Road test

It will be necessary to forecast the amount of traffic to be generated by the development within the site and to propose a form of junction that not only deals with the site s traffic but also adequately caters for the existing traffic on the road. Tests for capacity are required and attention should also be given to the safety of operation of the proposed access. 

These laboratory tests may be followed by engine dynamometer tests (BS5117 Section 2.4 1985(1989)) and finally by road tests in working vehicles (BS 5117 Part 2 Section 2.5 1985 (1989)), thus completing the sequence of laboratory, field, service testing. 

Ms. Banks s first rule of the road test a flavored spirit on its own merits, or don t mix with it. 

The improvement in PICO abrasion observed by use of QDI can be considerable. Improvements in treadwear have been confirmed in road testing. 

Correlation between Road Test Data and Laboratory Measurements.715... 

Correlation with Road Test Ratings of Compounds.718... 

Conditions for Tire Wear in Road Tests and Normal Usage.747... 

Correlation between Laboratory Road Test Simulation... 

Correlation with Truck Tire Road Test Ratings.753... 

CORRELATION BETWEEN ROAD TEST DATA AND LABORATORY MEASUREMENTS... 

The basis of comparison is Similar log a v values and track surface stmctures for laboratory and road test conditions. As discussed under Section 26.3.6 side force measurements at constant slip angle and load over a suitable range of speeds and temperatures form a very good basis for comparison with road data. 

The following laboratory surfaces have given high correlations with a wide range of road test data ... 

FIGURE 26.38 Correlation and regression coefficients between road test ratings obtained on three different wet road test tracks and laboratory ratings obtained on a wet Alumina 60 laboratory surface as function of... 

However, a correlation with road test ratings can often be improved if an independent term of log V is added to the transformation variable log a-jv. The friction or side force coefficient can then be written as... 

FIGURE 26.40 Correlation coefficient between road test ratings on a wet concrete track and laboratory measurements on a wet blunt Alumina 180 disk. Left as function of log a- v and right as function of log a-rv and log V. 

Figure 26.42 compares the correlation coefficient between a road test on wet concrete and the laboratory side force measurements of the six compounds of Table 26.2 on blunt, wet Alumina 180 (a) with a log oxv-log v evaluation and (b) with a temperature-log v evaluation. It appears that the... 

FIGURE 26.42 Comparison of the correlation coefficients between laboratory side force measurements with the six compounds of Table 26.2 on wet, blunt Alumina 180 and a concrete road test track as function of log ajv and log v (left) with function of temperature and log v (right). 

If laboratory abrasion data sets as described above are available for the compound ratings obtained in a road test, they can be compared with each other for all energy and speed levels of the laboratory rating tables. 

Relative Ratings of Four Passenger Commercial Tire Tread Compounds for Which Road Test Ratings Were Available as Function of Log Energy and Log Speed... 

Correlation, Regression Coefficients and Intercept of a Linear Relation between the Road Test Ratings from Table 26.4 and the Laboratory Ratings Obtained for Each Cell... 

FIGURE 26.70 Correlation coefficient between road test ratings of three truck tire compounds on re-treaded tires at two different axles and laboratory ratings as function of log energy and log speed. 

FIGURE 26.71 Correlation and regression coefficients between road test ratings of seven truck tire compounds 80 SBR/20 NR differing by type and amount of filler and laboratory abrasion ratings obtained on LAT 100 testing equipment. 

In tire tests, therefore, a stiffer tire construction reduces the wear. The stiffer construction not only includes the carcass and belt (i.e., height to width ratio), but also the tread pattern and the stiffness of the tread compound. Therefore, a correct road test requires two identical vehicles, each equipped with a test group of four identical tires. If this is not possible at least one axle has to have identical tires. If this is not the case an average slip will balance the acting force on the axle. This will be larger for the stiffer tire than is required if both tires had the same stiffness and smaller for the softer tire. Hence, the result is falsified to the advantage of the softer tire. The same argument holds for multi-section tires. 

FIGURE 26.77 Speed distribution in a controlled road test for passenger car tires also shown a distribution made up of two superposed normal ones. 

Table 26.7 gives a list of the boundary conditions which define a tire wear test simulation and in fact also an acmal road test. The road surface is the laboratory surface on which the abrasion data for the simulation were obtained. There is as yet no definition of a road surface and even if there were one, it would be of httle use since road surface structures change frequently along the road surface as pointed out earlier. 

Listing of the Boundary Conditions for a Road Test Stimulation... 

FIGURE 26.80 Major contributions to the wear in a road test simulation. 

It has already been shown how a correlation between road test ratings and laboratory abrasion can be obtained over a range of energies and speeds (Table 26.6). Usually, a good correlation, i.e., a high correlation coefficient and a regression coefficient near 1 are obtained only over a limited range. 

Correlation between Road Test Ratings and Laboratory Road Test Simulations of a Group of Four Passenger Tires, Discussed Above for Tbeir Laboratory Abrasion and Correlation to Road Test Ratings... 

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