Monday's assult was the latest in a string of shootings and explosions that have targeted traffic officers in the capital, worsening already severe gridlock during rush-hour.
Rattled by the attacks that have killed at least 12 colleagues, traffic policemen have demanded more protection and sought armed guards for themselves.
Authorities have pledged to put an end to attacks on policemen by improving firepower capablities.
"They only have pistols so we are giving them heavier firearms," General Nijim Abed Jaber, chief spokesman for the traffic police force, told Associated Press news agency.
"But let me remind everyone that combat is not the job of traffic policemen. They are peaceful individuals whose job is to help people."
Traffic policemen, who typically do not wear bullet-proof vests or carry any weapons but a pistol, have begun carrying Kalashnikov assault rifles in recent days in response to the increased threat.
"My sole duty now is to carry an AK-47 rifle and respond to any attack against my colleagues by terrorists," traffic policeman Jassim Mohammed said.
"We will not walk out on our jobs because some cowardly terrorists are trying to kill traffic policemen who are offering a service to people."
Continuing violence across the country has raised concerns about the readiness of Iraqi forces to control the security after US troops begin withdrawing from the streets.
Meanwhile, General Ray Odierno, the commander of US forces in Iraq, maintained that Iraq's military is ready to take over security operations even as the current political deadlock over the formation of a new government prevails five months after an inconclusive election.