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APPENDIX E Effects of Axle Weight Enforcement on Pavement Life
Pages 173-192

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From page 173... ... . The following discussion summarizes two methods of determining the increase in pavement life one could expect from reduced axle loadings accrued through enforcement activities. Read the entire page →
From page 174... ... (The rule states that the load equivalency factor increases approximately as a function of the ratio of any given axle load to the standard ~ 8-km single axle load raised to the fourth power.~(~) The approximation watt be reasonably accurate, but may be in error up to about 10% in estimated changes in pavement life expectancy as compared to the more precise method given in Section 5 of this appendix. Read the entire page →
From page 175... ... 3.0 FOURTH POWER RULE OF CALCULATING AXLE EQUIVALENCIES The formidable equations and calculations (Section 5 of this appendix) used to develop theoretically correct 1 8 Kip axle equivalency factors have led to much interest in handy methods of estimating those factors given a minimum of information. Read the entire page →
From page 176... ... el8= 1.0. In order to make full use of the fourth power rule in calculating equivalencies it is necessary to establish some bases for those calculations for tandem and truism loads and to reflect differences in ~ 8-km equivalencies relating to pavement type (rigid or flexible) Read the entire page →
From page 177... ... REAPPLICATION OF THE FOURTH POWER RULE TO DETERMINATION OF DAILY 18-KIP EQUIVALENCIES (ESALs) FOR A TYPICAL TRAFFIC STREAM Table E-2 provides an example of determining the average daily ESALs for a typical traffic stream both before and after weight enforcement. Read the entire page →
From page 178... ... Daily Factor Axles ESALs Axles ESALs 0.006 18 0.108 18 0.108 0.03 12 0.36 10 0 3 0.095 370 35.15 260 24.7 0.366 40 14.64 30 10.98 1 300 300 320 320 2.23 42 93.66 6 13.38 O O 0.005 18 0.09 16 0.08 0.042 24 1.008 23 0.966 0.16 50 8 40 6.4 0.76 48 36.48 36 27.36 0.976 25 24.4 123 120.048 1.38 43 59.34 52 71.76 2.11 163 343.93 27 56.97 ~7 ~653.052 Axle Load Ranges 3000 - 6999 7000 - 7999 8000 - 1 1999 12,000- 15,999 16,000- 19,999 20,000 - 23,999 Tandem 6000 - 11 ,999 Axles 12,000- 17,999 18,000 - 23,999 30,000 - 31,999 32,000 - 33,999 34,000 - 37,999 38,000 - 41,999 Read the entire page →
From page 179... ... ~1283-872~/1283 = 32.0%. 5.0 MORE PRECISE METHOD OF CALCULATING INCREASED PAVEMENT LIFE DUE TO WEIGHT ENFORCEMENT AASHTO design procedures provide for the traffic input to design to be in terms of accumulated (or projected) Read the entire page →
From page 180... ... Daily Factor Axles ESALs Axles ESALs 0.006 18 0.108 18 0.108 0.03 12 0.36 10 0 3 0.095 370 35.15 260 24.7 0.366 40 14.64 30 10.98 1 300 300 320 320 2.23 42 93.66 6 13.38 O O 0.01 18 0.18 16 0.16 0.074 24 1.776 23 1.702 0.284 50 14.2 40 11.36 1.35 48 64.8 36 48.6 1.73 25 43.25 123 212.79 2.45 43 105.35 52 127.4 3.74 163 609.62 27 100.98 Total 1283.094 872.46 Axle Load Ranges Single 3000 - 6999 Axles 7000 - 7999 8000 - 11999 12,000- 15,999 16,000- 19,999 20,000 - 23,999 Tandem 6000- 11,999 Axles 12,000 - 17,999 18,000 - 23,999 3O,000 - 31,999 32,000 - 33,999 34,000 - 37,999 38,000 - 41,999 Read the entire page →
From page 181... ... WX = number of loads of magnitude Ex required to reduce the PS} to pi, wig= number of {8 kip loads required to reduce the PS] to p', Ex = load on one single axle or one tandem axle set (kips) Read the entire page →
From page 182... ... Similar calculations produce the tabulation of flexible pavement tandem axle load equivalency factors for pi = 2.5 and structural numbers ~ through 6 given In Table D.5 of Me ~ 986 AASHTO Guide for the Design o/Pavement Structures. Studies by Treybig, et.al.~ have extended the AASHO Road Test results to trident axles. Read the entire page →
From page 183... ... Similar calculations produce the tabulation of rigid pavement tandem axle load equivalency factors for pi = 2.5 and slab thicknesses of 6 through 14 inches given in Table D.14 in the 1986 AASHTO Guide for the Design of Pavement Structures. Again, while the analysis of tridem axle equivalencies is well beyond the scope of the present study, Table D.15 in the 1986 AASHTO Guide for the Design of Pavement Structures is a tabulation of rigid pavement tandem equivalency factors for slab thicknesses of 6 Trough 14 inches and p' = 2.5. Read the entire page →
From page 184... ... Daily Factor Axles ESALs Axles ESALs 0.005 18 0.09 18 0.09 0.032 12 0.384 10 0.32 0.088 370 32.56 260 22.88 0.36 40 14.4 30 10.8 1 300 300 320 320 2.18 42 91.56 6 13.08 O O 0.005 18 0.09 16 0.08 0.037 24 0.888 23 0.851 0.151 50 7.55 40 6.04 0.758 48 36.384 36 27.288 0.974 25 24.35 123 119.802 1.38 43 59.34 52 71.76 2.08 163 339.04 27 56.16 Total 906.636 649.151 Axle Load Ranges Single 3000 - 6999 Axles 7000 - 7999 8000 - 11999 12,000- 15,999 16,000- 19,999 20,000 - 23,999 Tandem Axles 6000 - 11,999 12,000 - 17,999 18,000 - 23,999 30,000 - 31,999 32,000 - 33,999 34,000 - 37,999 38,000 - 41,999 Read the entire page →
From page 185... ... ~1301-871~/1301 = 33.~%. Again, the estimated increase in pavement life for this method is very close to that determined in Section 4 through Me fourth power rule for We same traffic stream on a generic ngid pavement. Read the entire page →
From page 186... ... Daily Factor Axles ESALs Axles ESALs 0.006 18 0.108 1 18 0.108 0.03 12 0.36 10 0.3 0.081 370 29.97 260 21.06 0.338 40 13.52 30 10.14 1 300 300 320 320 2.38 42 99.96 6 14.28 O O 0.085 18 1.53 16 1.36. 0.064 24 1.536 23 1.472 0.254 50 12.7 40 10.16 1.32 48 63.36 36 47.52 1.72 25 43 123 211.56 2.48 43 106.64 52 128.96 3.87 163 630.81 27 104.49 Total 1303.494 871.41 Axle Load Ranges Single Axles 3000 - 6999 7000 - 7999 8000 - 11999 12,000 - 15,999 16,000- 19,999 20,000 - 23,999 Tandem 6000- 11,999 Axles 12,000 - 17,999 18,000 - 23,999 30,000 - 31,999 32,000 - 33,999 34,000 - 37,999 38,000 - 41,999 Read the entire page →
From page 187... ... 6 = 2.6. 6.2 DETERMINATION OF ESTIMATED PAVEMENT LIFE FROM AASHTO EQUATIONS 6.21 FLEXIBLE PAVEMENTS 6.211 AASHTO Design Equation The AASHTO Design equation for flexible pavements is: tog,OW~ = ZR* Read the entire page →
From page 188... ... , SO = the overall standard deviation associated with pavement performance prediction (a typical value for flexible pavements is 0.35) , SN = the pavement structural number defined earlier, DPSI= the change in pavement serviceability during the design period (a typical value is 1.9) Read the entire page →
From page 189... ... FLEXIBLE PAVEMENTS Typical Material Thickness (h) Read the entire page →
From page 190... ... where n = the estimated pavement life in years, r = the annual growth rate expressed as a decimal, ESAL = the average daily ESALs at the beginning of the analysis period. Assuming a 5% annual rate of growth in traffic for the above example the pavement would have been predicted to last no = Fog* Read the entire page →
From page 191... ... 7.0 CONCLUSION The foregoing discussion of pavement design pnociples has addressed the major issues underlying methods of determining Me increase In pavement life one could expect from reduced axle loadings accrued through enforcement activities. The application of these principles is seen In the software product of NCHRP 20-34, the Truck Weight Enforcement Evaluation Tool. Read the entire page →
From page 192... ... L Von Quintus, "Equivalency Factor Analysis and Prediction for Triple Axles", Report No. Read the entire page →

From page 173...

... . The following discussion summarizes two methods of determining the increase in pavement life one could expect from reduced axle loadings accrued through enforcement activities.

APPENDIX E Effects of Axle Weight Enforcement on Pavement Life Pages 173-192

APPENDIX E Effects of Axle Weight Enforcement on Pavement Life
Pages 173-192