In 1993, Associate Professor Lee Jui-tsung of the general education center at Tsu-Chi College of Medicine and Humanities began researching the Old Hohuan Trail. He discovered that in fact the majority of the old trail lies within a distance of 50 meters above or below the Cross-Island Highway. But after the highway was built, the old trail fell into disuse and gradually faded back into the undergrowth, forgotten.
慈濟醫學院通識教育中心副教授李瑞宗在投入合歡越古道的二年調查中，發現，多數古道其實都在中橫公路上下五十公尺的範圍之內，只是在中橫公路開通之後，合歡越古道已喪失昔日的功能，慢慢的被遺忘在荒煙蔓草之間。