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Written by: Scott Franke
Written on: April 1st, 2000
Tags: civil engineering, transportation, lifestyle
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About the Author
At the time of writing, Scott Franke was a senior at the University of Southern Californa, pursuing his Bachelors degree in Computer Science.
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Volume I Issue IV > Intelligent Transportation Systems
Personal transportation is truly a marvel of the twentieth century. Advances in many fields of technology have made automobiles and channels of transportation available to almost anyone. However, the freeways in major cities, on which so many people depend on to get them to work or school every day, were not designed for the amount of traffic they are now required to accommodate. Because of this, there are many problems with heavy traffic, and we experience difficulty in quickly responding to problems that occur. A national program called Intelligent Transportation System (ITS) attempts to solve these problems through engineering and technology.

The Problems

Even with the technology embedded in today's automobiles, driving can be a frustrating and potentially deadly experience. This is especially true in large metropolitan cities, where the criss-crossing network of highways creates an amazingly complex system, just waiting for something to go wrong. And things will go wrong, there's no avoiding that, the system depends on far too many elements. However, there are still things that can be done to minimize the risk and effect of the occurrences. Generally the solution for reducing traffic has been to widen highways. However, this merely postpones the problem; the number of people and cars on freeways will continue to increase. A national program called Intelligent Transportation System (ITS) attempts to solve these problems through engineering and technology. ITS achieves this by combining the hardware, software, and networking necessary to gather, process, and distribute information important to the parties involved.

Goals of ITS

The official goals of all ITS organizations are to improve the safety and efficiency of traveling on city freeways. These are serious issues and have an effect on citizens of large cities on a daily basis. When there is an accident on the road, the response time of medical services is extremely important. Seconds can make the difference between life and death; Emergency Medical Services (EMS) needs to be on the scene right after the accident has occurred. If the system is integrated into the transportation infrastructure so that EMS is alerted within seconds of a traffic accident, many lives can be saved.
U.S. Department of Transportation
Figure​ 1: Vehicle to vehicle communications could help prevent crashes on freeways.
The next step to make transportation safer is to reduce the risks than can cause such accidents. This includes reducing traffic congestion, clearing accidents more quickly, and routinely checking the transportation channels for dangerous areas or obstructions (see Fig. 1). The problem is that it would require a massive workforce to successfully implement this sort of program in a major city like Los Angeles.
Luckily, there is a better solution. ITS proposes to work towards solving these problems through the application of technology. ITS does this by combining sensors to gather important information about traffic and accidents, a data network to transfer that information, and a base of operations with mainframe computers to process and distribute this information. This network of sensors and computers can provide instant and comprehensible access to a large set of complicated data [1].

Structure of ITS Gathering Information

To understand how an ITS system would operate, it is helpful to look at how all the parts work together. First, there is the information gathering stage. Here, many cameras and sensors around the whole city study and collect data 24 hours a day.This data can be visual or infrared images of traffic, or electronic sensors that measure traffic speed and density.
It is important for the computers and engineers studying the data that the visual images be not only clear and crisp, but that the visual coverage of the freeway is as complete as possible. If an accident happens on a part of the road that is not visible, the whole system is pretty much useless. Infrared cameras can provide information that a conventional visible light camera might miss, however they also require different processing than regular cameras.
Besides cameras, loop detectors can be used to determine traffic flow and density. These are loops of metal wire under the road; a small computer monitors the change in inductance in the loop caused by the magnetic field of a metal object (in this case a car) passing by. By measuring the time it takes for each car to pass by and the number of cars that pass by in a given amount of time, a computer can determine the average speed and density of traffic on the road. However, these computers cannot perform a useful function without the data from the sensors [2].

Information Transmission

Once this information-gatherin​g hardware has been put in place, all the information needs to be transmitted somewhere. This is a massive undertaking; imagine connecting a huge number of sensors spread out over the freeway system of an entire city! For security reasons, this network is typically kept separate from any existing networks. A wireless network is an option, but because of the immense size of data that needs to be transmitted and the speed at which it needs to be available, optical cables are usually used (see Fig. 2). It requires careful engineering to determine the best way to lay out the optical cable and space the mini-server computers that will help combine and transmit all this data to the computers where it can be processed.
U.S. Department of Transportation
Figure​ 2: ITS technology aims to allow for wireless communication among all modes of transportation.

Infor​mation Processing

When all the data has been collected and the network is in place to transmit it, there needs to be a central station to collect and process that data. This station needs to be equipped with a powerful mainframe computer and a lot of storage space. When the data first comes in, it is stored in short-term memory for processing. The computer must analyze frames of video, collections of traffic speed and density, and input from the engineers monitoring all of its outputs. All of this information has to be processed in regards to equivalent data from previous seconds and minutes in order to look for patterns or breaks in patterns; something that would hint at congestion or an accident. Needless to say, this requires very sophisticated hardware and software for the analysis, storage and display of such information.
After the important information has been gathered, the results must be stored in permanent or semi-permanent memory for long-term analysis. By having this depository available, programs can look for problems in daily or weekly traffic patterns. Later analysis could show that a certain road becomes very crowded for a few hours at a certain time of the day. Engineers and workers could then instruct the system to reroute certain incoming lanes to a different route to reduce the congestion. Amazingly, the computer software, with only a minor necessary input of an engineer, could do this whole process autonomously. The possibilities this offers in helping reduce traffic congestion are astounding, but it is important that the engineer is able to accurately and quickly monitor the entire system.

Information Display

The final stage in this process is the display of information. The data needs to be sent to the displays meant for drivers (lights, road signs, etc) (see Fig. 3), to the engineers monitoring the system, and to the general public when they're not actually on the freeways. This third category can range from traffic reports to radio stations, traffic summaries to television news networks, live traffic status displayed through the Internet.
U.S. Department of Transportation
Figure​ 3: An ITS driver dashboard displays important real-time messages informing the driver of possible driving hazards.
Most important is the display of the information to engineers working on and interacting with the system on a daily basis. These engineers need to make decisions based on this information to contact EMS or reroute traffic, but they also need to be able to make sure the hardware and software itself is functioning correctly. The problem of displaying such a large amount of information in a useful and meaningful way (just like every other stage in ITS development) is a large engineering project all by itself. Thankfully, a lot of research has been done in recent years for handling and displaying extremely complex data, so engineers working on this stage have a lot to draw from.
Modern computer systems already have very sophisticated interfaces with easy to navigate menus and flexible ways or presenting and organizing data in windows and lists. By basing a display on an existing system, engineers can focus on how the data itself is displayed to make it as useful as possible. This makes the process much more effective and fast. But every implementation is different and there are always new problems to solve; it requires a careful design and a lot of time [2].

Fault Tolerance and Redundancy

Hardware and software for these four components needs to be selected and designed for two important properties beyond the functions they need to fill for the whole system: fault tolerance and redundancy.
The sensors and computer equipment need to be able to function in the varied and potentially harsh environment of modern metropolitan freeways. They should not fail because of changes in temperature, moisture, or precipitation. The sensors, network hardware, and computers need to be able to handle the faults that can be caused by these changes in the environment. This goes beyond the functioning of the hardware through difficult environments; the software too needs to be able to handle these changes. Heavy rain or snow could easily disrupt the correct functioning of a computer vision algorithm that wasn't designed to account for precipitation and the resulting changes in the properties of the road surface. A quick downpour could leave a thick layer of oily water on the road; the reflections of cars lights off the oily water could cause a program to recognize two cars instead of just one. Problems like this require a sophisticated design and extensive testing.
Failure of a single component should not bring down the whole system or, optimally, even remove more than the slightest functionality from the system. Sensor coverage should overlap so if one goes down, another can cover the same area. The network paths should not be exclusively linear; if one segment is damaged, there should be an alternate path or mode of communication to transmit the data to the mainframe. If power or a piece of hardware fails, the data should be available from a secondary storage source and not lost. These are just examples of the many fault redundancies that need to be built into ITS to keep it functional as much as possible. The goal, according to a member of the design team for Transguide [3], is to be operational 99.9 percent of the time. This kind of stability requires a thorough understanding and extensive design of the entire system.

Progress for ITS

ITS is the next level in developing high capacity transportation freeway systems that are both efficient and safe. The United States government is backing ITS as a more useful method to solve the traffic problem than just building more roads. Several large US cities, such as Los Angeles, Chicago, and San Antonio, already have systems in place that fulfill the most important functions of ITS and improvements are constantly being worked on.World-wide, similar systems have been adopted in Europe, Japan, and Australia. Governments and politicians recognize that we need to make the highways smarter, not just wider.
ITS is a complex engineering design that will help reduce the frustration and danger in traveling by installing large information-driven systems to manage traffic and related emergencies.

References

    • [1] "Intelligent Transportation Systems of America." Internet: http://www.itsa.org/​, 2000 [Apr. 1, 2000].
    • [2] "Intelligent Transportation Systems Joint Program Office." U.S. Department of Transportation. Internet: http://www.its.dot.g​ov/, 2010. [Apr. 1, 2000].
    • [3] "San Antonio Transguide." Texas Department of Transportation. Internet: http://www.transguid​e.dot.state.tx.us/, 2000. [Apr. 1, 2000].