,188 2.5


5-axle tractor-semitrailer 1,027,760 1,198,880 43.0 71,920 83,895 65.4


7-axle tractor-semitrailer 8,972 10,466 0.3 468 546 0.4

3- or 4- axle truck-trailer 87,384 101,934 3.6 1,098 1,280 1.0

5-axle truck-trailer 51,933 60,579 2.2 1,590 1,855 1.4

6-axle or more truck-trailer 11,635 13,572 0.5 432 503 0.4

5-axle double 51,710 60,319 2.2 4,512 5,263 4.1

6-axle double 7,609 8,876 0.3 627 731 0.6

7-axle double 7,887 9,201 0.3 542 632 0.5

8-axle or more double 9,319 10,871 0.4 650 759 0.6

Triples 1,203 1,404 0.0 108 126 0.1

Table 1. Base Year and Forecast Commercial Vehicle Fleet and Travel

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and rail industrycompetitiveness wascompared to the impact thattruck operations would havein 2000 if no significantTS&W policy changesoccurred. This comparisonshows how changesestimated to occur between1994 and 2000, essentiallydue to growth in traveldemand, would compare toimpacts expected to resultfrom TS&W policy changesin the year 2000 Base Case.

The Vehicles

The truck configurationsanalyzed in this study andtheir current use in terms ofareas of operation, length ofhaul, types of commoditiescarried, and highways usedare described in Table III-2. The maximum weights anddimensions allowed for theseconfigurations in each Statehave been modeled bydividing the country into sixregions (see Figure III-3) andselecting the median weightsand dimensions for theconfigurations from amongthe States in the region (seeTables II-2 to II-4 in VolumeII). The regions are: North-east (14 States), Southeast (9States), Midwest (9 States),South Central (2 States),West (14 States), andCalifornia. Alaska andHawaii have not beenmodeled as data were notavailable and they depend on

marine links for connection tothe major U.S. truck and railnetworks.

The Networks

Single unit trucks (SUTs) andshorter single-trailer truckcombinations have access tovirtually all highways. “STAA” double trailercombinations andcombinations with 48-footsemitrailers operate on a200,000-mile networkdesignated under the SurfaceTransportation AssistanceAct of 1982 (STAA). Combinations with semi-trailers longer than 48 feetgenerally must comply withState routing requirementsand provisions to minimizevehicle offtracking.

Access Provisions

STAA combinations(vehicles authorized underthe STAA legislation) aregiven access to terminals(points of loading andunloading) and servicefacilities (for food, fuel, rest,and repair) under Stateprovisions that followFederal regulations called forby the STAA. All Statesmust allow access for STAAvehicles from and to the NNvia any routes they can safelynegotiate.

Uniformity Scenario

A myriad of TS&Wregulations affects U.S.trucking operations. Thesedifferences reflect variationsin economic and industrialactivities, freight flowcharacteristics, infrastructuredesign and maintenancephilosophies, systemcondition, traffic densitiesand modal options.Many believe that grandfatherrights create enforcementproblems. Also, there isconcern that vehicles withpotentially damaging axleweights may be allowed tooperate under grandfatherprovisions. Equity issues arealso important in that carriersin one State are affordedvaluable operating privilegesthat are denied to shippersand carriers (and theindustries they represent) inneighboring States. Finally,safety and congestion issuesrelated to large trucks are ofincreasing concern to auto, aswell as truck drivers. Thisscenario is designed to testthe impact of removing thegrandfather provisions and

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applying Federal weightlimits to all highways on theNN. States that currentlyhave higher weight limits onnon-Interstate portions of the

NN would have to lower those limits to the Federallimit, and the few States thathave lower weight limits on non-Interstate portions of the

NN would have to raise theirlimits.

ConfigurationType

Numberof Axles

CommonMaximumWeight (Pounds)

Current Use

Single-UnitTruck

3 50,000to

65,000

Single-unit trucks (SUT) are the most commonly usedtrucks. They are used extensively in all urban areas forshort hauls. Three-axle SUTs are used to carry heavyloads of materials and goods in lieu of the far more

common two-axle SUT.

4 or more 62,000to

70,000

SUTs with four or more axles are used to carry theheaviest of the construction and building materials inurban areas. They are also used for waste removal.

Semitrailer 5 80,000to

99,000

Most used combination vehicle. It is used extensively forlong and short hauls in all urban and rural areas to carryand distribute all types of materials, commodities, and

goods.

6 or more 80,000to

100,000

Used to haul heavier materials, commodities, and goodsfor hauls longer than those of the four-axle SUT.

STAADouble

5, 6 80,000 Most common multitrailer combination. Used for less-than-truckload (LTL) freight mostly on rural freeways

between LTL freight terminals.

B-Train Double

8 105,500to

137,800

Some use in the northern plains States and the Northwest. Mostly used in flatbed trailer operations and for liquid

bulk hauls.

RockyMountainDouble

7 105,500to

129,000

Used on turnpikes in Florida, the Northeast, and Midwestand in the Northern Plains and Northwest in all types ofmotor carrier operations, but most often it is used for

bulk hauls.

TurnpikeDouble

9 105,500to

147,000

Used on turnpikes in Florida, the Northeast, and Midwestand on freeways in the Northern Plains and Northwest for

mostly truckload operations.

Table 2. Current Use of Scenario Vehicles

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Figure III-3. Truck Size and Weight Analysis Regions

Historical Perspective

Grandfather Provisions

Current TS&W law includesthree grandfather provisionswhich allow higher StateTS&W limits than thoseindicated in the Federalregulations. The first,adopted in 1956, isconcerned with axle weightsand gross weights.

The second, enacted in 1975,deals principally with bridgeformulas and axle spacing tables. The most recentgrandfather clause was

created in 1991 and focuseson double-trailer or triple-trailer combination vehiclesoperating at weights greaterthan 80,000 pounds.

The Transportation EquityAct for the 21st Century didnot change existinggrandfather provisions. It didhowever, establish newgrandfather dates, by specialexceptions to the rules, forMaine and New Hampshire.

The Federal-Aid HighwayAct of 1956 imposed axleand GVW limits for trucksoperating on the Interstate

System. Because some Statesalready allowed motorcarrier operations at higheraxle or gross weights, agrandfather clause wasincluded in the legislation topreclude a rollback in thoseStates.

The Federal-Aid HighwayAmendments of 1974(enacted in 1975) mandatedthat maximum weights foraxle groups would bedetermined by a formuladesigned to protect bridges. A new grandfather provisionwas included in the 1975legislation that allowed

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States to continue to usealternative bridge formulasor axle spacing tables thatallowed weights greater thanthe new Federal formula. The grandfather provisions inthe 1956 and 1975legislations have beeninterpreted to includeexemptions for bothpermitted and non-permittedvehicles. Figure III-4explains divisible and non-divisible permittingregulations and practices.

The Intermodal SurfaceTransportation Efficiency Act(ISTEA) of 1991 froze theweight, length, and routes ofLCVs operating on theInterstate System as well asthe lengths and routes ofcommercial vehiclecombinations with two ormore cargo carrying unitsoperating on the NN. Withthis legislation, operations of LCVs, defined as anycombination of a truck tractorand two or more trailers orsemitrailers which operate onthe Interstate System at aGVW greater than 80,000pounds, are restricted to thetypes of vehicles and routesin use on or before June 1,1991.

Uniformity Legislation

The STAA of 1982 included

provisions that created moreuniform TS&W standardsnationwide. The actprovided that Federal-aidfunds would be withheldfrom States that enactedmaximum weight limits lowerthan the maximums specifiedby Federal law. These limitsare 20,000 pounds for singleaxles, 34,000 pounds fortandem axles, and GVWsdetermined by the FBF,subject to an 80,000-poundmaximum limit.

It raised the maximumvehicle width limit from 96inches to 102 inches, and, asamended, applied this limit tothe NN, subsequentlydesignated by the FederalHighway Administration andStates, as required by theSTAA of 1982.

It also set minimum lengthlimits of 48 feet (or longer ifgrandfathered) for semi-trailers in a single-trailercombination and 28 feet fortrailers in a double-trailercombination. It required theStates to allow trailers theselengths or longer on their NNroutes. However, the Statesare permitted to allow longertrailers. The STAA alsorequired the States to providereasonable access for theseSTAA vehicles between theNN and terminals and servicefacilities.


This scenario examines theimpact of establishing Statetruck weight limits at thecurrent Federal limits for alltrucks operating on the NN. All State grandfather rightswould be eliminated. Non- divisible load permits wouldcontinue. Off the NN,vehicles would continue tooperate at current State-regulated weights.

The Vehicles

Under the UniformityScenario, single unit trucks(SUTs) were analyzed asfollows: (1) the maximumGVW for three-axle trucks would be 51,000 pounds and(2) the maximum GVW forfour-axle trucks would bereduced to 56,500 pounds. These weights assume shortwheelbase vehicles, withweights determined by FBF. This assumption mayoverstate the impact of thisscenario because longerwheelbase vehicles couldcontinue to operate at higherweights. Also, manufacturers wouldprobably build longer wheelbase vehicles to

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States grant special permits exempting eligible motor carrier operations from Federal grossvehicle weight (GVW), axle weight and bridge formula limits. Federal law authorizes allStates to issue permits for non-divisible loads, and 21 States allow the operation ofoverweight divisible loads under grandfathered special permits. The interpretation ofdivisible versus non-divisible loads, however, varies from State to State.

In 1994, the Federal Highway Administration defined a non-divisible load or vehicle as onethat exceeds “applicable length or weight limits which, if separated into smaller loads orvehicles, would (1) compromise the intended use of the vehicle . . . , (2) destroy the value ofthe load or vehicle . . . , or (3) require more than eight work hours to dismantle usingappropriate equipment. . . .” (Part 658 of Title 23, Code of Federal Regulations).

However, because the definition is not commodity-specific and because States are left tointerpret the definition in application, there is ambiguity about what loads qualify as non-divisible and, therefore, may be treated specially. For example, some States considerequipment that has been spot-welded to be divisible, while other States categorize suchequipment as non-divisible. Further the burden of proof as to the effort required fordismantling lies with the applicant, and there is substantial variation between States as to theamount of proof required to demonstrate that dismantling a load requires more than eighthours of work.

The weights that can be allowed under non-divisible load permits are not restricted byFederal regulation. These permits are usually issued for a specific route, often for anindividual trip. They may be issued for very high GVWs, but the number of axles requiredgenerally goes up with GVW. Examples of non-divisible loads include manufactured homes,boats, cranes, mining equipment, major pieces of machinery, construction equipment, andpower plant components.

In contrast to non-divisible loads, divisible load permits apply to all other material. They aregenerally issued for regular operations at a specified GVW, usually on a quarterly or annualbasis. These permits apply to either entire systems or specified roads and often includerestrictions concerning seasons and weather extremes. About half of the States have claimedgrandfather clause authority to issue divisible load permits for operations over 80,000 poundsGVW on the Interstate.

Many States allow divisible load permits for specific commodities that are important to theeconomic health of their State. It is often argued, however, that exemptions are also instituted

Figure III-4. Divisible and Non-divisible Load Permits

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operate at higher grossweights.

All SUT unit andcombination vehicle typeswould be affected becauseStates would not havegrandfather rights to allowoperation of trucks withGVWs or axle loadsgreater than federally setlimits. For example, aseven-axle truck-trailercombination, currentlyallowed under grandfatherprovisions in some Statesat a GVW of 105,500pounds would be restrictedto an 80,000-pound limit on

the NN. In those rare caseswhere weight limits arelower on the NN ascompared to InterstateFederal limits, thisscenario assumes that theweights would beincreased. However, itshould be noted that themodeling capabilityunderlying the study is notsufficiently sensitive to thisparticular case.

The new limits wouldprohibit all LCVs fromoperating above 80,000pounds, rendering themimpractical for weight

limited loads but not cube-limited loads. Forexample, a seven-axletriple-trailer combinationcurrently operating undergrandfather provisions, at115,000 pounds, would berequired to operate underthe 80,000-pound limit.

The Network

The analysis networkassumed for testing thisscenario was the NN.

Access Provisions

Access provisions are

SU3

3-S2

2-S1-2

Three-axle single unit51,000 pounds (maximum)

Five-axle semitrailer combination80,000 pounds (maximum)

Five-axle STAA double-trailer combination80,000 pounds (maximum)

Main Feature

� Extend Federal grossvehicle weight limits onStates beyond theInterstate to NationalNetwork (eliminatesgrandfather provisions)

Available Highways

� National Network for LargeTrucks

Access Provisions

� Current Federal and Stateprovisions

Figure III-5. Uniformity Scenario

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assumed unchanged fromthe Base Case.

North AmericanTrade Scenarios

The North American TradeScenarios are focused ontrade among the NorthAmerican trading partners. Such trade could befacilitated by allowing theoperation of six-axletractor-semitrailercombinations at 97,000pounds, which is sufficientto carry a container loadedto the InternationalStandard Organization(ISO) limit on Interstatehighways without a specialpermit (as would berequired under today’sregulations).

To provide for theoperation of a six-axletractor semitrailercombination at 97,000pounds, a tridem weightlimit of 51,000 pounds wastested. Currently, theweight allowed on athree-axle group is limitedby the FBF. Introduction ofa tridem weight limitwould potentially impactthe four-axle SUT as wellas the eight-axle B-traindouble combination.

While the 97,000 poundsix-axle tractor semitrailer

combination and theeight-axle B-traincombination would havebenefits in terms of trade, atridem-axle weight limit of51,000 pounds would haveadverse bridge and safetyimpacts, especially for theshort wheelbase 4-axleSUT. The three scenariovehicles were also testedwith tridem axle weightlimits of 44,000 pounds. A 44,000-pound tridemaxle weight limit couldprovide a productivityincrease for the scenariovehicles while limitingvehicle stability andcontrol as well asinfrastructure impacts.

A tridem-axle weight limitof 44,000 pounds wouldassume 20,000 pounds onthe steering axle for anSUT, allowing up to 64,000pounds GVW. For asix-axle semitrailercombination, 12,000pounds is assumed for thesteering axle and 34,000pounds on the drivetandem, which would allowup to 90,000 pounds GVWfor this configuration. Forthe eight-axle B-traincombination operating at aGVW of 124,000 pounds,12,000-pounds is assumedon the steering axle, 34,000pounds on the drive axle,44,000 pounds on thetridem axle of the firsttrailer and 34,000 pounds

on the tandem axle of thesecond trailer.

A tridem-axle weight limitof 51,000 pounds wouldassume 20,000 pounds onthe steering axle for anSUT, allowing up to 71,000pounds GVW. For asix-axle semitrailercombination, 12,000pounds is assumed for thesteering axle and 34,000pounds on the drivetandem, which would allowup to 97,000 pounds GVWfor this configuration. Foran eight-axle B-traincombination operating at aGVW of 131,000 pounds,12,000 pounds is assumedon the steering axle, 34,000pounds on the drive axle,51,000 pounds on thetridem axle of the firsttrailer and 34,000 poundson the tandem axle of thesecond trailer.

Background: PolicyRelated Issues

North AmericanTrade

The United States, Canada,and Mexico signed theNorth American Free Trade

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Agreement (NAFTA) onDecember 17, 1992. Among other objectives,NAFTA is intended topromote competitiveness inthe global economy and toprovide for greaterefficiency in transportationamong the North Americantrading partners. Byeliminating unnecessarybarriers, the internationaltransport of goods andservices will be moreefficient.

Figure III-6 compares thevehicle mix of theCanadian, American, andMexican commercialvehicle fleets. The six-axletractor semitrailerconfiguration is widelyused in both Canada andMexico. This vehicle ispractical in Canada andMexico because they havetridem-axle weight limitsfor a 12-foot spread thatare considerably higherthan the U.S. Federal limits(see Table III-3). TheCanadian tridem-axleweight limit ranges from46,297 pounds to 52,911pounds, depending on howfar apart the axles arespread. Mexico’s tridem-axle weight limit is 49,604pounds. Unlike Canada

and Mexico whichestablish tridem-axleweight limits by regulation,the U.S. does not legislate atridem limit, rather it isspecified by the FBF.

There are also significantdifferences in the single-and tandem-axle weightlimits among the UnitedStates, Canada and Mexico. Table III-4 comparessingle- and tandem-axleweight limits in the threecountries. The UnitedStates and Canada havevery similar weight limitsfor single axles. Mexico,however, is 10 percenthigher for tandem-traileraxles and 20 percent higherfor tandem drive axles thanits NAFTA partners. In thecase of tandem axles, thereis an almost 9,000-pounddifference betweenMexico’s limit of 42,990pounds for a truck or truck-tractor tandem-axle and theU.S. Federal limit of34,000 pounds. Canadahas an intermediate limit of37,479 pounds.

This scenario tests theimpact of allowing the six-axle tractor semitrailer atweights of up to 90,000

pounds (assuming a44,000-pound tridem-axleweight limit) or 97,000pounds (assuming a51,000-pound tridem-axle weight limit). This wouldbe accomplished byallowing a higher tridem-axle weight limit andraising the maximum GVWlimit.

InternationalContainer Traffic

International containers area significant and growingfeature of contemporaryfreight transportation. Overthe 10-year period between1987 and 1996, worldwidecontainer port traffic grew124 percent. In the UnitedStates, containermovements grew 62percent during the sameperiod of time (see TableIII-5).

An international containerenters the United Statesthrough a marine port and isusually transported to a railterminal or its finaldestination via truck. These containers can causea vehicle to exceed the Federal axle and/or vehicleweight limits. When

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Canada United States MexicoTruck Configuration

15.3%2.3% 4.9%SU3

8.3%9.7% 35.5%SU2

1.6%2-S1

5.5%2-S2

42.2%51.0% 35.2%3-S2

3.0%18.5% 37.3%3-S3

2.7%2-S1-2

0.3%5.2%

0.4% 2.5%3-S2-4

5.3%3-S2-S2

7.9%3-S3-S2

0.1%Other Configurations 3.9% 1.4%

3-S2-2

Figure III-6. Comparative Fleet Profiles -- Canada, United States, and Mexico

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Axle Set CanadaUnited States

MexicoFederal State Max*

8 feet 46,297 34,000 44,000 49,604

8+ feet 46,297 42,000 58,400 49,604

10 feet 50,706 43,500 58,400 49,604

12 feet 52,911 45,000 59,400 49,604

* Grandfathered weights

Table III-3. Tridem Axle Weight Limits at Various Axle Spacings

Axle Set CanadaUnited States

MexicoFederal State Max*

Steering Axle 12,125 - 13,000 14,330

Single Trailer Axle 20,062 20,000 22,500 22,046

Single Drive Axle 20,062 20,000 22,500 24,251

Tandem Trailer Axle 37,379 34,000 44,000 39,683

Table III-4. Maximum Single and Tandem Axle Weight Limits – Canada, United States, Mexico

containers, particularly 40-foot containers, are loadedto the weight limitsestablished by theISO—the principalinternational agency thatsets standards forcontainers—they aregenerally too heavy fortrucks governed by U.S.weight limits. Many of theNAFTA and EuropeanCommunity countries allowhigher weights than theUnited States. isdemonstrated in Table

III-6.

A 20-foot marine container can be loaded to a grossweight of 44,800 pounds byISO standards and maycause a bridge formulaviolation in the UnitedStates. A 40-foot containercan be loaded up to an ISOweight of 67,200 poundsand may cause U.S. axle,bridge and gross weightlimits to be violated.

The Federal Highway

Administration allows, atState discretion, sealedshipping containers movingin international commerceto be carried at GVWs over80,000 pounds under non-divisible load permits (seeFigure III-7). However,this arrangement furtherexacerbates the variabilityin U.S. weight limits. Thiscreates difficulties forforeign shippers that maynot be

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Year US Ports World

1987 14,048 65,844

1988 15,252 73,810

1989 15,922 79,816

1990 16,651 85,957

1991 17,348 93,108

1992 18,627 102,906

1993 19,176 112,439

1994 20,230 128,320

1995 21,347 135,000

1996 22,788 147,348

Source: Containerization International, Yearbook, 1984-1997.

Thousands of Twenty-foot equivalent units

Table III-5. Container Port Traffic

The Federal Highway Administration made a policydecision in the early 1980's to allow goods transported ininternational containers to be treated as non-divisibleloads. Not all States utilize this provision. Some Statesrequire that U.S. Customs service container seals be brokenand a portion of the contents be removed when overweightcontainers are detected.

Figure III-7. Non-divisible Load Permits forInternational Containers

familiar with the variancein gross vehicle and axle load limits from State toState.

Four-Axle StraightTrucks

A tridem-axle weight limitsuch as assumed in thisscenario could also benefitshort-wheelbase vehiclessuch as dump, refuse, readymix concrete, farm andconstruction vehicles. Evidence indicates thatFBF is overly conservativefor short-wheelbasevehicles.

Tridem-axle weight limitsof 44,000 pounds and51,000 pounds are tested

for four-axle SUTs. Although the new limitsprovide for only somewhathigher payloads relative towhat can be carried today,these short wheelbase truckoperations would be able tocarry the weight on a muchshorter wheelbase withoutexcessive infrastructure

impacts, particularly forbridges. As expected, thetridem-axle weight limit of44,000 pounds isrelatively moreinfrastructure friendly thanwould be the 51,000-poundlimit.

It should be noted that, inmany States, these SUTshave grandfathered limitsabove the Federal limits.For example in Marylandand the District ofColumbia, three-axle dumptrucks with a specialregistration permit mayoperate at weights up to65,000 pounds regardlessof their wheelbase. In theEastern coal producingStates, trucks for haulingcoal generally are allowedto operate legally ondesignated highways orwith a permit at weightsabove the Federal limits.

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ConfigurationWeight

Container Plus Cargo (pounds)

20-footContainers

Which may beLegally

Transported

40-footContainers

Which may beLegally

Transported

United States(without permit)

Five-Axle Semitrailer 80,000 1 0

Six-Axle Semitrailer 80,000 1 0

Canada Five-Axle Semitrailer 87,000 1 0


Eight-Axle B-TrainDouble

137,800 1 1

Mexico Five-Axle Semitrailer 97,000 1 1


Nine-Axle Double 146,600 2 1

EuropeanCommunity

Five-Axle Truck Trailer 88,200 1 0

Five-Axle Semitrailer 97,000 1 1


Table 6. International Standards Organization Container Capacity


The Vehicles

Figure III-8 summarizesassumptions in the NorthAmerican Trade Scenario. The scenario tests theimpact of introducingtridem-axle weight limitsof 44,000 pounds and51,000 pounds. Theselimits are applied to thefour-axle SUT, the eight-axle B-train doublecombination and the six-axle semitrailercombination. The tridem-axle group has nine feetbetween the first and lastaxle in the group. If the

axles were to be spreadmore than this, pavementwear would increase whilebridge stress woulddecrease. Conversely, ifthe nine feet wereshortened, bridge stresswould increase, whilepavement wear woulddecrease.

The four-axle SUT with a44,000-pound tridem-axleweight limit would be allowed to operate at amaximum GVW of 64,000pounds and with a 51,000-pound tridem-axle weightlimit, at 71,000 poundsGVW.

The eight-axle doubletrailer combination isassumed to operate withtwo 33-foot trailers. Thisvehicle, operating atweights in excess of 80,000pounds, would most likelyoperate with a “B-train”connection (see Chapter 8on Safety Impacts). Thesevehicles are assumed tooperate at weights of124,000 pounds GVW witha 44,000-pound tridem-axle weight limit, and131,000 pounds GVW witha 51,000-pound tridem-axle weight limit.

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The maximum GVWallowed for a six-axlesemitrailer would increaseto 90,000 pounds or 97,000pounds with tridem-axleweight limits of 4,000pounds or 51,000 pounds,respectively.

The Network

The analysis network forthe six-axle tractorsemitrailer and the eight-axle B-train double is theNN. Rocky MountainDoubles (RMDs) and

Turnpike Doubles (TPDs)are assumed to operate ontheir current routes.However, for analyticalpurposes, the trips forRMDs and TPDs have beenrouted through that portionof the 42,500-mile long-doubles network which isavailable in the 14westernmost States,excluding Texas, NewMexico, California, Alaskaand Hawaii. For triples,the roadway network that ismodeled is the “LCVregion” of the 65,000-mile

network in the same States. For analysis purposes, theshort-haul SUTs are notmodeled using the studynetworks. In actualpractice, these vehiclesmay travel anywhere,without restrictions. Amore complete discussionof the analytical approachis contained in Chapter IV.

Access Provisions

The scenario assumesaccess provisions as in theBase Case, which impliesaccess for eight-axle B-train combinations (with33-foot trailers) to andfrom the NN.

Longer CombinationVehicles Nationwide

Scenario

The ISTEA of 1991, whichresponded to publicconcerns regarding thesafety of LCVs as well asconcerns regarding railcompetitiveness, includedlanguage to prevent theexpansion of LCVs intoStates that did not permitthem before June 1, 1991(see Figure III-9).

The LCV Nationwide

Four-axle single unit truck64,000 pounds or 71,000pounds maximum weight

Six-axle tractor-semitrailer90,000 pounds or 97,000pounds maximum weight

Eight-axle B-train double124,000 pounds or 131,000pounds maximum weight

Main Features

• Combination vehicles widely used in Canada and Mexico

• Introduces tridem-axle weight limits

Available Highways

• Current National Network for STAA vehicles

Access Provisions

• Current Federal and State provisions

Figure III-8. North American Trade Scenarios

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The Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991 imposed a freeze onStates to restrict the operation of Longer Combination Vehicles (LCVs) on the Interstate Systemto the type of vehicles in use on or before June 1, 1991. The ISTEA defined an LCV as acombination of a tractor and two or more trailing units weighing more than 80,000 pounds thatoperates on the Interstate. This freeze was continued with the Transportation Equity Act for the21st Century.

In addition to freezing the weights, lengths and routes of LCVs on the Interstate System, ISTEAfroze the lengths and routes of commercial motor vehicles (CMVs) having two or more cargounits on the National Network for Large Trucks. A CMV is a motor vehicle designed or regularlyused for carrying freight, or merchandise, whether loaded or empty.

Because of the freeze, States that did not allow LCV operations prior to June 1, 1991 areprecluded from allowing them or from lifting restrictions that governed LCV operations as of thatdate. Such restrictions may include route-, vehicle- and driver- specific requirements.

Figure III-9. The ISTEA Longer Combination Vehicle Freeze

Scenario explores theimpact of lifting the ISTEAfreeze. New Federal limitswould be established and anetwork of highways uponwhich these vehicles wouldbe allowed to operatewould be designated.

Figure III-10 illustrates thecommon LCVcombinations: the RMD,the TPD, and the triple-trailer combination. Adiagram of the eight-axleB-train double is alsoprovided, although thisvehicle, given currentTS&W laws, is far lesscommon than the otherLCVs. The figure alsoprovides, for comparison,typical non-LCV vehicles.

The reader will note that atractor, twin 28-foot trailercombination weighing lessthan or equal to 80,000pounds is not considered anLCV. This vehicle, theSTAA double (sometimesreferred to as a Westerndouble), is allowed tooperate in all States and in1994 accounted forapproximately 2.5 percentof all truck combinationsand 4.5 percent of all truckcombination VMT.

Figure III-11 illustrates thatLCV usage is a regionalphenomenon. Of the 21States that allow theoperation of LCVs, all butfive are west of theMississippi River. Some

of the eastern turnpikeStates (e.g., those allowingLCV operations only onturnpike facilities) haveallowed LCVs for about 35years. Some westernStates have permitted LCVsfor fewer than 15 years.

LCV operations aregenerally controlledthrough special divisibleload permits. (See FigureIII-12). These permitstypically, but not always,include limitations specificto LCVs and may dictateequipment maintenance

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Conventional Combination Vehicles

5-Axle Tractor Semi-Trailer 6Axle Tractor Semi-Trailer

STAA or “Western” Double

Longer Combination Vehicles (LCVs)

Turnpike DoubleRocky Mountain Double

8-Axle B-Train Double Trailer Combination

Triple Trailer Combination

Figure III-10. Comparison of Longer Combination Vehicles With Conventional Trucks

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States Allowing LCVs* States Allowing Triples

States Allowing Turnpike Doubles States Allowing Rocky Mountain Doubles

Figure III-11. States Allowing Various Longer Combination Vehicles

practices, driverqualifications, and routeselection, among otherfactors.

Most State LCVrestrictions also includelength and weightprovisions. In the majorityof LCV States, maximumvehicle lengths for LCVsare between 110 feet fordouble-trailercombinations and 115.5feet for triple-trailercombinations; maximumweights range up to147,000 pounds for TPDs

in Florida and 131,060pounds in Montana.

Background: VehicleDescriptions

This section providesdescriptions of the mostprevalent LCVs operatingtoday. It should be noted,however, that eight-axleB-train combinations atweights over 80,000pounds are allowed tooperate in the northernplains States and theNorthwest. They are usedmostly in flat bed trailer

operations and for liquidbulk hauls. Thesecombinations are notprevalent.

Rocky MountainDoubles

The RMD consists of athree-axle truck-tractorwith a long front trailer(40- to 53-foot) and ashorter (20- to 28.5-foot)rear trailer. A few tollroad authorities in the eastand

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Most States that allow Longer Combination Vehicles (LCVs) require special permits for theiroperation. These permits generally certify that (1) drivers have adequate and specializedtraining and experience, (2) the equipment is sufficient for handling heavier loads, (3) thecarrier is properly insured, and (4) the vehicle is properly maintained and meets safetystandards. State permits may be issued for single trips or on an annual basis.

In addition to these permit provisions, many States have special equipment requirements forLCV operations. These may include splash and spray suppression devices (such as mudflaps) and axle requirements. Other restrictions could include operating requirements such asminimum speeds, designated lanes, mandated distances to complete passing maneuvers and,load sequencing of the combination’s trailers. Many States impose special driverrequirements that are more extensive than those required for conventional trucks. Theserequirements may include minimum age limits and special training.

Special LCV permits often include route restrictions. Typically, these routes have, at aminimum, 12-foot lane widths, low to moderate grades, adequate space for executing turningmaneuvers at intersections and curves, bridge load-bearing capacities necessary to tolerateheavier loads, suitable passing lanes, and a positive crash history.

Figure III-12. Special Permits for Longer Combination Vehicles

midwest began to issuepermits for RMDs in 1959. Western States followed inthe late 1960s. Today,RMDs operate over anextensive network ofhighways and toll roads in21 States (six turnpikeStates and 14 westernStates). RMDs aregenerally used for generalfreight and short resourcehauls. They are useful infreight delivery to morethan one point on a route,because one trailer can bedropped at an intermediatepoint.

Turnpike Doubles

The TPD combinationconsists of a tractor towingtwo long trailers of equallength, typically from 40feet to 53 feet in length. Inthe 1960s, several easternStates began permitting theuse of these vehicles. Today, 19 States allowsuch operations. The TPDcombination is allowed inall but three of the States inwhich RMDs are allowedto operate. Theseoperations are generally,but not always, limited toInterstate and toll roadfacilities.

Compared to other LCVs,TPDs have more cubiccapacity and can carryhigher weights. TPDs areparticularly well suited tooperations where freight ismoved from origin todestination withoutintermediate pick-up ordelivery.

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Main Feature

• Broad national LCV operations

Available Highways

• RMDs and TPDs – 42,000 mile analysis network• Triples – 60,000 mile analysis

network• 8-axle B-train double – National

Network for STAA vehicles

Access Provisions

• RMDs and TPDs – none off theanalysis network

• Triples – State issued permits• 8-axle B-train doubles – current

Federal and State provisions

7-axle Rocky Mountain DoubleMaximum weight – 120,000 pounds

9-axle Turnpike DoubleMaximum Weight – 148,000 pounds

8-axle B-train DoubleMaximum weight – 124,000 pounds(33-foot trailers)

Triple-trailer combinationMaximum weight – 132,000 pounds

Figure III-13. Longer Combination Vehicles Nationwide Scenario

Triples

A triple-trailercombination generallyconsists of a two- or three-axle truck-tractor and threetrailers in tow. Eachtrailer is usually 28 feet to28.5 feet in length. Triple-trailer combinations areusually restricted tomaximum GVWs from105,000 pounds to 129,000pounds. Triples arepermitted to operate in 14

States on limited networks(on highways in 11 Statesand on toll roads in threeStates). They are usuallyrestricted to Interstatefacilities and four-lanehighways with low trafficvolumes.

In 1994, total VMT fortriple-trailer combinationswas 108 million miles outof 99,177 million milestraveled by all combinationvehicles. The predominant

users of triples are the less-than-truckload (LTL)industry and major packageexpress carriers. Thisconfiguration allows thedriver to drop off and pickup individual units atmultiple points in a givenrun. In addition, LTLloadings generally fill upthe trailer volume beforethey reach GVW limits.Therefore, they benefitfrom the additional cubiccapacity.

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Scenario Description

The LCVs NationwideScenario estimates theimpact of lifting the LCVfreeze to allow LCVoperations on a nationwidenetwork. The LCVs wouldbe afforded higher GVWlimits (see Figure III-13).All other Federal size andweight controls wouldremain. The scenarioassumes that all Stateswould uniformly adopt thenew limits, and thereforecaptures the maximumimpact.

The Vehicles

The longest and heaviestconfiguration tested in thisscenario is the nine-axleTPD. It would be allowedto operate at weights of upto 148,000 pounds GVWand have up to twin 53-foottrailers. The other LCVswould also realize weightincreases with the seven-axle RMD being allowedto operate at 120,000pounds, the eight-axle B-train double at 124,000pounds and the seven-axletriple-trailer combinationat 132,000 pounds. RMDsare assumed to operatewith 53-foot and 28.5-foottrailers. TPDs are assumedto operate with two 53-foottrailers. The eight-axle B-train is assumed to operate

with two 33-foot trailers.

The Networks

The analysis of thisscenario required use of allof the analytical networksdescribed in Chapter II. The 42,500-mile long-double network was used tosimulate travel by the RMDand TPD combinations. The more extensive(65,000-mile) analyticalnetwork was used toevaluate the operation oftriple-trailer combinations. The eight-axle B-traindouble combination wouldbe permitted to operate onthe same network as STAAdoubles which is the NN.

Access Provisions

Because of poor offtracking(cornering) performance,the analysis does not allowlong double-trailercombinations (TPDs andRMDs) off the designatedanalytical network. It isassumed that drivers ofthese vehicles will usestaging areas—largeparking lots—to disconnectthe extra trailer and attachthat trailer to another tractorfor delivery to its finaldestination. Drayage isassumed to be along themost direct route off thenetwork between theshipper or receiver and thenetwork.

Staging areas are assumedat key rural interchangesand the fringes of majorurban areas. Workcompleted for this study(see Chapter VII, RoadwayGeometry) indicates thatstaging areas would beneeded every 16 miles onrural freeways. On non-freeway rural highways,staging areas would beneeded about every 50miles. Urban staging arearequirements are estimatedto range from 2 to 14,depending upon the numberof LCV routes approachinga given area. Typically,the analysis indicates thatsix staging areas arerequired for each urbanarea. However, someurban areas requiresignificantly more, such asDallas which would needtwelve. Trucks with trip origins ordestinations in urban areaswould use urban fringestaging areas, whilethrough trucks would usethe Interstate or otherfreeway system to theirdestination. The cost ofthese facilities is set forthin Chapter VII.

Triple-trailer combinationsare allowed direct access,under a State-issuedpermit, to and from thenetwork withoutdisconnecting the trailers.

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H. R. 551 Scenario

H.R. 551, “The SafeHighways andInfrastructure PreservationAct,” was first introducedin 1994 during the 103rdSession of Congress, andagain in 1997, as H.R. 551,during the 105th Session. The bill would federalizecertain areas of truckregulation that are nowState responsibilities. Thisscenario is a subset of theUniformity Scenariodescribed earlier.

H.R. 551 contains threeprovisions related toFederal TS&W limits: (1)it would phase out trailerslonger than 53 feet, (2) itwould freeze Stategrandfather rights, and (3)it would freeze weightlimits (including divisibleload permits) on non-Interstate portions of theNHS. However, only thefirst provision wasanalyzed.

H.R. 551 Provisions andBackground

Phase Out of TrailersLonger than 53 Feet

The proposed legislationwould repeal provisions ofthe STAA of 1982 whichgrandfathered all trailer

lengths longer than 53 feetthat were in lawfuloperation in 1982. Stateswould be prohibited fromregistering new trailers,containers or other cargo-carrying units longer than53 feet for operation on theInterstate and those classesof qualifying NHShighways as designated bythe Secretary ofTransportation. Existingtrailers, semitrailers andother cargo units longerthan 53 feet or thosemanufactured up to one yearafter the date of enactmentwould be allowed tooperate indefinitely.

This section of H.R. 551 isintended to prevent theproliferation of very longsemitrailers. It has beenasserted that trailers longerthan 53 feet are relativelymore dangerous than shortertrailers because of off-tracking and swing-out laneencroachment. Further,some maintain that if theselonger trailers jackknifethey are more likely to hitother vehicles.

As shown in Table III-7, tenStates currently permit theoperation of semitrailersthat are over 53 feet long. Six of the ten States limitthe operation of theselonger trailers to the NN(which includes theInterstate).

Termination of StateDetermination ofGrandfather Rights

H.R. 551 includes aprovision, closely modeledon the ISTEA LCV freeze,which would codify andfreeze all Interstate Systemgrandfather rights. Theproposed legislationrequires the FHWA topublish a list of vehicles orcombinations which werelawfully operating atweights over the FederalInterstate weight limitsbefore January 1, 1997. This list would be by route,commodity and weight.

III-24

State authority to determineweight limits under the1956 or 1975 grandfatherclause—as provided for bythe Symms Amendment(see Figure III-14)—wouldbe repealed. The freezewould not prohibit any ofthe existing exceptions toFederal limits, but wouldconstrain States to theexisting limits. This wouldapply to both permitted andnon-permitted limits.

Freeze on NationalHighway SystemWeights

H.R. 551 proposes a freezeon non-Interstate NHSweight limits, greatly

expanding Federal authorityto regulate truck weightlimits. The freeze wouldalso apply to divisible loadpermits. At present, Statesestablish vehicle weightlimits for their highwaysother than those on theInterstate System.

For roads, where vehicleweight limits aredetermined by the Federalgovernment, the proposedweight limit freeze wouldincrease the number of roadmiles from 44,000 miles(the current InterstateSystem) to almost 156,000miles (the NHS). Thisproposal would effectivelyeliminate all Stateflexibility to allow higher

vehicle weights.


Figure III-15 summarizeskey provisions of thisscenario. The scenario hasbeen proposed to precludeStates from raising theirTS&W limitsprospectively. A review ofchanges in State TS&Wlaws over the past ten yearsrevealed that suchincreases have notoccurred except in alimited number of casesinvolving specificcommodities or truckconfigurations. Forexample, the kinds ofdivisible load permits havenot changed appreciablyover the last ten years. However, the number ofpermits issued hasincreased (see Table III-8).

This observation is notsurprising since the ISTEAfreeze has been in placesince 1991. The analyticalimplication, in terms of thisstudy, is that the onlyfeature of the H.R. 551proposal that can bemodeled is the limitationon trailer length. It is

State Length Limit

Alabama 57 feet

Arkansas 53 feet 6 inches

Arizona 57 feet 6 inches

Colorado 57 feet 4 inches

Kansas 59 feet 6 inches

Louisiana 59 feet 6 inches

New Mexico 59 feet 6 inches

Oklahoma 59 feet 6 inches

Texas 59 feet

Wyoming 60 feet

Table III-7. States Routinely Allowing Semitrailers LongerThan 53 Feet

III-26

The Surface Transportation Assistance Act (STAA) of 1982 provided more uniform trucksize and weight standards across the country by requiring States to raise weight limits thatwere lower than the Federal standard. Prior to this there was no Federal legislativeprovision that would prevent the States from enforcing lower limits.

The STAA of 1982 also gave States added authority to determine their own grandfatherrights. A provision introduced by Senator Symms, allowed the States to determine which“vehicles or combination thereof... could be lawfully operated within such State on July 1,1956.” Some States have argued, based on this legislation that they are the sole arbiters oftheir grandfather rights. As a result of this legislation, ten States have claimed grandfather

Figure III-14. The Symms Amendment

Year Divisible Single

Divisible

MultipleDivisible

TotalNondivisible

SingleNondivisible Multiple

Nondivisible Total

TotalPermits

1985 62,810 90,832 153,642 1,072,776 46,451 1,119,227 1,272,869

1986 53,976 96,193 150,169 1,149,625 59,274 1,208,899 1,359,068

1987 51,824 102,759 154,583 1,136,649 67,132 1,203,781 1,358,364

1988 64,955 112,801 177,756 1,151,732 61,222 1,212,954 1,390,710

1989 67,194 136,267 203,463 1,205,394 76,687 1,282,081 1,485,544

1990 73,270 140,697 213,967 1,321,261 88,362 1,409,623 1,623,590

1991 163,228 160,914 324,142 1,259,176 66,848 1,326,024 1,650,166

1992 184,711 162,040 346,751 1,347,773 92,734 1,440,507 1,787,258

1993 160,847 166,865 327,712 1,325,802 104,870 1,430,672 1,758,384

1994 157,114 198,236 355,350 1,426,143 116,934 1,543,077 1,898,427

1995 169,013 211,502 380,515 1,543,270 106,746 1,650,016 2,030,531

Source: FHWA Annual Inventory of State Practices, Overweight Vehicles–Penalties and Permits, FY85-FY94; and FY95 Annual State Certifications

Table 8. State Permitting of Overweight Loads – 1985-1995

III-26

impossible to predict whatStates might do in the future with respect tochanging their TS&Wlimits, since a meaningfulhistorical trend does notexist.

The Vehicles

H.R. 551 would phase outall semitrailers longer than 53 feet. These trailers areused primarily to transportlow-density freight thatbenefit from the additionalcubic capacity. The pro-

posed legislation would notimpact other equipment.

Because the longer trailersin use today would begrandfathered, the analysisassumes that these trailerswould remain in useindefinitely. The analysisalso assumes that theadditional increment offreight that longer trailerswould have hauled in the2000 analysis year willhave to be carried in theshorter, 53-foot trailers.

The Network

This scenario does notinclude any change to thestatus quo. It is notable,however, that an NHSweight-limit freeze wouldnot create an incentive toincrease weight on roadsoff the NHS becauserelatively little freight istransported between originsand destinations for whichnon-NHS routes arepractical.

Access Provisions

Main Features

• Phases in elimination of semitrailers over 53 feet long

• Assumes status quo weights

Available Highways

• National Highway System

Access Provisions

• Current Federal and State provisions

Two to four-axle single unit truckCurrent law at 54,000 pounds to 70,000 pounds

Five to six-axle tractor-semitrailerCurrent law at 80,000 pounds to 100,000 pounds

Five to six-axle STAA double trailer combinationCurrent law at 80,000 pounds

Figure III-15. H.R. 551 Scenario

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Current Federal and Stateaccess requirements wouldremain in effect.

Triples NationwideScenario

This scenario, a subset ofthe LCVs Nationwidescenario, would permit theoperation of triple-trailercombinations across thecountry.


Figure III-16 summarizes

key provisions of thisscenario.

The Vehicles

The Triples NationwideScenario focuses on theseven-axle triple-trailercombination which will bepermitted to operatenationwide at a GVW of132,000 pounds.

The Networks

This scenario was testedusing the 65,000-mileanalytical networkdeveloped to test triple-

trailer combinations. Thereader is referred toChapter II for a discussionof this network.

Access Provisions

Current State accessprovisions would remain ineffect. Triple-trailercombinations are assumedto have direct access to andfrom the network withoutdisconnecting the trailers,in accordance with Stateissued permits. Therefore,there is no requirement forstaging areas.

2-S1-2-2

Seven-axle triple-trailer combination132,000 pounds (maximum)

Main Feature

� Broad national operationof triple-trailercombinations and newweight limits fortriple-trailer combinations

Available Highways

� 65,000-mile system

Access Provisions

� State issued permits

Figure III-16. Triples Nationwide Scenario

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