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REPORT
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Publication Number:  FHWA-HRT-13-090    Date:  April 2016
Publication Number: FHWA-HRT-13-090
Date: April 2016

 

MEPDG Traffic Loading Defaults Derived From Traffic Pooled Fund Study

APPENDIX B-EVALUATION OF ATYPICAL APC COEFFICIENTS

Axle group types reported for individual vehicle classes 4 through 13 were reviewed to identify atypical axle group types for each class using the LTPP vehicle classification scheme. Atypical axle group types identified as a result of this review were reported to FHWA using feedback reports. A summary of the evaluation is presented in the following table.

Table 53. Summary of atypical axle group types.
State Code SHRP ID Class Reason(s) for Flag Comments
39 0100 4 Small number of tridems reported for buses. Possible misclassification. Tridems reported in buses for June 2005, February 2007, and March 2007 only. Only 3 of 22 months had significant tridems reported (with APC at least 0.01). From monthly NALS, 9 months have 100 percent in first load bin; none of the other SPS TPF sites had tridems reported for buses.
39 0200 6 High single APC, lower than expected tandem APC. Single APC values are higher and tandem APC values are lower in 2005 (May-August). Single axle class 6 RANALS peak is in the first bin (average 18 percent overall and 26 percent in May-August 2005). Tandem class 6 peak is in the third bin (average 30 percent at 8,000-9,999 lb) for all months.
53 0200 6 Highest single APC and lowest tandem APC among SPS TPF sites. Single and tandem APC are high for many months. Class 6 single axle plot has high percentage (average 9 percent) in the first load bin. Tandem class 6 peak is in the third bin (average 28 percent at 8,000-9,999 lb) for all months.
4 0100 7 High single and tandem APC. Single and tandem APC values are high for most months. No light weights observed in class 7 single and tandem RANALS.
6 0200 7 High single and tandem APC. Single and tandem APC values are high for most months. Some low weights (6.6 percent) observed in the 8,000-9,999-lb load bin in class 7 tandem RANALS plot. No light weights observed in single axle class 7 RANALS plots.
12 0100 7 Average total number of axles less than four. Possible misclassification. Single APC values are okay. Tandem APC values are higher than usual, and tridem APC values are lower than usual for outlier months. Outlier months are random. Also, there are no light weights observed in class 7 single and tandem RANALS.
12 0500 7 Average total number of axles less than four. Possible misclassification. Single APC values are okay. Tandem APC values are higher than usual, and tridem APC values are lower than usual for outlier months. Maximum outlier months are in 2004. Total APC value is low for these months in 2004 (January, April, and May). Low total APC is always associated with higher tandem APC. Also, there are no light weights observed in class 7 single and tandem RANALS.
35 0100 7 High single and tandem APC. Single and tandem APC values are high for most months. No light weights observed in class 7 single and tandem RANALS;
39 0100 7 High single APC. Single APC values are high for most months. Light weights observed in class 7 single RANALS in both second and third load bins (~14 percent in 3,000-3,999-lb and 4,000-4,999-lb bins). These light weights are observed in all months.
39 0200 7 High single APC. Single APC values are high for most months (> 1.5) and even higher for months in 2005 (> 2). Light weights observed in May-November 2005 (average 40 percent).
53 0200 7 Average total number of axles less than four. High tandem APC and low tridem APC. Possible misclassification. Low APC in 5 of 30 months (December 2006 to April 2007), primarily single axles. Possible misclassification. Tandem RANALS peak is at 0-5999 lb; tridems are okay.
4 0100 9 Highest single and lowest tandem APC among SPS TPF sites. Single APC consistently high and tandem APC consistently low. There is a secondary peak (8.32 percent at 16,000-16,999 lb) after legal limit in class 9 single axle plot in all months. It could be because of the presence of split tandem axle.
53 0200 11 Highest number of tandem among SPS TPF sites. Also, tridems are reported. Tandems and tridems reported for many months. Tandem class 11 peak is at fourth bin (average 27 percent at 10,000-11,999 lb). Very few tridems reported at level E for class 11.
53 0200 12 Only SPS TPF site that has tridems. Low percentage of tridems reported in most of the months, with January 2009 having the highest tridem APC = 0.18. Low weight tridems in first load bin (0-11,999 lb) for 4 of 26 months. January 2009 has the highest percentage in first load bin (~42 percent at 0-11,999 lb).
24 0500 13 Average total number of axles less than FHWA scheme. Possible misclassification. Misclassification possible. There are many months with total APC less than seven.

 

 

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