1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 7941-2:2000 ICS 17.040
2、.20; 93.080.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Surface friction of pavements Part 2: Test method for measurement of surface skid resistance using the GripTester braked wheel fixed slip deviceThis British Standard, having been prepared under the direction of the
3、 Sector Committee for Building and Civil Engineering, was published under the authority of the Standards Committee and comes into effect on 15 September 2000 BSI 09-2000 The following BSI references relate to the work on this standard: Committee reference B/510/5 Draft for comment 97/108144 DC ISBN
4、0 580 33210 1 BS 7941-2:2000 Amendments issued since publication Amd. No. Date Comments Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee B/510, Road materials, to Subcommittee B/510/5, Surface characteristics, upon which t
5、he following bodies were represented: County Surveyors Society Department of the Environment, transport and the Regions Institution of Civil Engineers Quarry Products Association Road Surface Dressing Association Society of Chemical Industry The following bodies were also represented in the drafting
6、 of the standard, through subcommittees and panels: Brick Development Association Britpave Department of the Environment, Transport and the Regions (Highways Agency) Ministry of DefenceBS 7941-2:2000 BSI 09-2000 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Terms
7、and definitions 1 3 Equipment 2 4 Calibration and maintenance 3 5 Test procedures 3 6 Sampling 4 7 Precision 4 8 Test results 4 Annex A (informative) Water flow rates 8 Figure 1 GripTester: General arrangement 5 Figure 2 GripTester header file layout: ROADS VERSION 3.1 6 Figure 3 GripTester header f
8、ile layout: AIRFIELDS VERSION 3.3 7ii BSI 09-2000 BS 7941-2:2000 Foreword This British Standard has been prepared under the direction of the Building and Civil Engineering Sector Policy and Strategy Committee by Subcommittee B/510/5, Surface characteristics. This standard is published in two parts.
9、Part 1 is entitled Method for measuring the surface friction of pavements using a sideway force coefficient routine investigation machine. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct applicati
10、on. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 8, an inside back cover and a back cover. The BSI copyright notice displayed in this document in
11、dicates when the document was last issued.BS 7941-2:2000 BSI 09-2000 1 1 Scope This British Standard describes a method for determining the skid resistance of a surface using the GripTester continuous reading braked wheel fixed slip device. The method is applicable to the following: highways: surfac
12、ings; highways: horizontal signs; airport runways; flight decks; footways; pedestrian precincts; test panels of surfaces intended for any of the above. The method is for measurement of skid resistance along a continuous surface on external paved surfaces or indoors. Test speeds can vary from 5 km/h
13、to 130 km/h depending on the application. The measured values can be affected by the test speed. 2 Terms and definitions For the purposes of this British Standard the following terms and definitions apply. 2.1 skid resistance property of the trafficked surface which limits relative movement between
14、a vehicle tyre contact patch and the road 2.2 slip resistance property of the trafficked surface to maintain the adhesion of a pedestrian sole 2.3 frictional force tangential force generated between the vehicle tyre/pedestrian sole and the trafficked surface 2.4 braked wheel friction tester apparatu
15、s that can be moved over the test surface at a known, steady speed and that includes a test wheel, a system for braking the test wheel and instrumentation for measuring the resulting friction between the test tyre and test surface 2.5 fixed slip a braking system that forces the test wheel to roll at
16、 a fixed reduction of its natural speed 2.6 GripTester a braked wheel fixed slip device friction tester capable of being manually pushed or towed at up to 130 km/h 2.7 load dynamic instantaneous vertical force acting on the test wheel 2.8 drag dynamic instantaneous horizontal force acting on the tes
17、t wheel2 BSI 09-2000 BS 7941-2:2000 2.9 instantaneous friction reading drag divided by load 2.10 GripNumber mean of a number of instantaneous friction readings over a defined length NOTE The range of the GripNumber is 0.00 to 1.20. 2.11 GripLength defined length over which the GripNumber is produced
18、 2.12 water deposition system system for depositing a given amount of water in front of the test tyre so that it then passes between the tyre and the surface being measured 2.13 rate of water deposition rate at which water is deposited on the surface to be measured in front of the test tyre 2.14 the
19、oretical water film thickness thickness of the water film that would exist between a test tyre with smooth tread and the surface being measured if this surface had zero texture depth 2.15 routine skid resistance testing measurement of the skid resistance of a surface in standardized test conditions,
20、 which normally include a defined rate of water deposition 2.16 operational skid resistance testing measurement of the skid resistance of a surface in response to an operational need and in whatever conditions exist at the time of the test, which may include contamination by ice, snow, slush or wate
21、r NOTE These tests do not include water deposition. 3 Equipment 3.1 Principle of operation The GripTester has two drive wheels and a single test wheel and is capable of being towed or manually pushed at speeds between 5 km/h and 130 km/h. It is illustrated in Figure 1. The test wheel is mounted on a
22、 stub axle and is mechanically braked by a fixed gear system with a ratio of 27:32 in relation to the drive wheels so that there is a relative slip speed between the drive wheels and the test wheel of just over 15 %. The drive wheel tyres have a patterned tread and carry just over three quarters of
23、the weight of the instrument: the test wheel tyre has a smooth tread. The two drive wheels are mounted on the main axle, which also carries a toothed wheel. A proximity sensor is mounted adjacent to this toothed wheel in such a way that signals from this sensor can be transmitted to a signal process
24、ing unit (SPU) for the calculation of distance. Two strain gauge bridges on the stub axle continuously measure drag and load and transmit these signals to the SPU, which calculates the instantaneous friction readings. These readings are sent in ASCII form to a data capture device where the GripNumbe
25、r is computed and stored. If the GripTester is to be used for routine testing it shall be connected to a water tank fitted with a control valve. In towing mode, water deposition is further controlled by a pump and may be monitored with a flowmeter.BS 7941-2:2000 BSI 09-2000 3 3.2 Physical characteri
26、stics Overall length (excluding removable tow-bar) 1 010 mm Overall width 790 mm Overall height 510 mm Test tyre3 1 10“ diameter smooth tread as approved by the manufacturer Drive tyres3 2 10“ diameter patterned tread as approved by the manufacturer Static load on test wheel under normal operating c
27、onditions Between 22 kg and 28 kg Data capture software As provided by the manufacturer Data capture device Various non-proprietary portable computers may be used 4 Calibration and maintenance 4.1 General principles The time-based schedule of inspection, calibration and maintenance set out in the ma
28、nufacturers current manual shall be adhered to. 4.2 Routine procedures 4.2.1 A pre-survey check shall be carried out in accordance with the manufacturers current manual before and after testing on each day of the survey. 4.2.2 The monthly maintenance procedure shall be carried out in accordance with
29、 the manufacturers manual not more than one month prior to the survey. 4.2.3 The annual maintenance procedure shall be carried out in accordance with the manufacturers manual not more than one year prior to the survey. 4.2.4 Full records shall be kept of the dates and details of all inspections and
30、calibrations. 4.3 Special procedures When required, the accuracy of distance measurement shall be checked and calibrated in accordance with the manufacturers instructions. NOTE Since speed measurements are derived from distance measurements, regular calibration of distance measurement is recommended
31、. 5 Test procedures 5.1 Safety When carrying out a friction survey on trafficked roads, the GripTester can operate at speeds different from normal road speed and as a result can create a hazard to other road users. It is essential that attention is paid to working in accordance with all current safe
32、ty measures and those required by current legislation. When carrying out a friction survey at an airport, ensure that all activities are under the control of the airport operators. Avoid carrying out tests involving water deposition if there is a risk of water freezing on the pavement. 5.2 Routine t
33、esting 5.2.1 General Wherever possible, the surface to be measured should be free from standing water, frost, grease, debris or other contamination. The water deposition system shall be set up to provide the required water deposition rate. NOTE Suggested guidelines for water deposition rates are giv
34、en in annex A. The temperature of water applied shall be not less than 58C and not greater than 258C.4 BSI 09-2000 BS 7941-2:2000 5.2.2 Towing mode Prior to the first test, check that the measuring system has reached the appropriate stable state. This shall be done by switching on the SPU for at lea
35、st 5 min and towing the GripTester over at least 500 m with the water deposition system in operation. If possible, the surface used should be representative of that initially to be tested. With the water deposition system in operation, tow the GripTester smoothly and at a standard speed, operating t
36、he data capture device in accordance with the manufacturers instructions. Examples of standard speeds are: (20 5), (50 5), (65 5), (95 5) km/h. 5.2.3 Pushing mode Prior to the first test, check that the measuring system has reached the appropriate stable state. This shall be done by switching on the
37、 SPU for at least 5 min and pushing the GripTester over at least 20 m with the water deposition system in operation. The surface used shall be representative of that initially to be tested. With the water deposition system in operation, push the GripTester smoothly and at the standard speed of (6 1)
38、 km/h, operating the data capture device in accordance with the manufacturers instructions. 5.3 Operational testing 5.3.1 Towing mode Prior to the first test check that the measuring system has reached the appropriate stable state. This shall be done by switching on the SPU for at least 5 min and to
39、wing the GripTester over at least 500 m. If possible, the surface used should be representative of that initially to be tested. Tow the GripTester smoothly and at a standard speed, operating the data capture device in accordance with the manufacturers instructions. Standard speeds are: (20 5), (50 5
40、), (65 5), (95 5) km/h. 5.3.2 Pushing mode Prior to the first test, ensure that the measuring system has reached the appropriate stable state. This shall be done by switching on the SPU for at least 5 min and pushing the GripTester over at least 20 m. NOTE If possible, the surface used should be rep
41、resentative of that initially to be tested. Push the GripTester smoothly and at the standard speed of (6 1) km/h, operating the data capture device in accordance with the manufacturers instructions. 6 Sampling The GripTester shall be set to a sampling rate of 40 mm, 160 mm, 400 mm or 800 mm. The dat
42、a capture device shall be set to give a GripLength of between 40 mm and 10 m. The sampling rate and the GripLength shall be as specified by the client. 7 Precision Trials at the Transport Research Laboratory in May 1993 showed that for routine testing at 50 km/h with a water deposition rate of 18 l/
43、min the repeatability of the GripTester was r = 0.02 and its reproducibility was R = 0.08. 8 Test results If the data capture device is used in accordance with the manufacturers instructions, the data file and the printed report will both contain all significant conditions under which the test was c
44、arried out as well as the actual test results. The structure of the ASCII data files is defined in the manufacturers manual.BS 7941-2:2000 BSI 09-2000 5 Figure 1 GripTester: General arrangement6 BSI 09-2000 BS 7941-2:2000 Record no. Record name Comments/ details 0 File format identifier Data file in
45、 format: ROADS VERSION 3.1, units 1 Authority Keyed in by operator: optional 2 Date Supplied by system 3 Time Supplied by system 4 GripTester Keyed in by operator: mandatory 5 Test tyre Keyed in by operator: mandatory 6 Site Keyed in by operator: optional 7 Surface Keyed in by operator: optional 8 D
46、irection Keyed in by operator: optional 9 Lane/track Keyed in by operator: optional 10 Speed(km/h) Keyed in by operator: mandatory 11 Water flow(l/m) Keyed in by operator: mandatory 12 Operator/s Keyed in by operator: optional 13 Weather Keyed in by operator: optional 14 Ambient temp (C) Keyed in by
47、 operator: optional 15 Surface temp (C) Keyed in by operator: optional 16 Tyre temp (C) Keyed in by operator: optional 17 Run number Keyed in by operator: mandatory 18 Data gathering computer type Supplied by system 19 Distance calibration data Supplied by system 20 Remarks (before survey) Keyed in
48、by operator: optional 21 Remarks (after survey) Keyed in by operator: optional 22 Marker Supplied and used by the DC software Figure 2 GripTester header file layout: ROADS VERSION 3.1BS 7941-2:2000 BSI 09-2000 7 Record no. Record name Comments/ details 0 File format identifier Data file in format: A
49、IRFIELDS VERSION 3.3, units 1 Airfield Stored in system 2 Date Supplied by system 3 Time Supplied by system 4 Subject Supplied by operator: mandatory 5 Side of c/l Supplied by operator: mandatory 6 Distance from c/l Supplied by operator: mandatory 7 Distance of keyed start from t/h 1 Stored in system 8 Distance of keyed start from survey speed 1 Stored in system 9 Distance of keyed start from t/h 2 Stored in system 10 Distance of keyed start from survey speed 2 Stored in system 11 Runway length (threshold - threshold
