During the pavement design process of a new 4-lane highway, the following data w
ID: 1714613 • Letter: D
Question
During the pavement design process of a new 4-lane highway, the following data were predicted:
Average Annual Daily Traffic (both directions) = 9,000
Trucks as percentage of AADT = 20
Directional split of traffic = 50/50
Lane Distribution = 2/3 of truck traffic use the design lane
The truck axle load distribution was obtained from a similar existing highway as follows:
If the average number of axles per truck on the existing highway is 3.1, determine the total ESAL in the design lane of the new highway during the first year assuming that ESAL per truck is the same for both highways.
Single Axles 16 18 20 Tandem Axles 30 32 34 1,800 1,500 700 0.6 1.5 1,200 1,000 800Explanation / Answer
The following equation would give the ESAL as :
ESAL = Tf T 365 GDLY
Where Tf is truck factor and is given as product of average number of truck axles and summation of equivalent axle load factor and percentage of repetitions
G is growth factor and is given as G= (1+g)^n -1 /g
Assuming growth rate of traffic at 5% per annum , g= 0.05
Thus for 1 year G = 1
T is annual truck traffic in ADT = 9000*0.2 = 1800
D is directional distribution factor which given above is 0.5
L is lane distribution factor given above as 2/3
Y is design period which is 1 as ESAL required during first year
Truck factor Tf for the given problem is :
Tf = (((1800*0.6)+(1500*1)+(700*1.5)+(1200*1.1)+(1000*1.4)+(800*1.8))/7000)*100*3.1 = 344.985
Thus ESAL = 344.985*1800*365*1*0.5*(2/3)*1=75551715
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.