ANALISIS ARUS LALU LINTAS DI SIMPANG TAK BERSINYAL (Studi Kasus : Simpang Timoho dan Simpang Tunjung di Kota Yogyakarta)

Abstract

Unsignalized Intersection in Yogyakarta city, especially Timoho and Tunjung intersection, recently have an accident and traffic congestion potency. The major streets to the economy centre, government and residential center causes these.. The research was conducted at the three arm unsignalized Intersection ( Tunjung Intersection: northern dr. Sutomo street – Tunjung street – southern dr. Sutomo street) and four arm unsignalized intersection ( Timoho Intersection: Timoho street – northern IPDA Tut Harsono street - Bale Rejo street – southern IPDA Tut Harsono street). The survey was held on the morning peak hour, off peak hour at noon, and evening peak hour by using video camera. The survey held at Timoho intersection on Monday and Wednesday , Tunjung intersection on Thursday and Tuesday. The analysis Unsignalized intersection performance used the Indonesia Highway Capacity Manual 1997. The analysis of critical Lag used Raff method. The analysis of traffic potential capacity of right turn from minor street on intersection traffic conflict volume used HCM 1994 formula. The purpose of the analysis is to acknowledge the traffic stream condition, critical lag and traffic potential capacity of right turn of minor street that has access to enter the unsignalized intersection Within the result of the both intersection performance, it could be acknowledged that the degree saturation is more than 1,00 and the average delay is more than 15 second/pcu and queue probability is more than 35%. These indicate that both intersection condition are bad. The critical lag value of Timoho intersection is 2.94 second and Tunjung intersection is 2.70 second. Thus, the driver behaviors within crowded traffic do not wait gap. The traffic potential capacity of right turn of minor street traffic within traffic conflict volume of Timoho intersection on the west approach 4,36 - 20,95%, on the east approach 7,51 - 34,56%, and within Tunjung intersection 0,78 - 16,32%. The right turn vehicle absorption of the minor street in Tunjung intersection is very small so that there is a vehicle heaping in minor street. Within Timoho intersection, the turn right vehicle absorption of the narrow minor street is small happened on the west approach of minor street. The aggressive driver behavior need stop and separated line. Its need the geometric intersection evaluation for west approach Timoho intersection that have width 4,65 m without shoulder. It causes of difficulty for vehicle to enter the west minor approach. Tunjung intersection need traffic signal because the performance intersection have been poor and the unsignalized intersection can not be accepted any more. Simpang tak bersinyal di Kota Yogyakarta khususnya simpang Tunjung dan simpang Timoho saat ini berpotensi terjadi kemacetan lalulintas dan kecelakaan. Hal ini disebabkan ruas jalan major merupakan jalan menuju pusat perekonomian, pusat perkantoran pemerintah dan pemukiman. Penelitian ini dilakukan di simpang tak bersinyal tiga lengan (simpang Tunjung : Jl. dr. Sutomo Utara – Jl. Tunjung – Jl. dr Sutomo Selatan) dan simpang tak bersinyal empat lengan (simpang Timoho : Jl. IPDA Tut Harsono Utara - Jl. Bale Rejo – Jl. IPDA Tut Harsono Selatan - Jl. Timoho). Survai dilakukan pada jam puncak (peak hour) pagi, jam tidak puncak (off peak hour) siang, dan jam puncak (peak hour) sore menggunakan kamera video. Hari Senin dan Rabu di simpang Timoho, hari Selasa dan Kamis di simpang Tunjung. Analisis Kinerja simpang tak bersinyal menggunakan Manual Kapasitas Jalan Indonesia 1997. Analisis Lag kritis menggunakan metode Raff. Analisis potensi kapasitas lalulintas jalan minor belok kanan pada volume konflik lalulintas simpang menggunakan formula HCM 1994. Analisis bertujuan untuk mengetahui kondisi arus lalulintas di simpang tak bersinyal, waktu lag kritis dan potensi kapasitas lalulintas belok kanan dari jalan minor yang dapat memasuki simpang. Hasil analisis kinerja kedua simpang terlihat derajat kejenuhan melebihi 1,00 dan tundaan rata-rata melebihi 15 detik /smp serta peluang antrian lebih besar dari 35%. Hal ini mengindikasikan kondisi kedua simpang tersebut buruk. Nilai Lag kritis simpang Timoho 2,94 detik dan simpang Tunjung 2,70 detik. Dengan demikian perilaku pengemudi pada lalulintas yang lebih ramai tidak menunggu celah. Potensi kapasitas lalulintas belok kanan dari jalan minor pada volume konflik lalulintas simpang Timoho di pendekat barat 4,36% - 20,95%, di pendekat timur 7,51% - 34,56%, dan di simpang Tunjung 0,78% - 16,32%. Serapan kendaraan belok kanan dari jalan minor di simpang Tunjung sangat kecil sehingga terjadi penumpukan kendaraan di jalan minor. Di simpang Timoho serapan kendaraan belok kanan dari jalan minor yang kecil terjadi di jalan minor pendekat Barat. Perilaku pengemudi tidak menunggu celah dan agresif, maka diperlukan pembuatan garis berhenti dan pemisah lajur kendaraan untuk memasuki simpang dengan marka dan rambu. Perlu evaluasi kesesuaian geometrik simpang terutama pada pendekat barat simpang Timoho yang mempunyai lebar hanya 4,65 m tanpa bahu jalan, sehingga menyulitkan kendaraan yang masuk ke jalan minor pendekat barat tersebut. Simpang Tunjung harus di pasangkan lampu lalulintas karena kinerja simpang sudah sangat jelek dan tidak dapat dipertahankan lagi sebagai simpang tak bersinyal.