A concrete portal to a culvert used to take watercourses under roads.
A culvert through an embankment can be represented by using a portal on either side of the embankment. The portal has 45-degree wing walls to protect the upstream-facing embankment from erosion. Open this asset's Properties editor to remove the wings on the downstream-facing portal.
The culvert bore is of 1m diameter. Use a 1m-diameter pipe spline to connect the 2 portals.