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This is the Second World War bomb which sparked traffic misery on Monday.

Birmingham motorists face one of their worst ever rush hour journeys home tonight after the bomb discovery caused huge delays across the city.

The A38 Aston Expressway remains closed in both directions, almost eight hours after police were alerted to the chilling discovery at a construction site in Priory Road, Aston.

West Midlands Ambulance Service shared a photo of the bomb, claiming it weighed a whopping 250kg - or just over 550lbs.

"We're working with WMPolice WestMidsFire and bomb disposal staff at the scene. A number of residents have been evacuated," WMAS added.

There is speculation that if one bomb has been found there could be others - German aircraft generally dropped explosives in 'sticks' - a number together.

Normally bomb disposal experts, if the device is small, like a grenade will take it away and destroy in a controlled explosion.

But as the picture shows, the Luftwaffe dropped 1,000 and 500 lb bombs on the city during the war - so large they could cause significant damage to the area.

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Typically, bomb disposal units will either opt for: a controlled explosion in a secure parameter, or detaching from trigger, removal and disposal in a controlled environment.

The first method - basically blowing the device up - is preferred, owing to its safer, quicker and less complex nature.

So, if a unit is able to create a safety radius, keep the public safe and away from it, and secure the area, it's job done.

However, this is not always a possibility.

Sometimes, the device is far too dangerous to approach.

In these circumstances, the device will be removed for disposal eslsewhere.

Because of the instability and complexity of modern bombs, however, this is rarely done.

Many techniques exist for the making safe of a bomb.

Selection of a technique depends on a variety of factors, including the proximity of the munition or device to people or critical facilities.

Typically, technicians have many tools for remote operations, one of which is the RCV, or remotely controlled vehicle, also known as the "Wheelbarrow".

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Outfitted with cameras, microphones, and sensors, the Wheelbarrow can help the Technician get an excellent idea of what the munition or device is.

Among other popular techniques are X-ray style items used to determine what the munition or device is, and what state it is in.

Another technique is Trepanation, where technicians bore a cut into the sidewall of a bomb and the explosive contents are extracted through a combination of steam and acid bath liquification of bomb contents.