If you live close enough to the train tracks in Portland, you can probably hear the somewhat frequent, dull rumble of both freight and passenger trains passing through.

What you don’t hear is the sounding of horns when those trains cross over city streets.

That’s because Portland is a federally designated quiet zone. Essentially, the Federal Railroad Administration has agreed that the city has implemented enough safety measures to deter cars and pedestrians from getting in the pathways of oncoming trains without those trains having to blow their horns.

But federal standards are getting tougher to meet, and as my friend David Harry from The Forecaster reported recently, the city now must consider spending between $1 million and $1.1 million for upgrades that will preserve Portland’s quiet zone status.

That’s ahead of what may be another $1.1 million in few years as well.

Without those investments, the city could become a very loud place.

“Essentially you’d have ongoing horn blasts throughout the city,” said Jeremiah Bartlett, a transportation system engineer for the city. “Because many of those crossings are in residential neighborhoods, that would be extremely detrimental to those communities. I don’t know if you’ve ever been near a train when its horn was sounding, but it’s a very loud noise.”

There are more than a dozen rail crossings along the Portland train corridor between Riverside and Congress streets, and as many as two dozen total freight and passenger train trips through the Forest City every day.

And outside quiet zones, trains are required to blow their horns both coming into and going out of crossings. Watch a few seconds of the video below as a reminder of what that sounds like.

Portland is not a hot bed of train collisions. As David reported, the last car-train collision in the city was in 2008.

What the city’s doing to prevent train crashes — simple gates, lights, warning signs, etc. — is basically working.

So why do local taxpayers need to pony up another $1.1 million — or $2 million-plus, if you’re looking ahead?

It’s because the Federal Railroad Administration is regularly moving the proverbial goal posts for what’s defined as safe. The agency has a complicated formula that considers nationwide train collisions and other risk factors, and issues a new minimum risk rating score every year or so.

Right now no quiet zone municipality can have a risk score of more than 14,347, and that number has been getting lower and lower every year. Portland’s at right around 14,000, Bartlett said.

“It’s generally been a steady drop,” he said. “Because it’s really based on nationwide issues — traffic seems to regularly go up and rail movements have gone up over the last 10 years — that’s an inevitable outcome.”

Bartlett estimates we’re no more than a year or so away from that FRA safety threshold dropping below Portland’s number.

“You’d get notified by the Federal Railroad Administration you’re potentially out of compliance, and given a window of time to address the compliance issue,” he said.

The city can reduce its number — again, derived from a complex formula considering traffic volume, crossings, signs, gates and other criteria — by paying for railroad owner Pan Am to build what’s known as a quad gate at one of its busier crossings.

(Under FRA rules, it’s incumbent upon the municipalities to fund and oversee train crossing safety measures, in case you’re wondering why Pan Am or the federal government isn’t paying for it.)

Quad gates drop from four corners around an intersection to create more obstructions for drivers, who might otherwise try to beat the trains by weaving around the single gates dropping in each direction.

Like this:

They also cost between $1 million and $1.1 million to install.

Bartlett said the city is considering one at either Allen Avenue or Brighton Avenue, with the other of the two likely to be done a few years down the road as the FRA number drops further.

“If you’ve got a high-risk location with scores in the thousands — and both Allen and Brighton are high-risk locations — and you could essentially cut the risk numbers for the location in half, it should cut the risk by a significant number citywide as well,” he said of the quad gate measure.

But what if Portland puts it off? The city could put away some cash every year for a while and install a quad gate or two later. If the quiet zone status lapses, it wouldn’t lapse for long, and maybe it’d be easier to make a public case for the project after folks get an idea what it’s like to hear train horns around the clock.

The trouble with that, Bartlett said, is that Portland’s quiet zone was established more than a decade ago, when the bar to qualify was much lower. The city’s grandfathered, but if Portland were to have to apply for entry into the program by the current standards — which it would if it let its quiet zone status lapse — it would need to do a lot more than build a quad gate or two.

“If we had to reapply from scratch, we would be required to look at measures like quad gates at every single one of our crossings from Riverside to Congress,” he said. “That would be a significant outlay of capital.”

Something along the lines of $14 million and change.

Bartlett said the $1.1 million expenditure is largely funded through the draft fiscal year 2017 capital investment budget, which the City Council will deliberate over this spring.

“Our hope would be we could get a design worked out later this year and hopefully have something done in 2017,” he said.

Bartlett acknowledged the quad gate project isn’t popular. But he said the prospect of nonstop train horns through Portland neighborhoods is even less popular.