chapter 3 rigid pavement - DOT On-Line Publications - Department ...

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Table 2. Encroachments on outside
shoulder, by type of terrain (reference 3).
Xl1
Terrain 205 133 64.9 677 5.09 3.30
Table 3 shows that the outside shouider encroachments occurred ior an
average of 4.5 seconds. The average encroachment was for a longitudinal distance cr’
approximately 400 ft (I 22 m) and 0.60 ft (0.18 m) laterally onto the shoulder strvx:‘z:e.
Item
Table 3. Average time and distances of outside
shoulder enaoachments (reference 3).
Outer .Median
Shoulder Shoulder
Average encroachments per truck in 10 Miles 3.30 0.25
Average time on shoulder per encroachment, sets. 4.30 3.40
Average longitudinal distance on shoulder per
encoachmen t, ft.
383.86 344.16
Average transverse distance on shoulder per 0.59 0.05
enaoachmen t, ft.
. Figure 1 is a summary of the transverse encroachments onto the shoulder. As
can be seen, the highest frequency of encroaching trucks was approximately 6 in (!32
mm) onto the shoulder. A high percentage of times when trucks encroach, their dual
tires are iiterally split between the pavement edge and shoulder.
The fact that shoulder encroachments occur regular& is well illustrated by the
Georgia study. In the IO-mi (16.1 km) test section, the average number of
encroachments per truck was 3.3. Of the 65 percent trucks encroaching, the average
number of encroachments per 10 miles was 5.1 (see table I?. Why do certain trucks
go onto the shoulder more than others. 7 The study was done with no cross-winds
present, which eiiminates an obvious external factor irom biasing the resuits. Truck
3.8.9