Study of vehicle speed in the design of roundabouts

Pojedini oblikovni elementi raskrižja s kružnim tokom prometa značajno utječu na brzinu kretanja vozila koja ima izravan utjecaj na razinu usluge i prometnu sigurnost raskrižja. U radu se kroz prikaz četiri urbana jednotračna kružna raskrižja grada Zagreba, analizira brzina in situ kao značajan element pri projektiranju kružnih raskrižja. Za definiranje i provjeru projektne brzine primijenjene su američka i australska metoda. Rezultati istraživanja dovode u korelaciju projektnu brzinu sa stvarno izmjerenom brzinom vozila na kružnom raskrižju.Some roundabout design elements significantly influence the vehicle driving speed, i.e. the trajectory of vehicles at roundabouts, which is directly responsible for the level of service and traffic safety at roundabouts. An "in situ" speed, taken as a significant roundabout-design element, is analysed in the paper using as an example four urban single-lane roundabouts located in the City of Zagreb. The American method and the Australian method are used for the definition and verification of the design speed at roundabouts. Results obtained show correlation between the design speed and the actual vehicle speed measured at roundabouts

THE REVALORISATION OF SECONDARY ROADS IN VELEBIT PODGORJE

Predočeno je opće stanje prometne infrastrukture i prometa u prostoru Velebitskog podgorja, s osvrtom na vremena nastanka povijesnih cesta, putova i staza. Ukazano je na važnije potencijale sekundarnih prometnica, koje bi trebalo vrjednovati u smislu opće ponude Velebita (turizam, sport, edukacijska komponenta…), ali isto tako u pogledu oživljavanja tradicionalnih vidova stvarnog života "in situ". Na tragu ovakvih postavki moglo bi se provesti modeliranje projekata za slučajeve zapuštenih povijesnih cesta (npr. cesta Jablanac – V. Alan – Štirovača, Majstorska cesta Obrovac – M. Alan – Sv. Rok) te projekata sezonsko-migracijskih staza od primorskih naselja do ljetnih stanova na plodnijim velebitskim lokalitetima (npr. staza Klada – Babrovača – Zavižan, Prizna – Mliništa – Šatorina, Cesarica – Radlovac – Dabrovi i sl.). Uz podsustav sekundarnih prometnica problematizirano je također stanje služnosti i sigurnosti prometa na Jadranskoj magistrali (turističkoj cesti) D-8 kao osnovnoj dužobalnoj poveznici Podgorja. Upozoreno je na loše stanje i potrebu što hitnije modernizacije cijele ceste od Senja do Maslenice, te na izvedbu obilaznice oko Sv. Jurja i Karlobaga. Isto tako je potrebno modernizirati poveznice do manjih naselja na obali (Lukovo, D. Klada, Starigrad itd.).The general condition of the transport infrastructure and traffic in the area of Velebit Podgorje is shown, with a reference to the times of the emergence of the historical roads, routes and paths. It is indicated in the more important potentials of secondary roads, which should be evaluated in the sense of the general offer of Velebit (tourism, sport, educational component...), but also with regard to the revival of traditional aspects of real life "in situ". Following on these kinds of assumptions, the modelling of projects could be carried out for the cases of neglected historical roads (e.g. the road Jablanac – V. Alan – Štirovača, the Majstorska cesta Obrovac – M. Alan – Sveti Rok) and the projects of seasonal-migratory paths from the littoral settlements to the summer dwellings on the more fertile Velebit localities (e.g. the path Klada – Babrovača – Zavižan, Prizna – Mliništa – Šatorina, Cesarica – Radlovac – Dabrovi and alike). Along with the subsystem of secondary roads also problematized is the condition of the access and safety of traffic on the main Adriatic highway – the magistrale – tourist road the D-8 as the basic coastal connection of Podgorje. The bad condition and the need of the very urgent modernisation the whole of the road from Senj to Maslenica is pointed out, as well as the construction of a bypass around Sveti Juraj and Karlobag. The connections to the smaller settlements along the coast (Lukovo, Donja Klada, Starigrad etc.) should also be modernised

An analytic hierarchy process model to evaluate road section design

The traffic system is as essential to modern society as the circulatory system to the human body. Road section design is therefore a key infrastructure activity for economic development, and multi-criteria decision-making can provide an interdisciplinary approach that moves beyond purely economic optimisation to include technological, technical and ecological factors. The present work describes applying the multi-criteria Analytical Hierarchy Process (AHP) method to evaluate road section design in an urban environment through differential weighting of various criteria and sub-criteria. The model is tested on a stretch of National Road D8 in the municipality of Podstrana near the city of Split (Croatia), which serves as an important route for commuters and tourists. The proposed AHP model provided reliable results that were robust to sensitivity analysis. This approach involving differential criterion weighting may prove useful for evaluating and selecting appropriate road section designs for this and other contexts. First published online: 30 Mar 201

Analysis of capacity of roundabouts in the city of Zagreb according to HCM C–2006 and Ning Wu Methods

Za proračun kapaciteta kružnih raskrižja u svijetu postoje razne metode. Pojedine metode su vrlo specifične i primjenjuju se u različitim zemljama za različite vrste kružnih raskrižja. U radu su prikazane dvije suvremene znanstvene metode za proračun kapaciteta kružnih raskrižja - metoda HCM C-2006 i metoda po Ning Wu-u. Uz pomoć metoda se prema stvarnim terenskim mjerenjima odvijanja prometnih tokova i uvjetima vožnje, analizirani su kapacitet raskrižja i pokazatelji efektivnosti (stupanj zasićenja, kontrola kašnjenja i duljina nakupljanja vozila). Analizom je obuhvaćeno 15 kružnih raskrižja koja se nalaze u urbanim i izvanurbanim područjima grada Zagreba. Rezultati bi trebali poslužiti kao osnova za daljnja sustavna istraživanja metodologije proračunavanja kapaciteta kružnih raskrižja na području Republike Hrvatske, ali i za mogući odabir određene inozemne metode uz potrebnu kalibraciju pojedinih koeficijenata određenih prema lokalnim uvjetima odvijanja prometnih tokova.There are various methods in the world for the calculation of the roundabout capacities. Some methods are very specific and implemented in different countries for different types of roundabouts. The paper presents two advanced scientific methods for the calculation of roundabout capacity – method HCM C-2006 and the method according to Ning Wu. Using the methods and according to the actual field measurements of traffic flows and driving conditions, the intersection capacity and the indicators of effectiveness (congestion level, delay control and vehicle queuing length) were analyzed. The analysis included fifteen roundabouts that are located in urban and suburban areas of the City of Zagreb. Results should also serve as basis for further systematic research of methodology for calculating the capacity of roundabouts in Croatia but also for possible selection of specific foreign method with calibration of certain coefficients according to local conditions of traffic flows

Some Experiences with Implementation of Roundabouts in Croatia / Požega

Suvremena sklonost sve većoj primjeni kružnih raskrižja nije zaobišla ni Hrvatsku, odnosno Požegu, ali bilo bi zanimljivo provesti savjesniju analizu njihove prometne i ambijentalno-estetske vrijednosti. Proceduralna je praksa da građevinsko-projektnoj dokumentaciji trebaju prethoditi višedisciplinarna prometna i urbanistička istraživanja, što se za slučajeve izbora kružnih raskrižja vrlo često ne provodi. Na osnovi najnovijih spoznaja u svijetu te nakon provedenih znanstvenih istraživanja na 30 lokaliteta u Zagrebu, moglo bi se procijeniti najbitnija kapacitivna i sigurnosna svojstva kružnih raskrižja u gradu Požegi i šire.The modern tendency to an increasing use of roundabouts is not bypassed nor Croatia nor our Požega, but it would be interesting to spend a conscientious analysis of their traffic and ambient-aesthetic values. Procedural practice that construction-project documentation should be preceded by multidisciplinary transportation and planning researches, as in cases of choice roundabouts are often not enforced. Based on the latest discoveries in the world and the scientific research conducted at 30 sites in Zagreb, one could estimate the most important capacitive and security features of roundabouts in the town of Požega and wider

Survey-based Impact of Influencing Parameters on Level Crossings Safety

Level crossing (LC) accidents are a significant safety challenge worldwide and for that reason they have been subject of numerous research activities. Joint conclusion is that human behaviour is the main cause of accidents. This study examines how and to which extent certain influential parameters cause accident mechanisms on level crossings. To gain the necessary data we used an on-line survey questionnaire that was sent internationally to key experts in the field of road and railway safety. A total of 185 experts were asked to rank how much certain parameters influence level crossings accident mechanisms and what are the best countermeasures for diminishing accidents at level crossings. To our knowledge, this is the first time that an international survey among key experts was used to gain necessary data about influential parameters regarding level crossings safety. The results of this study could be used by road and railway traffic engineers and policy makers for further enhancement of LC’s safety.</p

BEHAVIOUR ANALYSIS OF TRAFFIC PARTICIPANTS AT LEVEL CROSSINGS

Sa stajališta sigurnosti željezničko-cestovni prijelaz (ŽCP) kao mjesto neposrednog sučeljavanja željezničkog i cestovnog prometa točka je visokog rizika. Namjerno ili nenamjerno rizično ponašanje korisnika ŽCP-a glavni je uzrok izvanrednih događaja. Cilj ovoga rada jest utvrditi uzroke nepropisnog prelaženja pješaka i biciklista preko ŽCP-a te predložiti mjere prevencije. Istraživanjem se željelo utvrditi u kojim će situacijama pješaci i biciklisti nepropisno prelaziti preko pruge. Kako će na poštivanje prometnih propisa utjecati prisustvo službene osobe? Kako na poštivanje propisa utječe videonadzor? Utječu li edukativne kampanje na promjenu obrazaca ponašanja korisnika ŽCP-a? U ovome je istraživanju prvi su put primjenjivani kontinuirano videosnimanje i promatranje ponašanja korisnika željezničko-cestovnih prijelaza te anketno istraživanje, a u cilju utvrđivanja ponašanja sudionika u prometu na ŽCP-ima. Metodologija istraživanja primjenjena je na ŽCP-u Republike Austrije.From the aspect of traffic safety, level crossings (LC) are areas with increased risk for severe accidents. Intentional or unintentional risky behaviour of level crossing users is the main cause for all accidents. The main objective of this study is to determine the reasons for illegal pedestrian and cyclist crossing over LC and accordingly propose prevention measures. The study aim is to identify in which situations will pedestrians and cyclists illegally cross the tracks. How to road users affected by the presence of officials? How to road users affected by the presence of video surveillance? Do the educational campaigns can change behavior patterns of LC users? This is the first time for using survey and video surveillance for studying, describing and analysing correlation of nonmotorized LC users behaviour and TS on Croatian LCs. Research metodology is applyed on LC Republike Austrije

The influence of the European CiViTAS ELAN project on development of a better and sustainable public transport in the City of Zagreb

The CiViTAS Initiative is the EU response to the growing problems caused by traffic in European urban centres such as traffic congestion, noise, exhaust gases and difficult access to the city centre. The CiViTAS Initiative helps cities to test and develop an integrated set of measures for sustainable urban mobility. One of the projects is CiViTAS ELAN where five cities Ljubljana, Gent, Zagreb, Brno and Porto are cooperating. The goal of this project is to improve the quality of life for citizens and to implement better solutions in urban transport by promoting and enhancing sustainable, clean and energy efficient ways of transport. It is funded by the FP7 Programme and total duration of the project is 48 months from 2008 to 2012. As a part of CiViTAS ELAN, the City of Zagreb wants to discourage the use of cars by making public transport and cycling as a more attractive alternative. CiViTAS highlights in Zagreb are: decrease of traffic congestion, improvement of quality, accessibility and attractiveness of public transport, switch to cleaner modes of public transport, lower environmental impact of city fleet, inclusion of the existing railway into the city’s public transport system, improvement of cycling conditions and introduction of alternative modes of transport and mobility i.e. car pooling. The paper will present some measures and their results after three years of project implementation such as decreased congestion in pilot corridor along Savska street, decreased energy consumption and noise, improved public transport quality by purchasing 70 energy efficiency trams and 160 buses on gas or bio-diesel, e-ticketing, inter-modal solutions, etc

Policy and Programs for Cycling in the City of Zagreb – A Critical Review

Studying cycling traffic issues in a beginner city – City of Zagreb, stems from unclear development policy, an increase in cycling volume, a large number of traffic accidents, an inadequate infrastructure and legislation, a small number of high quality studies and published papers, and the question, did current cycling policy and programs advance cycling? A comprehensive search of available literature, including data from the Zagreb Traffic Department, was made. These data do not adequately address the direction of causality, such as whether current cycling policy and programs advance cycling or whether cycling demand led to increased levels of cycling. This review paper suggests that, it is not yet possible to evaluate which pro-bicycle packages are the most effective and, development of cycling traffic requires a coordinated holistic planning strategy. Results could serve as a beacon light for similarly sized beginner cities, especially those who are located in South-eastern and Eastern Europe