Kajian lapangan dijalankan di pelbagai jenis simpang T termasuk simpang T biasa (Jenis A) dan simpang T (Jenis B dan Jenis C) yang mempunyai lorong percantuman. Simpang Jenis B mempunyai lorong keluar pusing kanan yang pendek manakala Simpang Jenis C mempunyai lorong keluar terus yang pendek.Menurut kajian ini, purata kelajuan kenderaan yang membelok kanan dari lorong minor sebaik sahaja melepasi kawasan konflik ialah 30.09 km/jam dan 31.66 km/jam untuk simpang Jenis B dan Jenis C. Oleh itu, perlakuan mencantum kenderaan yang membelok kanan dari lorong minor adalah serupa untuk kedua-dua simpang. Peratusan kenderaan yang bergerak terus di lorong major akan mengurangkan kelajuan sama dengan atau lebih daripada 5 km/jam ketika berinteraksi dengan kenderaan yang membelok kanan di simpang Jenis B dan Jenis C ialah 24.24% dan 56.00%. Justeru, lorong percantuman yang pendek di simpang Jenis B dapat mengurangkan konflik antara kenderaan yang membelok kanan dari lorong minor dan kenderaan yang bergerak terus di lorong major di lorong yang jauh. Tingkah laku penerimaan sila berhenti selepas sela lebih daripada 12s di simpang Jenis A dan 11s untuk simpang Jenis B dan Jenis C. Nilai sela kritikal pembelokan kanan dari lorong minor untuk simpang Jenis A, Jenis B dan Jenis C adalah 5.12s, 4.29s dan 3.50s. Oleh itu, simpang Jenis C lebih berkesan dalam mengurangkan nilai sela kritikal tersebut. Masa susulan di simpang Jenis A lebih panjang (3.30s) daripada simpang Jenis B dan Jenis C (kedua-dua 2.97s) kerana pemandu di simpang Jenis A mengalami konflik yang lebih banyak. Simpang Jenis B didapati lebih baik kerana konflik kenderaan membelok kanan dari lorong minor dikurangkan. Walaupun simpang Jenis C mengurangkan nilai sela kritikal pembelokan kanan dari lorong minor, tetapi pergerakan lancar kenderaan yang bergerak terus di lorong major dijejaskan.
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Field study was carried out at different types of T-junctions which include a typical T-junction (Type A) and T-junctions (Type B and Type C) with short merging lane on the receiving approach. Type B junction has a short right-turn exit lane while Type C junction has a short through exit lane. From this study, the mean speed of vehicles making a right-turning maneuver from minor road as soon as they clear the conflict area were found to be 30.09 km/hr and 31.66 km/hr for Type B and Type C junctions respectively. Hence, the merging behavior of right-turning vehicles from minor road are similar for both junctions. There were 24.25% and 56.00% of major through movement vehicles reduced speed equal to or more than 5 km/hr when interacting with right-turning minor vehicles at Type B and Type C junctions respectively. Hence, the short merging lane in Type B junction reduces the conflict between right-turning vehicles from minor road and major road through movement vehicles in the far lane. The driver gap acceptance behavior was found to cease beyond gaps longer than 12s at Type A junction and 11s for both Type B and Type C junctions. The critical gap of right-turning minor vehicles for Type A, Type B and Type C junctions are 5.12s, 4.29s and 3.50s respectively. Therefore, Type C junction is more effective in reducing the critical gap of right-turning movement from minor road. The follow-up time at Type A junction is longer (3.30s) than Type B and Type C junction (both 2.97s) as drivers at Type A junction experienced more conflict. Type B junction was found to be better as it reduces the conflict of right-turning vehicles from minor road. Even though Type C junction reduces the critical gap of right-turning movement from minor road, but it affects the smooth movement of major through movement vehicles.
Study on the behavior of right-turning vehicles at different types of unsignalised intersections in Malaysia / Vivian Lim Wei Wen