70 mph limit should apply to metro Chicago

  • Steve Doner

    Steve Doner

By Steve Doner
Posted8/23/2013 10:33 AM

The recently signed 70 mph speed-limit bill begins to undo the damage done by the national 55 mph limit established in 1973. Illinois had a 70 mph speed limit 40 years ago, and it was not just for rural interstates. Most state highways, even two-lane highways, had limits higher than the 55 mph still in place on metro Chicago's interstates.

After reading the bill and discussing it with its sponsor, state Sen. Jim Oberweis, it is clear to me that the bill was intended to cover, and should apply to, metro Chicago for the same reasons that it makes sense downstate. The limit for all metro Chicago interstates will revert to 70 mph unless IDOT produces an engineering study proving the new limit unsafe. County boards may also be able to block the new limit.


If IDOT abides by the traffic engineering principles espoused by other transportation and police departments across the country and around the world, it is nearly certain that the findings would dictate a speed limit of 70 mph (or higher) for metro Chicago expressways, with the possible exception of those within Chicago city limits.

IDOT and the county boards should stand aside and allow metro Chicago limits to revert to 70 mph. All the evidence indicates that there would be no negative impact on safety. In fact, the opposite is true.  Overall metro Chicago highway safety would be improved. Here's why:

1. Nearly 90 percent of fatalities occur on secondary roads. Only 11 percent occur on Illinois interstates, including metro Chicago. So those big fatality counting signs over the tollways are telling us about the risk after we exit.

2. Higher speed limits on interstates help draw traffic away from more dangerous secondary highways. This is always a key point, but even more so in metro Chicago since roads like Interstates 355 and 294 charge tolls. There already is a big incentive to take secondary highways such as old Route 53 and Route 59, for example.

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3. For decades, traffic engineers have promoted establishment of speed limits based on 85th percentile speeds -- the maximum speed at which 85 percent of motorists travel when unencumbered by traffic or enforcement. Well-informed state police and transportation departments around the world advocate this approach. IDOT's position is inconsistent with its peers.

4. Speed limits have very little impact on the pace of faster traffic; most drivers, including the police, ignore under- (and over-) posted limits.

5. When limits are underposted, one group of drivers travels at careful and prudent speeds and another group tries to adhere more closely to the law. Higher interstate speed limits improve safety by reducing speed variance, road rage and weaving.

6. Underposted speed limits breed disrespect for all traffic laws. This leads to speeding in construction zones and other bad behavior.

7. Underposted speed limits also leave drivers bored, unengaged and distracted. Texting is probably not an issue on the autobahn.

8. Even with increased speed limits, Illinois interstates and other highways are still posted at or below the limits in place in 1973. Since then, the handling capability and safety equipment on vehicles has improved dramatically such that limits of 80+ mph should be the norm for rural interstates as in many other parts of the industrialized world.


9. Insurers and others who profit from speeding tickets tend to cite studies that count the raw number of fatalities rather than looking at the rate per mile driven. The actual fatality rate has fallen steadily for decades during times of both rising and falling speed limits.

10. Higher limits reduce congestion and may actually save fuel by allowing drivers to keep a steadier pace.

One final point: Beginning Jan. 1, unlucky Chicago-area drivers who "go with the flow" of average traffic speeds could pay a $1,500 fine and go to prison for six months. If nothing changes, that will be the penalty for going 81 mph in metro Chicago (26 over the 55 limit). This Class B misdemeanor penalty would be OK if the speed limit were 70 mph. In that case, 96 mph could lead to jail time.

It is critical that Chicago-area interstate speed limits be set properly. We all know the 55 mph limit is a bad joke. It's time we put an end to it.

• Steve Doner of Wheaton is a former coordinator for the Illinois chapter of the National Motorists Association.

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