The Indonesian Highway Capacity Manual project started in 1990 when it was found that western capacity manuals often produced misleading results. A draft manual for signalised intersections was published in January 1993 based on surveys at 52 signalised intersections in 15 cities using video recording of all traffic movements. Saturation flow was obtained using the TRRL time-slice method and step-wise regression regarding cross section parameters, city size, type of area and side friction. The discharge through unprotected conflict points was analysed based on observations of individual driver behaviour. For protected approaches, the saturation flow was approximately 600 pcu/hg/m; and pcu for heavy vehicles (HV) 1.3; motorcycles (MC) 0.2, and unmotorised vehicles (UM) 0.5. For opposed approaches, the discharge could be characterised as alternating `bunches' from the two conflicting streams, since Indonesian drivers do not respect any right-of-way rules. An explanatory model was developed resulting in lower saturation flows than western models, except at high ratios of right-turning traffic (Indonesia has left-hand traffic). Higher pcu-values were also obtained for MC (0.4) and UM (1.0). (A)
Abstract