1、Designation: E1957 04 (Reapproved 2018)Standard Practice forInstalling and Using Pneumatic Tubes With Roadway TrafficCounters and Classifiers1This standard is issued under the fixed designation E1957; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the use of pneumatic road tubes todetect the passing of load-bearin
3、g vehicle axles as part ofroadway traffic monitoring.1.2 The practice applies only to pneumatic road tubes usedfor the detection of load-bearing vehicle axles on a roadway.1.3 The values stated in SI units are to be regarded as thestandard. The inch-pound units given in parentheses are forinformatio
4、n only.1.4 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior
5、 to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBar
6、riers to Trade (TBT) Committee.2. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 axlethe axis oriented transversely to the nominaldirection of vehicle motion, and extending the full width of thevehicle, about which the wheels at both ends rotate.2.1.2 axle countera device that r
7、eceives signals from anaxle sensor and indicates the cumulative number of axles thatwere detected by the sensor during a specified time interval.2.1.3 axle sensora device that generates a signal indicat-ing the passing of a load-bearing vehicle axle.2.1.4 machine countthe cumulative number of axles,
8、vehicles, or vehicles within specified classes, or all of these,indicated or recorded by a traffic recording device for aspecified time interval.2.1.5 manual countrecorded vehicle counts or vehicleclassification counts, or both, based upon human observation.2.1.6 pneumatic road tubean elastic tube t
9、hat is stretchedacross a roadway for the purpose of detecting the passage of aload-bearing vehicle axle.2.1.7 traffc countera device that indicates, and usuallyrecords, the number of vehicles or vehicle axles, or both, thatpass over a point on a lane or roadway during a specified timeinterval.2.1.8
10、traffc recording devicean instrument 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.2.1.9 validation countan independent count made to es-tablish an accepted reference
11、value against which a recordedcount will be compared to determine its accuracy and reliabil-ity.2.1.10 vehicleone or multiple mobile unit(s) designed totravel upon a roadway; a vehicle comprises one powered unitand may include one or more non-powered trailer or semi-trailer unit(s).2.1.11 vehicle cl
12、assification countthe cumulative numberof vehicles of each defined type (class), recorded for a specifiedtime interval.2.1.12 vehicle classifiera device that senses and recordsthe number of vehicles of defined types (classes) that pass apoint on a lane or roadway during a specified time interval.2.1
13、.13 verification counta count made on the same seg-ment of roadway concurrently with a validation count to testthe performance of a traffic counter or vehicle classifier.3. Significance and Use3.1 This practice addresses the recording of trafficcharacteristics, using pneumatic tubing with recording
14、devices.This practice provides information for use with professionaljudgment by governmental agencies and private firms in themanagement of roads and roadway traffic.3.2 Traffic monitoring is important to the safe and efficientmovement of people and goods. The purpose of this practice isto ensure th
15、at traffic monitoring procedures produce traffic data1This practice is under the jurisdiction of ASTM Committee E17 on Vehicle -Pavement Systems and is the direct responsibility of Subcommittee E17.52 onTraffic Monitoring.Current edition approved Sept. 1, 2018. Published September 2018. Originallyap
16、proved in 1998. Last previous edition approved in 2010 as E1957 04 (2010).DOI: 10.1520/E1957-04R18.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized
17、principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1and summary statistics that are adequate to satisfy diverse andcritica
18、l traffic information needs.4. Procedure4.1 Installation Procedures and Techniques:4.1.1 Select a relatively straight and smooth section ofroadway with free-flowing traffic throughout the duration ofthe data collection session. For example, in selecting theroadway section, attention should be given
19、to avoiding prox-imity to driveways and intersections. The availability of a placeto anchor the traffic recording device is also important.4.1.1.1 In those areas that have designated parking spaces,where a parking vehicle might impinge upon the road tube,covering the affected part of the tube with a
20、 segment of angleiron with tabs welded thereto and fastened to the roadway isstrongly encouraged.4.1.2 Install the tubing on the surface of the roadway,perpendicular to the flow of vehicular traffic. The end awayfrom the recording device must be effectively sealed to preventleakage of air and to pre
21、vent the intrusion of foreign matter andwater. This end must be secured to the ground or pavementusing a suitable anchoring device, such as a nail, clamp, orbracket.4.1.2.1 A suitable small leak shall be provided between theother end of the tube and the attached air pressure sensingdiaphragm near th
22、e recording device. This leak shall be sizedso that the static air pressure within the sealed-end tube,affected by gradual temperature and atmospheric pressurechanges, will remain near ambient atmospheric pressure at alltimes and will not significantly affect the magnitude of thedynamic air pressure
23、 pulse generated inside the tube when amoving vehicle tire impacts the tube.4.1.3 Place a second anchoring device at the near edge ofthe pavement. This device must not restrict the flow of air. Pullthe tube across the roadway, and through the anchoring device.Between the anchoring devices, stretch t
24、he tube approximately10 % of its length, for example, for a 10.0-m (32.8-ft) length oftube, stretch the tube 1.0 m (3.3 ft). While it is stretched taut,secure the tube with the second anchoring device.4.1.4 The tube may be secured to the pavement surfacebetween the anchoring devices with other appro
25、priate anchor-ing devices, such as asphaltic or adhesive tape. This tape can bespaced at 1-m (3.3-ft) to 1.5-m (5-ft) intervals along the lengthof the tube.4.1.5 The installation of tubes should be accomplished in amanner that places no nails in the wheel path on the surface ofthe traveled roadway.4
26、.1.6 When the use of more than one tube is required, forexample, for vehicle classification or speed data collection,both tubes must be exactly the same length from the counter tothe near edge of the pavement. The spacing between the roadtubes must be the same distance at both ends and in the middle
27、to ensure the accuracy of the speed and vehicle classification.In addition, the two sections of tube should be of the samecross section, approximate quality, durability, and age.4.1.7 The length of the pneumatic road tube should bebetween the minimum and maximum specified by the manu-facturer of the
28、 traffic monitoring device. The use of shorterlengths of tubing may result in damage to the recording device.The strength of the air pulse, and therefore the accuracy of thecount, can be influenced by a number of factors, including:tube length, tube cross section, hardness of the tube, speed oftraff
29、ic, tire widths, distance between recording device and pointof impact on the tube, and uncontrolled movement of the tube.4.2 Once the tube or tubes have been installed and con-nected to the traffic recording device, a verification count mustbe made to determine if the air pulses are being recordedco
30、rrectly.4.2.1 Validation CountInitialize the traffic recording de-vice (note the indicated axle count) and then have one or morepersons count and record manually the number of axles thatpass over the tube or tubes (validation count) until at least 50axles have passed. Concurrently, note the indicate
31、d machinecount (verification count) on the traffic recording device.Compare the machine count(s) with the manual count(s)(validation count(s) to verify that the axle counts are beingdetermined correctly.4.2.1.1 If more than one manual count is made, there shallbe no more than 2 % difference from the
32、 largest value for anycount to be acceptable for use in determining the validationcount. Repeat the manual counts (and the machine countsconcurrently) as necessary until this condition is satisfied; thencalculate the mean value of all manual counts and round themean value to the nearest integer. Use
33、 this integer value as thevalidation count. For acceptable performance, the machine(verification) count should not vary from the validation countmore than 4 %, preferably less. Do not begin a data collectionsession until the pneumatic road tube(s) and the associatedtraffic recording device are perfo
34、rming acceptably.4.2.2 On low-volume roads, it may be necessary to manu-ally check the performance of the pneumatic road tube(s) usingan alternative method.As an example, the equipment installersvehicle may be used to test the installation.4.2.3 At the end of the data collection session, repeat thep
35、rocedure outlined in 4.2.1 to make certain that the installationis still properly registering the axles. If the installation is notfunctioning acceptably, the entire count should be retaken.4.3 Pressure Testing of Road TubeVerify that the roadtube or tubes can hold 7 kPa (1 psi) of air pressure for
36、1 min;if not, discard the road tube. At this time, the tube should becleaned by blowing compressed air through it. Care must betaken to not damage the tube(s) during removal of the endplug(s).4.3.1 At regular intervals such as at the end of each datacollection session, inspect each road tube, paying
37、 particularattention to the area around the clamps. During the inspection,check the tube for chafing, abrasions, or punctures. The tubesshould be tested at least once every month of use for airpressure retention, in accordance with 4.3.5. Keywords5.1 axle counters; axle sensors; pneumatic road tubes
38、;vehicle axles; vehicle classifiers; vehiclesE1957 04 (2018)2ASTM 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 determination of the validity of any such p
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41、r 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 reprints (single or multiple copies) of this sta
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