Chicago Tollway Speeding Renews Speed-Limit Debate


Drivers around our Chicago offices are channeling their inner Sammy Hagar, it seems. Studies obtained by the Chicago Tribune found that along seven stretches of Illinois tollway with 55-mph posted speed limits, most cars exceeded 66 mph. In fact, just one in 20 drivers went at or below the speed limit, the Tribune reports.

Data gathered in April, May and September show that 91 to 98 percent of tollway drivers exceeded the 55-mph limit, with average speeds of 66 mph to 70 mph. This comes despite a Tribune analysis that found each state trooper along the tollway issued an average of 72 tickets per day — and they're among the most productive officers, an Illinois State Police spokeswoman told the newspaper. The story comes as Illinois moves to increase speed limits to 70 mph for three stretches of tollway in Chicago's outlying suburbs. The new limits take effect in January 2014.

Would a higher limit encourage drivers to speed more? It's up for debate. A study published in 2010 in the Journal of Trauma and Acute Care Surgery found that when New York State thruways and interstates increased speed limits from 55 mph to 65 mph in the 1990s, the percentage of traffic speeding by more the 10 mph fell from 39 percent to 8 percent. The National Motorists Association points to the New York Thruway example, too, noting that during the two posted limits, average traffic speed remained at 68 mph.

Indeed, the Tribune analyzed speeds on two stretches of Illinois tollway — a patch of Interstate 88 west of Chicago and I-94 north of the city, with respective speed limits of 65 mph and 55 mph. Despite the difference in posted limits, the Tribune reported that traffic moved at about the same speed along each stretch.

The Michigan State Patrol has a booklet that tackles the subject. Speed limits should adhere to the "85th percentile" rule, where 85 percent of drivers move at or below the speed.

"Posting speed limits lower or higher than what the majority of drivers are traveling produces two distinct groups of drivers — those attempting to observe the limit and those driving at what they feel is reasonable and prudent," the booklet says. "These differences in speeds may result in increased crashes due to tailgating, improper passing, reckless driving and weaving from lane to lane."

The Tribune notes that 85th percentile rule would suggest a tollway speed limit of 70 mph or 75 mph.

However, the Insurance Institute for Highway Safety says absolute speed — not just speed differentials — is an equal safety problem. Raising speed limits can cause drivers just to speed more, IIHS notes. The institute references studies in Texas, California, Nevada and New Mexico, which found that raising speed limits significantly increased the proportion of drivers who went 5 mph higher above the new limits. Revising speed limits to the 85th percentile would only push drivers to eventually go even faster, the agency says.

IIHS says speed plays a part in nearly a third of all motor-vehicle fatalities. It's a statistic that plays a tragic note on the heels of "Fast and the Furious" star Paul Walker's death in a California car crash in a 2005 Porsche Carrera GT. The Los Angeles County Sheriff's office said speed played a part in the Saturday afternoon accident, which left fans and celebrities stunned.

Illinois Tollway engineers said some highways near Chicago have too much traffic to safely raise the 55-mph limits. "Increasing the speed limit on some sections may exacerbate safety and operational issues that are currently marginal," engineers said in a September memo, according to the Tribune.

Speed limits remain an ongoing debate — and not just in Illinois. Florida is debating higher limits in rural areas. Pennsylvania will go ahead with it.

What are your thoughts? Weigh in below.

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By Kelsey Mays | December 2, 2013 | Comments (9)



Speed does not kill. Speed differences kill. There is a great deal of evidence to suggest that the majority of drivers travel at a speed they find comfortable, regardless of the speed limit. A limit of 55 on a highway or thruway causes accidents. A conflict develops between people driving at the limit and those driving at a more comfortable 65. Don't forget that 55 is an artificially low limit designed to save fuel while highways were designed to be safe at speed up to 70 mph. The biggest problem is lane hogs who trundle along at the limit in the "fast lane." Speed kills when idiots drive too fast in urban areas on residential streets. Paul Walker's tragic death was caused by driver error and stupidity. Speed was a factor but not the primary factor.


Having traveled nearly the entire length of the Tri-State Tollway this past summer on the way to Wisconsin, I would agree that 55 mph is a joke. 65 mph would be very reasonable for the road, and there are still plenty of drivers going 80+ mph to generate revenue.

Posted limits ignored by 91% to 99% of all drivers are utter nonsense. The Tollways operate very safely with actual 85th percentile speeds in the low to mid 70s - despite the deliberate mis-engineering of the posted limits (limits that are likely politically motivated, rather than done by correct engineering principles).

The IIHS and Illinois State Police are more likely motivated by $$$ than safety in supporting artificially low limits ignored by 90+% of the drivers on these very safe roads. IIHS member insurance companies make money when they surcharge policyholders who get tickets so the IIHS fights very hard to keep improperly low posted limits for profits. If state police actually sought out dangerous drivers to ticket, rather than being road tax collectors, the Tollways would be even safer.

James C. Walker, Life Member-National Motorists Association


I guess the laws of physics are completely being ignored here. Compare an accident at 50mph to a similar one at 70mph. Compare losing a front tire at 50mph to 70mph in an SUV. Compare breaking distances of large SUV's/Trucks to compact cars at 70mph. Very few drivers leave enough "space cushion" at 70mph. I often end up driving closer together to prevent idiots from weaving in and out of lanes to pass everyone, without signaling of course.

If you drive between point A and point B within a certain time frame you should get a ticket. This would free up all those super troopers to focus on unsafe vehicles and poor drivers.

Safe driver training should be mandatory every two years. We're all paying higher insurance and wearing the roads down more quickly at higher speeds.

How about half the cars with daytime running lights being off just because many drivers don't know enough NOT to turn the know all the way down?

Most commutes are under an hour so you're only talking about saving 5-7 minutes on each commute. Insurance companies and municipalities want you to speed. Keep buying into any false justification you want to drive faster. You're wrong on all counts and you know it.


Even if the 'speed limit' is set to the 85th percentile, the safest drivers are usually the ones at the 90th percentile.

On the Tri-state, people drive 80mph during the daytime when there is good weather, and 70mph at night.

Speeding ticket=revenue generation. No victim, and no criminal intent, no crime.


I don't understand there's too much traffic to raise the 55 mph speed limit on Chicago area toll ways before 1974 they were 65 mph and we did fine with them the tri state was 65 mph except for the last 6 months they raised it to 70 mph on the tri state 6 months before the federal government made them lower it to 55 mph during peak hours you can't go that fast anyway the speed would be self regulating and you can only go that fast when rush is over just like before and the Indiana toll road is 70 mph up to the Chicago city limits so we already have one Chicago area interstate we can drive 70 all the way in on all we have to do is look at Indiana and see how it works.


"IIHS says speed plays a part in nearly a third of all motor-vehicle fatalities."
*Does NOT mean it is the cause of the situation that led to a fatal outcome. There is no checkbox for "idiot driver" for the police accident investigators to rule as the cause of an adverse outcome. There is no such thing as an accident. If you don't know why you crashed, you're an idiot who wasn't paying attention to your surroundings or your car.
The only things that are truly accidents are things like bridges or trees or powerlines falling on a car. Something completely unexpected and even then most people know to stay off the road when the weather is so bad that trees or powerlines can come down.
Paul Walker's death, while tragic, is the end result of so much time spent driving like an idiot. (Driving at or over the limits of control) Eventually the odds will catch up with you and physics will not be on your side.

Do NOT let the circumstances of a tragic death of a young movie star be hi-jacked for a political feel-good policy.

Set reasonable upper speed limits based on the 85th percentile and a lower limit for trucks and be done with it.

I would argue that enforcing the limits only creates an outlaw attitude; what should instead be enforced are in-attentive, careless, and reckless driving citations in lieu of speeding tickets. Those are the true causes of preventable dangerous circumstances.


Lowering speed limits does little other than save energy and help to keep idiot drivers that mindlessly follow rules IN the gene pool. That population is indeed a rare species so maybe the DNR should enforce it like they would an endagered species law. jk

Since using too much energy isn't a crime yet maybe you should just be taxed for being wasteful when caught driving significantly faster than the 85th percentile. You wouldn't even need to be pulled over. They could just take a photo of your license plate and add the fee to your tax bill.


Speed is a factor in that once an object becomes a projectile (no longer under the control of the driver) it is the primary factor that determines the energy that must be dissipated upon impact.

What that means is that if for any reason your vehicle becomes a projectile - the speed at which you're travelling creates very unfavorable possibilities should the vehicle you're in suddenly stop.

"Increasing the speed limit on some sections may exacerbate safety and operational issues that are currently marginal," engineers said...

OK. So, keep those sections at lower speed limits but also increase the number of lanes through those areas to enable equal traffic flow into and out of those sections to prevent panic braking into those zones.

If more lanes are not feasible, you could paint solid lane marker lines through those areas on deep grooves that reduce the likelihood that people would change lanes unless of an emergency. The edges of the grooves could be angled to make lane changing easier in one direction- say for an off-ramp. Then in the area where there's a merge, angle the opposite edge to encourage lane changing away from the merging lane.

This would be most bothersome to cars and motorcycles with narrow and/or small diameter tires. (motor-cycles would be allowed to drive at speeds no greater than 30 MPH over other traffic on the shoulder during stop-go traffic)

Also institute cameras to ticket people tail-gating when traffic is flowing faster than 55 MPH.

We have the technology - it wouldn't be that hard to do. We could replace speed limits with guidelines AND make the roads safer to drive.

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