The GT46C-ACe Gen I, manufactured by Downer EDi Rail at it's Cardiff workshops, from 2007 to 2014, is one of Australia's premier engines when it comes to intermodal and other heavy commodity workings.

​

First purchased by Specialised Container Transport (SCT) Logistics, and introduced respectively as the "SCT" class in 2007, further cemented the ongoing reliability, and power produced by EMD for the Australian rail industry. 

​

Powered by EMD 16-710G3C-ES engine with a rated output of 4300hp (net), the GT46C-ACe series has become one of the most favored engines by Australian rail companies.

​

Later introductions of the locos followed through the manufacturing of the "LDP" class, as rail hire assets from Downer EDi, with units 004-009 immediately going into long-term lease with QR National released with associated livery artwork as of 2009.

​

In the same year and supply order, Pacific National (PN) purchased the "TT" class (denoted as such for "Tonnage Transferable"), units 01-06, allocating them to heavy coal train workings in the NSW Hunter Valley region. These engines differed with higher axle loading with the addition of 7t of ballast plates for associated region-specific working.

​

Following in 2010, PN further ordered additional ACe's, with the order of more TT's, this time denoted with the 101-132 number range. Unlike their similarly-classed sister engines, 101-132, were "light weight" and utilised on coal workings with lighter axle loading, as well as various intermodal, limestone and aggregate work. Whitehaven also ordered 3 units, denoted "WH", for working on their coal trains in the Gunnedah area, however, they are crewed and operated by PN.

​

In 2011, Genesee and Wyoming Australia (GWA) ordered 10 units, denoted "GWA", for Adelaide to Darwin services, as well as various grain workings in South Australia. Later handed over to OneRail after GWA sold their company share, and further changed hands to Aurizon under the sale of OneRail's interstate workings.

​

Later on in 2014, Southern Shorthaul Railroad (SSR), ordered 2 units, denoted the "SSR" class. These engines were distinct, as SSR's first "new-build" engines, not to be confused with the BRM class as operated under the CRL subsidiary. The SSR class, originally planned for coal working in the Hunter Valley, later found home to various grain workings throughout NSW and interstate. These 2 units, were also the last engines of the GT46C-ACe series to be built in Australia, with the evolution of this series (Generation II), now being built in the United States.