Roads & Highways
Precast Box Culvert Program
A family of standard precast box culvert designs that replaced 40 failing road crossings faster and at lower cost than cast-in-place work.
- Year
- 2019
- Client
- Rural roads department
- Location
- Rural road network
- My role
- Lead design engineer
The challenge
Dozens of corroded pipe culverts were collapsing across a rural road network, and each replacement was being designed one at a time. Design fees, long road closures and inconsistent details were eating the maintenance budget.
The approach
I grouped the crossings by flow and fill height and designed six standard precast box sizes that cover them all, with matching headwalls, wingwalls and bedding details. Each crossing then needed only a short hydraulic check and a site-specific layout sheet.
- Structural design for fill heights from 0.6 to 6 m under heavy truck loading
- Standard drawings approved once by the department for repeat use
- Installation sequence that reopens a lane within 48 hours
The outcome
All 40 crossings were replaced over two seasons. Typical installations took two to four days instead of three weeks, and the program came in about 30 percent below the cast-in-place estimate.