There was a rail crash near Welwyn Garden City railway station in Hertfordshire, England, in 1935 which killed fourteen people, and another in 1957 with one fatality.

1935 Welwyn Garden City rail crash
Details
Date	15 June 1935 23:27
Location	Welwyn Garden City, Hertfordshire
Country	England
Line	East Coast Main Line
Operator	London and North Eastern Railway
Cause	Signalling error
Statistics
Trains	2
Passengers	337
Deaths	14
Injured	29
List of UK rail accidents by year

On 15 June 1935, a train from London King's Cross to Leeds collided with the rear of a train from Kings Cross to Newcastle at night. Fourteen people were killed and 29 injured.

The accident was a caused by a signalman's error: the signalman at Welwyn Garden City, who had been fairly recently appointed to the box, became confused and accepted a second train into a block section that was already occupied. The Newcastle train, arriving first, received a signal check and was slowed to 15‒20 mph; the Leeds train, consisting of 11 coaches hauled by Class K3 2-6-0 No 4009, ran into it at approximately 65 mph.

There were several significant features. Firstly, the modern rolling stock with buckeye couplings withstood the violent collision well, apart from the last coach which was totally destroyed; older coaches would have been crushed, with much heavier loss of life. Secondly, the Inspecting Officer felt that the signalman had been promoted beyond his level of competence for such a busy box, and that the assessment and training procedures for signalmen should be improved. Different commentators have disagreed on this; Rolt and Hamilton supported the Inspector, Vaughan felt the signalman had had insufficient time to become fully experienced in working the box. Thirdly, the Inspector recommended that the block instruments should be linked to the track circuits to prevent future occurrences in such a way that a "Line clear" indication could only be given on the block instrument if the track circuits had registered passage of a train; this was widely adopted and known as Welwyn Control.

1957 Welwyn Garden City rail crash
Details
Date	7 January 1957
Location	Welwyn Garden City, Hertfordshire
Country	England
Line	East Coast Main Line
Cause	Signals passed at danger
Statistics
Trains	2
Deaths	1
Injured	25
List of UK rail accidents by year

There was another rear-end collision, about half a mile south of Welwyn Garden City station, at dawn on 7 January 1957, with a different cause. The accident was due to the driver of an Aberdeen to London express passing signals at danger with visibility reduced due to mist, and not hearing the explosion of emergency detonators as his locomotive ran over them.

The express was travelling at around 60‒65 mph when it collided with the rear of a local train, which had just pulled away from the station and was travelling at around 30‒35 mph. The rear coach of the local train was wrecked in the collision and two more were overturned. One passenger in the local train was killed and 25 injured. The locomotive of the express overturned, and the driver suffered severe shock.

• Lists of rail accidents

• Railways Archive summary and link to accident report for 1935 collision
• Official Railways Inspectorate accident report for 1935 collision
• Railways Archive summary and official accident report for 1957 collision
• Official Railways Inspectorate accident report for 1957 collision

51°48′07″N 0°12′11″W / 51.80194°N 0.20306°W / 51.80194; -0.20306