E721 series

The E721 series (E721系) is an AC electric multiple unit (EMU) train type operated by East Japan Railway Company (JR East) on services in the Sendai area of Japan since February 2007.

E721 / SAT721 / AB900 series
E721-0 series (right) and SAT721 series (left), August 2007
Manufacturer	Kawasaki Heavy Industries, Tokyu Car Corporation, J-TREC (Niitsu and Yokohama)
Replaced	455 series, 417 series, 717 series, 719 series
Constructed	2006–
Entered service	February 2007
Number under construction	36 vehicles (9 sets)
Number built	146 vehicles (63 sets)
Number in service	142 vehicles (61 sets)
Number scrapped	4 vehicles (2 sets, tsunami damage)
Formation	2/4 cars per set
Fleet numbers	P1–P44, P501–P504, P4-1–P4-19, SA101–SA103
Operators	JR East Sendai Airport Transit (SAT721) Abukuma Express (AB900)
Depots	Sendai
Lines served	Tohoku Main Line Joban Line Senzan Line Sendai Airport Line Abukuma Express 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	950 mm (3 ft 1 in)
Doors	3 pairs per side
Maximum speed	120 km/h (75 mph)
Power output	125 kW per motor
Electric system(s)	20 kV AC (50 Hz) overhead catenary
Current collector(s)	Pantograph
Bogies	DT72 (motored), TR256 (trailer)
Safety system(s)	ATS-Ps
Multiple working	701 series
Track gauge	1,067 mm (3 ft 6 in)

Variants

•    E721-0 series 2-car sets, since February 2007
•    E721-500 series 2-car sets, since March 2007
•    E721-1000 series 4-car sets, since November 2016
•    SAT721 series 2-car sets, since March 2007 (owned by Sendai Airport Transit)
•    AB900 series 2-car sets, since July 2019

• 
  E721-0 series set P-4 in March 2007
• 
  E721-500 series set P-502 in November 2007
• 
  E721-1000 series set P4-14 in January 2017
• 
  SAT721 series set SA102 in March 2008
• 
  AB900 series set AB-1 on delivery at Zushi Station in February 2019

Operations

• ■ Banetsu West Line (since March 2017)^[1]
• ■ Joban Line
• ■ Senzan Line
• ■ Sendai Airport Line (E721-500 series and SAT721 series only)
• ■ Tohoku Main Line
• ■ Abukuma Express Line (AB900 series)

Formations

As of 1 October 2015^[update], the fleet consists of 42 two-car E721-0 series sets (P-2 to P-44), four E721-500 series two-car sets (P-501 to P-504), and three SAT721 series two-car sets (SA101 to SA103), formed as follows with one motored (Mc) and one trailer (Tc') car.^[2]

E721-0 series

Designation	Mc	Tc'
Numbering	KuMoHa E721-xx	KuHa E720-xx

The KuMoHa cars have one PS109 single-arm pantograph. The KuHa cars have a toilet.^[2]

E721-500 series

Designation	Mc	Tc'
Numbering	KuMoHa E721-50x	KuHa E720-50x

The KuMoHa cars have one PS109 single-arm pantograph. The KuHa cars have a toilet.^[2]

E721-1000 series

The 19 four-car E721-1000 series sets (P4-1 to P4-19) are formed as follows, with two motored ("M") cars and two non-powered trailer ("T") cars.^[3] The KuHa E720 is located at the southern end.^[3]

Designation	Tc'	M	T	Mc
Numbering	KuHa E720-10xx	MoHa E721-10xx	SaHa E721-10xx	KuMoHa E7210-10xx
Weight (t)	34.3	32.0	37.2	39.1
Capacity (seated/total)	50/132	62/152		56/138

The two motored cars (KuMoHa and MoHa) each have one PS109 single-arm pantograph.^[3] The KuHa cars have a toilet.^[3]

• 
  The interior of car KuMoHa E721-1005 of set P4-5 in January 2017
• 
  An LED passenger information panel above the doorway in car KuMoHa E721-1005 of set P4-5 in January 2017

SAT721 series

The two-car SAT721 series sets are formed as follows.

Designation	Mc	Tc'
Numbering	SAT721-10x	SAT720-10x

The KuMoHa cars have one PS109 single-arm pantograph. The KuHa cars have a toilet.^[2]

• 
  The interior of car SAT721-101 in April 2017
• 
  Priority seating and luggage space in car SAT721-101 in April 2017

AB900 series

The Abukuma Express AB900 series are derived from the E721-500 and SAT721 series used for JR East.

Sets are formed as follows.

Set	Numbering
AB-1[4]	AB901-1	AB900-1
AB-2[5]	AB901-2	AB900-2
AB-3[6]	AB901-3	AB900-3
AB-4[7]	AB901-4	AB900-4
AB-5[7]	AB901-5	AB900-5

History

The first E721-0 series sets were delivered from December 2006, and entered service on 1 February 2007 on Tohoku Main Line services.^[2] The first E721-500 and SAT721 series sets were delivered from February 2006 and entered service on Sendai Airport services on 18 March 2007.^[2]

Two sets, P-1 and P-19, were derailed and badly damaged by the 2011 Tōhoku earthquake and tsunami on 11 March 2011 while at Shinchi Station. Both sets were written off and scrapped.^[2]

• 
  The remains of sets P-1 and P-19 at Shinchi Station after the tsunami in 2011

Intermediate cars for the first two E721-1000 sets on delivery from J-TREC Niitsu in September 2016

The first of a fleet of 19 new four-car E721-1000 sets (76 vehicles in total) was introduced on 30 November 2016^[8] on Tohoku Main Line, Joban Line, and Senzan Line services, replacing older 719 series units.^[9] The new trains are built by J-TREC, with construction shared between the company's Yokohama and Niitsu factories.^[9] These trains feature LED interior lighting.^[9]

The first four E721-1000 series intermediate cars were delivered from J-TREC's Niitsu factory to its Yokohama factory in September 2016 to be combined with driving cars built there.^[10]

In order to replace their 8100 series trains, Abukuma Express announced the order of new AB900 series trains in summer 2018.^[4] They are based on the E721 series,^[11] and are the first new trains for Abukuma Express since 1988.^[12] The first AB900 series set was delivered in February 2019.^[4] It entered service on 1 July 2019.^[12]

Fleet/build details

The manufacturers and delivery dates for the fleet are as shown below.^[2]

E721-0 series

Set No.	Manufacturer	Date delivered	Date withdrawn
P-1	Kawasaki Heavy Industries	28 November 2006[13]	12 March 2011[Note 1]
P-2		17 January 2007
P-3
P-4
P-5	Tokyu Car	18 December 2006
P-6
P-7	Kawasaki Heavy Industries	15 January 2007
P-8		6 February 2007
P-9
P-10		23 February 2007
P-11
P-12	Tokyu Car	15 January 2007
P-13
P-14	Kawasaki Heavy Industries	28 February 2007
P-15
P-16		8 March 2007
P-17
P-18		23 March 2007
P-19		23 March 2007[13]	12 March 2011[Note 1]
P-20		23 March 2007
P-21
P-22		17 April 2007
P-23
P-24		27 April 2007
P-25
P-26
P-27
P-28		31 May 2007
P-29
P-30
P-31
P-32		6 July 2007
P-33
P-34	Tokyu Car	30 August 2007
P-35
P-36		26 September 2007
P-37
P-38	Kawasaki Heavy Industries	2 November 2007
P-39
P-40		13 September 2010
P-41
P-42
P-43
P-44

1. Destroyed by tsunami on 11 March 2011.

E721-500 series

The delivery of E721-500 series cars are as follows:^{[citation needed]}

Set No.	Manufacturer	Date delivered
P-501	Kawasaki Heavy Industries	17 February 2006
P-502		30 September 2006
P-503
P-504	Tokyu Car	25 October 2006

E721-1000 series

All manufactured by J-TREC.

Set No.	Date delivered
P4-1	21 October 2016[14]
P4-2	26 October 2016[14]
P4-3	11 November 2016[14]
P4-4	16 November 2016[14]
P4-5	28 November 2016[14]
P4-6	1 December 2016[14]
P4-7	6 December 2016[14]
P4-8	14 December 2016[14]
P4-9	27 December 2016[14]
P4-10	26 December 2016[14]
P4-11
P4-12
P4-13
P4-14
P4-15
P4-16
P4-17
P4-18
P4-19

SAT721 series

The three SAT721 series units being delivered in November 2006

All sets are manufactured by Kawasaki and delivered as of 20 November 2006.^{[citation needed]}

Set No.
SA101
SA102
SA103

AB900 series

All sets are manufactured by J-TREC.

Set No.	Date delivered
AB-1	21 February 2019[4]
AB-2	February 2020[5]
AB-3	25 January 2022[15]
AB-4
AB-5

See also

• Aoimori 703 series, a derivative for use on the Aoimori Railway
• Railway electrification in Japan