Bio Edit

The EMD (Electro-Motive Division) GP15 Series is a series or line of 8-12 cylinder, 1,500hp, four-axle diesel locomotives consisting of three models built between 1976 to 1983 with 368 built.
UP GP15-1 with Mopac Lettering Font

A UP (ex-MP) GP15-1 wearing Mopac-style lettering following the 1982 UP-MP merger.

Many are still currently in service, though some have since been retired or scrapped. They currently operate in yard and local service, for they were intended as road-switchers.


Devised at the behest of the Chicago And Northwestern (CNW), the GP15 was designed to compete with the road's capital rebuild program which was conducted on aging GP7 and GP9 units at their Oelwein shops. Initially, the concept for the locomotive line was essentially a trade-in deal for railroads. Reviving the concept of reusing components from trade-in locomotives, a practice that peaked in the mid-1960's as roads turned back first-generation diesels for credit towards newer power, EMD endeavored to keep the GP15 price tag as competitive as possible with the rebuild option, by allowing a road to trade-in a worn GP7 for a newer, similar model; albeit with reused or refabricated components (such as an alternator or trucks). Nevertheless, many railroads opted to redevelop or rehabilitate existing units from within their rosters themselves, and sales of the "Baby Geep" were decidedly lackluster, for the roads simply couldn't justify the purchase of new locomotives for low-priority yard, local, and transfer service where cascading aging road units built by the company (rebuilt or not) seemed to work flawlessly compared to EMD's competitors. Fortunately for EMD, a few roads bought into the concept, and took relatively larger orders than expected.

Despite being a successful line, the GP15 concept unfortunately was the only remotely successful trade-in scheme developed by EMD, for locomotive contractors (such as MotivePower/MK Rail, NRE, and ProgressRail) have superseded the primary builder's further attempts at mass-producing locomotive trade-ins in exchange for newer units utilizing existing parts. Such examples, like the GP15D, and GP20D (hybrid cab-end switchers jointly built between EMD and MK Rail in the 1990s) sold in smaller numbers, while the BL20-2 never made it past the demonstrational stages (despite being an actual rebuild rather than a new, trade-in offer).


The GP15-1 was built between 1976 to 1982 with 310 built. Essentially a road-switcher version of the MP15, the GP15-1 consisted of an unusual blend of new and old technology, from its "Tunnel Motor" style radiator section and cooling system,
Early GP15-1

A BNSF (ex-BN, nee SLSF) GP15-1.

to a bare bones "Dash 1" electrical system; which was essentially a downgrade from EMD's increasingly-successful "Dash 2" line, intended to accomodate remanufactured components, particularly main generators, traction motors, and trucks from GP7 and GP9 (and subsequent F-Unit) trade-ins. The Chicago And North Western (CNW) was initially the first railroad to embark on the GP15 trade-in program, though the road only acquired a mere 25 units in 1976. Frisco (SLSF) caught on to the concept, and also ordered 25 units. Meanwhile, the largest orders for the model were generated by the Missouri Pacific (MP) and Conrail between 1976 and 1982. Conrail initially placed a 100-unit order in 1979 as a replacement for aged F-units, ALCO's, and earlier Geeps inherited from bankrupt predecessors. Mopac on the otherhand, placed an order for 60 units in four seperate orders beginning in 1976, while eventually settling on 100 more by the spring of 1982, furthermore receiving nearly two-thirds of the entire units built.

Years later, after numerous mergers and acquisitions between the remaining Class 1 carriers, many GP15-1 units saw new life on various roads prior to their final disposition. Many are still currently in service with various shortlines and leasing companies, while others are still in service with Union Pacific (UP) and CSX.


After the success of the GP15-1, Mopac commissioned a variant which had an AC transmission to power the

A UPY (ex-MP) GP15AC. Although nearly identical to is DC-transmission counter-part, the GP15AC bears no external distinction with the previous model.

electrical system. Gone were the original D32 trade-in generators; the otherwise outdated pure-DC transmission system which proved to be at its peak with the GP35. In its place was the revolutionary AR10 alternator found on all "Dash 2" models like the SD40-2 and GP38-2. Between November and December 1982, EMD built 30 units and were delivered to Mopac as MP #1715-1744.

Most are currently in service with UP, while others have since been retired or side-lined in storage for future use.


In a last ditch effort to attract more buyers, EMD launched an 8-cylinder turbocharged variant of the GP15-1 which also included an AC transmission system. Built between October 1982 and March 1983, EMD built a mere 28 total units: 25 for Chessie System (CSX) and 3 for Apalachiola Northern (AN). In an unusual request, Chessie had their units built with dynamic brakes, while AN specified the same traditional louvers found on most early GP15-1 units; further lacking inertial air filters.

All are still in service with their respective owners.


Model GP15-1 GP15AC GP15T

Production Dates

1976-1982 1982 1982-1983
Total Built 310 30 28
Length 54' 11" 54' 11" 54' 11"
Wheel Arrangement B-B B-B B-B


12-645E 12-645E 8-645E3C


1,500 1,500 1,500
Alternator D32/B32 (DC generator trade-in for DC transmission) AR10 (AC transmission) AR10-D14 (alternator)
Traction Motors D77B D77B D77B
Weight x 1,000lbs. 240,000 261,000 240,000

GP15-1 Production RosterEdit

Company Quantity Road Number(s) Disposition
Chicago And Northwestern (CNW) 25 #4400-4424 Most in service with Union Pacific (UP). Some retired, scrapped, or sold to a leasing or shortline operator.
Conrail (CR) 100 #1600-1699

Most in service with CSX Transportation (CSX/CSXT). Some retired, scrapped, or sold to a leasing or shortline operator.

All retired by Norfolk Southern (NS). Sold to leasing company or shortline.

Missouri Pacific (Mopac/MP) 160 1555-1714 Most in service with Union Pacific (UP). Some retired, scrapped, or sold to a leasing or shortline operator.
St. Louis-Fan Francisco (Frisco/SLSF) 25 #100-124 Some in service with BNSF Railway. Others retired, scrapped, or sold to a leasing or shortline operator.

GP15AC Production RosterEdit

Company Quantity Road Number(s) Disposition
Missouri Pacific (Mopac/MP) 30 1715-1744 Most service with UP; others retired (now UPY 715-744).

GP15T Production RosterEdit

Company Quantity Road Number(s) Disposition
Apalachiola Northern (AN) 3 720-722 All still in service.
Chessie System (CSX Transportation/CSXT) 25 1500-1524 Most still in service with CSX.


Some railfans or train enthusiasts often refer to the GP15 Series models as the "Baby Tunnel Motor" or "Baby Geep", for the GP15 contains the same radiator section as the SD40T-2 and subsequent SD45T-2, and the simple fact that the units are relatively smaller than most other second-generation road diesels.

The 25 GP15T units built for Chessie System were among some of the last new diesel locomotives built for the corporation prior to the finalization of the CSX merger in 1986 (besides their fleet of SD50 units).

Although not an actual unit from the model, the Montana Rail Link (MRL) rebuilt a single GP9 unit into what was once dubbed as a "GP15-1" (later "GP19-1"), and was built to similar specifications as the actual GP15-1 production model: having a modern "Spartan cab", rewired circuitry, and 645 engine power assemblies. Said unit was initally a testbed from a rebuild program that never lifted, and unfortunately was scrapped after having been involved in a wreck in 2008.