Too many Denver motorists refuse to yield the road to emergency vehicles. The problem is bad enough that a dozen Denver Health ambulances have been equipped with subwoofers that shake the ground as sirens blare.

“People seem to be more aware now,” said Scott Bookman, chief paramedic for Denver Health EMS.

The 100/200-watt siren amplifiers point at the ground, generating a frequency low enough to vibrate everything outside the ambulance — an experience akin to pulling up next to a club kid blasting hip-hop from a trunk filled with speakers.

It turns heads.

“They vibrate the entire ground,” Bookman said. “People can feel it throughout their car. It’s pretty neat.”

After testing the boom-boom sirens for 18 months, Denver Health is satisfied with the results and is making them standard issue for all new vehicles, Bookman said.

Bookman said St. Anthony’s Flight for Life ground crews also have the subwoofers.

Paramedics try to respond to a call within nine minutes, meaning unexpected obstacles make moments seem like minutes for crews and their patients. “This is especially the case when we are on a cardiac-arrest call,” Bookman said.

Drivers probably don’t mean to hinder an ambulance or firetruck speeding to an emergency call, Bookman said. But they may be panicked by the lights and sirens, distracted by gadgets in the car or are driving vehicles engineered to keep sound out.

And the problem seems to be getting worse, Denver Fire Department spokesman Phil Champagne said. “It’s like people aren’t even connected to the outside world anymore.

“I have seen people just keep going 30 mph with us right behind them, and there is no way they haven’t noticed us,” he said. “It is a matter of getting out of the way so we can do our job but also realizing your car will not match up well against our trucks.”

Champagne warned that people can pay with their lives from being unaware that a fire engine is coming their way. An 80-year-old woman died in January after she pulled out in front of a department engine at East Hampden Avenue and South Yosemite Street.

Denver paramedics respond to an average of 230 calls a day, Bookman said. Denver Fire vehicles are called out an average of 274 times a day.

Denver police ticket more than 70 people a year for failing to yield to an emergency vehicle. From Jan. 1 to May 8 of this year, 18 tickets were issued. The ticket carries a four-point penalty and an average fine of $100 in Denver County, officials said.

“Even we (police officers) pull over if we are not on an emergency call,” police spokeswoman Raquel Lopez said.

Police must witness the act in order to issue a ticket, which means it has to happen in the right place and right time, Lopez said.

Public service announcements reminding people to pull over and let emergency vehicles pass need to make a return, Champagne said.

“I haven’t seen one in decades, but, yeah, I think it’s time to start running them again,” he said.

Emergency personnel realize there are extenuating circumstances for a driver not getting out of the way — such as panic — especially on a one-way street downtown.

“Everyone just needs to stay calm,” Bookman said. “Make a rational decision of getting out of the way, which should be decided by watching which way the emergency vehicle is trying to go.”

Ryan Parker: 303-954-2409, rparker@denverpost.com, or twitter.com/yhRyan

What to do when the lights and sirens start

Colorado Department of Revenue spokesman Mark Couch said the booklet that people study in order to get their driver’s license covers the basics of responding when emergency vehicles approach.

The booklet states that a driver must pull over to the right edge of the road, Couch said. If at an intersection, proceed through, then pull over, he said.

Denver cops say drivers stopped at a light when an emergency vehicle shows up should stay put so the firetruck or ambulance can pick its way through the intersection — and don’t try to guess the emergency vehicle’s route.