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34 · MODULUS gave no indication of invalid FWD data, included deflection data taken at 200 m (656 ft) dis- whereas EVERCALC gave an error message. tances in both directions and moduli are backcalcu- · MODULUS and EVERCALC gave similar results, but lated using an "equivalent thickness approach." EVERCALC worked within the Windows GUI and · Ireland--FWD data are collected in 200 m (656 ft) sec- MODULUS required a DOS command line interface. tions "with measuring distances of 25 to 50 m (82 to Additionally, EVERCALC was more sensitive to seed 164 ft)." These data are used to classify pavement layer moduli. Furthermore, EVERCALC was accompanied bearing capacity, subgrade layer bearing capacity, and by software for overlay design and stress simulation AC overlay thickness. but had poor user manuals. · Sensor D6--placed 36 in. from the load plate-- better In the state of Western Australia, FWD testing has gradu- measured subgrade response than sensor D7. This ally replaced the Benkelman beam as the standard deflection observation may have been unique to Florida. testing mechanism since the 1990s. Two FWDs are present · While finite-element analysis was generally reliable, in Western Australia. "With the arrival of FWDs, Main bedrock and subgrade moduli were occasionally Roads Western Australia (MRWA) commenced conducting overestimated. network level FWD deflection survey together with profi- · Soil moisture was not considered for back-calculation lometer survey for roughness, rutting, and texture measure- strategies, but it can drastically change soil properties. ments in annual basis." Annual calibration was required and · Bedrock depth was not considered for back-calculation a calibration center based on the SHRP 1994 protocol was techniques, but it can be determined through finite- built in Perth. Traffic control was performed by a "driver element analysis. operator" with an escort vehicle warning sign behind the · FWD data should be coupled with other data to be FWD trailer. Test methods followed the ASTM D4694-96 useful. Such data include bedrock depth and layer protocol. Sensors were located at 0, 203, 305, 406, 508, 610, thickness. 762, 914, 1,524 mm (0, 8, 12, 16, 20, 24, 30, 36, and 60 in.) from the load plate. Tests were conducted at 50 kN (11,200 lbf) to simulate Western Australia tire pressure loads. Data CASE 13. INTERNATIONAL PRACTICES were collected every 0.8 km (0.5 mi) in the outer wheel path. The data gathered were used "together with Rutting, A nation-by-nation assessment of FWD usage and nonde- Roughness, Surface Texture, and Skid Resistance to the structive testing was provided in a report by the European key pavement performance indicators for the Road Network Cooperation in the Field of Scientific and Technical Research Maintenance Contracts," and thereby to determine payment (COST), under the auspices of the European Union. The fol- to contractors. Furthermore, "based on the network deflec- lowing are some of the findings (Beuving 2000): tion data the Contractors select the sections requiring project level pavement investigation for rehabilitation works." The · Spain--At the project level, FWDs were used exclu- presence of FWDs has greatly increased testing efficiency. sively on rigid pavements; flexible pavements were "Average production rate was 250 deflection tests per day. tested using either Lacroix deflection measurement Typical production rate of Benkelman Beam tests is 80 to devices or FWDs. Measurements are taken every 200 100 per day." Testing integrity is validated through calibra- m (656 ft), and surveys are completed every 4 years. tion, data auditing, marking the test point, and accounting · Finland--Structural assessments are performed using for environmental factors. Additionally-- KUAB FWD data. Measurements are taken "not fur- ther apart than 500 m (1,640 ft)" and are completed Deflection data from the tests carried out on or close every 3 to 5 years. The primary parameter derived from to the outer wheel path after the rainy season were FWD data is the spring Bearing Capacity Ratio; how- generally high. This reflected wetting of subgrade ever, plans were under way to switch to the Structural and weakening pavement edges. Seasonal effects on Condition Index. deflection data between the successive surveys can · Denmark--Deflection data from FWD and average be reduced if deflection testing is carried out around daily traffic are used to determine structural pave- the same time of the year (Sapkota 2003). ment capacity. Denmark's PMS, in place since 1988,