1、Designation: E1957 04 (Reapproved 2010)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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Termi
5、nology2.1 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 receives signals from anaxle sensor and
6、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,vehicles, or vehicles within specified
7、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 that is stretchedacross a roadway for th
8、e 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 traffc recording devicean instrument th
9、at 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 value against which a recordedcount wil
10、l 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 classifiera device that senses and reco
11、rdsthe number of vehicles of defined types (classes) that pass apoint on a lane or roadway during a specified time interval.2.1.12 vehicle classification countthe cumulative numberof vehicles of each defined type (class) recorded for a specifiedtime interval.2.1.13 verification counta count made on
12、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 traffic charac-teristics, using pneumatic tubing with recording devices. Thispractice provides infor
13、mation for use with professional judg-ment 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 that traffic monitoring procedures p
14、roduce 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 April 1, 2010. Published April 2010. Originallyapproved in 1998. Last previous edition
15、approved in 2004 as E1957 04. DOI:10.1520/E1957-04R10.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.and summary statistics that are adequate to satisfy diverse andcritical traffic information needs.4. Procedure4.1 Installation Proc
16、edures and Techniques:4.1.1 Select a relatively straight and smooth section ofroadway with free flowing traffic throughout the duration of thedata-collection session. For example, in selecting the roadwaysection, attention should be given to avoiding proximity todriveways and intersections. The avai
17、lability of a place toanchor 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 segment of angleiron with tabs welded thereto and fastened to
18、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 prevent the intrusion of foreign matter andwater. This end must be
19、 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 the recording device. This leak shall be sizedso that the static
20、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 pulse generated inside the tube when amoving vehicle tire impa
21、cts 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 the tube approximatelyten percent of its length, for example, fo
22、r a 10.0 m (32.8 ft)length of tube, stretch the tube 1.0 m (3.3 ft). While it isstretched taut, secure the tube with the second anchoringdevice.4.1.4 The tube may be secured to the pavement surfacebetween the anchoring devices with other appropriate anchor-ing devices, such as asphaltic or adhesive
23、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.4.1.6 When the use of more than one tube is required, fore
24、xample, 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 middleto assure the accuracy of the speed and vehicle classific
25、ation.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 traffic monitoring device. The use of shorterlengths of
26、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 oftraffic, tire widths, distance between recording device and po
27、intof 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 recordedcorrectly.4.2.1 Validation CountInitialize the traffic reco
28、rding 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 indicated machinecount (verification count) on the traffic record
29、ing 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 largest value for anycount to be acceptable for use in d
30、etermining 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 this integer value as thevalidation count. For acceptabl
31、e 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 performing acceptably.4.2.2 On low volume roads, it may be nec
32、essary to manuallycheck the performance of the pneumatic road tube(s) using analternative 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 theprocedure outlined in 4.2.1 to make certain that the instal
33、lationis 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 1 min;if not, discard the road tube. At this time, the tub
34、e 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 eachdata-collection session, inspect each road tube, paying particu-lar attention to the area around the clamps. Duri
35、ng theinspection, check the tube for chafing, abrasions, or punctures.The tubes should be tested at least once every month of use forair pressure retention, in accordance with 4.3.5. Keywords5.1 axle counters; axle sensors; pneumatic road tubes;vehicles; vehicle axles; vehicle classifiersE1957 04 (2
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39、mmittee 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 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).E1957 04 (2010)3
