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Siemens "ACS-64" Locomotives

Published: November 21, 2023

By: Adam Burns

The ACS-64, also known as the "Amtrak Cities Sprinter", is an electric locomotive that is used for passenger train service in the United States.

Manufactured by Siemens Mobility, the ACS-64 is designed for high-speed service, capable of reaching speeds up to 125 mph. It is used primarily by Amtrak in the Northeast Corridor between Boston and Washington D.C., and by SEPTA on its Regional Rail lines.

The locomotive is known for its energy efficiency and safety features, including crash energy management components.


205821387423857829609240937.jpgAmtrak ACS-64 #600, named the "David L. Gunn" (former Amtrak president), hustles through Seabrook, Maryland along the Northeast Corridor. Loyd Lowry photo.


The ACS-64, also known as the "Amtrak City Sprinter," is an American electric locomotive designed by Siemens Mobility. The ACS-64 electric locomotives were purchased by two major railroads in the United States: Amtrak and the Southeastern Pennsylvania Transportation Authority (SEPTA).

In his book, "Locomotives, The Modern Diesel & Electric Reference: Second Edition," author Greg McDonnell notes Siemens was awarded a $466 million contract from Amtrak in October, 2010 to build 70 ACS-64s to replace its entire fleet of aging AEM-7s and unreliable HHP8 motors for service on the Northeast and Keystone Corridors.

The ACS-64s were based from Siemens' European Eurospinter and Vectron designs.  It featured the builder's SIBAS 32 traction and locomotive control systems.  The double-ended, AC design is capable of operating within all three of Amtrak's electrified (25kV 60Hz, 12.5 kV 60Hz, and 12 kV 25Hz). 

The prominent German manufacturer, Siemens, undertook the production of these locomotives. Siemens Mobility, a leader in transport solutions for more than 160 years, assembled the locomotives at a plant based in Florin, California (Sacramento) built specifically for this purpose.

The ACS-64s predominantly operate in the Northeastern corridor of the United States. These powerful machines transport passengers between the key cities of Washington D.C., New York City, and Boston, and serve the Southeastern Pennsylvania region between Philadelphia-Harrisburg.

Themodels were built between 2013-2018 with the first three completed examples unveiled on May 13, 2013.  Following several months of testing, #600 departed Boston with Northeast Regional train #171 on the morning of February 2, 2014.  The Amtrak fleet bore road numbers ranging from 600–665, 667–670 while the SEPTA units were numbered 901-915.


Wheel Arrangement
66' 6"
9' 9 ½"
12' 6"
Wheel Base
32' 5 19/32"
215,537 Lbs
Catenary Voltage & Frequency
25kV 60Hz/12.5 kV 60Hz/12 kV 25Hz
Maximum Speed
125 mph
Tractive Effort (Starting)
70,000 Lbs
Tractive Effort (Continous)
63,000 Lbs at 40 mph
Minimum Curve Radius
Head End Power (HEP)
1,340 HP

The total cost for the acquisition of these locomotives was substantial. Amtrak's 70 locomotives came in at a cost of around $466 million, while SEPTA's 15 units came with a price tag of approximately $113 million.

The ACS-64 is an impressive piece of machinery. Its powerhouse boasts a hefty starting horsepower of 8,600 and a continuous rating of 6,700.

The locomotive itself measures 66 feet, 8 inches in length; stands 12 feet, 6 inches tall (sans pantograph); and stretches 9 feet 9 ½ inches wide. It has a wheelbase of 32 feet and 5 19/32 inches, and its hefty weight totals to around 215,537 pounds. Its maximum operating speed clocks in at an impressive 125 miles per hour.

The ACS-64 acquires electricity through an overhead apparatus called a pantograph. This device is in constant contact with a suspended wire structure known as catenary, transferring electrical energy to power the locomotive.

The locomotives were officially introduced to passenger service not long after production. After Amtrak commissioned their first examples in February of 2014, SEPTA introduced their new units in February, 2018.


The ACS-64 has established itself as a potent force in present-day passenger rail service. From powering the bustling Northeast Corridor for Amtrak to serving SEPTA's regional rail services, the ACS-64 has made a robust mark on the landscape of American rail travel.

The design and construction of the locomotive exemplify Siemens' commitment to creating reliable, high-performing, and sustainable train technology. Every unit incorporates Siemens’ energy-efficient, high-performing electric drive technology for locomotives.

The ACS-64 allows for easier maintenance, reduced costs, and emphasis on the passengers' comfort. The locomotives are equipped with regenerative braking systems that can feed up to 100% of the energy generated during braking back into the power grid.

The design is substantially different from traditional locomotives. They are extremely efficient and allow for higher and smoother acceleration, a vital requirement for stop-and-go intercity travel.

The ACS-64's high-speed capabilities allow for quicker travel times, enhancing the passengers' experience. The modern design aesthetic of the locomotive further adds to its appeal and enhances its presence in the railways of the Northeast Corridor..

The locomotives' reliability and performance are testaments to Siemens' engineering prowess. Its high level of technological advancement and the detailed thought put into its design speaks volumes about the future of electric rail transport.

The operational history of the ACS-64 is marred by very few incidents, demonstrating the locomotive's resiliency. Moreover, its stringent safety features make it a reliable choice for public transport.

As of 2021, all locomotives are in service and continue to deliver exceptional performance in passenger transportation. They are an indispensable part of the Northeast Corridor's railway landscape.


The ACS-64’s legacy carries the promise of efficient, electrified railway travel. With its current run, this locomotive is helping reduce greenhouse gas emissions and is contributing to sustainable railway operations.

Amtrak’s examples have served over 200 million passengers since entering service in 2014. They are helping to drive passengers to choose railways as a mode of transportation over air and road travel.

The success of the model in the U.S has led Siemens to promote its electric locomotives for several international markets, underlining the appeal and significance of the ACS-64 design.

The presence of these locomotives on two of America’s busiest passenger rail lines speaks volumes about their quality and reliability. This locomotive will continue to be a significant player in the railway industry for years to come.

A testament to its effectiveness, countries across the globe continue to express interest in the ACS-64, heralding further possibilities of seeing these locomotives serve in different parts of the world.

The ACS-64's story is sprinkle with facts compelling enough to pique the interest of any railway enthusiast. Whether it is the high-performance stats, the manner in which they are powered, or the railroads that they serve, there is an utter fascinating narrative that surrounds these locomotives.

The future of these locomotives appears promising, with continuous improvements in technology and sustainability in the transportation sector. The ACS-64 locomotives show the world the capability of electrical power in terms of efficiency and sustainability.

The model is undoubtedly a symbol of technological advancement and a beacon for sustainable rail transport. The impact this locomotive has left on American rail history will continue to be felt and appreciated for years to come.

The ACS-64 electric locomotives exhibit the transformative power of innovation in the railway industry, standing as a testament to the potential of an electric future in railway transportation.

They form an integral part of the current rail landscape, promising enhanced passenger experiences with its efficient and prompt services. More environmentally friendly, and equipped with modern technology, these locomotives are a glimpse into the future of rail.

In conclusion, the ACS-64 represents a significant chapter in railway history, shedding light on the potential of innovation and sustainable practices in shaping the future of transport. It stands as an enduring symbol of progress in railway technology and sustainability.

While these locomotives continue to write their story on the rails, their contribution to American rail history, and to the global railway landscape, continues to garner appreciation, becoming a vital part of narratives about advances and fascinating developments in rail technology.

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