Onshore Pipelines
1. The use of casings for the crossing of roads or railways should be discouraged because of the difficulty in providing the pipeline with adequate protection against external corrison.
2. Whe casings are stipulated by local authorities, the cathodic protection of the pipeline section within the casing shall be carefully reviewed.
3. Recommendations on pipeline crossings of roads and railways are contained in API RP 1102.
4. Directional drilling is particularly suitable for long crossings e.g. rivers and waterways; the method can achieve large burial depths and at is insensitive to current, river traffic etc.
5. The recommended minimum covers at the crossings is given in Table 4.
6. A minimum vertical separation of 0.3 m should be kept between the pipeline and any other buried structures e.g. existing pipelines, cables and foundations etc.
Offshore Pipelines
1. A minimum vertical separation of 0.3 m should be kept between the pipeline and any other underwater structures such as existing pipelines and submarine cables.
2. Mats or equivalent means should be used for local positive separation at crossing locations.
Methods Used
1. Cased and Un-Cased crossings for Roads and Railways.
2. Open cut and horizontal directional drilling (HDD) for minor and major river crossing.
3. Jacking and boring
4. Micro-Tunneling
