The Baghdad Bridge which was bombed by insurgents in 2007 is one of the portents of Hazrat Mahdi's (as) appearance

Related from Ali (r.a), the Amir of believers:

WHEN THE BRIDGE IS CONSTRUCTED UPON BAGHDAD

AND

¹COMETS APPEAR FROM THE EAST

²THE CAVALRIES OF THE ARMY

WILL BE KILLED ON THE BRIDGE   

(Muhtasar al- Basair-id Darajat Page:237 and At Tashrif Bil Menun Page:367 and Bihar Volume:41 Page:178)

1.     ...WHEN COMETS APPEAR FROM THE EAST...

COMMET HALLEY APPEARED VERY CLOSE TO EARTH IN 1986

In H. 1406, that is to say, in 1986, Comet “Halley” appeared very close to the Earth. This Comet  is a very bright star.

Before the appearance of Hazrat Mahdi (pbuh) a comet that enlightens (all around) will appear. (The Portents of the Day of Judgment, p. 200)

Before his appearance, a comet that gives light from the East is seen.  (Ibn Hajar al-Haythami, Al-Qawl al-Mukhtasar fi `Alamat al-Mahdi al-Muntadhar, p. 53)

THE COMET LULIN CAME CLOSEST TO THE EARTH IN 2009.

Just like the Commet Halley, the Commet Lulin appeared close to the Earth on 24 February 2009, in other words in Hijri 1430. Scientists state that this star will presumably appear a 1000 years later again.

Its daily passage, on the other hand, is from east to west…

According to his Companions, the Messenger of Allah (saas) said:

"When Abbasi Malik arrives at Khorasan, one of the signs of the coming of the promised Mahdi, A DOUBLE-TOOTHED (1) LIGHT SHEDDING (2) HORN (3) WILL APPEAR IN THE EAST." IT IS FROM  WEST TO  EAST (4)

Imam Rabbani, The Letters of Rabbani, Letter 381, p.1184

You repeatedly ask about the A BRIGHT PILLAR BORN FROM THE EAST.

Know that,

According to the news given by the Companions, our Prophet (saas) related thus:

"When Abbasi Malik arrives at Khorasan, one of the signs of the coming of the promised Mahdi, A DOUBLE-TOOTHED (1) LIGHT SHEDDING (2) HORN (3) WILL APPEAR IN THE EAST." IT IS FROM  WEST TO  EAST (4)

According to the account, that pillar had two heads.

The first birth of this pillar was at the time of the destruction of the people of the Prophet Noah (pbuh). The same  thing was born when they cast the Prophet Abraham (pbuh) into the fire. It was born again in the time of Pharaoh and his people.

It was born again at the time of the martyring of the Prophet John pbuh).

Let whoever sees it seek shelter in Allah from the evil of corruption.

That whiteness emerging from the East was formerly in the shape of a radiant pillar. A curvature then came to it, and it took the form of a horn.

It is probable, therefore:

-it is described as double-headed probably because both sides will be thin and resemble a tooth, and it will have a head at both ends. Indeed, if a blade has a cutting edge on two sides,

-They use the term double-headed.

My brother Sheikh Muhammad Takhir Badahshi came from Confor. He says:

-There are two heads on the upper part of that pillar. They resemble two teeth. There is a short space between them.

This was recognized at the desert.

But this birth is not that which will appear at the coming of the Mahdi. That is because his appearance will be at the beginning of the century. Eighteen years have currently gone by since the beginning of the century.

The hadith says this about the portents of Hazrat Mahdi (pbuh):

"A TAILED STAR (COMET) WILL BE BORN IN THE EAST AND SHED ITS LIGHT."

That comet has been born. But is it that one, or another similar one?

-That this star is called a comet, is probably based on the following:

-The course of the constant IS FROM WEST TO EAST (4)...

The situation of this star follows this course. In other words, its head faces east and its tail faces west. The long white part is in its rear. Therefore:

-It is appropriate for it to be described as having a tail.

ITS DAILY PASSAGE, ON THE OTHER HAND, IS FROM EAST TO WEST. (5)

Allah best knows the truth.

2.    ... THE CAVALRIES OF THE ARMY...

         DATE: 2007

The al-Sarafiya bridge, connecting KIRKUK IN THE NORTH TO THE BAGHDAD WAS DESTROYED BY THE EXPLOSION OF A SUICIDE TRUCK BOMB STAGED BY INSURGENTS.