By Rebecca Everett and Len Melisurgo | NJ Advance Media for NJ.com

We all know the excuses.

You're late for work. Your wife is in labor. Your speedometer is broken. Police officers have heard them all before.

Whatever the reason, the radar gun doesn't lie: New Jersey drivers are going over the speed limit — WAY over the speed limit. We've been watching, and you make New Jersey highways look like the Daytona Speedway.

During the past several weeks, we got to play traffic cop, scoping out big highways across the state, armed with a high-quality radar gun, similar to the ones used by real cops. We checked 50 cars in each spot from the sides or overpasses of highways — and documented it with the video above.

Of the 350 drivers we monitored, only 26 -- or 7 percent -- were obeying the legal speed limit, and some zoomed by at more than 20 mph over the limit.

Real police officers are trained to estimate a car's speed to within 1 to 2 mph. Let's see how good you are at spotting speeders. Watch the GIFs below, guess the speed, and swipe to see how you did.

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Results of our radar checks

Here's what we found when we clocked the speeds of cars and trucks on seven major highways across New Jersey. In short: The Garden State is overloaded with excessive speeders.

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We checked the speeds of cars on the Garden State Parkway in the Union County township of Clark, from the overpass on Madison Hill Road, shortly after noon on June 18, 2018.

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We clocked speeds in the northbound cars, trucks and buses lanes of the New Jersey Turnpike from the Ward Avenue overpass in this Burlington County township around 2:30 p.m. on June 12, 2018.

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We checked speeds on the eastbound lanes of the Atlantic City Expressway from our perch on the Malaga Road overpass in Sicklerville, in Camden County near the border of Gloucester County, around 1 p.m. on June 12, 2018.

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We clocked the speeds of cars on Interstate 287 in the Morris County town of Morristown, from the Franklin Street overpass, during the early afternoon on June 18, 2018.

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We recorded speeds on Interstate 295 North near Exit 11 by standing on the Route 322 overpass in the Gloucester County township of Logan around 10:15 a.m. on June 12, 2018.

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We took our radar gun to the northbound side of Route 1 near Green Street, in the Middlesex County township of Woodbridge, at 2 p.m. on June 6, 2018.

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We checked speeds on Route 55 North from the Landis Avenue overpass in the Cumberland County city of Vineland shortly before noon on June 12, 2018.

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Star-Ledger file photo

How radar guns work

The devices used by police officers are also used by baseball scouts and TV networks to clock how fast a pitcher is throwing a ball.

When a radar gun is aimed at a moving target, like a car, it sends out pulses of high-frequency electromagnetic waves that are reflected off the vehicle and sent back to the gun, said Scott Horvath, a patrolman who works in the traffic unit at the Woodbridge Police Department in Middlesex County.

Radar guns have a tiny built-in computer that converts the electromagnetic waves into speeds, measured in miles per hour.

Experts say radar guns are very accurate, as long as they are properly calibrated and aimed as straight as possible at oncoming vehicles. Pointing a radar gun at a slight angle can result in readings that are low by one or two miles per hour, so for our experiment, we tried to get as close to straight on as we could.

Fun fact: The word “radar” is actually an acronym for radio detection and ranging.

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Excessive speeding in your town?

We found some fast spots, but we know there are plenty more.



Are there roads in your town where people drive way too fast? Let us know in the comments.

Now that we have our trusty radar gun, maybe we'll visit your neighborhood next to see if we can catch some speed demons.

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Read More

The number of speeding tickets issued in each county last year, ranked

75 mph? Petition seeks speed limit change

Man pulled over for speeding while wife was in labor agrees to pay fine

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Reporters

NJ Advance Media data reporter Carla Astudillo and NJ Advance Media videographer Andre Malok contributed to this report.

Rebecca Everett may be reached at reverett@njadvancemedia.com. Follow her on Twitter @rebeccajeverett. Len Melisurgo may be reached at LMelisurgo@njadvancemedia.com. Follow him on Twitter @LensReality or like him on Facebook. Find NJ.com on Facebook.