Articles written in Sadhana
Volume 32 Issue 4 August 2007 pp 309-328
Trafﬁc on Indian roads (both urban and inter-urban) consists of a variety of vehicles. These vehicles have widely different static and dynamic characteristics. The trafﬁc is also very different from homogeneous trafﬁc which primarily consists of motorized vehicles. Homogeneous trafﬁc follows strict lane discipline as compared to non-homogeneous trafﬁc. Western trafﬁc planning methodologies mostly address the concerns of homogeneous trafﬁc and therefore often prove inadequate in solving problems involving non-homogeneous trafﬁc conditions as found in Indian cities. This paper presents studies conducted on non-homogeneous trafﬁc. Section 1 presents a methodology to verify the continuity equation, the basic block of any trafﬁc planning analysis. In § 2, the methodology developed is applied to modify the Highway Capacity Manual (HCM) 2000 density method to derive passengercar equivalencies (PCEs) or units (PCUs) for heavy vehicles and recreational vehicles. These PCUs appear as ‘ET’ and ‘ER’ in HCM tables. The density method assumes motorized, four-wheeler trafﬁc, i.e., homogeneous traffic, and does not include motorized three-wheelers, motorized two-wheelers, and non-motorized trafﬁc often present on Indian highways. By modifying the density method to represent non-homogeneous trafﬁc, which includes signiﬁcant percentages of motorized, three-wheelers, motorized two-wheelers, and non-motorized trafﬁc entities, one can derive more accurate passenger car units for Indian conditions. Transport professionals can use these PCU values for accurate capacity, safety, and operational analysis of highways carrying non-homogeneous trafﬁc.