GENERAL DATA COLLECTION location of bridge site. Transportation of bridge site. Nature of crossing and affordability. Availability of local material. Traffic volume. Availability of local bridge builders. Temporary crossing. Local participation.
Important Definition Linear water way. Economical span. Design discharge. Scour depth. Vertical clearance above HFL.
LINEAR WATER WAY A river or canal,or other body of water serving as a route or way of travel.
Economic span Economic span depend upon the cost of : Substructure Superstructure
Scour Depth The depth which is produced due to scouring action of water Depth of scour below the high flood level Scour depth has important in determination depth of foundation Mean scour depth(d)=9.2m Max.scour depth for piers=2d =18.4m
VERTICAL CLEARANCE Minimum vertical clearance of 5m should be ensure over the full width of roadway. The vertical clearance should be measured with regard to the highest point of carriageway. Allowance for any future raising of pavement is also be made.
a)Geometric condition of the site(road alignment, design flood and highest water mark) b)Traffic capacity. c)Structural stability. d)Foundation conditions and strength of a abutment. e)Available material. f)Knowledge and equipment of the contractor. g)Clearance requirement above and below the road way. h)General requirements with respect to location,financing and community values. POINTS FOR SELECTION OF BRIDGE TYPE