On this occasion I was just across the Tigris River when the bomber struck. His explosive charge sent a huge mushroom of white smoke into the air, followed by black clouds from the burning cars. Ambulances raced to the scene, policemen fired shots into the air to clear a way through the traffic in a well-rehearsed response that is played out daily, sometimes hourly, on the streets of Baghdad and other Iraqi cities.

The killing has reached record levels. Insurgents have killed around 400 Iraqis in the past two weeks. Yesterday 71 died in four suicide bombings in Baghdad, Tikrit and Hawija. There was also a bomb attack on a fertiliser plant in Basra, a mortar attack on the old Oil Ministry and a drive-by shooting in the capital, in which two Iraqi soldiers were killed.

Yet what is more stunning to a temporary resident of this ancient city is the response of the people. Those on the street alongside me when the explosion went off barely looked up. Men and women continued walking to their offices. Drivers stuck in tailbacks honked and cursed.

If the intent was to terrorise the population, as well as kill Americans, it was a failure. The intended target, a US military convoy, drove past unscathed. Those who survived put their good fortune down to luck.

Most Baghdad residents agree that the most dangerous stretch of road in this city is the 300 metres between Tahrir Square to Nasr Square running along Sadoun Street, the heart of the capital’s commercial district. The grimy street, favoured by US military patrols and contractors, was hit on Saturday, killing twenty-two people, and again on Tuesday, with the loss of seven more lives.

So it is all the more extraordinary to find Sabah Boutrous Mansour, 70, a stationery shop owner, sitting on the pavement chatting to a friend. The burly Christian is lucky to be alive. He was standing in exactly the same spot on Saturday when the blast shredded the inside of his shop with glass and shrapnel, but left him unscathed. His guardian angel stood over him again on Tuesday in a copycat attack down the street.

“The first bomb killed a friend of mine who sold falafel from a stall. Five of my neighbours were wounded and taken to hospital,” he said bluntly.

“This is my life. I have worked in this shop since January 1, 1960, and I am not about to quit now. I have replaced the glass in my shopfront 20 times since the Gulf War in 1991 and I expect it will happen again. But what can I do? I can’t stay at home all day. In Iraq you can be killed anywhere. I’d rather go right here.”

His hardiness, or possibly foolhardiness, is no exception. We found scores of store owners picking through the remains of their shops and haggling over the price of replacement furniture and glass.

Abdul Salam Mujbil, 45, was chatting to a friend in the remains of his money-changing shop a few doors down, which had taken the full brunt of Tuesday’s blast. Chunks of twisted metal from the car bomb lay on the pavement in front of his shop beside the charred skeleton of what had been his car.

“It was pathetic,” he said. “The only people killed were the tea-sellers, the shoeshine boys and the other innocents.

“I am back here today because this is my only livelihood. I have a mother to look after. I want to get married. I want to make something of my life and I am not going to be chased off my own property.”

Even three members of the Abed Ali family, who work on the street making advertising boards, vowed that they would be back as soon as they had recovered from their shrapnel wounds and broken limbs.

In spite of the stubborn Iraqi character, the new Government of Ibrahim Jaafari, the Prime Minister, knows that it must staunch the wave of insurgent attacks if it hopes to win the confidence of the people who elected it to power in January. Last month there were about 150 suicide attacks, up from 64 in February.

The only meagre comfort that the Government can take from the appalling statistics is the growing evidence that many of the suicide bombers are volunteers from outside Iraq and that the carnage they are causing is turning ordinary Iraqis against the insurgency.