# Thread: How far/how long does it take to slow down to PSL?

1. ## How far/how long does it take to slow down to PSL?

If you want a safe and reasonable answer to that question, have I got a chart for you!

This chart is based on a deceleration rate of 12 fpsps and .75 second reaction time... It's international in scope (shows MPH and KPH) with results in seconds to slow and feet travelled while slowing... So you can see whether you'll be able to slow down to the PSL in time.

Since the 12 fpsps is conservative, it should be possible for folks with worn out tires, or on rain slick roads, or with bad brakes, but not more than one of the variables... and all bets are off on snow or ice.

The 3/4 second reaction time is a national average... some will do better, some worse...

All of that said, here is a disclaimer for you, too:

Use the chart at your own risk. I do not guarantee that it will represent your driving capabilities or work with your vehicle. As in life, your mileage may vary... I will not pay speeding tickets if you rely on this chart to save your butt... I offer it only as an exercise in mathematics and what could be possible if you decelerate in time! Have fun with it!

Two varieties:
http://www.guysoflidar.com/files/speed_sheet3.xls

A wep page you can see right away (on a PC: right click, open in new window) (on a mac, go punt! I don't know, honest!)
http://www.guysoflidar.com/files/speed_reduction.htm

Thanks to Jimbonzzz for hosting these files on the Guys of Lidar site!

2. good info here!

You are forgetting the 2 second reaction time it takes for most of us to comprehend that we are in fact being hit with laser :wink:

3. Originally Posted by Sethy
good info here!
Thanks! your endorsement and Jimbonzzz willingness to host it says a lot to me!

You are forgetting the 2 second reaction time it takes for most of us to comprehend that we are in fact being hit with laser :wink:
Yeah! I'll bet! I've not been so lucky, yet... I'd like to get an AL before I am so fortunate!

4. Interesting to see those average times/distances.

GOOD JOB!

5. This is a shamless bump to move topic up...

It's the holiday weekend, folks.... Accidents up, citations up, LEOs are everywhere this weekend... Here in Iowa, they're warning people in radio and TV ads that they will be out "hunting."

So, "Let's be careful out there!" After all, most of the drivers we'll be dealing with are not situationally aware by any means of the term...

But, that said, what a weekend to test equipment, eh?

6. how long it takes to slow down to the psl depends on how fast your going and what car you have.

also how long you have got to slow down to the limit before you see the cop or pass the trap!

the better the brakes, tires, are the better your chances, it also helps having a good detector to give plenty of warning instead of having to take instant action and possibly causing an accident.

7. Probably the best thing to do is to drive along at whatever speed you do, make sure nobody's behind you, have a co-pilot with a stopwatch and pay a bit of attention to your odometer's tenth scale (ie 1/10 mile or 100 m) have the co pilot shout "LASER" and nail the brakes.

8. Originally Posted by SmaartAasSaabr
Probably the best thing to do is to drive along at whatever speed you do, make sure nobody's behind you, have a co-pilot with a stopwatch and pay a bit of attention to your odometer's tenth scale (ie 1/10 mile or 100 m) have the co pilot shout "LASER" and nail the brakes.
Agreed... but I think the chart is a good, general, rule-of- thumb, starting point, no?

Originally Posted by laserblaster
how long it takes to slow down to the psl depends on how fast your going and what car you have.

also how long you have got to slow down to the limit before you see the cop or pass the trap!
Yes, but... the chart provided in the links take into account your speed, and the PSL. The numbers can be improved on, with practice, etc., as pointed out by "...Saabr"

9. Yep indeed. Speaking of braking to the PSL, last night around midnight I was going home, and as I merge onto the highway I get blown past by a Subaru Impreza with decals down the sides, a loud exhaust and big rims. So I punch it. I get up to around 165 km/h (105 mi/h) and he is still accelerating. Then I get a K blip and back off. 2 seconds later Subaru slams on the brakes, so I follow suit. Provincial police cruiser poking along in the right lane at 100 - 110 km/h (PSL is 100). I follow the cruiser and was having fun watch people fly by me at 130 - 150 then boom on the brakes as soon as they notice the cruiser Funny as hell.

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