The Calgary-based company (TSX:TRP) said major construction on the $2.3-billion pipeline is expected to wrap up by the end of October.
"Further work will need to be done before we begin filling the pipeline with crude oil and that work is expected to be completed in the near future as well," company spokesman Shawn Howard said in an email.
"Commissioning of the pipeline is already underway and is expected to be completed in early November. Line fill can begin shortly thereafter. We remain focused on the project becoming operational near the end of 2013."
The pipeline's initial capacity will be 700,000 barrels per day, with the ability to expand to 830,000 barrels per day.
The prospect of crude soon being able to move from Cushing to the Gulf sent oil prices higher, with West Texas Intermediate crude for November delivery gaining US$2.06, or two per cent, to close at US$104.10 a barrel on the New York Mercantile Exchange.
An oversupply of oil at Cushing has been a major issue for the industry, with producers clamouring to get their oil to lucrative refining markets, such as the Gulf.
Meanwhile, TransCanada is still awaiting a decision by the U.S. State Department on the more contentious northern portion of its Keystone XL pipeline.
TransCanada, which filed its application for Keystone XL more than five years ago, was able to go ahead with the southern leg first as a separate project because it doesn't cross an international border.