21% of accidents on the Metropolitan Expressway occur at certain curves (6% of the total length). A field trial of AHS was conducted at one of such curves, Sangubashi curve on Shinjuku Route (Route No. 4) from March to May 2005. Another similar field trial is being conducted since September 2005.
The objective of the experiment was to reduce accidents and incidents at the curve, using a roadside sensor to detect congestion and standing and slow vehicles ahead of the blind curve in real time, and transmitting the information from a VICS beacon installed about 300 m before the curve to approaching vehicles through on-board car navigation devices equipped with 3-media VICS. The car navigation devices that received the information warned drivers by beeping and displaying simple images showing "Congestion ahead. Slow down", etc.
Of the drivers who experienced the service, 90% answered that the service will be effective also at other sections and the warning by voice was effective, showing that the information provision service will improve safety.