DESIGN ASPECTS AND CHALLENGES IN AUTOMATED HIGHWAY SYSTEM
Piyush Sharma Department of Civil Engineering, Amity School of Engineering Engineering & Technology
Amity University, Haryana, India
Email:
[email protected]
Abstract: Since last decade, the technology required for highway automation has experienced extensive advances. An automated highway system (AHS) or Smart Road is a proposed intelligent transportation system technology designed to provide for driverless for driverless cars on specific rights-of-way. It is most often touted as a means of traffic relief, as it would drastically reduce following distances and headway, thus headway, thus allowing more cars to occupy a given stretch of road. It is a vehicle and road based system that can drive vehicle automatically. The AHS is a large, complex system, in which vehicles are automatically controlled. The design and implementation of the AHS required advances in sensor technologies, as well as the design, analysis, simulation, and testing of large-scale, hybrid control systems. This is done using sensors that serve as the vehicle's eyes, determining lane position and the speed and location of other vehicles. vehicles. Keywords: Artificial Keywords: Artificial Intelligence, Automation, Highway, Platoon, Hybrid Systems.
1. Introduction
There is a growing need of full automation as it can greatly increase highway capacity while improving safety. A key to greater capacity is the organization of traffic in groups of up to twenty tightly-spaced cars called platoons. platoons. Although the spacing between these platoons is large (about 60 meters), platooning decreases the mean inter-vehicle distance to achieve a capacity of up to 8,000 vehicles per hour per lane, as compared with a capacity of 2,000 in today’s highways with manually-controlled manually-controlled vehicles. Because the maintained distance between cars within a platoon is small (1-2 meters), in the event of a collision the relative
impact velocity (and hence the impact energy) between colliding vehicles is small. [8] As a consequence, platooning can increase safety. The cars have have power steering and automatic speed controls, which are controlled by a computer. The cars organize themselves into platoons of eight ei ght to twenty-five cars. The platoons plat oons drive themselves them selves a meter apart, so that air resistance is minimized. The distance between platoons is the conventional braking conventional braking distance. In case, if anything goes wrong, the maximum number of harmed cars should be one platoon. Today, some systems treat AmI (Ambient Intelligence) incorporates only a limited amount of intelligence. Some researchers are building AmI systems without AI (Artificial Intelligence), concentrating on the operational technologies, such as sensors, actuators, communications, and ubiquitous computing. However, sooner or later, that low level of intelligence will be a clear drawback. AmI’s acceptability will result from a balanced combination of operational ope rational technologies and AI. [9] 2. Technology used in design of AHS The automated highway system is one aspect of intelligent transportation systems, which
apply many electronic, computer devices and control technology mainly developed for aviation, space program and defense to the improvement of highways, vehicles and public transportation.
Automated highway systems combine magnetic sensors, computers, digital radio, forwardlooking sensors, video cameras, and display technologies. Various combinations of these technologies are being applied in different pilot tests. The controllers are derived using vehicle conservation flow models and Lyapunov stability techniques. [20]
Magnetic Sensors: Sensors: Magnetic sensors could be imbedded along the highway lanes. Magnetometers under the car's bumpers would sense the magnets and automatically keep the cars in the center of the lane.
Networked Computers: Computers: The system would not rely on a central computer to direct the movement of all vehicles. Rather, networks of small computers would be installed in vehicles and along the sides of roadways to coordinate the flow of traff ic.
Digital Radio: Radio: Digital radio equipment in each car would allow the computer on board to communicate with other vehicles in the vicinity and with supervisory computers monitoring the roadway.
Forward Looking Sensors: Sensors: Using radar or an infrared laser, these sensors would detect dangerous obstacles and other vehicles ahead.
Video Cameras: Linked Cameras: Linked to computers that process images rapidly, video cameras could detect dangerous obstacles and other vehicles ahead. They could also be used along with or instead of magnets to track lane boundaries.
Visual Displays: Mounted Displays: Mounted on the dashboard or projected onto the windshield, it would give the driver information about the operation of the vehicle.
The various elements of automated highway system are shown in the Figure 1.
Figure 1: Elements of automated highway system [15]
3. Architecture of AHS
The influence of the control architecture in the design of a complex system like the AHS cannot be overestimated. A good architecture simplifies controller design and testing through the functional decomposition in self-contained layers, and well-specified well-specified interfaces interfaces simplify software design and code development. [20]
Joe Palen et al [4] studied the need for surveillance surveillance in intelligent transportation systems. According to Joe Palen, anything that changes the detected background intensity, frequency, or spatial orientation of the measured wave energy can add noise and reduce accuracy. Video image processing is notorious for problems induced by day-night transitions, shadows, and headlight reflections off wet pavement. Fog, smog, dust, snow, rain and road wash behind trucks can all reduce the transmission of waves of different frequencies, and therefore reduce
accuracy. Additionally, detectors that rely on precise timing circuits can be corrupted by temperature extremes. 4. Characteristics Characteristics of ideal AHS
1. Affordability: The Affordability: The AHS must be affordable and cost-effective t o users and operators. 2. User Desirability: The Desirability: The AHS must be practical, desirable, and user-friendly. 3. Dual-Mode Vehicle Instrumentation: Instr umentation: Only Only vehicles instrumented for and operating under full automated control will operate on AHS roadways. AHS-instrumented vehicles must be able to operate on regular (non-instrumented) roadways, and use some of the AHS instrumentation for safer operation including collision avoidance. 4. Reliable, Modular System Technology: The Technology: The AHS must be highly reliable and modular to accommodate continuing advances in technology. [12] 5. Support for Various Vehicle Types: Types: The AHS must support all normal vehicle types, including cars, buses, and trucks, although not necessarily intermixed. 6. Intermodality: Intermodality: AHS must reflect the intermodal nature of our surface transportation system; consideration must be given to ensure convenient transfer between modes such as private vehicles and public transportation. 4.1 Automation systems Two types are there:
Partially Automated Systems
Fully Automated Systems
Partial Automation – Automation – This This system rely on the driver for most driving functions having limited li mited control of the vehicle during an emergency. [15] Full Automation – In this case, drivers are totally disengaged from driving tasks, therefore safer. [15]
5. Challenges in using Automated Highway System in India
1. Social and institutional challenges for AHS -
Land Use
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Environmental impact
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Effect on people’s mobility on their inability to use new technology
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Effects on government owned transport systems
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Financial impacts
2. Social and environmental impacts -
Congestion at entry and exit: more number of vehicles using the AHS could congest the entry and exit sectors.
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AHS might trigger urban sprawl, thus increasing the dependence on vehicles that leads to higher emissions.
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Safety: break failure can lead to chain reaction of accidents.
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Equity: possibilities of clash of federal and state government funding.
3. Financial Challenges -
Covering the cost of AHS is a vital challenge; Priority in investment v/s national highways can be a serious issue for government.
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Rights and privileges of the operating entity.
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Inventory problem: new funds to cover the factors or a result based investment.
4. Organizational Issues -
State Government can face many problems to manage high intensity traffic on AHS.
5. Liability Issues -
Responsibility for accidents is the main issue of liability.
5.1 Vehicle control in designing AHS Vehicle control is probably the most important part of the advanced AHS applications. Implementation of AHS necessitates automatically controlled vehicles as mentioned previously. Achieving the optimal solution to congestion and safety problems requires extensive research in system modeling, lateral (steering) controls and longitudinal (speed and headway) controls. In a fully automated highway system, these control systems will rely on vehicle-to-vehicle communication, as information on velocity and acceleration of other vehicles will be utilized in individual vehicle controllers. Automated highway system has been successfully implemented at many places as shown in figure 2.
Figure 2: A demonstration of successful automated highway system in San Diego [11]
6. Conclusions
Following are some conclusions related to design, planning, safety and feasibility aspects of Automated Highway System: 1. Without the advantage of increased efficiency through platooning, the only advantage of using automation in mixed traffic is improved safety. 2. Although safety is an important improvement, it may not be enough to justify investment.
3. The cost/benefit ratio may be too low for government and consumers to make an investment, especially since the value of added safety is difficult to measure. 4. Mixed traffic intelligent vehicles may be an important first step in the use of AHS that will lead to the building of more and more dedicated lanes. 5. Vehicles should be able to run in either scenario, but perhaps would have some functions limited while driving in mixed traffic. The AHS is a complex large-scale control system, whose design required advances in sensor, actuator, and communication technologies and in techniques of control system synthesis and analysis. Acknowledgement
I would like to thank Prof. Meeta Verma, Prof. Sarah Khan, Prof. Sakshi Gupta, Dr. D.K Singh, Prof. R.C Sharma and Prof. M.K Sinha for their valuable discussions on the Intelligent Transportation System including Automation. References
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