floodways Road Construction

Floodways Construction

Frequently streams in flood overflow their banks and spread over floor plains which may be  many  kilometres  wide.  Because  of  the  amount  of  water,  the  nature  of  the  terrain  and  the status of the road,  it  is sometimes  not economically  justifiable to pass all the water under the road.  Instead,  some  of  the  water  is  allowed  to  flow  over  the  roadway  at  depressed  sections known as floodways.

The  pavement  at  floodways  must  be  designed  to  resist  scouring  and  to  withstand  the expected traffic loading while inundated. Embankment batters must be protected from scouring.

Floodway Pavements

The types of pavements used include:-

•    A  good  quality  crushed  rock  or  soil  aggregate  base  sealed  with  a  2  or  3  coat  sprayed bituminous seal. This type of pavement is used for light traffic and infrequent low velocity inundation.

•    Cement, bitumen or lime stabilised crushed rock or soil aggregate with a 2 or 3 coat sprayed bituminous seal.

•    Asphalt  or  Portland  cement concrete  pavements  which  are  suitable  for  the  more  heavily trafficked roads.