3.1 – Scope
The CSMP should outline procedures for designing, constructing, and maintaining culverts. The railway company should include requirements to ensure that culverts are sized to accommodate the expected flows and that they have sufficient structural capacity for the applied loads.
3.2 – Procedures for designing, constructing, and maintaining culverts
The railway company documentation should include:
- standards or drawings for designing, constructing, and maintaining existing and new culverts
- procedures to ensure design, construction, and maintenance work follows standards and procedures
- procedures to ensure maintenance activities that affect load carrying capacity of a culvert are assessed, recorded and approved by a railway engineer before being deferred
- procedures to ensure on-site construction changes are recorded and approved by a railway engineer
3.3 – Replacing and repairing existing culverts
The CSMP should include procedures for assessing the structural and hydraulic adequacy of existing culverts when signs of distress are observed or where they regularly show an inability to handle normal flows.
Before replacing or repairing an existing culvert, consideration should be given to its design flow and determine its adequacy when choosing repair or replacement options. Always consider inlet and outlet improvements to address any increased scour potential as a result of a culvert repair or replacement.
Section analysis 3.2 and 3.3 – Designing and installing new culverts and replacing and repairing existing culverts
Railway companies should consult the manufacturer’s installation instructions for each of their products. Industry standards or guidelines, such as American Railway Engineering and Maintenance of Way Association, are also available to assist railway companies in the design and installation of culverts.
The hydraulic requirements of a culvert usually determine its size, shape, slope, inlet, and outlet treatments. Culvert hydraulics can be divided into 2 general design elements:
- hydrological analysis to determine the design discharge or the amount of runoff the culvert should be designed for
- hydraulic analysis to select a culvert or evaluate whether an existing culvert is capable of adequately conveying the design discharge
Good quality backfill material, proper placement technique, and adequate compaction are of critical importance when installing a culvert. The culvert installation crew should have adequate training, experience, be knowledgeable of sound culvert installation techniques, and equipped with proper materials and equipment.