Last month, a 51-year-old woman was crossing the street in the Loop, right at City Hall, when she was plowed into by a two-ton U.S. Postal Service truck.

Her injuries were bad enough – a punctured lung, a fractured pelvis, two broken bones in one leg, a fracture in the other leg and fractured ribs.

If you don’t see the video above, click here and watch it on CBS2.

But what came next made things much worse: An ambulance didn’t show up for 16 minutes – 10 minutes past the acceptable limit, as determined by state safety regulators.

“I was trying to breathe and pray, and keep positive hopes that they would get there soon enough to get me to the hospital,” the injured woman, Lynn Ramos, said later in an interview from her hospital room.

A Better Government Association/CBS2 investigation found such ambulance delays appear to be increasingly common because of shortages of the life-saving vehicles within the Chicago Fire Department – meaning people’s lives and health are being put unnecessarily at risk because, critics say, the fire department brass won’t adequately tend to the fleet.

Ramos, a South Side resident, isn’t a household name. But similar problems surfaced as paramedics responded to an emergency call about prominent chef Charlie Trotter.

Trotter apparently suffered a stroke at his Lincoln Park home on Nov. 5, and after a family member called 911, it took about six minutes for a paramedic to arrive on the scene in a fire engine, according to city and county records.

It took eight minutes more for an ambulance to show up, records show.

While a paramedic on an engine can initiate life-saving treatment, a patient can’t be transported until an ambulance has arrived – and, in trauma cases, that means an “advanced life support” or ALS ambulance.

Trotter ended up dying, although there’s no indication the ambulance delay contributed to his demise.

His widow, through an attorney, declined comment.

Either way, who’s to tell when an ambulance delay might contribute to a death or exacerbate an injury.

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Numerous Chicago Fire Department paramedics relayed anecdotally to the BGA and CBS2 that delays are worsening, largely because there aren’t enough ALS ambulances on the street. As the BGA previously reported, the city’s ALS ambulances are also prone to breakdowns because of their age.

City officials, who are in contract talks with the firefighters union, said the number of emergency calls is staggering: Roughly 300,000 for each of the last three years.

But how long it takes for crews to arrive on the scene of a call is difficult to accurately gauge because of the way the city does – and doesn’t – track paramedic responses.

Chicago’s inspector general – the in-house watchdog for Chicago’s municipal government led by Mayor Rahm Emanuel – released a report this past October blistering the fire department for not assessing paramedic response times accurately and not meeting response-time standards as it claimed.

While the fire department can provide ambulance response times for specific incidents, the department does not analyze or keep data in a way to track trends over periods of time, according to spokesman Larry Langford.

Illinois Department of Public Health guidelines say that an ALS-equipped vehicle should show up at a scene within six minutes of dispatch – but the agency doesn’t differentiate between fire engines with ALS equipment and a paramedic, and ALS ambulances, which can actually transport patients.

There are usually 60 ALS and 15 “basic life support” ambulances available at any given time, city officials said. Basic life support ambulances lack the equipment, medicine and paramedic staffing as ALS vehicles.

Ramos’ case illustrates the problem well, said Patrick Fitzmaurice, a Chicago paramedic field chief. “We need more ambulances on the street,” he said.

An ambulance didn’t show up for 16 minutes – 10 minutes past the acceptable limit

When Ramos was hit at Washington and La Salle on Jan. 10, a paramedic was on the scene within about four minutes, but Ambulance 35 – dispatched from Pershing Road on the South Side, roughly five miles away – was the first ALS rescue vehicle to show, and it arrived well past the state guidelines, records show.

There were apparently no available ambulances any closer.

“There’s a public health problem here and does it matter in the vast majority of times that we take an extra five to 10 minutes longer?” a paramedic who wanted to remain anonymous said. “No, but what about the one time” it does matter?

While city officials contend there is not an ambulance shortage, they acknowledge there have been incidents where ambulances took way too long to arrive at a trauma scene.

And they also acknowledge they’re studying whether to shift ambulances to other firehouses to improve the responses. What’s more, the fire department is considering converting some of its basic life support vehicles to ALS vehicles, Langford said.

Fire Commissioner Jose Santiago said in a statement emailed to the BGA and CBS2: “The Chicago Fire Department takes its calls for medical assistance very seriously and does not have a shortage of ambulances, nor is the City refusing to hire paramedics. We plan on hiring paramedics in 2014 after a temporary delay due to our updating testing requirements. We are fully staffed every day with a mix of paramedics working straight time and overtime, the majority of which is voluntary. This allows us to respond quickly to start care and transport patients.”