VOLUME 20 COMMUNICATIONS 3/2018 REVIEW ARTICLE 9 1. Introduction The aim of this paper is to provide an estimation of the economic and environmental costs due to the forced deceleration or stopping and the subsequent acceleration of a motor vehicle in urban traffic. This estimation is based on a dynamic vehicle model with variable parameters and thus it can be obtained from the data generated by an arbitrary floating car. The problem discussed in this treatise is particularly topical in rapidly developing urbanized areas around cities - see [1]. 2. Vehicle dynamics 2.1 Forces acting on a vehicle Consider a vehicle moving with an acceleration α. In the travel direction, a driving force F is acting. The movement is opposed by a vehicle resistance that includes: 1 tire rolling resistance: R fmg f = (1) 1 A movement in a horizontal plane is considered. For an uphill journey, a climbing resistance R C = mg sin α should be added, where α denotes an angle between a road and a horizontal direction. Similarly, all mentioned forces containing a term mg would be multiplied by cos α . Nevertheless, we suppose that a driver getting over an elevation h, which requires an additional work W A B = # mg sin α ds = mgh, later returns to the initial altitude and earns the same energy back. In the case of the most frequent grades, the term cos α would influence the price of one stopping and a subsequent acceleration at the third decimal position or further, the fuel consumption estimation would be affected at the fourth decimal position. erefore, we put α = 0 and thus α = 1 in this paper. aerodynamic drag: R c Av 2 1 v d 2 t = (2) acceleration resistance of rotating parts: R ma R p = (3) breaking force: R mgx B n = (4) Here f denotes a rolling resistance coefficient, m vehicle mass, g gravitational acceleration, ρ air density, c d aerodynamic drag coefficient, A projected front area, v vehicle velocity, a vehicle acceleration, ξ coefficient including the inertia of rotating parts, μ tire adhesion coefficient, x breaking intensity expressed by a value from the interval [0,1]. As a model vehicle for calculations, Skoda Octavia 1.4 MPI/55 kW with gasoline ignition engine has been chosen, since it belongs to the best-selling cars in the Czech Republic. Therefore, the following values are considered (see [2]): f = 0.015, m = 1560 kg, c d = 0.30, A = 2.069 m 2 , ξ = 0.04, 2 g = 9.81 ms -2 , ρ = 1.25 kgm -3 , μ = 0.8 (for asphalt). If the vehicle velocity v is constant, the first Newton’s motion law implies that the sum of acting forces is equal to zero: F R R F c Av fmg 0 2 1 v f d 2 t = - - = - - (5) The driving force F can therefore be expressed in the form: F c Av fmg 2 1 d 2 t = + (6) For the mentioned model vehicle, the driving force necessary to maintain a constant velocity of e.g. v = 50 kmh -1 0 13.89 ms -1 is 2 We consider the least value from the interval between 0.04 and 0.7, convenient for personal vehicles. Oldrich Hyks - Kristyna Neubergova - Pavel Pribyl* The paper is focused on the influence of driving behaviour on fuel consumption and the subsequent environmental impacts. The main issue is to estimate the economic and environmental costs connected with the forced deceleration or stopping and the subsequent acceleration of a motor vehicle in urban traffic. Authors introduce a physical model of a vehicle with variable parameters that allows the calculation of economic and ecological losses in congestions on the basis of data generated by an arbitrary floating car. The losses include the lost kinetic energy of a vehicle during the forced braking, accelerated degradation of vehicle components, the loss of time of drivers and passengers and the increased ecological footprint. Energetic costs are estimated from the vehicle engine efficiency with which the fuel energy is transformed during an acceleration to kinetic energy of a vehicle lost during braking. Further, these costs are estimated from fuel calorific value and fuel price. Costs resulting from the degradation of vehicle components are estimated from their average stated lifetime. Keywords: vehicle dynamics, fuel consumption, forced vehicle deceleration INFLUENCE OF DRIVING FLUENCY ON ECONOMIC AND ECOLOGICAL ASPECTS OF TRANSPORT * 1 Oldrich Hyks, 2 Kristyna Neubergova, 2 Pavel Pribyl 1 Department of Applied Mathematics, Faculty of Transportation Sciences, Czech Technical University in Prague, Czech Republic 2 Department of Transportation systems, Faculty of Transportation Sciences, Czech Technical University in Prague, Czech Republic E-mail: hyks@fd.cvut.cz https://doi.org/10.26552/com.C.2018.3.9-14