Highway Engineering

Highway Pavement Materials and Design 207

Example 7.3

Using the total commercial flow per day in one direction at opening and the

proportion in the OGV2 category from the previous example, estimate the

cumulative design traffic for the four road types detailed in Figs 7.7 to 7.10.

Solution

(1) From Fig. 7.7, for flexible and flexible composite pavements (20-year

design life) – single carriageway

Cumulative design traffic =40 million standard axles (msa)

(2) From Fig. 7.8, for flexible and flexible composite pavements (20-year

design life) – dual carriageway

Cumulative design traffic =35 million standard axles (msa)

(3) From Fig. 7.9, for rigid, rigid composite and flexible pavement (40-year

design life) – single carriageway

Cumulative design traffic =105 million standard axles (msa)

(4) From Fig. 7.10, for rigid, rigid composite and flexible pavement (40-year

design life) – dual carriageway

Cumulative design traffic =100 million standard axles (msa)

Figure 7.11 illustrates how the solutions to these four cases are derived.

Traffic flow at opening (cv/d) – 1 direction

100 1000 10000 30000

1

10

100

1000

Design traffic (msa)

75%

50%

25%

100%

OGV2

Figure 7.10Design traffic for rigid, rigid composite and flexible pavement
(40-year design life) – dual carriageway (HD 24/96) (DoT, 1996).