I think @m0ngy has a point here, although I don’t think it will...

I think @m0ngy has a point here, although I don’t think it will be quite as bad as he is predicting.

You would have to assume that Jemena have presented their P50 schedule to the NT Government and the public, and that they would be keeping their schedule contingency (~15-20%) in their pocket. They have awarded the construction scope to McConnell Dowell, who do have significant experience in pipeline construction in Australia, including in remote locations.

In all fairness to m0ngy Australia recently has not performed on time for large infrastructure projects, with all of the LNG Projects going over schedule (Gorgon, Wheatstone, APLNG, Ichthys, etc). Admittedly these are very large (>$15B) & complex projects.

Although CTP can be complimented on constructing the 50km Dingo pipeline within schedule, that was a much simpler project.

So I think there is an element of construction schedule risk, but there have been quite a few large projects completed recently in Australia on schedule. The Caval Ridge coal mine in Moranbah was recently completed (2014) ahead of schedule, and it was just under $4B, and had quite a few environmental, regulatory and civil complexities. The schedule from Jemena looks reasonable to me, but we cannot be naïve to think there is no likelihood the schedule won't be exceeded…
  
Links to data;
https://jemena.com.au/industry/pipelines/northern-gas-pipeline
http://www.mcconnelldowell.com/capability/pipelines-hdd
http://www.mcconnelldowell.com/news/3172-mcconnell-dowell-to-construct-north-east-gas-interconnector