| Naka-Meguro train disaster | |
| Date: | 8 March 2000 |
| Time: | approx 9:00 am |
| Location: | Near Naka-Meguro Station |
| Country: | Japan |
| Line: | TRTA Hibiya Line |
| Operator: | TRTA |
| Type: | Derailment |
| Trains: | 2 |
| Deaths: | 5 |
| Injuries: | 63 |
The Naka-Meguro train disaster occurred in Japan on 8 March 2000. Five people were killed and 63 were injured when a derailed TRTA Hibiya Line train was sideswiped by a second train near Naka-Meguro Station.
At around 9 a.m. on 8 March 2000, the rearmost car of an eight-car TRTA Hibiya Line (now Tokyo Metro Hibiya Line) train from to derailed on the tight curve immediately before Naka-Meguro Station. The derailed car was then hit by the fifth and sixth cars of an eight-car Tobu Railway train travelling in the opposite direction from Naka-Meguro to .
It is generally the case that if the distance between tracks is less than the width of the carriages this only allows about 600 mm clearance, so that if a train derails on the same side as the other track, it will almost certainly obstruct the other track, making a collision inevitable. Track circuits detect the presence of a train via electric current passed through the rails, which is shorted by a train car's axle or a physical break in the rails. If a derailment on an adjacent track, that doesn't cause a physical break in the other track, won't cause the track circuit to 'short' resulting in a stop signal. In this situation, a train crew member must either warn railway signal staff of the derailment, stop other trains using a handheld signal, such as a red flag, or manually short the track circuit using a specialized equipment, such as a track circuit operating clip.