TRAFFIC LOADING Tefoowng table is based on a single day traffic count for a 4-la

Question

TRAFFIC LOADING Tefoowng table is based on a single day traffic count for a 4-lane county highway that is scheduled to be repaved later this year. (Hint: assume that the daily Calculate the ESALs for the 20-year design life of the pavement. ESAL count is representative of what the traffic will be every day for the life of the pavement) 1. 2. The county is trying to develop an industrial park along the highway. It is projected that the park will result in a 10 percent increase in passenger vehicles and a 30 percent increase in Semi- tractor trailers. Re-calculate the ESALs for the 20-year design life of the pavement after development of the industrial park. Traffic Volume Axle Load and Type Axle 2 Vehicle Description Axle 3 Ibs Axle 1 Passenger vehicle Recreational vehicle School bus lbs 2000 | SI 2000 S 4000 S 4000S 800 2000 S 4000 S Greyhound MC-12 bus Delivery truck Garbage/dumpster truck Dump truck (full) 13400 | S | 18400 | SI 6000 s 4000 S 14000S 20000 | S| 35000 | T 20000 | S| 48000 | T 12000 |S| 34000 | TI 34000 | T Semi-tractor trailer 60 Note: S = Single axle; T-Tandem axle

Explanation / Answer

Step 1:

Passenger vehicles=800

Recreational vehicles=1

School bus=4

Grey hound bus=1

Delivery truck=8

Garbage truck=1

Dump truck=2

Semi tractor=60

Total=877

Step 2:

The % of vehicles for each and every individual type:

Passenger vehicles=91.22%

Recreational vehicles=0.11%

School bus=0.45%

Grey hound bus=0.11%

Delivery truck=0.91%

Garbage truck=0.11%

Dump truck=0.22%

Semi tractor=6.84%

Step 3:

Let us assume a uniform growth rate of 4% for all the vehicles, it can be seen that only passenger cars and semi tractor axles have more than 98% of the design volume, so calculate the E.S.A.L for only those 2 types of vehicles

ESAL=fdxGxAADTX365XNXFei

fd=% of the Traffic for that particular class of vehicle

G=Growth factor

AADT=Annual average daily traffic

N=Number of axles

Fei=Load equivalency factor

ESAL=fdxGxAADTX365XNXFei

ESAL=0.9122x29.78x(800x365)x365x2x0.0002=1.15x106 (For passenger cars)

ESAL=0.0684x29.78x(60x365)x365x1x0.213=3.46x106 (For semi tractor trailer single axle)

ESAL=0.0684x29.78x(60x365)x365x2x1.11=35.82x106 (For semi tractor tandex axles)

Total ESAL=40.43x106

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