Quick Facts

Build Dates: 1998-2001 Territory: Amtrak's Northeast Corridor, Washington, DC - Boston, MA Top Speed: 150 mph (240 km/h) Number in Service: 2 of 20 (February 2001) Supply Voltages: 25kV 60Hz AC, 12kV 60Hz AC, 12kV 25Hz AC. Traction:8 3-phase AC asynchronous motors, total power 9200 kW (12300 hp) Length and Weight: 663 ft (202 m) / 624 tons (566 tonnes) Configuration: 1 power car + 6 cars + 1 power car, 304 seats (260 Business, 44 First) Performance Metrics: 16.3 kW/tonne / 1.9 tonnes/seat / 30.3 kW/seat Photos: [TGVweb] Scale Paper Model: Print, cut out and assemble a 1/140 scale model which you can get here.

Acela Express Interior Layout

Overhead Power Collection. The NEC electrification must be accomodated:

• 12kV 25Hz from Washington to New York City
• 12kV 60Hz from New York City to Shell, phase breaks at 7.5 mi. intervals
• 12kV 60Hz from Shell to New Haven, phase breaks at 12 mi. intervals
• 25kV 60Hz from New Haven to Boston, phase breaks at 20 mi. intervals

Traction Systems. The power cars use the newest TGV (3rd generation) traction technology. (See here for a more complete explanation). The main transformer is mounted underfloor. Its primary winding is split into two parts to accommodate the different supply voltages mentioned above; it has four secondary windings, each feeding a PWM rectifier that supplies a voltage regulated DC link which operates at 2850 VDC. The DC link feeds two inverters (one per truck) based on water-cooled GTO technology. The inverters supply three-phase, frequency and voltage controlled waveforms to the asynchronous induction traction motors. Each power car develops 4600 kW of tractive power, for a total of 9200 kW per trainset, and can start with 50,000 lbs of tractive effort. Under regenerative braking, each power car can provide 3000 kW of braking power. Should the catenary not be receptive to the regenerated power, a chopper modulated resistor grid is used to dissipate the energy (the "dynamic brake"). EMI (Electromagnetic Interference) is a specific concern in the traction components since modern AC traction drives operate at frequencies that can potentially interfere with the cab signal and other safety critical systems. This is an especially difficult problem on the Northeast Corridor, where many relatively low frequencies must be protected from interference.

Auxiliary Power. Each power car has a dedicated HEP (head end power) inverter with enough capacity for a 1+10+1 trainset configuration. The inverter operates off the DC link and provides 480V 60Hz three phase power. The system is redundant; should the HEP inverter in one power car fail, the other one's takes over. In case of a second failure, one of the traction inverters can be used at the cost of somewhat reduced traction power.

Trucks and Tilt System. The six passenger cars are fitted with an active tilt system based on Bombardier's proven LRC (Light, Rapid, Comfortable) technology. The tilt system compensates a maximum of 75% of the lateral force felt by the passengers when running through a curve, and becomes fully active above 60 mph. The trucks are related to the standard TGV design, with a long wheelbase dual transom H frame welded steel construction with outboard mounted tapered roller bearings. There are three brake disks fitted to each axle (as opposed to the TGV's four). As in TGV practice the primary suspension is swing-arm coil spring, and the secondary suspension uses air springs with a coil spring backup in case of pneumatic failure. The tilt system is accommodated by a tilting bolster, which is suspended from the truck frame by four swing arms. The tilting is hydraulically actuated by an under floor hydraulic power unit. Each car has a tilt control processing unit and tilts independently of the others by up to 6.5 degrees either side of vertical; tilt functions are controlled by the tilting master sensor and master controller located in the power car. The power cars themselves do not tilt.

Carbodies. Vehicle structures are built from stainless steel and are designed to survive major impacts. Crash energy management techniques based on 3rd generation TGV technology control the structural deformations in the event of an accident, to increase the safety of the passengers. Under floor equipment is specially reinforced to withstand the rigors of operating in urban areas, where shopping carts, tires and other debris frequently find their way onto the tracks. (The Northeast Corridor is only partially fenced in, as opposed to European high speed lines.) The Acela Express is the first train to comply with the Federal Railroad Administration's Tier II crashworthiness standards, touted to be the toughest in the world. The downside of the heavy emphasis on passive safety is the significantly higher weight of the trainset, compared to worldwide high speed rail practice. The Acela Express is built about 45% heavier than a typical TGV.

Signalling and Safety. For operation at 150 mph the trainsets are fitted with a two frequency, nine aspect cab signal system to supplement wayside signaling. (In a cab signal system, signaling information is transmitted through the rails in the form of electrical signals, decoded by the train and displayed to the engineer directly in the cab). An ATC (Automatic Train Control) system watches over the engineer, who is in full control of the train at all times. In addition, Amtrak's ACSES system (Amtrak Civil Speed Enforcement System) ensures observance of all speed limits.

Monitoring System: The train's digital monitoring system provides status information to the cab and the crew office. Data on propulsion, HEP, tilting, braking, and fire protection systems can be displayed on screens, as well as wheel bearing temperatures and truck hunting dynamics. (At high speeds trucks may go unstable in the case of a damper failure; if that ever happens the train's speed is reduced until the side-to-side hunting motion stops.) The monitoring system is based on LonWorks technology.

Noise. The specifications require a sound level of 90 dBA or less at 100 meters from the track centerline at 150 mph, and 75 dBA or less at 5 meters from the track centerline when stationary with all cooling fans and auxiliary equipment operating simultaneously.

Interiors. The train is fully accessible for the disabled. The pneumatically operated sliding plug doors are designed for both high and low platforms. The intercar passageways are spacious and as warm and quiet as the passenger cabin, and feature pneumatically operated sliding doors.

• The First Class car seats 44 passengers in a 2-1 reversible seat configuration, with audio and video entertainment and a 115V outlet available at each seat. Airline type food service is provided through two food galleys. There is a phone booth accessible to the disabled, as well as enclosed and open type seat groups for business meetings. Other features include enclosed airline style luggage racks, a magazine display, two spacious restrooms and a garment bag holder.
• The Business Class cars seat 71 passengers in a 2-2 configuration, with audio entertainment only. A 115V outlet is available at each seat. Phone booth, enclosed and open seat groups, 2 restrooms, enclosed luggage racks, and a garment bag holder are provided as in first class.
• The Cafe (dining) car has capacity for 34 passengers, and features a lounge area with high and low stool seating, a dining area for meals, a business center with fax, copier and printing facilities, two phone booths (one of which enclosed), video and audio entertainment, and galleys for coach passengers. A crew office can provide en-route ticketing, scheduling and seat assignment changes.

Diagrams & Drawings

		A front view of the American Flyer power car. Several details differ in the final Acela Express design. From a 1997 Bombardier marketing brochure.

		Two profiles of an Acela Express power car. Top, as shown in a 1997 American Flyer marketing brochure from Bombardier. Bottom, as shown in the Acela Express seatback safety brochure (although a few details are different on the real Acela Express...)

		Two profiles of an Acela Express Business Class car. Top, as shown in a 1997 American Flyer marketing brochure from Bombardier. Bottom, as shown in the Acela Express seatback safety brochure.

		The interior layout of an Acela Express trainset.

An early (1997) artist's impression of the American Flyer, as Bombardier's proposal was then named. Several details differ from the final Acela Express design. From a Bombardier marketing brochure.

Don't miss a special feature article on the new NEC maintenance facilities by Jeffrey Nagy, Mechanical Foreman at Amtrak's Ivy City Maintenance Facility in Washington, DC.

The Bombardier consortium is fully responsible for the maintenance of the trainsets for a 10-year contract period. Each trainset is serviced as a whole, with 45-day, 92-day and 360-day inspections. On-board monitoring systems can identify and diagnose many failures, as well as transmit them to the maintenance base via data radio so the proper equipment and personnel is on hand at arrival. Maintenance facilities include:

• A wheel diagnostic machine, used to measure wheel profiles every two to three days.
• A tandem under floor wheel profiling machine by Simmons Machine Tool Corp., capable of re-profiling the wheels on an entire trainset in eight hours.
• Pedestal tracks, to allow undercarriage inspections and maintenance
• A high reach to give access to roof and sides of trainset
• A toilet dumping vacuum system
• A car wash with deicing system for winter operations
• A Management Information System (MIS), which coordinates all maintenance tasks, labor and materials.

Links

Several interesting links are available. See under World Links by Country > USA > Acela Express.

Sources:
American Flyer brochure, Bombardier, courtesy of Mark Williams.
System Compatibility of the HST. Chance and Grabowski, ASME Joint Railroad Conference, 1997.
Tilt System for Amtrak High Speed Trainsets. Kolig and Hesser, ASME Joint Railroad Conference, 1997.
Program Update: Amtrak's High Speed Trainset Program. Bell and Annechini, ASME Joint Railroad Conference, 1997.
Railway Age online.

Last Update: February 2001