In fiscal 2001, we have been making improvements to applied system design aimed toward practical application from next fiscal year, and implementing individual system design for each proving test location. (Figure 1)

Figure 1

   Changes in the system design come under the three headings of changes to service definitions, changes to service provision sections, and changes to information transmission location resulting from changes to service upper speed limits, deceleration, and so on. (Figure 2)

Figure 2

   Under applied system design improvement, we studied the practical application of spot communications instead of the continuous communications used formerly. Transmission of information to a vehicle requires the target vehicle to be specified. Under the continuous communication system, the direction and the start point location could be recognized using radio wave start point markers. We have changed the system design, however, so that these markers are used for communication. This was done by adding start DSRC (dedicated short-range communication) and information DSRC so that the order in which vehicles received marker and information signals would determine the targeted direction of vehicle movement. Alternatively, the distance from start DSRC could be handed over to the vehicle so that it could judge whether it was a target by whether it was within that range. We are implementing the design in this way so as to determine whether a vehicle that enters midway is a target. (Figure 3)

Figure 3

   The provisional target value for safety is set at 95% or better, and the target values for reliability are 99% or better system availability rate and 95% or better service availability rate. The system functions perform mutual monitoring and the system performs error monitoring in order to make a final determination of whether the system as a whole is sound. (Figure 4)

Figure 4

   Specifically, the system performs the operational status of roadside data processing facilities monitoring by having the AHS center device send queries about the status of roadside data processing facilities. It performs response monitoring of the operational status of the road-to-vehicle communication facility by sending response data to it at set periods. For the sensor systems, roadside data processing facilities received information from the sensors on a 100-mm cycle. The system judges whether the reception interval is valid, and if information is not received, it judges the sensor system to be malfunctioning. The data sent periodically from the sensor side also includes the equipment status so that the system receives information indicating which part of a sensor is malfunctioning. Determination of malfunctions for the system as a whole is conducted mutual monitoring, and the vehicle side is informed of whether the system is in sound condition. This is the approach we are taking to meet our target values for safety, reliability and so on.

   The next topic is an example of AHS technology utilized for road management (Figure 5). We are moving forward on design of this system with the intention of applying it this fiscal year in the Miyako Tunnels in the Tohoku Region.

Figure 5

   Testing may be conducted on a test course where tests are reproducible, on actual roads where the serviceability of designs can be determined, or on a driving simulator. The system design here is applicable to testing facilities on test courses and actual roads. (Figure 6)

Figure 6

   Over the past several years, we have been improving the various types of facility on the test course in its capacity as a proving test system. The improvements of larger facilities were along the lines of improvement of the effectiveness of services using spot communications in order to perform evaluation tests, improvement of the efficacy of the layout for spot communications, and improvement of spot communications functions used for detection. (Figure 7)

Figure 7

   Tests were also conducted to verify detection ranges. For this, since last fiscal year we have been making some improvements to something called the two-lane detection function. We have also been adding sensor functions to build test systems for detection of vehicles squeezing through into intersection.

   We have been going forward with designs for tests on actual roads at seven locations in last fiscal year. This is being done for five locations on expressways and one location on a general road. In addition, we plan to implement tests at one location in the Miyako Tunnels for the purpose of application to road management.

   Last fiscal year, we formed a project team for each of the locations to create facilities for the construction of these proving test systems. Although research teams for element technologies, system design, and test evaluation exist within the AHSRA organization, we initiated a project team for proving test facilities to carry out design work together with specific road managers and so on.

   This is an overview of the configuration of a system for a road section of uninterrupted flow field, which is one of the current test systems. (Figure 8)

Figure 8

   The basic procedure is to place a dedicated building for test purposes near the road where tests are to be conducted. Devices are stored in that building.

   In the last fiscal year, design work was done on six locations, and various issues were raised. These are now being sorted out and organized. An overview has been prepared to show those items for which existing conditions have been determined. (Figure 9)

Figure 9

   Next I will provide some description of two locations for actual proving test facilities, the Nagoya Nishi Junction on the Higashimeihan Expressway and the Maitani District on the Meihan Highway.

§ West Nagoya Junction on the Higashimeihan Expressway

   On entering the Nagoya Nishi Junction from the main line, there are two curves of 100-m radius. This location is said to have about the second-highest incidence of accidents of all such junctions in Japan. (Figure 10)

Figure 10

   The test vehicle approaches from the right and the information beacon passes it information to the effect that there is a stationary vehicle 300 m ahead. It then passes the message that there is a curve, and to pay attention to speed. When the vehicle is closer to the curve, the beacon passes on a warning, "Reduce speed." This causes the vehicle to decelerate to an appropriate speed before entering the curve.

   A truck actually crashed into the junction area, knocking over some light poles there and then falling onto the bed of a truck on Route 302, below the curve, on December 22,2000. Given that accidents of this kind have actually occurred, the five cameras placed here to cover the entire curve area have been laid out in locations well removed from the roadway. (Figure 11)

Figure 11

   An example of proving test system configuration is shown here (Figure 12). Infrared imaging devices are linked optically, and there are five image processing devices. The image processing devices are integrated by an integrated processing device, and when an incident is detected, it is fed to a roadside processing device. This generates the information that is passed on to vehicles under the support service for stationary and slow-moving vehicle and the support service for prevention of over shooting on curves. In this configuration, that information is then handed over to the start DSRC or information DSRC of a road-to-vehicle communication device.

Figure 12

   The functional structure of the system is shown here. (Figure 13)

Figure 13

§ National Highway 25, Maitani District of Meihan Highway

  The target here is a left-turning, omega-shaped curve section of road that links the Nishi-Meihan Expressway and the Higashimeihan Expressway (Figure 14). This is a rather sharp curve that is 300–330 m in length. There are three information beacons laid out immediately adjacent to the various segments of the curve to provide information. (Figures 15 and 16)

   Actual testing will start at Maitani from this fiscal year.

Figure 14

Figure 15

Figure 16

   Definitions of the requirements and the basic design for the overall AHS system and its individual services, treated specifically as an AHS service system, were created last fiscal year. Interface technical information materials were created to deal with the common components of the system, such as interfaces for road-to-vehicle communication devices and for sensor systems. In addition, the provision of multiple services at the same location was formulated. Management and operational guidelines are scheduled to be put into effect this fiscal year. (Figure 17)

Figure 17

---

Copyright (C)1998-2002 Advanced Cruise-Assist Highway System Research Association