ST. LOUIS • Recent traffic crashes that killed two city police officers had three common factors, Chief Dan Isom said Wednesday: They were driving too fast, didn't slow down enough at intersections and weren't wearing seat belts.

It fits a national trend, with more officers dying in wrecks than at the hands of criminals.

Isom said it's impossible to know whether seat belts would have saved Julius Moore and David Haynes. But in an interview, he pledged new emphasis on traffic safety, with required annual driving refresher courses for all officers and the possible use of a seven-acre tract at Lambert-St. Louis International Airport to simulate high-speed chase conditions.

He also called for mandatory remedial driver training for officers involved in crashes and reiterated the department's strict seat belt policy.

His remarks came after a meeting of the Board of Police Commissioners, where a member, Bettye Battle-Turner, and the president, Todd Epsten, asked the chief to review the department's policy in the wake of the deaths of Moore and Haynes, and of a 20-year-old woman killed when a fleeing carjacking suspect's vehicle collided with her car.

One key challenge for police behind the wheel is chasing criminals in vehicles.

St. Louis County Police Chief Tim Fitch said the city modeled its pursuit policy from his department's guidelines, which allow officers to pursue if they believe "that the suspect has committed a felony involving the use or threatened use of deadly force and a delay in apprehending the suspect will pose a danger to other people."

Fitch noted, "At some point, you have to draw the line because there are crimes that we cannot allow an individual to flee from."

City police adopted the policy in May 2002. Since then, Isom said, the department has seen a 50 percent decrease in pursuits, from 132 in 2001 to 65 in 2009.

Since 2008, only two have been found to violate the policy, Isom said.

St. Louis police are supposed to slow at intersections during emergency driving. As for Haynes and Moore, "If there was slowing, it wasn't enough," Isom said.

"You have to slow to a degree in which you make sure it is safe to pass through the intersection. Some departments say officers must stop at intersections, but that would in effect eliminate pursuits. Asking officers to slow to a reasonable speed has given officers a little more flexibility."

The policy also has earned a reputation among criminals — especially those involved in property crimes — that they are free to run, said Tom Walsh, president of the St. Louis Police Officers Association.

"They're not afraid of high-speed pursuits anymore because ... they feel confident that they're not going to be chased," Walsh said.

On March 24, Haynes, 27, pursued a suspect in a home burglary in which the homeowner's son had interrupted the crime. The earliest reports suggested there had been an altercation, so it's not clear whether Haynes believed that deadly force had been used or threatened. He was fatally injured in a collision at Kingshighway and Oleatha Avenue.

Moore, 23, was on his way to help fellow city officers thwart a burglary on Oct. 6 when his patrol car collided with a tractor-trailer at Broadway and Arsenal Street and was wedged against a building. He died nine days later.

Both were rookies and had recently been through the department's driving courses.

The week before Haynes' death, a teenager who ran a stop sign in a stolen car while being chased by city police was charged with murder for a death in the resulting collision. A motorist, Angela Robertson, 20, died at a hospital after the crash on March 19 at West Florissant and College avenues. A 22-year-old passenger who was riding in her car suffered critical injuries.

That pursuit met guidelines, officials said, because the fleeing driver was wanted in a major crime, a carjacking at gunpoint.

Carjacking was the most common reason police initiated pursuits in 2009 — accounting for 16 of 65, department figures show.

The National Law Enforcement Officers Memorial Fund says the number of officers killed in traffic-related incidents increased 17 percent during the first six months of 2009, to 35 from 30.

Those incidents — which included automobile and motorcycle crashes and officers struck outside their vehicles — remain the leading cause of death among police officers in the United States, a trend that began 12 years ago, according to the nonprofit organization.

After Trooper Matt Mitchell killed two teens in a high-speed collision in St. Clair County in 2007, the Illinois State Police made sweeping policy changes that among other things limited emergency driving to 20 mph above the posted limit, or 30 mph in certain cases.

The Houston Chronicle reported in March that about 40 percent of officers killed in car accidents from 2004-08 were not wearing seat belts, based on National Highway Traffic Safety Administration data.

The numbers don't speculate on whether belts would have saved them, but one study suggested that an officer is nearly three times more likely to die in a crash without one.

Walsh said many officers prefer not to wear seat belts, which can hinder them from bolting quickly from their cars and get tangled in their guns, handcuff cases, radios or other tools.

Missouri's seat belt law exempts "persons employed by the United States Postal Service while performing duties for that federal agency which require the operator to service postal boxes from their vehicles, or which require frequent entry into and exit from their vehicles ..." but does not mention police.

Department policy insists upon seat belt use, and since January 2009, officers have been given one-day unpaid suspensions for violations. Last year, 45 officers were given suspensions, and two of them were repeat offenders. So far this year, 10 have been suspended and none has repeated.

Anytime a city officer is involved in a crash, the car's "black box" recorder is checked for seat belt use, officials said.

Isom said the policy was in effect well before Haynes' and Moore's deaths.

"If we're talking about this, and it will convince officers to wear their seat belts, then that's what anybody would want us to do," he said.

Heather Ratcliffe, Matt Fernandes and Patrick O'Connell of the Post-Dispatch contributed to this report.