Automated and Driverless Cars: Great for Safety, Not So Much for Congestion.

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California Path
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California Path

BY PANOS PREVEDOUROS PHD – Can automated cars “cure” crashes and congestion? Renown (ex) Stanford University professor Sebastian Thrun who’s team won ARPA’s $2,000,000 driveless car challenge a few years ago thinks so as he presents the Google driverless Toyota Prius in this TED video.

This is an area where I believe that lawyers and politicians have more impact than engineers and technologists. The US had a fully developed and tested AHS or Automated Highway System in the mid-1990s as the sample article Whatever Happened to Automated Highway Systems? reminds us.

For those of us involved with intelligent transportation systems (ITS) the image below of eight large Buicks developed by California’s Partners for Advanced Traffic and Highways (PATH) remains etched in memory. Observe the 0.2 second clearance between the AHS Buicks at 60 mph and the typical 2.0 second clearance in regular traffic.

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When success was fully demonstrated, the government cut AHS funding because the issue became liability not technology. However, many of the technologies trickled down to piecemeal applications, some of which I summarize below.

Greyhound buses in the mainland have vibrating steering wheel (modeled after the aviation stick shaker to warn of impending stall) activated by radars if the bus tries to change onto a lane that is occupied by a vehicle. This also serves as an alarm if the drivers becomes drowsy. Daimler has introduced this to Mercedes cars but the system is not available in the US (due to liability.)

Since 2005 one can purchase many luxury vehicles with intelligent cruise control that can follow the car ahead. Some of them will bring a car to a complete stop automatically if the leader car comes to a stop. Some companies brand it as Adaptive Cruise Control and here is a demonstration dating to back 2008 at about 90 mph by a motorist on an autobahn.

In Europe higher priced BMWs will soon be offered with a system that if its driver becomes incapacitated, the car will maneuver itself, at German autobahn speeds, all the way from the fast lane to the right side shoulder, stop and send an SOS.

Many inexpensive cars in Europe in the $20,000 bracket have optical sensors on the bottom side of their exterior mirrors that follow the lane markings. They issue a “lane departure” warning to their driver. A handful of cars brought in the US in 2012 have this option too.

The US federal government has a major research initiative called https://www.its.dot.gov/press/2010/vii2intellidrive.htmIntelliDrive to further boost these efforts.

And now for the conclusion and why AHS was terminated as a capacity enhancement: On a busy highway most drivers follow each other at a headway of about 1.5 seconds. As a result, the maximum sustained capacity of a freeway lane is 3600 seconds in one hour divided by 1.5 second headway equals 2400 vehicles per hour.

If car technology takes over, this headway can be reduced to 0.5 seconds which triples the capacity of the same freeway lane. So one lane could carry as many cars as an entire 3-lane section of the H-1 Freeway! This is clearly a bargain for our highway infrastructure.

However, if this was ever launched, it would require the presence of a largely empty lane next to the AHS lane (such as a bus-only lane with large gaps between the buses) so that vehicles can be merged in and out the tight AHS platoon; see the empty lane next to the platoon of fast moving Buicks in the picture above.) Only professional race drivers can routinely cope with 0.5 second headways (and they fail almost at every NASCAR race.)

With the press of the AHS button, merging into the tight lane, traveling at 60 mph and exiting the AHS lane will be done entirely by the computer, sensors and servos of the car in dense traffic. Now visuallize such a car with mommy, daddy and two kids in the back on a dusty, rainy or dark environment which may affect sensor performance and image recognition. There is clear risk and because of the tightness of the platoon, one mishap will likely cause large losses. Who is liable? The feds wanted none of this on the federal interstate system.

AHS has a tremendous promise for safety bust much less promise for direct congestion reduction. However, crash reduction does help traffic congestion because by most accounts 30% to 60% of the annual traffic congestion in a metro area is caused by accidents that block traffic lanes. Intelligent systems minimize driver error and accidents, so lanes become closed less often.

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11 COMMENTS

  1. This expression is so appropriate and I am so excited to get this allocation indeed. I can say that it would come to help us more. So pleased to get this information about the Automated and Driverless Cars. Love your job…

  2. From this website I have got some valuable information about the Google driverless Toyota Prius in this TED video. Actually this is an interesting and awesome information which is so important to know. Thanks and inform like this…

  3. I don't think so this driverless car concept is going to put more effectiveness to the car market. I just think that how the accident rate will increase with this invention. We can not leave a car with allowing the technology to ride it. If there are some technical problems in it then a massive accident will happen and a great risk may be there for the peolple who drive in that same road. Here, i want to share some of my experience regarding cars that cars are the stylish and luxurious invention that ever had. So to maintain these cars we have to take care of these cars. we have to maintain our cars like we have to wash it in proper interval to maintain its look, we have to service it after particular kilometers of run and also we have to repair our cars from good Mercedes Service Los Angeles centers whenever required to get better performance from it and for our cars smoother running. .

  4. I've recently bought a Chevrolet Volt and I am very satisfied of it. Besides being energy efficient, it is a reliable and comfortable car. I've also purchased some Xenon headlight bulbs and accessories form https://www.mkmcustoms.com/ in order to personalize it.

  5. I consider this driverless cars a very good idea, but they are only in the testing phase and they cost lots of money. When they break down, the replacement parts are also very expensive. Maybe you can find a little bit cheaper parts at Indypicapart.

  6. I find these driverless cars really awesome, I'm even thinking about opening a car dealership in the next few years. But first of all I heard that I need an insurance for car dealerships. After long documentations I decided that I should choose Risk Point, all my friends told me they are the best in insurances.

  7. I'm thinking for a long time to buy myself a car, but driverless car would be a little bit to much for me. I have a limited budget so I cannot have big expectancies from it, all I want is to have Xenon headlight bulbs and air conditioning.

  8. If car technology takes over, this headway can be reduced to 0.5 seconds which triples the capacity of the same freeway lane. So one lane could carry as many cars as an entire 3-lane section of the H-1 Freeway! This is clearly a bargain for our highway infrastructure.

Comments are closed.