現今高速公路採用的 LED可變式資訊系統 (VMS) 顯示面板由於本身設計特性以及外在環境干擾，會影響駕駛者的視認度；因此，探討駕駛者對於可變式資訊系統字體色彩的視認角度並比較年輕及高齡駕駛者對可變式資訊系統的視認能力為本研究之目的。實驗條件包括：模擬不同明暗的可變式資訊系統背景色、黃昏低色溫環境、起霧的環境、日照及夜間環境等條件。研究採實驗室模擬，量測受測者視認可變式資訊系統文字的視角的最小絕對閾值。實驗結果顯示，現有標準紅色字體的視認性不佳。若以黑色為背景，其視認角度以黃色最佳，藍色最差，紅色次差；若以白色為底，則結果相反。視認角度主要受明暗對比的影響。年輕及高齡者兩受測族群的視認能力有顯著差異，高齡受測者的視認能力僅約為年輕受測者的二分之一。此外，在白色背景的文字視認度低於黑色背景，而在夜間環境視認度高於日照環境。高齡者在多數實驗中未能達到理想視認距離，尤其以霧氣環境中最為嚴重，若從通用設計的角度來看，在限速 110km/hr下，須考慮將現有標誌提先安置於 37.8公尺，或改變現有標誌高度尺寸，從 1.2增大至 1.8公尺，才能達到高齡者的理想視認距離。

VMS (Variable Message System) with LED as the light source has been widely used on highways throughout Taiwan. This research intended to investigate if the drivers could recognize the information displayed on the VMS under various environmental conditions, such as sunset as well as fog, etc. and with various design parameters, such as font colors as well as background colors. Lab simulation was conducted. The results show that yellow font on black background can be best recognized by both young and elderly participants, and blue is the worst, red is just better than blue. When background is white, blue is the best, and yellow was the worst. Recognition was affected by contrast and brightness. In all experiments, significant differences exist between young and elderly groups in recognizing VMS. The size of the information needed to be well recognized by the elderly is nearly double that for the young subjects. The white background is better than the black one, and the recognition in the nighttime is better than during the daytime. From the viewpoint of Universal Design, the sign sizes must be enlarged from 1.2 m to 1.8 m or the sign must be installed 37.8m farther away from the location the sign indicates.