1、Designation: E 2467 05Standard Practice forDeveloping Axle Count Adjustment Factors1This standard is issued under the fixed designation E 2467; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in
2、parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This standard practice describes techniques for adjustingobserved or assumed axle counts so that they will representcorresponding estimated vehi
3、cle counts as part of roadwaytraffic monitoring.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and to determine theapplicability of re
4、gulatory limitations prior to use.2. Referenced Documents2.1 Other:Traffic Monitoring Guide, U.S. Department of Transporta-tion, Federal Highway Administration, Washington, DC205903. Terminology3.1 Definitions:3.1.1 axle, naxis oriented transversely to the nominaldirection of vehicle motion, and ext
5、ending the full width of thevehicle, about which the axle wheels at both ends rotate.3.1.2 axle count, ntotal number of vehicle axles that areenumerated at a point on a lane or roadway during a specifiedtime interval.3.1.3 axle counter, ndevice that receives signals from anaxle sensor and indicates
6、the cumulative number of axles thatwere detected by the sensor during a specified time interval.3.1.4 functional classification, na stratification of high-ways based on their common usage or function.3.1.5 machine count, nthe cumulative number of axles,vehicles, or vehicles within specified classes,
7、 or all of these,indicated or recorded by a traffic recording device for aspecified time interval.3.1.6 traffc counter, na device that indicates, and usuallyrecords, the number of vehicles or vehicle axles, or both, thatpass a point on a lane or roadway during a specified timeinterval.3.1.7 traffc r
8、ecording device, na device that receivessignals from a sensor(s) and registers axle count, vehicle count,vehicle classification count, speed, gap, or headway (any or allof these) for defined time intervals.3.1.8 vehicle, nan assembly of one or more mobile unitscoupled together for travel on a highwa
9、y; a vehicle comprisesone powered unit and may include one or more unpoweredfull-trailer or semi-trailer unit(s).3.1.9 vehicle classification, nthe process of categorizingvehicles into various classes, usually according to their respec-tive axle or mobile-unit(s) configuration.3.1.10 vehicle classif
10、ication count, nthe cumulative num-ber of vehicles of each defined class indicated or recorded fora specified time interval.3.2 Definitions of Terms Specific to This Standard:3.2.1 axle count adjustment factor, nthe number thatwhen multiplied by an axle count (3.1.2) will adjust the axlecount to an
11、estimate of the total number of vehicles thatproduced the axle count.3.2.1.1 DiscussionThe adjustment factor is sometimesbased upon the premise that (1) the portion of all vehiclesincluded in each of various vehicle classes, and (2) therespective average number of axles per vehicle class for thevehi
12、cles that produced the axle count being adjusted are knownor are assumed to be the same as the two corresponding valuesused to characterize the vehicles in a chosen, representative, orsimilar traffic stream.4. Summary of Practice4.1 Basic StepsDevelopment of an axle count adjustmentfactor involves t
13、wo basic steps: (1) defining a time intervalalong with the characteristics of the vehicles that comprised thetraffic stream during the time interval, and (2) obtaining thedata needed to characterize the vehicles in the traffic stream.Depending upon the type of data available, one of the follow-ing m
14、ethods may be used to calculate the factor.4.1.1 Direct MethodIf, for a chosen time interval, re-corded data are available (e.g., from anASTM Type I and TypeII WIM system or from certain types of traffic counters ortraffic recordings devices) concerning the total number ofvehicles in the traffic str
15、eam concurrently with the total axlecount (3.1.2), the axle count adjustment factor can be calcu-lated directly as the ratio of the two numbers. The total numberof vehicles in the traffic stream may be determined from a1This practice is under the jurisdiction of ASTM Committee E17 on Vehicle-Pavemen
16、t Systems and is the direct responsibility of Subcommittee E17.52 onTraffic Monitoring.Current edition approved Oct. 1, 2005. Published November 2005.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.recorded machine count (3.1.5) or b
17、y summating the number ofvehicles in each applicable vehicle class as recorded in avehicle classification count (3.1.10). This method of derivingan axle count adjustment factor is illustrated in Appendix A asAppendix X2.4.1.2 Alternative MethodIf specific data such as thatdescribed in 4.1.1 are not
18、available for the chosen time interval,in order to develop an axle count adjustment factor it might beexpeditious to characterize the vehicles in a representative presumed to be similar traffic stream by obtaining for a timeinterval of the same duration as that for the axle count to beadjusted, conc
19、urrent data samples of: vehicle classificationcount, average number of axles per vehicle class, and total axlecount. The average number of axles per vehicle class may beeither calculated from observed data or estimated from previ-ous experience.An example is shown in Table 1 for the averagenumber of
20、 axles per vehicle class (suggested by descriptions ofvehicles in each of the 13 vehicle classes defined in the TraffcMonitoring Guide. To derive the axle count adjustment factor,divide the sum of the vehicles in all classes (total number ofvehicles) by the sum of the products of the number of vehic
21、lesin each class times the respective average number of axles pervehicle class (total number of axles). This alternative methodof deriving an axle count adjustment factor is illustrated inAppendix A as Appendix X1. The axle count adjustment factordeveloped from this method may be applied to an axle
22、countwhen it is assumed that the traffic stream which produced theaxle count being adjusted had essentially the same portion ofvehicles in each designated vehicle class and average numberof axles per vehicle class as the traffic stream that was chosento be representative.4.2 Time IntervalIt is recom
23、mended that a series of axlecount adjustment factors be developed for application to axlecounts taken during weekdays (Monday Friday), weekends(Saturday and Sunday), months, quarters (either calendarquarters or seasonal quarters), and calendar year. Specialevents that produce significant traffic vol
24、umes and recurperiodically such as festivals, fairs, and sporting events might justify the development of a separate axle count adjust-ment factor for the specific time interval and locality.4.3 Vehicle CharacteristicsThe critical vehicle character-istic required for developing an axle count adjustm
25、ent factor isthe number of axles on each individual vehicle that producedthe axle count to be adjusted, or a credible estimate thereof.Various sensor types vehicle-presence, axle-passage, tire-presence, and others are employed in various arrays andteamed with various signal-processing algorithms and
26、 trafficrecording devices to count vehicles, and sometimes count andclassify them according to their axle number and spacing, or toonly count axles with respect to time. Application of appropri-ate and capable traffic recording devices is required foracquiring data with proper analysis needed to dev
27、elop anaxle count adjustment factor.4.4 ApplicationThe derived axle count adjustment factor always less that 0.5 may be correlated with other param-eters such as volume, density, speed, highway functional class,designated truck routes, parkways, and geographic locale tofurther describe the character
28、istics of the observed trafficstream and suggest potential future applications of the factorwhen only axle count for a similar traffic stream is known.5. Significance and Use5.1 This practice addresses the development of axle countadjustment factors, using axle counts and vehicle classificationcount
29、s. This practice provides information for use with profes-sional judgment by governmental agencies and private firms inthe management of roads and roadway traffic.5.2 Traffic monitoring is important to the safe and efficientmovement of people and goods. The purpose of this practice isto ensure that
30、traffic monitoring procedures produce traffic dataand summary statistics that are adequate to satisfy diverse andcritical traffic information needs.6. Keywords6.1 axle; axle count; traffic counter; vehicle; vehicle axles;vehicle classificationTABLE 1 Average Number of Axles per Vehicle ClassVehicleC
31、lassDescription AverageNumber ofAxles perVehicle1 Motorcycles 22 Passenger Cars 23 4-Tire Single Unit Trucks 24 Buses 25 2-Axle, 6-Tire Single Unit Trucks 26 3-Axle Single Unit Trucks 37 4 or More Axle Single Unit Trucks 48 4 or Fewer Axle Single Trailer Trucks 49 5-Axle Single Trailer Trucks 510 6
32、or More Axle Single Trailer Trucks 611 5 or Fewer Axle Multi-Trailer Trucks 512 6 Axle Multi-Trailer Trucks 613 7 or More Axle Multi-Axle Trucks 7E2467052APPENDIXES(Nonmandatory Information)X1. Sample Calculation of Axle Count Adjustment Factor by Alternative MethodX1.1 For a specified time interval
33、, obtain a previousclassification count from the same section of roadway or asection of roadway with similar traffic characteristics.X1.2 Using data such as that illustrated in Table 1 as aguide, multiply the estimated average axles per vehicle class(e.g., Table X1.1, Col 2) by the vehicle count by
34、class (Col 3)to determine the calculated axle count (Col 4) for each vehicleclass.X1.3 Determine the total axle count by summating thecalculated axle counts for each vehicle class (total Col 4).X1.4 Summate all vehicle-count-by-class (Col 3) to deter-mine the total vehicle count, and divide this tot
35、al vehicle countby the total axle count (total Col 4) to determine the axle countadjustment factor.X1.4.1 As shown is Table X1.1, the total vehicle count was10 507. Using the suggested average number of axles pervehicle, the total axle count was 33 086. By dividing theformer number by the latter num
36、ber, the axle count adjustmentfactor of 0.3176 is determined.X1.5 If at some future time, only an axle count is taken atthis location on a weekday, e.g. 33 086, (or at another locationwith a similar mix of vehicle types and percentage of eachtype) the estimated number of vehicles that produced the a
37、xlecount would be calculated by multiplying the axle countadjustment factor of 0.3176 by the axle count of 33 086 to givean estimated 10 508 vehicles.X2. Sample Calculation of Axle Count Adjustment Factor by Direct MethodX2.1 In the situation where a traffic counter capable ofrecording vehicle count
38、s is available at a site, an axle countermay be installed adjacent to it.X2.2 While one device is enumerating the total number ofvehicles, the other is enumerating the total number of axles.X2.3 At the end of the specified time period, the recordedvalues from the two devices should be recorded.X2.4
39、By dividing the total number of vehicles by the totalnumber of axles, the axle count adjustment factor is deter-mined.X2.5 Using Table X1.1 as an example, only the Totals linewould be utilizedX2.5.1 The total vehicle count was determined to be 10 507and the total axle count was determined to be 33 0
40、86.X2.5.2 By dividing the former by the latter, an axle countadjustment factor of 0.3176 is calculated.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that d
41、etermination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved
42、 or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel
43、that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprin
44、ts (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE X1.1 Example Weekday Traffic Count (Rural Interstate)1234VEHICLECLASSAVERAGEAXLES PERVEHICLECLASSVEHICLE COUNTBY CLASSCALCULATEDAXLE COUNT12002 2 3 929 7 8583 2 2 049 4 0984 2 68 1365 2 331 6626 3 139 417743128 4 355 1 4209 5 3 122 15 61010 6 154 92411 5 249 1 24512 6 52 31213 7 56 392TOTALS 10 507 33 086E2467053
