By siren, I mean the (usually) electronic device that makes a wailing sound on police cars, fire trucks, and ambulances. The wailing sound is used to warn other vehicles that an emergency vehicle needs the right-of-way. I’ve been a fan of sirens since watching Emergency! in my early days.
So, a few questions:
How does the siren know to stop when the vehicle has arrived at the scene? Does the driver have to turn it off? Does it turn itself off when the vehicle’s transmission is set to park?
Can the siren sound when the vehicle is parked?
Why are the sirens on ambulances so much weaker (in my opinion) than those of other sorts of vehicles?
In movies and TV shows, I notice that European emergency vehicles have a different siren sound than is found in the US. Is there a sound that is particularly effective at getting the attention of other drivers?
Regarding a police car, does the officer driving have discretion as to when to use the siren and/or lights? Does the dispatcher tell the officer when to use the siren? Are there certain calls that the officer simply knows ALWAYS get the siren treatment while other calls just get the lights?
Here in Texas, police cars tend to have light bars attached to the roof. These lights flash blue and red and are VERY bright. Upon making a traffic stop at night, the officer can turn on lights that illuminate the scene in front of him/her so for the safety of the officer, stopped driver, and other drivers still moving. However, I have noticed in other states (such as Michigan), the state police only has a single, large cherry light. Why don’t these states adopt something that is brighter and, I assume, more safe for everyone involved?
There’s a switch on its control panel to turn the siren on and off and also choose what mode – wail, warble, etc. it’s in.
Yes. I’ve seen a parked cop car blip someone passing through the lot faster than they thought prudent.
Not sure I’ve noticed any difference. Fire trucks have those air horns they love to use, presumably because they are harder to stop.
They also paint their cars funny colors like hi-vis green. I don’t think there’s been any international research done on which sounds are more effective so various departments go with what they like.
Way back when on Adam-12 you’d sometimes hear a call include “Code 3.” That meant lights and siren in LAPD parlance. I would imagine when to use and not to use would be spelled out in the department’s handbook of procedures.
Tradition, cost, the commander’s brother-in-law owns an old cherry-light factory, who knows?
It’s all electric. There’s a switch that’s turned on and off manually as needed.
Yes, see #1.
They probably aren’t. It has more to do with the age of the vehicle, variation in the suppliers and specs of the siren and the aggressiveness of the operator. In most cases the latter is the biggest factor. Not to be confused with the air horns…those are stupid loud on the fire trucks and most ambulances don’t have them.
It’s all electronic so the sound design is entirely arbitrary. The chosen noise by location is just tradition.
There are lots of policies around when first responders can and should use their sirens, aka, running hot. But, it’s entirely in the discretion of the car’s operator as to when they are turned on. Many cities have serious problems, resulting in a lot of death and dismemberment, with cops breaking policy on the use of sirens. As you’d expect there’s rarely any accountability here.
Money mostly. And tradition, but mostly money. Nearer cars with LEDs and light bars that can be switched on in multiple configurations will become more common over time but older fleets will have simpler, less omnidirectional lights installed. It’s entirely up to the municipality to select and purchase the equipment and there’s several vendors and price points so you’ll see some variation in what they buy.
Here in the NE US fire trucks often have a mechanical siren. You can tell because they don’t shut off instantly, but have to wind down. I don’t remember a mechanical siren on any other emergency vehicles though.
the probability of a visibility-related accident is higher for a red or red-and-white pumper than for a lime-yellow fire truck. Lime yellow, which falls in the middle of the color spectrum, is easy to see during the day, when we rely on our trichromatic cone vision, and is the most visible wavelength at night, when human vision is dominated by achromatic rods rather than cones. Red may mean fire, but lime yellow is the real eye-catcher
In England, research conducted by the Lanchester College of Technology and Coventry Fire Brigade in 1965 concluded that the color lime or bright yellow was actually easier to see in a variation of lighting — including at night. Research findings also suggested that the color yellow was more visible during inclement weather.
In response, most U.K. fire service vehicles started including retroreflective yellow markings on their rigs.
And these findings just don’t apply to our friends across the pond — we’re progressively seeing more and more lime or bright yellow rigs in suburbs and smaller cities around the U.S.
They sure do. And around here, fire trucks also carry the world’s loudest PA system. I saw it in action once when a fire truck was behind an idiot in congested traffic who refused – or couldn’t figure out – how to get out of the way despite the siren, lights, and air horn. Added to the cacophony was the extremely loud announcement from the fire truck: “GET OUT OF THE WAY NOW!!”.
It worked, rather impressively! It seemed to me that if he had not done so, the big sturdy fire truck would have plowed ahead anyway.
Old fashioned mechanical sirens produce a lot of sound in the ultrasonic range above what humans can hear, but within the range dogs can hear. Apparently dogs find that distressing.
Modern electronic sirens don’t waste any energy creating noise humans can’t hear. Rather the opposite: they’re designed to channel as much as possible of their total input energy into whatever noises humans can hear best. So dogs are spared since they’re not part of the “target audience”.
I have seen some VERY bright flashing lights on police cars making a traffic stop. I don’t know whether they’re the same ones in use in Texas. I do know that they’re entirely blinding to other traffic coming upon the scene and (in a legal, slow, and cautious fashion) passing through, and I was seriously afraid that there would be a second accident caused because I, and probably anybody else in the vicinity, couldn’t see where I was going.
Some of the ambulances in my neighborhood now have two sirens on one vehicle, presumably to trick a driver into thinking there are multiple emergency vehicles behind them and actually get out of the way (which is rare here).
Sort of in a round about way. Since they are harder to stop, they have air brakes (like all big trucks), which gives them a source of compressed air on board, which also can be used to power very effective air horn.
They are pretty bright here in Texas. I believe they can flash their red and blues to the rear, to the front, or both. As well as flash sequential amber lights simultaneously with the red and blues or independently.
In the early 90’s, our office had a typical fax machine that, when there was an error, played those dual error tones that sounded like European sirens. We’d always announce, “it’s the French police again…”
When we lived in Boston (up to a year ago) our dog would try “singing” along with one particular siren. Her ears would perk up at the sound of the other sirens, but only this one particular wailing prompted her to try to join in.
Since we’re talking about sirens here, I have an additional question. What is up with someone, I don’t know if its police or ambulance, fiddling around with their siren, making odd BLOOP BLEEP BLORT noises? Random times of day or night. How can that be permitted?
I live within shouting distance of a state hospital, so they have their own police, fire and I reckon ambulance stationed there, so I figure someone is just fooling around. It just seems pretty inappropriate to mess around like that with emergency gear. Not that it’s hurting anything, just a bit annoying when you’re trying to enjoy your backyard.
Speaking of the state hospital, they used to have a very loud air raid style siren that would go off at 8:00 am and 5:00 pm on weekdays, I guess to signal the start and end of the workday. Thank Og they knocked that off.
In my lifetime, in the UK they’ve gone through several different versions, from a simple bell in the 50s through two-tone nee-ners up to today’s banshee wails. I assume there’s some sort of research gone into it, but the primary driver AFAIK is simply that there are more and more other distracting sounds in the environment, so they’ve gone for something that cuts through anything and is MUCH louder.
