We don’t want automated cars driving the current speed limits

Should automated vehicles follow all the current traffic laws or will they need to be changed?

When Delphi took its prototype Audi robocar from San Francisco to New York in April, the car obeyed every traffic law, hewing to the speed limit even if that meant impeding the flow of traffic.

“You can imagine the reaction of the drivers around us,” Michael Pozsar, director of electronic controls at Delphi, said at a conference in Michigan last week, according to Automotive News.  “Oh, boy. It’s a good thing engineers have thick skin. All kinds of indecent hand gestures were made to our drivers.”

And that indicates that a problem is brewing, argues Prof Alain Kornhauser, who directs the transportation program at Princeton University. “The shame of the driving laws is that they all sort of have a ‘wink’ associated with them,” he says. “It says 55 miles per hour, but everyone knows that you can do 9 over. If that’s the situation, why isn’t it written that way—with a speed limit at 64?”…

In fact, if all cars were autonomous and connected to each other wirelessly, they wouldn’t need stop signs even at the intersections of multilane highways…

I imagine following the speed limit in the Chicago area would lead to some very unhappy drivers. Theoretically, we might not even need speed limits with driverless vehicles as it would all be dependent on the conditions. This might mean that vehicles would go slower at times than drivers might like (perhaps in inclement conditions) but could go a lot faster and more safely even with a good number of drivers nearby.

But, if traffic laws need to be changed, when exactly would this happen? Presumably, it will take some time to introduce these vehicles onto the road and some time for them to grab a large part of the market. Of course, the government could push all new cars in this direction – particularly since they could be so much safer – but older models would still be on the road for some time. To change the laws, all the cars need to switch over at once, an unlikely event. Until all cars are driverless, traffic laws would have to be more conservative to account for drivers but that probably wouldn’t make the new owners happy.

Overall, I haven’t seen much discussion of how automated cars and cars with drivers will mix even as we creep closer and closer to this eventuality.

Recommendation that many Chicago area highways have 60 or 65 mph speed limits

A new investigation from an state agency suggests speed limits on several Chicago-area highways should be raised:

Higher speed limits on parts of I-294, I-88 and I-355 were recommended for approval Thursday by the Illinois Tollway’s customer service and planning committee.

According to the state’s vehicle code, the tollway is required to conduct an engineering and traffic investigation before raising its maximum speed limits.

The investigation — which took factors like prevailing speed, high-crash segments, access point density and the volume of traffic congestion into consideration — determined that the 70 mph maximum that is allowed by the state is not a “safe and reasonable increase in the speed limit” for certain sections of the highway…

Once all the necessary approvals are complete the Illinois Secretary of State can publish the updated rules and the new speed limit signs can be installed. Tollway officials estimate that the new speed limit signs could be posted this summer.

It sounds like safety concerns led to this slight increase. But, I would be interesting in seeing this study as the reasoning behind a slight increase is not clear. If prevailing speed is a factor, we know that a good number of Chicago-area highway drivers still go faster than the new 60 or 65 mph speed limits. How many more crashes and deaths will occur with a 60 or 65 mph speed limit? Does this mean Illinois is not joining the move toward zero-death roads? And if there is more damage, how is the positive side calculated (less time lost, less congestion, etc.)? At the same time, raising the speed limits won’t necessarily lead to faster driving; evidence from Michigan suggests people will continue to drive at the speed at which they feel comfortable.

Chicago area highway drivers going faster: 85th percentile between 71 and 75 mph

A new report highlights the fast highway driving along Chicago area highways:

Only a few are obeying the law. In those stretches, an average of 1 out of 20 motorists drives at or below that limit…

The data, gathered in April, May and September, showed that, depending on which tollway stretch was tested, 91 to 98 percent of drivers exceeded the 55 mph speed limit. In those stretches, the average speed ranged from 66 to 70 mph.

The studies followed a 2012 National Highway Traffic Safety Administration report that showed that average highway speeds increased to almost 71 mph in 2009 from 65 mph two years earlier. At the same time, traffic fatalities — 33,561 last year — are dropping, except for a slight increase in 2012. The report concluded that the higher speeds might have been the product of less speed enforcement in 2009 and fewer cars on the road that year, leading to less congestion…

But perhaps the most fundamental metric in deciding where to set a speed limit is a concept known as the 85th percentile, or the speed at which 85 percent of drivers are either traveling at, or below. In essence, it measures the limit that most drivers place on themselves, regardless of posted speed limits.

Tollway data showed that the 85th percentile speed ranges from 71 to 75 mph.

Read on for more discussion of then how Illinois might or might not increase speed limits.

I’ve talked to numerous people over the years who are nervous about driving in the Chicago area because of these speeds. On one trip that involved driving through the Chicago region, I was asked to drive since I was used to it. While the speed is one factor, I wonder how much the overall traffic, particularly the large trucks, matter. It is one thing to drive fast in more open spaces – Michigan, for example, has had 70 mph speed limits for at least several years but it often doesn’t feel as bad with less people around. It is another thing to have at least three lanes and often four in each direction full of drivers of different sizes and speeds.

One thought: if we end up with a world of driverless cars in a few years, what speed would these cars travel on a highway? Presumably, the cars could go faster because the cars would share information and maximize the speed. But what then would be considered “safe”?

Raising speed limits doesn’t lead to faster driving

I’ve seen several articles about this lately as several states consider raising highway speed limits: raising the speed limits does not lead more people to drive faster.

Traffic experts say that motorists tend to drive at a speed they feel comfortable, regardless of the posted speed limit. And according to Michigan Department of Transportation spokesman Rob Morosi, comfortable drivers generally make for safe roads.

“There’s a misconception that the faster the speed limit, the more dangerous the road,” said Morosi, “and that’s not necessarily true. Speed limits are most effective when the majority of people driving are comfortable at that speed.”…

Common sense, then, would suggest that increasing a speed limit would lead those motorists to increase their speed at a similar rate. But Megge, pointing to I-96 in Flint as a striking example, says that belief is not supported by the research.

Before 2005, traffic studies indicated that most motorists were traveling the Interstate at roughly 73 mph, he said. After the speed limit was increased, most motorists still traveled the Interstate at roughly 73 mph.

“When we raise a speed limit, traffic speed does not automatically increase. That’s a myth,” Megge said. “I’ve been doing this 15 years and raised 300 speed limits, and never have we seen or observed a wholesale increase in traffic speeds. It’s a very counter-intuitive idea. But the science and engineering works. We want to ensure it’s safe and fair to the public.”

Common sense approaches often don’t apply to traffic. This finding about speed limits fits with another finding about traffic signs: drivers don’t necessarily pay attention. Read about several places in Europe that have no traffic signs and few traffic markers and safety improves. In the case of driving speed, drivers seem to pay more attention to nearby drivers rather than the official speed limit. So even as people often drive solo and might argue their actions on the road are the result of their own individual choices, driving is indeed a social activity.

Here is a second good example regarding traffic that counters “common sense” or common behavior: using all possible lane space to merge is more efficient for everyone rather than having drivers block off lanes that will soon close.