A Look at Traffic

Case studies to allow an analysis of traffic.

Monday, February 22, 2010

Inter-vehicle Communication

In 1986, a group of transportation experts from academia and the public and private sector looked ahead by 5 years to 1991, when a new transportation bill was scheduled to be enacted, to develop what the future of transportation should look like1. This became known as "Mobility 2000". Mobility 2000 proposed for a natural effort that helped set the foundation for future technological growth in transportation, they called it Intelligent Vehicle Highway System or IVHS for short. By 1990’s road transportation professionals began to recognize that electronic sensors and computational power were decreasing in price and could become highly applicable to traffic and vehicular management, thus a new field of study was discovered. This technological gold mine became known as Intelligent Transportation Systems2. ITS, as defined by Joseph M. Sussman, “combines high technology and improvements in information systems, communication, sensors and advanced mathematical models with the conventional world of surface transportation infrastructure”3. Essentially ITS is taking advanced knowledge from mathematics and technology and implementing it into transportation to improve safety, reduce environmental impact of transportation and increase efficiency. The emergence of this new technology in an old field allows for increased efficiency for road conditions and enhanced safety to drivers and passengers alike.

ITS has now become a much broader term to describe many areas of technology being implemented on the roadways. Some of these technological ideas include; automatic road enforcement, collision avoidance systems, dynamic traffic light sequence, drive log recording, pedestrian awareness system, and Inter-Vehicle Communication, among many other flourishing ideas. In this section of the post I will focus primarily on Inter-vehicle communications. IVC allows for instant, automatic, wireless transfer of information between two or more vehicles on a roadway. With wireless communication and processing of live data on a road way, drivers can become aware of critical information before it's too late. The overall theory of IVC is essentially, taking data from each of the cars on the roadway, (ie. their position, location, speed, proximity to other cars, origin, # of miles driven on current trip, destination, etc.) and sending it to other IVC implemented cars. The majority of this data would be collected through a built in GPS device and on-board sensors. All this data can then be transmitted to nearby cars on the road and displayed to drivers to be informed about the road ahead.

To see the effectiveness of IVC let's look at an example of how this would all work. Imagine a car, let’s call it Auto1, driving along a slowly winding highway at the speed limit of 65mph. To Auto1 everything seams fine, with light traffic on the road, and minimal congestion to worry about. Normally, Auto1 would be fine and arrive at his/her destination on time. However, today there is an accident just up the road. This accident has caused major congestion on the highway segment that Auto1 is about to pass through. Due to the quickness of the accident occurring, the radio has not given any updates on the highway that Auto1 is on. However, because of the implementation of Inter-Vehicle Communication, cars at the location of the crash are able to transmit their speed. At the accident site, these speeds would be typically less than 10 mph, or possible even 0 mph. IVC is able to collect these real time speeds of the cars around the accident and process this information, using a computer algorithm, to conclude that there has been an accident or some other reason for slow down, on the highway. Using a multi-hop relay signal between the accident and Auto1, Auto1 can be notified of the accident and then re-route its path so it does not experience any traffic.
Now that an example of Inter-vehicle communication has been outlined and put into context of it applicability and safety I would like to write about the heart of the technology. IVC relies on multiple technological advancements and I will show how it all comes together. It allows for a whole new range of possibilities on the highway, but IVC also has its limitations.

The actual device for IVC would be about the size of a cell phone and installed somewhere within the dash of a car. It would operate on the 5.850-5.925 GHz frequency5. This range of frequency has been dedicated for use of IVC in America. The 5 GHz range allows for high bandwidth of data transfer on an uninterrupted channel. Current speeds of up to 6 Mega bits per second, but future developments would allow for 27 Mega bits per second6. However, unlike GPS and cell phone wireless signals, this Dedicated Short Range Communication (DSRC) link in the 5 GHz band only allows for communication within a 1000 meter radius. Furthermore, actual operating range is limited to a 200 meter radius, but this distance allows for sufficient communication on most roadways. Each device on a car will be able to broadcast a message, as well as receive multiple incoming messages from other vehicular broadcasts. Research in Europe on a project called CarTALK and Fleetnet have looked into the potential of ad hoc communication between vehicles. An Ad hoc network allows for communication between vehicles to connect and transmit signals on the fly without the need for a base station. Essentially this saves money on implementation costs and increases efficiency in communication between cars.

CarTALK researchers found that a multi-hop communication link between cars worked very well in sending information back upstream7. Multi-hop communication allows for a broad casted signal to be "grabbed" by cars upstream and rebroadcasted for cars further up stream to grab the signal and retransmit it. Implementation of multi-hop communication allows for information and warning signals to be alerted to drivers before they would be visually aware of the situation. Studies in Europe have shown that warning signals about the road ahead allows for early braking which resulted in crash reduction of 3.6%8. This multi-hop communication design will make roads safer for drivers and allow for low implementation costs making it economically feasible.
A major drawback to IVC is that it relies on a significant percentage of cars on the roadway, having the technology installed to be useful. Both for effective data transfer and amount of information to be relevant, about 2% of cars would need to have the technology implemented9. It is expected that IVC would have similar implementation characteristics to GPS. GPS stands for Global Positioning System and uses 24 orbiting satellites to find the exact location, within 3 meters, of a GPS device. GPS allows for speed, miles traveled, and routes to be determined on the fly. Although GPS has not been required by law, it has infiltrated about 7% of American vehicles through consumer demand10. GPS offers drivers an improved driving experience that allows drivers to calculate directions and view dynamic maps of city streets and highways. IVC expands these capabilities for drivers and allows for more advanced features of drivers that GPS alone wouldn’t be able to offer. Recently, we have seen Google introduce it's own GPS software on it's Android cell phone platform with Google Navigation. I belive it would also be possible for Google to develop an IVC type application for cars to communicate with one another almost automatically, similar to their implementation of croud souring for speeds on roadways. This would do away with alot of the barriers associated with IVC, like the base stations and the DSRC antenna. Essentially this would replace the proposed base station network and just use the exciting cell phone tower network. The possibilities of bringing IVC technology to the everyday user with a android supported cellphone would be phenomenal. A move by google to support this feature could really change the future of IVC.

Taking a step back and looking at Inter-Vehicle Communication, we see that is amazing technology that is being developed for future improvements in transportation. It is my personal belief that this technology has the capabilities to change travel as we know it today. In 2003, ITS America, an organization whose mission is to improve transportation through research, promotion and deployment, set a goal to have zero fatalities on roadways. With the design of IVC, I believe we are one step closer to that goal.

It is my belief that Intelligent Transportation Systems has the ability to change transportation as we know it today. Inter-Vehicle Communication has the potential to increase efficiency on the roadways and well as increase safety. I hope to see an adoption of change towards this technology.


Sussman, Joseph M. Perspectives on intelligent transportation systems (ITS). New York: Springer, 2005. Pg. 4

Bishop, Richard. Intelligent transportation systems library. Boston: Artech House, 2005. Pg. 2

Sussman, Joseph M. Perspectives on intelligent transportation systems (ITS). New York: Springer, 2005. Pg 1

4 http://www.ece.osu.edu/~ekici/images/v2i.jpg

Bishop, Richard. Intelligent transportation systems library. Boston: Artech House, 2005. pg. 180

Recker, Wilfred W.. "Instantaneous information propagation in a traffic stream." Transportation Research Part B: Methodological 40Mar 2006 230-250. Web.25 May 2009. <http://cat.inist.fr/?aModele=afficheN&cpsidt=17547219>.

Bishop, Richard. Intelligent transportation systems library. Boston: Artech House, 2005. pg 188

Bishop, Richard. Intelligent transportation systems library. Boston: Artech House, 2005. pg. 189

Recker, Wilfred W.. "Instantaneous information propagation in a traffic stream." Transportation Research Part B: Methodological 40Mar 2006 230-250. Web.25 May 2009. <http://cat.inist.fr/?aModele=afficheN&cpsidt=17547219>.

Fehrenbacher, Katie. "GPS Navigation: Nokia Looks to Cars." GigaOM. 30 Oct. 2006. 25 May 2009 <http://gigaom.com/>.


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