Civil engineers play a big part in the mapping, soil evaluation for equipment movement and road crossings.
The structural guys may come in if a bridge is used (very rare today) and if equipment is need at each end of the line, like supports for pigging facilities Above ground pipe supports.
Typically, the two intertwine so much that they can do each others part fairly well with minimal training or education.
Never met a structural engineer who wasn't a civil engineer first. A structural may have a different focus than a civil, but as noted above, they often overlap their areas of competence.
Is there a problem with defining a scope for a particular project or task?
Scope is an important thing here. A 50-inch line from the North Slope of Alaska to Montana operating at very high pressures will have a team of Civil Engineers, Surveyors, and GeoTech engineers spend a couple of years picking and marking a route. Concurrently a team of structural guys will be working on supports for a few years. Concurrently a team of stress guys will be working on pipe stresses.
On the other hand a 20-inch gathering system trunk line would have someone like me hiring a surveyor to stake the route I picked from topo maps, hiring arch and enviro pukes to do their stuff, then doing all the above ground drawings in my spare time and doing the pipe stress stuff on the back of an envelope. No Civil types involved at all.
This is the gammut from none to platoons. My last 20-inch gathering job was 5 miles and cost around $1.5 million. The Alaska Gas Pipeline will cost over 1,000 times that for the front-end engineering alone.
