esalcalculations.pdf
DESCRIPTION
ESAL calculation for pavement designTRANSCRIPT
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Roadway and Pavement Design
References: AASHTO Guide for Design of Pavement Structures, 1993 Huang’s Pavement Analysis and Design, 1993
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m = number of axle load groups F = the equivalent axle load factor (EALF) for the ith axle load group n = the number of passes of the ith axle load group during the design period
Class Description
1 Motorcycles (optional) 2 Passenger Cars 3 Other Two-Axle, Four Tire Single Unit Vehicles 4 Buses 5 Two-Axle, Six Tire, Single Unit Trucks 6 Three-Axle Single Unit Trucks 7 Four or More Axle Single Unit Trucks 8 Four or Less Axle Single Trailer Trucks 9 Five-Axle Single Trailer Trucks
10 Six or More Axle Single Trailer Trucks 11 Five or Less Axle Multi-Trailer Trucks 12 Six-Axle Multi-Trailer Trucks 13 Seven or More Axle Multi-Trailer Trucks
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160 kN 36,000 lb
Tandem Axle
160 kN 36,000 lb Single Axle
1.38 ESAL 13.93 ESAL
67 kN 15,000 lb 0.48 ESAL
27 kN 6,000 lb
0.01 ESAL + =
151 kN 34,000 lb
1.10
151 kN 34,000 lb
1.10
+ = 54 kN
12,000 lb 0.19
+
0.49 ESAL
2.39 ESAL
BIG TRUCK
Little Truck
Pavement Type Single Unit Multiple Unit
Flexible 0.600 1.300
Rigid 0.900 2.000
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We need to know: Average daily traffic (ADT) Average daily truck traffic (ADTT) Traffic mixture (number of vehicles in each class)
Average weight of the vehicles in each class
Given: ADT = 3500 VPD, Class 9 – 30%, Class 5 – 5%
Use the ESAL data from earlier slide
ESALo = [(0.49)(0.05) + (2.39)(0.30)](3500)(365)
ESALo = 947,266
Initial traffic in two directions Must correct for one direction Usually a factor of 0.5 is used This can vary depending on the traffic
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100% for two lane highways Outside lane is design lane for multilane facilities (truck or driving lane)
AASHTO, PCA, and Asphalt Institute all recommend slightly different methods
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Used to project total design traffic from the estimated first year traffic
Multiply initial year traffic by appropriate growth factor
Note that growth factors can be different for the different vehicle classes
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Should consider: Expected traffic attracted or diverted due to new/improved facility
Normal growth due to increased activity Number of motor vehicles and their use Future development (land use)
Given Four lane highway, traffic measured in two directions
Flexible pavement with pt = 2.5 and SN = 5 Traffic measurements over a 24-‐hour period Traffic data as previously shown Growth factor = 2%
Find 20 year design ESAL ignoring light traffic (eg. passenger cars) using AASHTO method
Assumptions: Traffic volume (all vehicle types) will increase at 2% per year
Axle weights of various vehicle types will remain constant over design period