IMPACT OF ROAD ALIGNMENT ON FUEL CONSUMPTION AND GAS EMISSIONS – EXPERIMENTAL AND ANALYTICAL RESEARCH

This research analysed the impact of road alignment on the fuel consumption and gas emissions of a vehicle driven at a free-flow speed by an 85th percentile driver. The field experiment included constant and free-flow speed rides by a personal car equipped with a high-performance (10 Hz) Bluetooth global position device and on-board diagnostics connector, with which the travel path, speed, acceleration, and consumption data were recorded. Regression analyses of the dependence of free-flow speed and fuel consumption on the geometric characteristics of the road (curvature, length, longitudinal slope, etc.) resulted in the formation of a reliable model that could compare alternative road designs for a given corridor in terms of route economy and safety. The main parameters contributing to the consumption on tangents were the slope and radii of adjacent curves. For constant speed, the slope was the only geometric parameter that had an impact on fuel consumption

Use of simulation models in traffic analysis

Opisan je metodološki pristup pri izradi prometne analize utjecaja planiranih zahvata u prostoru na odvijanje prometa u neposrednom okruženju. Prikazane su osnovne karakteristike simulacijskih modela kojima se procjenjuje kvaliteta odvijanja prometnih tokova. Dan je primjer prometne analize gospodarske zone Podi-zapad primjenom navedene metodologije, uz upotrebu simulacijskog modela CORSIM koji omogućuje određivanje kritičnih lokacija i usporedbu mogućih varijantnih rješenja.The methodological approach used in traffic analysis, and aimed at determining the influence of planned developments on the operation of traffic in the immediate vicinity of such developments, is described. Principal properties of simulation models used for estimating quality of traffic flow are presented. An example of traffic analysis conducted according to the above mentioned methodology, and involving the use of CORSIM simulation model for determining critical locations and comparing possible alternatives, is presented for the economic zone of Podi-West

Sensitivity analysis of the CORSIM simulation model parameters

Ističe se važnost računala za simulaciju odvijanja prometnih tokova. Ukratko je opisan mikroskopski simulacijski model CORSIM te su prikazani rezultati analize osjetljivosti određenih ulaznih parametara koji se upotrebljavaju pri analizi učinkovitosti semaforiziranih raskrižja. Dobiveni rezultati upozoravaju na utjecaj pojedinog parametra na procjenu prosječnog zakašnjenja po vozilu te koji od njih je potrebno kalibrirati s obzirom na lokalne uvjete odvijanja prometnog toka.The significance of computers in traffic flow simulation is emphasized. The microscopic simulation model CORSIM is briefly described, and results are given for sensitivity analysis of some input parameters used in studying efficiency of traffic light intersections. The results obtained show the influence individual parameters exert on the estimate of an average delay per vehicle, and indicate which parameter needs to be calibrated to take into account local traffic flow conditions

Sensitivity analysis of the CORSIM simulation model parameters

Ističe se važnost računala za simulaciju odvijanja prometnih tokova. Ukratko je opisan mikroskopski simulacijski model CORSIM te su prikazani rezultati analize osjetljivosti određenih ulaznih parametara koji se upotrebljavaju pri analizi učinkovitosti semaforiziranih raskrižja. Dobiveni rezultati upozoravaju na utjecaj pojedinog parametra na procjenu prosječnog zakašnjenja po vozilu te koji od njih je potrebno kalibrirati s obzirom na lokalne uvjete odvijanja prometnog toka.The significance of computers in traffic flow simulation is emphasized. The microscopic simulation model CORSIM is briefly described, and results are given for sensitivity analysis of some input parameters used in studying efficiency of traffic light intersections. The results obtained show the influence individual parameters exert on the estimate of an average delay per vehicle, and indicate which parameter needs to be calibrated to take into account local traffic flow conditions

Modelling Free Flow Speed on Two-Lane Rural Highways in Bosnia and Herzegovina

Free flow speed is used as a parameter in transportation planning and capacity analysis models, as well as speed-flow diagrams. Many of these models suggest estimating free flow speed according to measurements from similar highways, which is not a practical method for use in B&H. This paper first discusses problems with using these methodologies in conditions prevailing in B&H and then presents a free flow speed evaluation model developed from a comprehensive field survey conducted on nine homogeneous sections of state and regional roads

An analysis of intersection traffic signal warrants

This paper presents an analysis of the existing traffic signalwarrants and the cmresponding threshold values. The analysisof unsignalized intersections was conducted according to theanalytical procedures of Highway capacity manual. Traffic signaloptimization was conducted using Synchro software. Theresults showed that the cun-ent wan·ants are not sufficiently reliablein some situations and can be misleading in the process ofselecting the intersection control type. There are three majorreasons for insufficient reliability of the existing wan·ants. First,they are p1imarily based on total major and subject minor streetvolumes, so they do not take into account all the possible combinationsof volume distribution and composition of the turningmaneuvers. Second, they do not make difference betweenthree-leg T intersections and four-leg intersections, and finallythey are based only on an overall system operation without regm·ding the functionality of a specific approach

Review, Testing and Validation of Capacity and Delay Models at Unsignalized Intersections

This paper deals with problems related to the capacity anddelay models at unsignalized intersections. The parameters ofvarious models are calibrated based on the on-site data obtainedin the countries where the models were developed. Thispaper deals with two problems: The first is the reliability of appliedmethodology in general, and the second is the acceptabilityof model parameters for the use in prevailing road and trafficconditions in Croatia.The first section presents the background review of the gapacceptance theory which is the basis for the development of thecapacity and delay models. The mathematical derivation of thebasic capacity models is presented as well as the resulting capacitymodels according to the assumed theoretical distributionof head ways in the priority stream. This paper also presents themethods for the calculation of the capacity considering the existenceof traffic streams of different hierarchies. The results ofvmious theoretical capacity models testing are presented. Thesecond section presents a review of queuing theory and the resultingstationary and time-dependent delay models. The underlyinghypothesis as well as reliability and limitations of thedelay models are presented. Also, the Highway capacity manualdelay model was tested against field data

Modelling Free Flow Speed on Two-Lane Rural Highways in Bosnia and Herzegovina

Free flow speed is used as a parameter in transportation planning and capacity analysis models, as well as speed-flow diagrams. Many of these models suggest estimating free flow speed according to measurements from similar highways, which is not a practical method for use in B&H. This paper first discusses problems with using these methodologies in conditions prevailing in B&H and then presents a free flow speed evaluation model developed from a comprehensive field survey conducted on nine homogeneous sections of state and regional roads

Methods for ensuring consistency of horizontal alignment elements

Na izvangradskim dvotračnim cestama, koje u većini zemalja čine više od 80 % ukupne duljine cestovne mreže, najveći se broj nesreća događa u krivinama. Najčešći je uzrok nesreća nekonzistentnost elemenata trase s obzirom na mogućnost održavanja željene brzine. U radu su izložene postojeće metode i najnovija istraživanja vezana za procjenu operativnih brzina i osiguranje konzistencije elemenata horizontalnog toka trase na izvangradskim dvotračnim cestama te su opisane prednosti i nedostaci smjernica pojedinih zemalja.On rural two lane roads, which form over 80 percent of the total road network in most countries, most accidents are caused in curves. The most frequent cause of accidents is the inconsistency of horizontal alignment elements with respect to possibility of maintaining the desired speed of travel. An overview is given of existing methods and latest research, as related to the evaluation of vehicle operation speeds, and consistency of horizontal alignment elements on rural two lane roads. Advantages and deficiencies of guidelines applied in individual countries are also presented

Possibility of Microsimulation Models Calibration – Case Study in the City of Split

The paper presents a comparison of the possibility and complexity of the calibration process of two microsimulation models. The first model CORSIM is simple for use while the second named S-Paramics is more complex software. For research purposes, a model of street network with defined geometry (number, width and purpose of lanes) has been made. The volume and distribution of traffic as well as the data about traffic signals were input in the models. Numerous simulations were performed, first with the default parameters of models, and then with the calibrated parameters. Both programs have resulted in very good prediction of the intersection capacity and discharge volumes. However, for the calibration of speed more time and effort have been made in S-Paramics in which the average speed may be higher than the defined free-flow speed. This can present a problem in determining the level of service and comparing the S-Paramics results with other simulation models and analytical method results. On the other hand S-Paramics has greater capabilities than CORSIM (roundabouts modelling, dynamic traffic assignment, opportunity to interact with traffic signals...). Thus, for each specific task, one should carefully choose an appropriate program which would result in necessary and reliable output data with minimum effort and time consumed