Learning / bridge engineering
drain
Deck runoff estimate
Lesson review: expert verification remains open
This lesson has received a full-context editorial review and a check of its technical explanations. Selected arithmetic has been checked separately. This is not independent engineering sign-off.
Checks needed for project use
- Bridge component studies and adjustable examples still need an independent bridge-engineering review, including applicability, load models and detailing guidance.
- Specialist review remains for: A rational runoff estimate gives peak inflow for a small catchment. A drainage design also needs rainfall duration, time of concentration, hydraulic capacity, blockage and safe overflow routes. The runoff calculation is a local idealisation; it does not verify the displayed bridge or applicable design requirements.
These are educational models and exercises. Check their assumptions before using the results. The full technical content and every diagram have not yet been independently verified.
Concrete and steel calculations retain their stated first-generation Eurocode teaching basis. Use the standards and amendments specified for your project; do not mix generations without an appropriate design basis.
Read the lesson register and outstanding review notesLoads and actions
Runoff comes from the contributing area and design storm; water below ballast may follow a separate collection plane. Debris, ice or deformation can reduce outlet capacity.
Choose a model
A rational runoff estimate gives peak inflow for a small catchment. A drainage design also needs rainfall duration, time of concentration, hydraulic capacity, blockage and safe overflow routes.
Design considerations
Set deck falls and collection levels together. Compare channels, gullies and downpipes with accessible rodding and a protected outfall; avoid discharge onto bearings, concrete faces or an operational route.
Durability and maintenance
Inspect during or after rain to distinguish ponding, leakage and overflow. Clean the inlet and downstream pipe; clearing one visible grille does not prove the entire path works.
Deck runoff estimate
Illustrative rainfall, not a local design storm. Inflow does not establish channel, pipe or outfall capacity.
C = 0.9, A = 280 m²: Q = CiA/3600 in litres/second.
Q = 5.25 L/s