As citizens of this macro-reality, we can often feel as if we are but pawns in the vast global chess game being played by multinational corporations, traditional superpowers, new and emerging nuclear powers, and the economic pushbuttons of development and consumer capitalism. Within such a world, some may find it difficult to believe that our individual choices can make a difference in our communities. So what if a few dozen or even a few hundred people in our city get together for an interfaith meal? So what if families from different cultures living together in a town get to know each other? What difference does it make in the end? Political powers and other forces call the larger shots and will send us all into war and conflict if they so desire. Human nature being what it is, we will succumb to our baser instincts in hard times no matter how many positive interfaith or intercultural experiences we’ve had with others.

Critics of interfaith dialogue often make this case. They point to examples from Bosnia, the Middle East, Kashmir, Punjab, Rwanda and elsewhere to illustrate that people who coexist peacefully for centuries can be manipulated into barbarically killing each other relatively quickly. Tyrants, insurgents and other power-seekers have learned that cultural, ethnic, and/or religious differences can form natural fault lines in a given communal fabric, which can be exploited by skillful media messaging and the opportunistic staging of current events into powerfully persuasive political theater. Once the mass media have been harnessed, if not outright hijacked, power seekers can move populations as if mountains – whipping up mass fear, anger, hysteria and eventually an appetite for genocide.

Interfaith dialogue seems no match for these gargantuan modern monstrosities. And, in many cases, it isn’t. The warmly felt bonds of interfaith harmony that thrive in times of relative peace and prosperity chill easily in times of strife and hardship, especially when political, economic or national security interests are at stake. In such times, usually all but a few individuals will succumb to fear, and then retreat to their respective religio-ethnic corners to prepare for a fight. The individuals who maintain their commitment to peaceful coexistence with their neighbors resist the fight, try to save their friends who have suddenly become “the enemy” because of their religion or ethnicity, and often lose their lives in the process. They may be heroes, to be sure, but they are dead. And they do not win in the end; the warmongers do – at least, most of the time.

But not all the time. Occasionally, we find exceptions to this all too common trajectory in human socio-political relations. Situations wherein populations held themselves together despite enormous pressures to fight and kill one another. Where community leaders resisted the gravitational pull of hatred that strips them of their voices and replaces them with those of fear mongers and peddlers of hatred. When we find these exceptions, we must review and analyze the exact conditions that made them possible in the first place, and determine if they can be replicated in other situations of strife and war.

I encountered such an exceptional situation this past spring while visiting Croatia. Fuzine is one of several quaint mountain villages in the district of Gorski Kotar in northern end of the Dalmatian coast of Croatia. I recently listened to the former governor of the district and a local radio producer tell their stories from the period of the war in 1991.

A Yugoslavian Army base camp was built near the district, on top of a hill. Normally, the existence of this base would have been the beginning of the end for peaceful relations between the Croat and Serbian villages of the district. Croats would view the base as a danger and a provocation, as well as a support camp to the Serbian villages. The Serbians, for their part, would have used the base as a “back-up” for their own violence against their Croat neighbors. Since violence begets violence, Croats or Serbs would make the first strike and the cycle would begin. Many would die, the villages would be destroyed, and the resulting “life” would resemble existence on the surface of the moon.

That’s not what happened.

In a stunning turn of events, the municipal leaders of all the villages – Serb and Croat – approached the base commanders and established a relationship with them. After several meetings, it became clear that none of them wanted either to shoot at each other or to be shot. So, they made a written agreement that constituted the “terms” of their coexistence during those months. For example, when the Yugoslav army was required to fire on the villages, per orders from up the chain of command, they warned the citizens ahead of time and instructed them on how to survive the barrage. They provided the citizens with maps of the mines they laid. The village leaders returned the favor and provided base commanders with a “heads up” when they were forced, by public opinion and the radical fringe, to fire on the army base. The local radio producer treated the army base as another “village” in the district and reported its news, events, and played music for the troops, etc. They called the families of wounded guards to apologize – and did so publicly on the radio – when radical elements in their midst broke the agreement and fired on the soldiers. Media reports stayed ahead of the rumor mills, reported the facts of things, and controlled the message to minimize the inflammatory impact of the angry rhetoric coming from other sources.

As a result of the extraordinary bravery and commitment from people on both sides, no one from the district was killed and no one was taken to a wartime prison camp.

Leaders on both sides suffered consequences. Two of the base commanders went to prison for 12 years. One of them disappeared into the mists of “the system” while the other was killed by civilians after being released. The radio producer in Gorski Kotar was banned from media and only recently has begun to work again. Other city leaders voluntarily disappeared into anonymity – this story was kept quiet at first – so as to avoid persecution and death for their actions.

Upon analysis, a few things stand out about this exceptional situation. First of all, there were conditions on the ground that the village leaders exploited to their advantage. The Gorski Kotar district was somewhat geographically remote from the heart of the fighting during the war. As such, neither the base nor the villagers had direct daily involvement in the heart of the war’s operations. Without interventions for peace that could have certainly changed, and the district could have become an additional center or “theater” of the war; however, the interventions took advantage of the district’s “off the beaten path” status. An additional opportunity came in the fact that one of the base commanders was nearing retirement, weary of his job and of fighting, and was inclined to strike a deal with the villagers as long as he could save face. Therefore, when village leaders approached him and his colleagues with a plan for peaceful coexistence, they were ready to negotiate a plan that would let both sides fly under the radar of the larger war and possibly come away from it largely unscathed.

Secondly, media leaders took their share of responsibility for the creation and maintenance of the arrangement with the base camp, as well as for keeping the peace between the villages during particularly tense weeks. Put simply, radio and print media controlled the message in favor of peace. When infractions to the agreement happened from time to time, from both sides, reporting of the story was done in the least inflammatory way possible. For example, when the base camp did an obligatory firing on the villages (after warning the villagers of the times and locations) and accidentally damaged the radio transmission tower, the base commander sent his own soldiers to repair it immediately so that broadcasts could resume as soon as possible. More importantly, this fact was reported to the community so as to minimize anger and outrage over the incident. In short, media operatives used their power for peace and not for war. They recognized the power of media to incite, enflame, and create the larger narrative in which people experience things in their communities. Through skillful messaging and the coordination of communication lines, they maintained and nurtured the agreement for peace through its many months, creating the very conditions for peaceful coexistence.

Finally, we can see that community leaders in the villages refused to relinquish immediately their roles as leaders to the larger forces of the army. They easily could have done otherwise. Once the base camp was established, they could have decided that war was now inevitable, that their little villages stood no chance to resist the war tide rolling towards them, and that each village needed to now begin fortifying themselves against the army and each other, and prepare to fight and die.

They didn’t do this. Instead, they banded together, created a plan, and took a huge risk in walking up the hill to the base camp and presenting it to the commanders. The creativity, courage and will power this required of them simply cannot be overstated. In the end, this human element is what makes the ultimate difference. Human beings are endowed with self-consciousness, agency and imagination, which allows us to not only visualize alternative scenarios in any given situation, but also to imagine and implement alternative courses of action within them – for ourselves and for others. These leaders together resisted the war tide, created an alternative possibility for their district, and bravely took radical steps to implement it. And it worked. Not flawlessly, but enough to keep their people, their homes and their way of life from going up in flames.

Can what happened in Gorski Kotar work everywhere? No and yes. No, in the sense that certain conditions in place on the ground in this district that contributed to the peace are not in place ubiquitously. Most army base commanders aren’t open to illegal agreements with “enemy” villagers. Not all regional or district leaders – in the media or otherwise – have working relations good enough to band together in wartime to create and implement such a thing as this. Many other factors prevent any one exception, such as what happened in Gorski Kotar, from providing a stable template for peace easily applicable to any other situation. These situations are exceptions, after all.

Nevertheless, what happened here can be instructive for other areas. The positive and necessary role of media in maintaining the peace agreement in Gorski Kotar is abundantly clear. Those who find themselves in similar situations of religious and ethnic conflict will do well to procure access to media, if possible, sooner rather than later in order to shape the messaging toward peace and restraint, away from hatred and violence. Today’s 21st century media technology resists totalitarian control in important ways, as recent events in Iran, China and even North Korea indicate. Those with skills can exploit media for peace as well as for war.

Finally, in the end, much turns on the simple power of human agency and choice, and the willingness of people to join together and exercise that agency in the direction of peace in the face of seemingly impossible circumstances. Of course, such principled action plans don’t always make a difference. In fact, such plans may often fail in times of war. But, they certainly have no chance of success at all if people give up on the fight from the beginning and refuse even to attempt to alter the course of things. On this point, people on the brink of war in all sorts of situations have at least a chance – perhaps not a big chance, but a chance nevertheless – to turn the tide in another direction, or at least to reduce the body count and carnage.

I am haunted by an image one of the community leaders in Gorski Kotar used in telling us their story when we met with them. The radio producer told us that media flies “as fast as a bird, as fast as the speed of light” even; however, it typically arrives after the dead bodies already lay on the ground. The producer and the other leaders in the community wanted to avoid bodies on the ground altogether. They wanted media to be faster than the dead.

It seems, in this case at least, they succeeded.

B. Jill Carroll is an Adjunct Associate Professor in the Department of Religious Studies at Rice University.

In 1896, Marconi was successful in sending signals through a wireless telegraph to a distance of a few kilometers away. However, how would it be possible to provide intercontinental communication via radiotelegraphy and radiotelephone? In 1901, together with his assistants, G.S. Kemp and P.W. Paget, Marconi successfully transmitted and received transatlantic signals between Poldhu, Cornwall and New Foundland, Canada, using a kite aerial at Signal Hill in Cornwall, England. It was Edward Appleton who first discovered that radio waves were broadcast around the world after they are reflected back from the ionosphere, one of the highest electrified layers of the atmosphere that contains large concentrations of charged particles (ions) and free electrons. Electromagnetic waves that are sent from radio transmitters to outer space are reflected back to every corner of the Earth after hitting this gas and plasma layer that is composed of charged particles. Thus, radio and radiotelephone communication is made possible for the benefit of human beings. After that time, being able to use a law that had been ordained by the Supreme Creator, human beings were able to reach a level that enabled them to conduct transatlantic communications via radiotelegraphy. But what makes radio waves so special?

Radio waves

The frequency spectrum of electromagnetic waves begins from the “sub-sound frequency region” (1Hz) stretching up until cosmic rays (Figure 1). Radio communication is made using the electromagnetic waves that form part of this frequency spectrum. Radio communication systems can be classified into four groups relating to their frequency regions:

– LF/MF (Low Frequency/Medium Frequency)

– HF (High Frequency)

– VHF/UHF (Very /Ultra High Frequency)

– SHF (Super High Frequency)

Specifications of radio waves are taken into account in this classification. The main element that makes radio waves similar or different from each other is the frequency band that determines their wave length. Radio waves move at the speed of light (300 thousand km per second), much faster than sound itself, so to find the wave length of a radio wave, we divide its velocity by its frequency.

Frequencies used within the radio frequency spectrum measure between 20 KHz and 30 GHz. Theoretically, the high frequency band is between 3 and 30 MHz, while in practice it is between 1.6 and 30 MHz. The interval between 4 and 18 MHz is the most-widely used region in the spectrum.

The atmosphere

Our Lord, Who incessantly prepares the Earth in a beautiful manner, also protects all of life with a perfect shield called the “atmosphere.” Scientists have divided the atmosphere into seven layers in order to reveal the unknown facts about it. These seven layers are different from each other in terms of temperature, pressure and humidity levels, and the natural events that occur in them. If we ascend from the Earth toward the sky, we pass through the layers of the troposphere, stratosphere, ozonosphere, mesosphere, thermosphere, ionosphere and the exosphere. All these layers cover a distance of about 3,000 km. Each of the atmospheric layers serves a vital cause. Every layer has many functions, ranging from the formation of rain clouds to the prevention of harmful beams reaching the Earth, from reflecting radio waves to inactivating meteors. One duty of the ionosphere that we are aware of today is to act as a reflector and distributor for radio waves.

The ionosphere and distribution of radio waves

Good transatlantic radio communication depends upon many factors. Depending on the frequency of the radio waves, the season of the year, the position of the Sun, the location of the broadcasting area and the time of day, the communication area may vary from 100 km to 10,000 km.

Radio waves are propagated around the Earth in two forms, either as ground waves or as sky waves (Figure 2). In high-frequency radio communication, it is important to choose the best frequency for the time and means of propagation.

Starting from 50 km above the Earth and stretching 440 km, the ionosphere is filled with a high concentration of free electrons and gases. Why is the ionosphere important for transatlantic radio communication? The electrified ions that fill the whole of the ionospheric layer that completely surrounds the Earth reflect radio waves from all directions to every part of the world. According to their frequencies and ionization, radio waves are completely absorbed in the ionosphere and they are either partly refracted and distributed to the outer space or are reflected and returned to the world. The electromagnetic waves within a range of 30 MHz can return to Earth after being reflected by the ionosphere.

It is accepted that the ionosphere is formed at different ionizing levels in different layers, known as D, E, F1, and F2 (Figure 3). The ionization level in the outer layers of the ionosphere is higher than that of the inner layers. The D layer, the innermost layer of the ionosphere, is 76-93 km above the Earth and is characterized by low ion densities and low collision frequencies of electrons and ions with neutral particles. Serving to absorb most energy below 7 MHz, this layer is ionized during the daylight hours, completely disappearing at night. It reaches full ionization level just after sunrise and is at its peak at noon time, immediately losing energy after sun-set.

The E layer is the region of the ionosphere that was discovered first. In this layer, molecular ion production is at its peak at about 110-115 km above the Earth. There are plenty of molecular gases at this height. This layer is a suitable platform from which radio operators can reflect signals to distant stations. Reaching a maximum at noon, the ionization in the E layer decreases towards the end of the day, disappearing completely at midnight. Moreover, at unpredictable intervals, ionized gas clouds accumulate in certain regions of this layer. This can be detected by the variable dense clouds of ionization that occur in the E layer due to the spatial and temporal structure in the ionizing particle precipitation. The plasma density of the E layer can be greatly changed because of these occasional formations. These formations, which are called “sporadic E layers,” are used by radio amateurs for long distance VHF (Very High Frequency) operation. Since the plasma density in layers D and E is highest at noon and present during the other hours of daylight, these layers are used in the daytime.

The next layer of ionosphere exists at about 160 and 400 km above the Earth and consists of layers that have a higher density of free electrons caused by the ionizing effect of solar radiation. Since the density of gas molecules at this height is low, ion and electron collisions occur very slowly in this layer. When solar radiation is high (during the day) this layer can be divided into two independent regions, F1 and F2. The F1 layer is present at 152 and 203 km above the surface of the Earth. During the night, the F1 layer merges with the F2 layer. The F2 layer exists at 250 and 400 km above the surface of the Earth. The majority of HF (shortwave) transmissions are propagated by the F2 layer, which is the main reflecting layer for HF communications both at day and at night. Reaching its maximum level of ionization just after midday, the layer is at its minimum just before sunrise. The F2 layer can be used for 10-20 MHz during the day and 3-8 MHz during the night. Since the F layer exists at a very high altitude, it is exposed to sunlight for longer periods of the day and it dissipates very slowly at night. In this case, the only layer of the ionosphere that can be used during the night is the F layer, which I is composed of the F1 and F2 layers.

Solar radiation, and consequently ionization, alters periodically. For instance, as the days are long during the summer months, ionization is also high at this period. During this time, radio waves are absorbed or attenuated more in layers E and D, and propagation covers only a small area. However, since the days are shorter during the autumn and winter, less solar energy reaches these ionospheric layers. Hence, low frequencies can easily pass through the weakly ionized D and E layers and reach the stronger F layer from where they can be propagated over long distances.

Another long term factor in ionization is the regular 11-year activity cycle of sun spots. Sun spots are believed to be caused by violent eruptions on the Sun and they are characterized by unusually strong magnetic fields. During periods of maximum sun spot activity, the density of ionization increases in all the layers of the ionosphere. During these periods, the D layer absorbs more and the critical frequencies of layers E, F1 and F2 are higher, therefore, for long distance communication higher operating frequencies over 30 MHz should be used. During terms of minimum sun spot activity, the E and F layers have weak ionization, so they cannot reflect the radio waves back onto the Earth. In this period, frequencies over 20 MHz are not used much. Along with this regular variation, “sudden ionospheric disturbances (SID)” also negatively affect the propagation of radio waves. SID are thought to be caused by severe solar eruptions, but the real cause of this phenomena is still not clearly known. (Figure 4)

Sudden ionospheric disturbances can disturb radio communication for hours or even days. Strong solar eruptions cause a sudden abnormal increase in the ionization density in the D layer, hence even the high frequency radio waves coming from the side of the Earth that is facing the Sun are completely absorbed by this layer and frequencies above 2 MHz are unable to penetrate it. When SID occurs, long distance propagation of HF radio waves may be completely blocked.

Ionospheric storms are another disturbing factor for radio communication. When a solar eruption occurs, it takes between 20 and 40 hours for the magnetic storm to reach the Earth. The ionospheric storms cause the F2 layer to virtually lose its ion density. At this time, when the range of frequencies used for communication is much smaller than normal, communication is only possible at lower frequencies.

Frequency and propagation routes in radio communications

The definition of the frequency to be used for radio communication is an important parameter for ensuring healthy propagation. For this, the Maximum Usable Frequency (MUF), and the Lowest Usable Frequency (LUF) are determined. Frequencies over MUF penetrate the ionosphere, shooting right through the ionosphere and going out into space, whereas frequencies below MUF are reflected. LUF is the lowest frequency that is completely absorbed in the D layer. To conduct good communication, a frequency, calculated as MUF×0.85, should be used. This frequency may be lower at night and higher during the day.

Apart from the propagation frequency, the path that is chosen to transmit the radio waves from one point to the other also must be calculated accurately. The angle at which the radio waves enter the atmosphere (angle of incidence) defines the path that will be covered by the waves on their way to Earth. The angle of incidence should be small enough for the waves to be reflected back to Earth and large enough so that the waves will not penetrate the ionospheric layer. Smaller critical angles should be used for smaller frequencies and larger critical angles should be used for larger frequencies so that they will not penetrate through the ionospheric layer and be lost in space.

Consequently, apart from periods when solar eruptions are strong, radio waves that are over 30 MHz frequency are not reflected and can penetrate the atmosphere and reach outer space, hence making the communication between outer space and the Earth possible.

For transatlantic communications conducted via communication satellites, radio waves over 30 MHz are used. Artificial satellites imitate the ionospheric layer, their original source of inspiration, and act as a reflector for these waves (Figure 5). Waves coming from the Earth are reflected by these satellites if they are within their coverage area. However, these manmade satellites have very limited coverage areas. Although they are produced with the highest technology available, their cost is very high and they last only for about 25 years. Nevertheless, for radio waves lower than 30 MHz, the ionosphere, that covers the whole of our planet, acts as a natural satellite. Because of this characteristic of the ionosphere, we do not have to focus at any certain point. Moreover, there is no need for maintenance, nor any energy supplement, and the ionosphere is permanent. The atmosphere has been granted for our service for as long as Earth survives. Through searching and exploring new facts about the universe and all beings, we realize more and more that neither meaningless nor useless matter exists in the material world of creation. Therefore, we are better able to understand that the universe is packed with wonderful favors and blessings that are addressed directly to humanity.

Driver Information

The most recent applications sought to complement the driver’s ability by targeting such “hands-off, feet-off” driving systems (Fig. 1) as PATH (Partners for Advanced Transit and Highways) and PROMETHEUS (Program for European Traffic with Highest Efficiency and Unprecedented Safety).

For transportation, IT generally can be classified into four groups: Driver Information and Route Guidance, Traffic Flow and Parking Control, Public Transport and Fleet Management, and Automatic Debiting. Only the first item will be discussed in this article.

Driver Information and Route Guidance

Driver Information (DI) and Route Guidance (RG) systems help drivers navigate unfamiliar roads or find the quickest route. The information, especially that given by more advanced systems, consists of advice that drivers can accept or ignore, or a directive with which they are expected to comply. DI and RG can help them reduce or curtail poor route choice as well as excess distance and travel times. The most likely information requested is shortest recommended path, state of the road and weather conditions, unexpected incidents ahead, and the general traffic situation (to estimate travel time).

Disseminating Information

Roadside displays, consisting of fixed road signs and variable message signs, are the simplest DI systems (Fig. 2). The relevant technology is quite basic, as the goal is to give all drivers general information about existing roadway conditions. Variable message signs are used mainly on highways. In urban areas, they are particularly well-suited for providing information about roadway conditions and parking lot availability.

The second method, cellular-radio networks such as the Radio Data System-Traffic Message Channel (RDS-TMC) proposed by the European Broadcasting Union, enable digital information to be superimposed on normal VHF/FM broadcasts. Information can be filtered (drivers call up only what they need and when they need it), updated any time, and broadcast in different languages.

Also, there is no need to lay cables, as is the case with beacon-based RG techniques.

The third (and most sophisticated) method is the electronic RG system, which consists of in-vehicle units, roadside equipment, and control centers (Fig. 3 ). It is usually difficult to start installing the ground infrastructure before ensuring the wide use of onboard systems. Onboard equipment for dynamic navigation comprises a transceiver, a router with a display, a locator with sensors, dead-reckoning devices, and a map memory. The usual indicators of route selection criterion are shorter distance, minimum cost, less traffic, fewer stops, and greater safety. The result of route optimization is the recommendation of how to reach a destination from a given starting point. This can be done by calculating the optimum route for an origin-destination, and by determining the turning directions from the vehicle’s route and position.

Some Examples in Use

CARIN (CAR Information and Navigation System) is an autonomous (static) navigation system used in route planning and guidance. A simplified digital map, stored on a CD, shows the best route. It also offers verbal guidance via a speech synthesizer and gives general tourist information. Other in-vehicle equipment consists of a sensor (magnetic compass) and a navigation computer that carries out the main task. Data collection, in terms of positioning and directing, is implemented by the moving vehicle’s sensors. This information, updated every 3 seconds, is used for map-matching.

The system’s basic advantage is that it does not rely on any external sources, like expensive beacon infrastructures. The route planner algorithm determines the best route for minimizing travel time and distance. However, as CARIN cannot receive current network and traffic situation reports, it is being modernized so that it can receive external information via the car radio with the introduction of RDS-TMC. Moreover, in the future CARIN will offer a fully interactive traffic management opportunity using the European D-net telephone system.

TrafficMaster was one of the first in-vehicle information systems introduced. It was applied first to the M25 London orbital highway, and then to the whole UK highway network. Data is obtained through sensors installed on highway bridges. In case of congestion, messages (such as locations and types of traffic jams and average traffic speed) are generated and transmitted by the control center. The in-vehicle unit displays the current status of the roadway network covered by the sensors. This dissemination is performed minute-by-minute. enabling the driver to make convenient route choices.

In Euro-Scout, the driver enters a destination into a small in-vehicle computer. As the vehicle moves, the in-vehicle navigation equipment determines its position. Whenever it passes a beacon, the user receives the best route, generated by the central computer, for all destinations.

Communication is performed through a two-way infrared link. Beacons located next to the signal heads can use existing cables when they are mounted with traffic lights. Guided vehicles can measure link travel times, which are then returned to the central computer via the beacons in a so-called vehicle telegram. This information is updated continually by the center. The system, therefore, is characterized by its centralized feature: The main data process is carried out in the control office rather than in-vehicle units.

The system has been introduced in Stuttgart by installing 130 beacon heads on traffic lights. A second system of 340 beacons is located in Berlin, and a third one is in Oakland county, Michigan, with 100 beacons and 1,000 equipped vehicles. Start-up costs are high, but in-vehicle equipment costs and the cost of increasing users are low.

In comparison, SOCRATES’ start-up costs are much lower, while the costs of equipping each vehicle and adding additional users are high. This system does have some weak points, though:

The routing algorithm does not take multi-destination users into account, the system is heavily dependent of roadside infrastructure, and a breakdown in the center may cause a system-wide failure.

SOCRATES (System Of Cellular RAdio for Traffic Efficiency and Safety), a two-way communication system, is based on the Global System for Mobile Communications (GSM) cellular radio network. SOCRATES measures the travel times of all guided vehicles from point to point, and uses this information to determine the best routes. In-vehicle units, an odometer, a compass for dead reckoning, and a map pass information to and from roadside units, which are connected to the central computer over telephone lines that allow medium-range communication.

The downlink from the base station to the vehicle is operated in a broadcast mode for disseminating traffic information. The uplink to the base station allows multiple access by floating cars in order to collect travel time patterns. The system’s main disadvantage is the cost of using the mobile phone network. However, a significant benefit is that using the cellular radio requires no additional infrastructure investment because of the introduction of GSM.

The Need for Such Systems

Transport enables socioeconomic relationships to be developed and sustained. This is clear in the continuous dependence on various means of transport to move goods and people. Neglecting transport would bring society to standstill, literally and metaphorically. The introduction of the car put personal transport on the top and increased the need for more roads. The greater the demand for individual mobility, and hence roads, the more complex road transport problems become.

The number of cars per mile of road grows daily. At the same time, lack of space, budgetary priorities, and environmental considerations restrict the extent to which new road construction and increased capacity can be undertaken. But people still want to travel as smoothly as possible.

Therefore, the central idea is that traffic information and communication systems will offer effective solutions-especially where physical changes to the existing infrastructure, such as constructing new links or widening roads, are almost impossible. Closer following distances between intelligent vehicles on automated highways will eventually increase road network capacity.

The Advantages of RG Systems

The main appeal of dynamic RC systems is their ability to recommend paths based on current traffic conditions. Recent research and systems development have focused mainly on dynamic RC systems, which are superior to static systems. Dynamic RC is particularly well-suited for tackling urban congestion, and has advantages over other technological measures, such as vehicle-actuated traffic signals or a system of dynamically updated VMS.

Drivers normally reach their destination by following a route based on previous experience, maps, street signs, and radio traffic bulletins. However, studies show that drivers are unable to select the shortest route, leading to some 6 to 8 percent errors. Preventing this by even static RG could save millions of dollars per year. Driver misperceptions, due to the absence or scanty amount of information about travel time and alternative routes, as well as about specific route incidents, lead to delay and wasted mileage. In Orlando, tourists driving RC-equipped vehicles made 30 percent fewer wrong turns and shortened their travel times by 20 percent, compared to drivers who used paper maps.

Research indicates that applying dynamic RG systems shows great potential for improving travel times, safety, and environmental effects. This is based on the assumption that more drivers will opt to use the services. Other benefits could include satisfaction derived from choosing the best route and being better informed, reduction in the total distance travelled, and incident detection and warning. The real benefit will depend largely on the quality of information provided. With more computing power becoming available and increased technological advancement, more high-quality information is available to drivers.

RG not only guides vehicles through unfamiliar areas, but also increases roadway safety. For example, research indicates that 60 percent of crashes at intersections, and about 30 percent of head-on collisions, could be avoided if drivers had an additional half-second to react. Systems like automatic collision notification (not readily available yet) immediately signal for help if a vehicle’s airbag deploys. In addition, drowsy-driver warning systems keep drivers from falling asleep at the wheel.

The Shape of Things To Come

The discussion so far has focused on the present state of intelligent transport systems. In-vehicle information systems provide information on road conditions and offer advice. They also can provide information about a city’s hotels, catering, theater, cinemas, and even the entire yellow pages. In-vehicle systems can function as hand-held car locators, whether in a busy parking lot or in the remote countryside.

The future of such systems already is taking shape. Dual-purpose and hand-held in-vehicle systems can be used as personal security guards that send a discrete message to a control center when a user is in danger. They could sound an alarm to scare off potential attackers and draw attention to oneself. They also could be built into a car’s security system to prevent theft and send messages in case of an accident.

Hands-free cars are being developed to navigate the road network by the use of a button relying on in-built computers. In addition, car prototypes are being developed that do not require roads-they will fly from origin to destination. All of these require intelligent navigation through a combination of computing and communication. The merging of computing and communication is the bedrock of a revolution to unify all technologies. Journeying intelligently will be at the forefront of this revolution.

Conclusion

Applying these systems, both vehicle- or network-based, depend heavily on the society’s living standards and the country’s economic level of development. Variable message signs and TMCs are the most convenient systems for developing countries, due to their simplicity and cheapness. A typical variable message sign only costs about $200,000, while more sophisticated systems requiring computer centers, roadside equipment like beacons and in-vehicle units, are more expensive. However, in cities with high traffic levels, authorities may consider establishing electronic navigation and information systems with the cooperation of private investors and vehicle manufacturers.

People tomorrow will be more mobile than ever. To provide better transportation systems for the twenty-first century requires the integration of people, vehicles, and network, as well as the improved safety and efficiency of transport systems. Therefore, dynamic DI systems should be able to offer improved mobility for travelers, reduced travel times and operation costs, reduced transportation infrastructure costs, improved highway safety, and reduced transportation energy consumption, transport-generated pollution, and noise.

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