1. Introduction
   I gave a presentation on the recent situation of AHS in Japan at the TRB (Transportation Research Board) Vehicle Highway Automation Committee held in Washington DC on January 12, 2002, after which we inspected the snowplow support systems in Minnesota and California. We also saw a snowplow automated driving system at the 1st International Winter Road Committee held in Sapporo. In this report, I would like to introduce these snowplow related support systems.

2. Snowplow Support System of Minnesota

1) Outline
   We saw the snowplow support system developed by the DOT of the State of Minnesota which is currently being tested on actual roads in the suburbs of Saint Paul City. In Minnesota, 1,600 people are engaged in snowplow work using approximately 800 snowplows. With the aim of enhancing the safety and operability of this snowplow work, the State of Minnesota developed a snowplow support system and has built eight test cars.

2) Support
   The support provided by the system consists of information on keeping lanes so the snowplow knows where it is positioned in respect to the lane, warnings on departure from lanes (lane keeping support), information on forward road shapes and road structures such as guard rails (look-ahead information support), information on distance with obstacles such as stationary or slow-moving cars ahead (collision prevention support), etc.

3) Technical features
   Basic technologies include "detailed maps", "high precision GPS", "lane markers", "obstacle detection radar", and "HMI". Using maps detailing information on lanes and road structures, the system grasps lateral and longitudinal positions of the vehicle with great accuracy using RTK-GPS and provides relative information and warning for lane keeping support and forward warning information support. It uses RTK GPS to detect positions at accuracies of two to three inches. A GPS signal compensation base is installed every five miles. At areas difficult to receive GPS, function compensation is done by magnetic markers (magnetic tape). The system also uses a millimeter-wave radar to detect cruising lanes of forward vehicles ahead and the following distance which are difficult to see due to blizzards and accumulated snow, to provide information on the following distance and collision warnings in collision prevention support. Information is generally provided on a transmissive head-up display (Picture 2). Warnings which apply vibrating motions to the driver's knees (left-right separately) and voice information are also used.

3. Snowplow Support System of California   

1) Outline
   We also saw the snowplow support system (Picture 3) developed by the California DOT which is currently being tested on the roads of the Donner Pass, a snowbound area. The system is similar to Minnesota's. Position detection is mainly done by magnetic nails.

2) Support
   Like Minnesota's, the system provides lane keeping support, forward warning information support, and collision prevention support.

3) Technical features
   The basic technologies include "detailed maps", "lane markers", "obstacle detection radar", and "HMI". Using maps detailing information on lanes and road structures, the system grasps lateral and longitudinal positions of the vehicle with lane markers using magnetic nails and provides information and warning. Information on vertical position is provided by incorporating milepost information for every 1/4 mile by SN signals of the magnetic nails, and based on this, measuring the cruising distance of cars. Experiments are also being carried out on the use of RTK GPS. They use the millimeter-wave radar to detect forward vehicles ahead and obstacles. Information is generally provided on a head-up display (Picture 4). The head-up display of the test car was not of the transmissive type. Voice warning is also used.

4. Snowplow Support System of Sapporo

1) Outline
   This snowplow automated cruising system was developed by Construction Technology Research Department, Advanced Technology Research Team of the Independent Administrative Institution Public Works Research Institute (PWRI). It was shown at the Technical Visit of The XIth PIARC International Winter Road Congress 2002 Sapporo Meeting held in Sapporo. The aim of the system is to realize efficient snowplow work by enabling one-man operations of rotary snow remover.

2) Support
   Snowplow work in Japan using rotary snow remover requires skills due to complicated road conditions and roadside environment. It is usually carried out by two persons; the operator driving the snowplow and the operator operating the blade blower. The aim of this project is therefore to automate vehicle steering and speed control (support) to realize one-man operations.

3) Technical features
   Using detailed maps with recorded information on roads to be snowplowed and the peripheral environment, cruising plans based on snowplow work demands (route and speed) are described on the map. Lane markers are then arranged along the route for realizing the cruising plan. The current position of vehicles is grasped using lane marker sensors, and speed and operations are controlled so the vehicle cruises along the cruise plan. Experiments were conducted by installing a less than 200m long course in the Disaster Prevention and Technical Center Building near the Sapporo dome. The course is made up of curves (radius 12 m) and lines based on the steep curves and intersections of highways. For lane markers, magnetic and electric wave types using technologies developed by AHSRA are being attempted. Application of GPS is also being considered. Steering is controlled using hydraulic cylinders. In experiments opened to the public, rotary snowplows were run at 4 km/h along the course in one-man snowplow work. (Picture 5)

5. Conclusion

   The cruise-assist system realized by vehicle-road infrastructure cooperation is effective for realizing safe and efficient road traffic by supporting vehicle cruising. Developments are carried out with its realization looked forward to all over the world. The snowplow support systems of Japan and US seen this time are only examples of the system. In the US, progress is just a step away from practical application. Japan is also committed to its development. The aims and effects of the snowplow support system are evident, and practical use from an early stage and development of applications are anticipated.