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Some typical design details are presented in the following figures. Figure 13.40 shows the typical details for a drainage channel to be installed in the verge between the pavement and a cutting slope, Fig. 13.41 shows the likely details to be employed

hard shoulder, hardstrip
or carriageway

min. 1.20 m

Fig. 13.40 Cuttings – Standard concrete channel in verge with drain and pipe

Fig. 13.41 Drain for use in conjunction with concrete barrier and linear slot drainage channel

hard shoulder, non-pavement verge made

hardstrip or of impervious material

carriageway

Fig. 13.42 Cutting – Combined surface water and groundwater filter drain and drain pipe

concrete

channel

in the vicinity of...

In order to estimate the water flow into drainage pipes, one should differentiate between the two distinct situations introduced earlier:

• pipes above the water level (intersection drains); and

• pipes below the water level (groundwater lowering) drains.

When the drainage system is above the water level, the infiltration water from edges, channels and gutters, and from some of the transverse drainage that is covered by permeable surfacing, must also be considered according to the relationship of Eq. 13.2.

qL = R ■ B ■ L (13.2)

where qL is the water flow through the pipe (m3/s), R is the surface runoff water flow (m3/(s. m2)), L is the section’s length (m) (see Eq. 13.3) and B is the width of the section requiring calculation (m) (see Eq. 13.3 as shown in Fig. 13.39).

n

B ■ L = Y, bi...