[[alternative]]The Visual Threshold of Point Source under Curve Road Driving Condition

[[abstract]]本研究在於探討彎道駕駛情況下點光源的視覺閾值(E(下標 th)，視覺閾值可用以評估在黑暗中點光源的視覺績效，諸如信號燈或反光標記。本實驗在一個U型道路上模擬彎道上左彎與右彎的駕駛狀況。道路中心線上擺置大約110個半球型反光標記，在車燈燈光照射下就形成一顆顆的點光源。受試者的工作就是偵測最遠處的反光標記。實驗的結果顯示，動態駕駛狀況下的E(下標 th)(1.12-1.61×10^6 lx)都顯著的高於Blackwel1與Wyszecki & Stile在靜態實驗狀況下的建議值；然而與CIE在動態駕駛狀況下的建議值則相當接近。其間右彎的E(下標 th)，(1.12×l0^(-6) lx)與CIE的E(下標 th)(1.04×10^(-6) lx)沒有差異，可是左彎的E(下標 th)(1.61×10^(-6) lx)則顯著的高於CIE的建議值。其原因應可歸結於擋風玻璃的左側“A柱”將中央視野分割爲二個不連續的視野，導致視覺行爲不同。根據實驗結果，駕駛情況下點光源視覺閾值應該採取左彎的E(下標 th)(1.61×l0^(-6) lx)才合乎安全。 The study was to investigate the visibility threshold of a point source, such as a lighthouse signal or a retroreflective pavement marker, under curve road driving condition. A U-shaped experimental road was set up to simulate curve road driving conditions, both for the right turn and the left turn. Approximately 110 pavement markers were placed on the central delineation. While driving, the subject was asked to detect the most remote visible marker. The results show that Eths of the dynamic viewing condition of the curve road driving are significantly larger than the recommendations for static viewing conditions, such as Blackwell and Wyszecki and Stile, but are comparable with the CIE recommendation for straight road driving condition, The results also show that the E(subscript th) 1.12×10^(-6) lx for the right turn is not significantly differs from the CIE recommendation, but the left turn E(subscript th) 1.61×10^(-6) lx on the other hand, is significantly larger than CIE recommendation 1.04×10^(-6) lx. This difference can be attributed to the ”A-pillar effect”. The ”A-pillar effect” is that the left A-pillar splits the central visual filed into 2 discontinuous ones, and affects the visual behavior of the driver. To insure safety on the curve road driving condition, the E(subscript th) for the left turn, l.61×10^(-6) lx is recommended