• Geetam Tiwari

      Articles written in Sadhana

    • Traffic planning for non-homogeneous traffic

      Geetam Tiwari Joseph Fazio Sushant Gaurav

      More Details Abstract Fulltext PDF

      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.

    • Should bus commuting be subsidized for providing quality transport services? – A case for Delhi

      Akshaya K Sen Geetam Tiwari V Upadhyay

      More Details Abstract Fulltext PDF

      Urban transport has serious problems that are symptoms of the general process of rapid urbanization and environmental degradation. Policymakers in general and urban economists in particular have paid little attention to public transport system pricing leading to the absence of a financially viable, self-supporting urban transport system.

      In this paper, we report a partial equilibrium model developed by us, which captures transport tax reforms in the presence of certain transport externalities. Our theoretical model shows that the question of public transport subsidies to reduce congestion and provide quality transport services depends on three factors:

      the extent to which such subsidies induce people to switch from private transport to public transport;

      if the price elasticity of current users of public transport is higher, there may be a sharp rise in public transport ridership as a reaction to increased subsidies, which will have an undesirable effect; and

      there is the danger that subsidies will cause a loss in productive efficiency.

      The numerical model of our paper for Delhi shows that the cross price elasticity of public transport demand with respect to the price of private transport is significant (0·63) in the off-peak period whereas the same in the peak period is somewhat low (0·16) and the combined effect of these elasticities will result in a considerable modal shift in favour of bus transport demand (19%) if the price of public transport were to be subsidized and private transport were to be priced optimally. Even without subsidy, the modal shift will be significant (18%), if the under-priced private transport modes are optimally priced keeping the current bus prices constant. This paper shows that there will be significant welfare gains in both these scenarios.

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