Learning / bridge engineering
waterproof
Water head on a membrane
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: Trace a continuous drainage plane including falls, upstands, penetrations and joint returns. Treat details as interfaces; a perfect field membrane can still leak at its edge. The head 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
The membrane faces water, local contact, thermal cycles and relative movement at cracks and joints. Protection layers prevent damage under ballast or surfacing.
Choose a model
Trace a continuous drainage plane including falls, upstands, penetrations and joint returns. Treat details as interfaces; a perfect field membrane can still leak at its edge.
Design considerations
Compare compatible systems and protection arrangements, substrate preparation, curing conditions and inspection/testing before covering. Ensure water has a route to a maintainable outlet.
Durability and maintenance
Water staining does not locate the breach directly because water can travel along interfaces. Record defects before removal and test repaired transitions before re-covering.
Water head on a membrane
Hydrostatic pressure only; no puncture resistance, adhesion or waterproofing system qualification is calculated.
Water pressure p = γwh, with γw = 9.81 kN/m³.
p = 0.490 kPa