The E531 series (Japanese: E531系, Hepburn: E531-kei) is an electric multiple unit (EMU) train type operated by East Japan Railway Company (JR East) in Japan.^[1] It was introduced by JR East on 9 July 2005 to replace the aging 403 and 415 series EMUs running on the Jōban Line from Ueno Station in Tokyo. The stock is a dual-voltage (1,500 V DC & 20 kV AC) development of the DC-only E231 series suburban EMU design, and can run at speeds of up to 130 km/h (81 mph) in service.^[2]

Quick Facts In service, Manufacturer ...

E531 series
An E531 series train on the Joban Line (in March 2019 Between Matsudo Station and Kanamachi Station)
In service	2005–present
Manufacturer	Tokyu Car Corporation, Kawasaki Heavy Industries, JR East, J-TREC
Replaced	403 series, 415 series, some E501 series
Constructed	2005–2020, 2024
Entered service	9 July 2005
Number built	461 vehicles 26 × 10-car 40 × 5-car 1 × end car
Number in service	460 vehicles
Formation	5/10 cars per trainset
Fleet numbers	K401–K426 (10-car sets) K451–K483 (standard 5-car sets) K551–K557 (cold-weather 5-car sets)
Operators	JR East
Depots	Katsuta
Lines served	■ Ueno–Tokyo Line ■ JJ Jōban Line ■ Mito Line ■ Tōhoku Main Line
Specifications
Car body construction	Stainless steel
Car length	20,000 mm (65 ft 7 in)
Width	2,950 mm (9 ft 8 in)
Floor height	1,130 mm (3 ft 8 in)
Doors	4 pairs per side
Maximum speed	130 km/h (81 mph)
Traction system	PWM 2-level IGBT–VVVF (Hitachi)
Traction motors	4 × 140 kW (190 hp) 3-phase AC induction motor (Hitachi)
Power output	1.12 MW (1,500 hp) (5-car sets) 2.24 MW (3,000 hp) (10-car sets)
Acceleration	2.5 km/(h⋅s) (1.6 mph/s)
Deceleration	4.2 km/(h⋅s) (2.6 mph/s)
Electric system(s)	1,500 V DC and 20 kV 50 Hz AC, both from overhead catenary
Current collector(s)	PS37A single-arm pantograph
Bogies	DT71 (motored) TR255 (trailer)
Braking system(s)	Regenerative brake
Safety system(s)	ATS-SN, ATS-P, ATS-Ps
Track gauge	1,067 mm (3 ft 6 in)

Close

• Tōkaidō Main Line (Shinagawa–Tokyo)
• Ueno–Tokyo Line
• Jōban Line (Ueno–Haranomachi)
• Mito Line
• Tōhoku Main Line (Kuroiso–Shin-Shirakawa)

Trains are formed in 10-car (set numbers K401–K426) and 5-car (set numbers K451–K483, K551–K557) sets. 15-car formations are generally run between Shinagawa and Tsuchiura. 10- and 5-car sets operate singly north of Tsuchiura, and 5-car sets are used on the Mito Line. 5-car cold weather sets (E531-3000 series) are used on the Tōhoku Main Line between Kuroiso and Shin-Shirakawa, to handle the change of electrification from DC to AC just north of Kuroiso.

• An ordinary-class car with longitudinal seating in January 2022
• An ordinary-class car with a mixture of longitudinal and transverse seating in January 2022
• Priority seating in January 2022
• The lower deck of bilevel Green car SaRo E531-17 in January 2022
• The upper deck of bilevel Green car SaRo E531-17 in January 2022
• A toilet in January 2022

The first E531 series trains entered service on 9 July 2005.^[5]

Pairs of double-deck "Green" (first class) cars were added to the ten-car sets from 6 January 2007, and all ten-car sets included Green cars by the start of the revised timetable on 18 March 2007. Two trailer cars from sets K401–K411 (cars 4 and 5) were repurposed as cars 6 and 9 in sets K412–K422. As there were 12 SaHa E531-2000 cars and 10 SaHa E530-2000 cars being repurposed (the latter type has an air compressor missing from the former type), the SaHa E531-2012 car was modified to become SaHa E530-2022.

In September 2014, an additional ten-car set, K423, was delivered from the J-TREC factory in Yokohama, four years after construction of the original fleet had ceased.^[6] This was followed by seven new five-car sets (K469–K475) also delivered from J-TREC in Yokohama from December 2014 to March 2015.^[7] Seven cold-weather E531-3000 series sets (K551–K557) were built between October 2015 and March 2017. Later in 2017, three more 10-car sets (K424–K426) and two more five-car sets (K476 and K477) were built. Then, between 2019 and 2020, six more five-car sets (K478–K483) were built.

On 26 March 2021, set K417 was involved in a collision between Tsuchiura and Kandatsu. It collided with a passenger vehicle which caught fire and caused damage to the KuHa E531-17 car (car 10).^[8] The damaged car was replaced with car 10 (KuHa E531-9) from set K409, which later received a new-build end car, also numbered KuHa E531-17.^[9][10]