Hi Sina

Please note that there are many factors involved in designing road in flood plain. Depending on traffic volume, importance of this road (if it connects two major towns or minor villages), design life, flood immunity, long-term maintenance cost, availability of pavement materials, funds available etc. Major highway carrying over over 10,000 vehicle per day should be designed with 1 in 50 year flood immunity if not 1 in 100 year flood immunity. Minor regional roads carrying 1000 vehicles per day should be designed for 1 in 10 year flood immunity. Well, if funds are not there, then flood immunity for minor road can be reduced to 1 in 5 year . Please remember if the road is going to be available at all weather conditions, then more culverts or bridges and raised pavement are required. When it comes to pavement material, concrete pavement is preferred in flood-prone area as there is a reduction of maintenance cost. Sometimes, bridges are constructed at higher level to reduce flood risk, but approaches will be washed away during major flooding. You may consider various scenarios and carry out option analysis in terms of cost and benefits, community issues and environmental issues.

Best regards

Ravi

Sinnappoo (Ravi) Ravindran thank you for your help. The road that i want to optimize, is a 4 Lane Divided Rural Road with paved shoulders and the pavement material is concrete. Do you know any sources about the factors that you have mentioned to read in?

Hi Sina

My response is based on experience. But, I have googled and found the following for you:

Best regards

Ravi

https://www.brisbane.qld.gov.au/planning-and-building/planning-guidelines-and-tools/brisbane-city-plan-2014/fact-sheets/flood-planning-provisions

http://www.charim.net/use/322