Signal passed at danger
Encyclopedia
A Signal passed at danger (SPAD), in British railway terminology, occurs when a train passes a stop signal without authority to do so. It is a term primarily used within the British Railway Industry
Rail transport in Great Britain
The railway system in Great Britain is the oldest in the world, with the world's first locomotive-hauled public railway opening in 1825. As of 2010, it consists of of standard gauge lines , of which are electrified. These lines range from single to double, triple, quadruple track and up to twelve...
, although it can be applied worldwide.
Categories of SPAD
There are a number of ways that a train can pass a signal at danger without authority, and in the UK these fall into four basic categories;- A Category A SPAD is where the signalling equipment was working properly, but the train passed the signal at danger even though there was adequate opportunity for it to stop.
- A Category B SPAD is where the signal reverted to danger in front of the train due to an equipment failure or signaller error, and the train was unable to stop before passing the signal.
- A Category C SPAD is where the signal reverted to danger in front of the train due to an emergency, and the train was unable to stop before passing the signal.
- A Category D SPAD is where the train ran out of control and could not be stopped from passing a signal at danger.
Causes
As it takes a considerable distance to bring a train to a standstill, many Category A SPADs occur at low speed where the driver has applied the brakes too late. Very often this occurs when the signal at danger cannot be clearly discerned until close up.It can also be due to;
- Inattention
- Distraction
- Fatigue
- Misreading of an adjacent signal due to line curvature, or sighting on one beyond
- Misunderstanding
- Miscommunication with a Signaller or Shunter
- Signal being poorly lit or mis-showing
Almost all railways require a dim or dark signal to be treated as if it were displaying its most restrictive aspect, i.e., stop for a stop signal or caution for a distant signal. In most cases, the type of signal can be determined by a plate or coloured marking on the signal post. A somewhat related fault is when a semaphore signal's
Railway semaphore signal
One of the earliest forms of fixed railway signal is the semaphore. These signals display their different indications to train drivers by changing the angle of inclination of a pivoted 'arm'. Semaphore signals were patented in the early 1840s by Joseph James Stevens, and soon became the most...
arm is stuck in the 'clear' position, e.g. by frost or snow.
In some situations, however, the driver is unaware that he has passed a signal at danger and so continues until a collision occurs, as in the Ladbroke Grove rail crash
Ladbroke Grove rail crash
The Ladbroke Grove Rail Crash was a rail accident which occurred on 5 October 1999 at Ladbroke Grove, London, England. Thirty-one people were killed and more than 520 injured...
. In this instance, it is up to the safety system (where fitted) to apply the brakes, or for the signaller to alert the driver.
Automatic Train Protection
ATP (Automatic Train Protection) is a much more advanced form of Train Stop, which can regulate the speed of trains in many more situations other than at a stop signal. ATP supervises speed restrictions and distance to danger points. An ATP does take into account individual train characteristics such as brake performance. Thus, the ATP determines when brakes should be applied in order to stop the train before getting beyond the danger point. In the UK, only a small percentage of trains (First Great WesternFirst Great Western
First Great Western is the operating name of First Greater Western Ltd, a British train operating company owned by FirstGroup that serves Greater London, the South East, South West and West Midlands regions of England, and South Wales....
and Chiltern Railways
Chiltern Railways
Chiltern Railways is a British train operating company. It was set up at the privatisation of British Rail in 1996, and operates local passenger trains from Marylebone station in London to Aylesbury and main-line trains on the Chiltern Main Line to Birmingham Snow Hill with its associated branches...
) are fitted with this equipment.
Driver's Reminder Appliance
The DRA is an inhibiting switch designed specifically to prevent 'Starting Away SPADsDing-ding, and away
Ding-ding, and away is a slang expression used by the UK Media and railway enthusiasts to describe an incident in the British railway industry where a train driver is incorrectly given a bell code or green flag telling him to start the train despite the platform starting signal being at danger, and...
' by passenger trains. The driver is required to operate the DRA switch whenever the train is brought to a stand, either;
- after passing a signal displaying caution
- or at a signal displaying danger
Once applied, the DRA displays a red light, and prevents Traction power from being taken.
Collision avoidance
Whilst the ideal safety system would prevent a SPAD from occurring, most equipment in current use does not stop the train before it has passed the Danger signal. However, provided that the train stops within the designated overlap beyond that signal, a collision should not occur.Track circuits
Track circuitTrack circuit
A track circuit is a simple electrical device used to detect the absence of a train on rail tracks, used to inform signallers and control relevant signals.- Principles and operation :...
s detect the presence of trains and can, for example, hold signals at stop in the first place to prevent accidents. All other safety system such as train stops rely on detection systems such as track circuits.
Train stops
On the London UndergroundLondon Underground
The London Underground is a rapid transit system serving a large part of Greater London and some parts of Buckinghamshire, Hertfordshire and Essex in England...
(for example), train stop
Train stop
Part of a railway signalling system, a train stop or trip stop is a train protection device that automatically stops a train if it attempts to pass a signal when the signal aspect and operating rules prohibit such movement, or if it attempts to pass at an excessive speed.- Basic operation :The...
s are fitted on the track to stop a train, should a SPAD occur. When a train is stopped under such circumstances, delays occur because the train's trip cock has to be reset, and a replacement needs to be found as the driver is not permitted to continue with the train. Train stops (and trip cock equipped trains) are also operated by the main line railways, in many places where extensive tunnel operation is carried out.
Train Protection & Warning System
On the UK mainline, TPWS consists of an on-board receiver/timer connected to the emergency braking systemEmergency brake (train)
On trains, the expression emergency brake has several meanings:* The maximum brake force available to the driver/engineer from his conventional braking system, usually operated by taking the brake handle to its furthest postion, through a gate mechanism, or by pushing a separate plunger in the cab*...
of a train, and radio frequency transmitter loops located on the track. The 'Overspeed Sensor System' pair of loops is located on the approach to the signal, and will trigger the train brakes if it approaches faster than the 'set speed' when the signal is at danger. The 'Train Stop System' pair of loops is located at the signal, and will trigger the brakes if the train passes over them at any speed when the signal is at danger.
TPWS has proved to be an effective system in the UK, and has prevented several significant collisions. However its deployment is not universal; only those signals where the risk of collision is considered to be significant are fitted with it.
Flank protection
At certain junctions, especially where if the signal protecting the junction was passed at danger a side collision is likely to result, then flank protection may be used. Facing points beyond the signal protecting the junction will be set in such a position to allow a safe overlap if the signal was passed without authority. This effectively removes the chance of a side-impact collision as the train would be diverted in a parallel path to the approaching train.SPAD indicators
Prior to the introduction of TPWS in the UK, "SPAD indicators" were introduced at 'high risk' locations (for example: the entry to a single track section of line). These SPAD indicators are placed beyond the protecting stop signal and are normally unlit. Should a driver pass the signal at 'danger', a track circuitTrack circuit
A track circuit is a simple electrical device used to detect the absence of a train on rail tracks, used to inform signallers and control relevant signals.- Principles and operation :...
or treadle
Treadle (railway)
In railway signalling, a treadle is a mechanical or electrical device that detects that a train axle has passed a particular location. They are used where a track circuit requires re-inforcing with additional information about a train's location, such as around an automatic level crossing, or in an...
detects this and causes the SPAD indicator to flash red lights to warn the driver of his error. Whenever a SPAD indicator activates, all drivers who observe it are required to stop immediately, even if they can see that the signal pertaining to their own train is showing a proceed aspect. Since the introduction of TPWS, provision of new SPAD indicators has become less common.
Passing signals at danger - with authority
Signals form part of a complex system, and it is inevitable that they may go wrong. They are designed to fail safeFail-safe
A fail-safe or fail-secure device is one that, in the event of failure, responds in a way that will cause no harm, or at least a minimum of harm, to other devices or danger to personnel....
, so that when problems occur the affected signal indicates danger (a notable exception to this being the Clapham Junction rail crash
Clapham Junction rail crash
The Clapham Junction rail crash was a serious railway accident involving two collisions between three commuter trains at 08:10 on the morning of Monday, 12 December 1988....
). To keep the network running, safety rules enable trains to pass signals that cannot be cleared to a proceed aspect. Provided that authority for the movement is obtained, a SPAD does not occur. Basically there are two types of signal, and they are treated differently:
- Automatic signals (those worked by the passage of trains) may be passed at danger by the driver under his own authority (however this is normally authorised by communicating with the controlling signaller). If the driver is stopped at an automatic signal at danger and is unable to contact the signaller by all possible means, he is entitled to pass that signal at danger . He must proceed with extreme care as he should expect to find a train or other obstruction, such as a broken rail, in that section. If the driver fails to regulate the speed of his train, and is unable to stop it within the distance he can see is clear, accidents such as the Glenbrook train disasterGlenbrook train disasterThe Glenbrook rail accident occurred on 2 December 1999 at 8:22 am in New South Wales, Australia, in which seven passengers were killed and 51 passengers were transported to hospital with injuries. The accident occurred when an interurban train collided with the rear wagon of the Indian Pacific...
can occur. In any case, as soon as he reaches the next signal, he must stop and inform the signaller of what he has done—even if that signal shows a proceed aspect.
- Controlled signals (those worked by the signaller to control the entry to junctions or conflicting movements) can only be passed at danger with the signaller's authority. The driver and signaller must both come to a clear understanding, and ensure they agree about how it is to be done. In the UK the signaller tells the driver of a specific train to pass a specific signal at danger, proceed with caution and travel at a speed that enables him to stop short of any obstruction, and then obey all other signals. If the signal is fitted with TPWS, he advises the driver of this. Then, if necessary the driver pushes the TPWS Trainstop Override button in his cab, sounds his horn, and proceeds cautiously through the section. If he reaches the next signal without finding an obstruction, he obeys its aspect, at which point he reverts to normal working.
Accidents involving SPADs
- SloughSlough rail accident
The Slough rail accident happened on 16 June 1900 at Slough railway station on the Great Western Main Line when an express train from to ran through two sets of signals at danger, and collided with a local train heading for Windsor...
, 1900 (UK) - Tonbridge, 1909 (UK) - Ais Gill, 1913 (UK) - Charfield
Charfield railway disaster
The Charfield railway disaster was a fatal train crash which occurred on 13 October 1928 in the village of Charfield in the English county of Gloucestershire....
, 1928 (UK) - Norton Fitzwarren
Norton Fitzwarren rail crash (1940)
The Norton Fitzwarren rail crash occurred on 4 November 1940 between Taunton and Norton Fitzwarren in the English county of Somerset, when the driver of a train misunderstood the signalling and track layout, causing him to drive the train through a set of points and off the rails. 27 people were...
, 1940 (UK) - Eccles
Eccles rail crash (1941)
The 1941 Eccles rail crash occurred on 30 December 1941 at the east end of the station at Eccles, Lancashire, in northern England. A westbound train passed danger signals in fog during the wartime blackout, and collided at about 30 mph with an eastbound train traversing a crossover; 23 people...
, 1941 (UK) - Potters Bar, 1946 (UK) - Kew Gardens, New York
Kew Gardens train crash
The Kew Gardens train crash is the worst railway accident of Long Island Rail Road history, and one of the worst in New York State history. It happened during the evening rush hour of November 22, 1950 between Kew Gardens and Jamaica stations in New York City and killed 78 people...
, 1950 (US) - Harrow and Wealdstone
Harrow and Wealdstone rail crash
The Harrow and Wealdstone rail crash was a major railway disaster and collision on the British railway system on 8 October 1952.The accident took place from central London...
, 1952 (UK) - Luton, 1955 (UK) - Lewisham
Lewisham rail crash
The Lewisham rail crash on the British railway system occurred on 4 December 1957 just outside St Johns railway station in Lewisham, south London...
, 1957 (UK) - Dagenham East
Dagenham East rail crash
The Dagenham East rail crash was a railway accident on the London, Tilbury and Southend Railway line of British Railways which occurred at Dagenham, United Kingdom....
, 1958 (UK) - Newark Bay, New Jersey, 1958 (USA) - Harmelen
Harmelen train disaster
The Harmelen train disaster was the worst railway accident in the history of the Netherlands. Harmelen, in the central Netherlands, is the location of a railway junction where a branch to Amsterdam leaves the Rotterdam to Utrecht line...
, 1962 (Netherlands) - Marden, 1969 (UK) - Violet Town, Victoria
Violet Town railway disaster
The Violet Town rail accident, also known as the Southern Aurora disaster, was a railway accident that occurred on 7 February 1969 near the McDiarmids Road crossing, approximately 1 km south of Violet Town, Victoria, Australia.-Overview:...
, 1969 (Australia) - Paisley Gilmour Street, 1979 (UK) - Invergowrie, 1979 (UK) - Otłoczyn
Otłoczyn railway accident
The Otłoczyn railway accident was a train wreck which occurred on August 19, 1980, near the village of Otłoczyn . At 4:30 a.m., a freight train collided with a passenger train which ran from Torun Main Station to Łódź Kaliska...
, 1980 (PL) - Wembley Central
Wembley Central rail crash
The Wembley Central rail crash occurred on 11 October 1984 just outside Wembley Central railway station, Greater London.The 17:54 passenger train from Euston to Bletchley, formed by two Class 310 electric multiple units, collided with a Freightliner train which was leaving Willesden yard...
, 1984 (UK) - Eccles
Eccles rail crash (1984)
This article is about the 1984 rail accident. For the 1941 accident, see Eccles rail crash .The 1984 Eccles rail crash occurred on 4 December 1984 at Eccles, Greater Manchester, when an express passenger train collided at speed with the rear of a freight train of oil tankers. The driver of the...
, 1984 (UK) - Hinton, AB
Hinton train collision
The Hinton train collision was a railway accident that occurred on February 8, 1986. Twenty-three people were killed in a collision between a Canadian National Railway freight train and a Via Rail passenger train. It was the most lethal Canadian rail disaster since the Dugald accident of 1947...
, 1986 (Canada) - Colwich Junction
Colwich rail crash
The Colwich rail crash occurred on the evening of Friday 19 September 1986 at Colwich Junction, Staffordshire, England. It was significant in that it was a high speed collision between two packed express trains...
, 1986 (UK) - Chase, Maryland, 1987, (US) - Glasgow Bellgrove
Glasgow Bellgrove rail crash
On 6 March 1989 two Class 303 commuter trains crashed on the Springburn branch of the North Clyde Line, just east of Bellgrove station in the East End of Glasgow, Scotland...
, 1989 (UK) - Purley
Purley station rail crash
The Purley station rail crash was a train accident on the British railway system that occurred just to the north of Purley railway station in the London Borough of Croydon on Saturday 4 March 1989, leaving five dead and 94 injured....
, 1989 (UK) - Shigaraki
Shigaraki train disaster
The was a railway accident that occurred in Shigaraki , Shiga Prefecture, Japan on May 14, 1991. A Shigaraki Kōgen Railway train and a West Japan Railway Company train collided head-on, killing 42 people and injuring 614 others...
, 1991 (Japan) - Newton, 1991 (UK) - also single lead junction - Cowden
Cowden rail crash
The Cowden rail crash occurred on 15 October 1994, around 350 metres southeast of Cowden Station in the English county of Kent. There was a head-on collision between two trains in heavy fog after the driver of a northbound train ran past a red signal and entered a single line section.Five people...
, 1994 (UK) - Secaucus, New Jersey
Secaucus, New Jersey
Secaucus is a town in Hudson County, New Jersey. As of the 2010 United States Census, the town population was 16,264. Located within the New Jersey Meadowlands, it is the most suburban of the county's municipalities, though large parts of the town are dedicated to light manufacturing, retail, and...
, 1996 (US) - Silver Spring, Maryland, 1996 (US) - Hines Hill, Western Australia
Hines Hill train collision
The Hines Hill train collision occurred on the Eastern Goldfields Railway on 14 January 1996 at Hines Hill, Western Australia. Two trains entered a crossing loop simultaneously in opposing directions, although signals at the exit from the crossing loop were correctly showing red for...
, 1996 (Australia) - Southall
Southall rail crash
The Southall rail crash was an accident on the British railway system that occurred on 19 September 1997, on the Great Western Main Line at Southall, west London. Seven people were killed and 139 injured...
, 1997 (UK) - Beresfield, New South Wales
Beresfield rail disaster
In the Beresfield rail accident of 23 October 1997, a coal train passed a red signal and ploughed into the rear of another coal train, causing a collision and derailment that blocked all four tracks...
, 1997 (Australia) – Suonenjoki, 1998 (Finland) - Spa Road Junction
Spa Road Junction rail crash
The Spa Road Junction rail crash was an accident on the British railway system which occurred during the peak evening rush hour of 8 January 1999 at Spa Road Junction in Bermondsey, southeast London.-The incident:...
, 1999 (UK) - Winsford
Winsford rail crash
There have been three major rail accidents near Winsford in Cheshire:-1948 accident:On the evening of 26 December 1962, cold weather and snow in and around Crewe had caused points to become frozen and trains were being detained at signals...
, 1999 (UK) - Ladbroke Grove
Ladbroke Grove rail crash
The Ladbroke Grove Rail Crash was a rail accident which occurred on 5 October 1999 at Ladbroke Grove, London, England. Thirty-one people were killed and more than 520 injured...
, 1999 (UK) - a SPAD that led to dozens of deaths. Prompts TPWS. - Pécrot, 2001 (Belgium) - Norton Bridge, 2003 (UK) - Qalyoub, 2006 (Egypt) - Arnhem
Arnhem rail crash
In the Arnhem rail crash of 21 November 2006 – Arnhem, Netherlands - A cargo train driver ignored a red signal and collided almost head-on into a passenger train which was about to enter the railway station, injuring 31.- See also :...
, 2006 (Netherlands) - Chatsworth, California
2008 Chatsworth train collision
The Chatsworth train collision occurred at 16:22 PDT on Friday September 12, 2008, when a Union Pacific freight train and a Metrolink commuter train collided head-on in the Chatsworth district of Los Angeles, California, in the United States...
, 2008 (USA) - Halle
Halle train collision
The Halle train collision was a collision between two trains in Buizingen, in the Belgian municipality of Halle, Flemish Brabant, on 15 February 2010. It was Belgium's worst rail disaster in over fifty years....
, 2010 (Belgium) - Badarwas
2010 Badarwas train collision
The 2010 Badarwas train collision occurred on 20 September 2010, at Badarwas, Madhya Pradesh, India, when two trains collided with each other. Twenty three people reported died as a result of the accident, and 30 people were reported injured.- Accident :...
, 2010 (India) - 2011 Saxony-Anhalt train accident
2011 Saxony-Anhalt train accident
The 2011 Saxony-Anhalt train collision occurred on January 29, 2011, when a freight train and a passenger train collided near Hordorf in Saxony-Anhalt, Germany on the Magdeburg–Thale line. The passenger train derailed in the collision. Ten people were killed and 43 people were injured, some of them...
, 2010 Germany
Accidents involving stop and proceed
(In a stop and proceed accident, a train passes a stop sign according to the rules, but fails to keep to a low speed prepared to stop short of any obstruction)- Stratford (London Underground)
Stratford tube crash
The Stratford tube crash occurred on 8 April 1953, on the Central Line of the London Underground. 12 people were killed as a result of a rear-end collision in a tunnel, caused by driver error after a signal failure....
, 1953 (UK) - Coppenhall Junction, 1962 (UK) - Wrawby Junction
Wrawby Junction rail crash
The Wrawby Junction rail crash was a train crash which occurred on 9 December 1983, at Wrawby Junction, near Barnetby station in North Lincolnshire, England....
, 1983 (UK) - Glenbrook
Glenbrook train disaster
The Glenbrook rail accident occurred on 2 December 1999 at 8:22 am in New South Wales, Australia, in which seven passengers were killed and 51 passengers were transported to hospital with injuries. The accident occurred when an interurban train collided with the rear wagon of the Indian Pacific...
, 1999 (Australia) - Vittorio Emanuele (Rome Metro)
2006 Rome metro crash
The 2006 Rome Metro crash occurred on October 17, 2006 at 9:37am local time , when one train ploughed in another train as it unloaded passengers at the Piazza Vittorio Emanuele II underground station in the city centre, killing a 30-year-old Italian woman, named Alessandra Lisi, and injuring about...
, 2006 (Italy)