- 2068 Magh (old course) · 1+2+3 marks
Street inlets: curb vs gutter inlet
Short answer
Street inlets are structures that admit road storm water into drains, located at corners, low points, and 30–60 m intervals. Curb inlets have a vertical kerb opening, less prone to clogging but less efficient on slopes; gutter inlets use a horizontal grating, better on continuous grades but clog more.
What do you understand by street inlets? Where are these located? Differentiate between a curb inlet and a gutter inlet.
Street inlets
Street inlets are openings or structures that admit storm water from the street surface into the storm drain or combined sewer.
Location
- At the street corners (upstream of pedestrian crossings) and along the kerb.
- At low points and sag points of the road where water collects.
- At intervals of about 30-60 m on a continuous grade, closer when the road is flat and the area is large; also at the end of a catchment length where gutter flow exceeds its capacity.
- In the side of the road at the downhill side of junctions, so that water does not cross the intersection.
Difference between curb inlet and gutter inlet
| Point | Curb inlet | Gutter inlet |
|---|---|---|
| Opening | Vertical opening in the kerb face | Horizontal opening in the gutter |
| Cover | Open, sometimes with a bar | Cast iron grating |
| Water enters | Sideways, as the gutter water flows past | By falling through the grating |
| Clogging | Less by leaves and paper | More by leaves, paper and debris |
| Efficiency | Good on flat slopes and at sags; loses efficiency on steep grades | Better on continuous (moderate to steep) grades, but some fast flow may skip over the grating |
| Safety | Safe for traffic and cyclists | Grating can be a hazard to bicycles |
| Capacity | Smaller; depends on the depth of water at the kerb | Larger when the grating is clear |
| Suitable for | Kerbed roads on flat grades, sag points and where debris is heavy | Roads on continuous grades with little debris |
✓ Answer checked by Claude Opus 5.5 (high effort)
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