According to IRC, the minimum vertical clearance on urban roads should be: 

Explanation:

Urban roads

1. Single carriageways:

For kerbed roads, the carriageway width is widened on both sides under structures (underpass etc.) by 0.25 metre in the case of lower category urban roads and by 0.5 metre in the case of higher category urban roads to account for kerb shyness. If a footpath does not form the cross-section of the urban road, the minimum lateral clearance in addition to the above values shall be 0.5 metre for lower category roads and 1 metre for higher category roads. Where a raised footpath is provided, it is not necessary to have additional clearance beyond the width of the footpath.

2. Divided carriageways:

The extra width to account for kerb shyness on kerbed roads is the same as in (1) above. The lateral clearance on the left side shall be same as in (1) above. Right hand clearance shall be, in addition to the factor to account for kerb shyness, 0.5 metre in the case of lower category roads and 1 metre in the case of higher category roads.

3. Vertical clearance:

The minimum vertical clearance shall be at least 5 metres. However, in urban areas, this should be increased to 5.5 metres so that double decker buses could be accommodated.