TGV world speed record

The current world speed record for a commercial train on steel wheels is held by the French TGV at 574.8 km/h (357.2 mph), achieved on 3 April 2007 on the new LGV Est.

The TGV 001 was an experimental gas turbine-electric locomotive-powered trainset built by Alstom to break speed records between 250–300 kilometres per hour.

However, some sections of the line's profile had been planned since 1982 (shortly after the TGV Sud-Est world speed record of February 1981) to allow very high-speed running.

The two branches separate at Courtalain, 130 km west of Paris, where movable frog points good for 220 km/h (137 mph) in the diverging route direct trains towards either Le Mans or Tours.

The basic purpose of the test program was to push the envelope of the TGV system, and to characterize its behavior at very high speeds.

Today, the only distinguishing feature on 325, as compared to other Atlantique trainsets, is a blue ribbon painted across the nose, and bronze plaques bolted to the sides of the two power cars to commemorate the event.

The Tours branch of the line was tested by special computerized Maintenance of Way equipment manufactured by GEISMAR, from the Track Research department of SNCF.

As a train approaches this critical speed, the pantograph catches up with the disturbance, causing dangerously large vertical displacements of the wire and contact interruptions.

Technicians had decided upon 4000 rpm at 420 km/h (261 mph) to be the optimal ratio, after testing trainset 325 at high speeds with stock traction equipment.

The main transformers in both power cars were replaced by larger models, each able to handle 6400 kW (8500 hp), or double the usual load, on a fairly continuous basis.

The 1981 test campaign provided valuable data and computer models for interaction of the pantograph with the catenary contact wire, and shed light on the very sensitive dynamics.

In one high-speed test, technicians attempted to provoke a truck into unstable oscillation by drastically reducing the yaw damping, but failed to achieve this.

Technicians at Châtillon put 4500 hours of work into the modifications, which was impressive when one considers that their first priority was the routine maintenance of the TGV Atlantique trainsets in revenue service.

After several runs, problems with pantograph contact required manual adjustments to be made by first grounding the catenary and then sending technicians onto the roof.

After a series of increasingly fast runs, the first official speed record of 482.4 km/h (299.8 mph) was set at kilometer point 166 on 5 December 1989, with engineer Michel Boiteau at the controls.

These "snow shields", mounted beneath the couplers, were designed to prevent the formation of a low pressure area between the vehicles, which had induced significant drag in the earlier testing.

On the power cars, sheet metal shields were added over the trucks, and the front airdam was extended downwards by 10 cm (4 in) to compensate for the larger wheels.

On the first high-speed run, an electrical malfunction destroyed the main transformer of the rear power car and damaged many low voltage circuits.

Instability of the contact dynamics between the pantograph and catenary caused trouble during the next several days, although intermittent runs achieved speeds above 500 km/h.

Following the resolution of this problem, the final record attempt took place on 18 May 1990, with dignitaries, and journalists joining the usual complement of technicians on board the train.

The 325 started its run at 9:51 from Dangeau and accelerated for 15 minutes, achieving a top speed of 515.3 km/h (320.3 mph) at the bottom of the hill at kilometer post 166.8.

Operation V150, where 150 again refers to a target speed in metres per second, was a series of high-speed trials carried out on the LGV Est prior to its June 2007 opening.

The trials were conducted jointly by SNCF, TGV builder Alstom, and LGV Est owner Réseau Ferré de France between 15 January 2007 and 15 April 2007.

[2][3] The top speed of 574.8 km/h (159.7 m/s, 357.2 mph) was reached at kilometer point 193 near the village of Le Chemin, between the Meuse and Champagne-Ardenne TGV stations, where the most favorable profile exists.

The record runs took place on a 140 km section of track 1 on the LGV Est, usually heading west, between kilometer posts 264 (town of Prény) and 120 (near the Champagne-Ardenne TGV station).

This section of the LGV was chosen for its vertical profile and gentle curves, with favorable downhill segments leading to the highest speeds between kilometer posts 195 and 191, near the border between the Meuse and Marne departments.

This unusual composition was used to obtain high-speed test data on disparate technical elements including the new asynchronous traction motors on the POS power cars, the lightweight synchronous permanent magnet traction motors on the AGV bogies, the actively controlled pantograph, and the Duplex bi-level configuration which had never been used in very high-speed trials.

Aerodynamic improvements, similar to the 1990 record train, were refined in a wind tunnel and provided a 15% reduction in drag from the standard configuration.

These improvements included a front air dam, roof fairings over the pantograph openings, membranes to cover the space between the cars, and a flush-mounted windshield.

This sweep was performed at a sustained 380 km/h, incidentally the peak speed reached in the record of 1981, with TGV POS trainset 4404 in a standard 8-car configuration.