> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-downloads/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/os-downloads/products/transport-network-portfolio/os-multi-modal-routing-network/os-mrn-technical-specification/code-lists/tunnelvalue.md).

# TunnelValue

This code list is used in association with the Tunnel attribute which is present within the Transport Link Feature Type. On Transport Links that represent a road feature, it indicates whether there is a presence of a Tunnel, e.g 'yes' or Null.

| Label             | Definition                                                                                               |
| ----------------- | -------------------------------------------------------------------------------------------------------- |
| yes               | Indication that there is a tunnel                                                                        |
| building\_passage | A tunnel passage that goes through/under a building, but is not inside the building itself.              |
| canal             | Tunnel for navigable canals                                                                              |
| culvert           | For a stream/drain/ditch passing under a road. Use it on the section of waterway passing under the road. |
| flooded           | A long (>100 m) tunnel where flowing water or other fluid prevent humans from safely walking inside      |


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