Vladan Tubić

Design and evaluation of a grade-separated intersection: a case study of the proposed Belgrade ‘Hipodrom’

This paper presents the evaluation results of three traffic solutions for the complex grade-separated intersection located in the old part of Belgrade at the junction with the new bridge over the Sava River. The corridor to which the intersection belongs together with the new river bridge are parts of a great urban artery called the Inner Half Semi-Ring Road (IHSRR). The traffic solutions that are evaluated are defined in the preliminary design phase, based on two opposed concepts: a complete grade separation of all intersection legs (the CPV alternative – ‘grade-separated’) and a grade separation designed to minimise construction costs (DMC 1 and 2 alternatives – ‘minimise cost’). The evaluation procedure is conducted in three steps: first, the score based on expert assessment of the functionality of the design solutions is determined; second, the alternatives are ranked according to the value of a set of state indicators obtained by micro-simulation using PTV–VISSIM 4.10; and third, the final score is obtained by multi-criteria evaluation using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. The results of the first evaluation step show a small advantage for DMC 2, a sub-alternative of the DMC 1 alternative. The results of the micro-simulation give advantage to the DMC 1 alternative. The multi-criteria evaluation provides a better ‘goodness factor’ for the CPV alternative against the DMC 1 alternative. At the same time, the least construction cost favours alternative DMC 1.

Straight Lane Saturation Flow and Its Rate In Serbian Cities

Abstract Saturation flow is the base rate in the procedure for optimizing traffic signal operation and determining the measure for effectiveness of intersection operation. Different approaches and structures of analytical value models indicate the complexity of the problem of determining the saturation flow value in real conditions. This paper presents the synthesis of the results and conclusions of studying the saturation flow rate phenomenon at signalised intersections in Serbia in the last thirty years, by applying various survey techniques. The surveys relate to straight lane saturation flow value, in the survey conditions mostly resembling the idealised conditions in which saturation flow can be generated. The obtained results indicate that there is a significant trend of changes in the base saturation flow value compared with those first referred in 1963 by Webster and Cobbe, change in the significance of impact factor on saturation flow value, and the necessity to determine them on the local level.

TRAFFIC FLOW CHARACTERISTICS AND CONDITIONS ON RURAL STATE ROAD NETWORK OF REPUBLIC OF SERBIA

U radu su prikazani rezutati generalne kvantitativne i kvalitativne analize promena potražnje (saobracajnih tokova) na primarnoj putnoj mreži Republike Srbije u periodu 1990-2016. godine. Analize se zasnivaju na dostupnim podacima sa automatskih brojaca saobracaja sa fokusom na promene saobracajnih zahteva na primarnoj vangradskoj putnoj mreži, odnosno promenom i podelom po klasam Prosecnog godisnjeg dnevnog saobracaja (PGDS) i transportnog rada. Posebno su analizirane promene saobracajnih tokova sa sezonskim varijacijama na Panevrospkom mulitmodalnom Koridoru X i njegovim kracima na teritoriji Srbije, odnosno glavnim potezima autoputeva, kojima se realizuje daljinski tranzitni saobracaj. U radu je sprovedena i Ex-post analiza transportnih zahteva na Koridoru X, sa ciljem utrvđivanja realno ostvarenih efekata i identifikacije svih odstupanja u vremenskoj dinamici. Analiza stanja potražnje zajedno sa analizom ponude (stanja putne mreže) predstavlja osnov za generalnu ocenu kvaliteta ponude (iskoriscenost kapaciteta, nivo usluge). To formira osnov za definisanje opstih zakljucaka i preporuka za buduce aktivnosti na nivou mreže.

Analysis of design hourly volumes in the procedures for creating project solutions of roads

U procesu planiranja, projektovanja i definisanja argumenata neophodnih za donosenje odluka o ulaganju investicija u predložena resenja puta ili mreže, znacajno mesto zauzimaju i faze vrednovanja projektnih resenja. Pod pojmom vrednovanje podrazumeva se definisanje argumenata na osnovu kojih se donose odluke od kojih zavisi hoce li, kada, gde i koja od planiranih resenja prerasti u realnost, ili ce ostati neostvarene ideje. Za efikasno izvrsavanje proracuna ukupnih koristi, u analitickim postupcima, znacajnu ulogu imaju merodavni parametri saobracajnog toka, a pre svega PGDS i merodavni saobracajni protoci. Međutim, problem se javlja u slucaju pogresnog koriscenja merodavnih protoka u fazama projektovanja i vrednovanja. Uputstva preporucuju i obavezuju analiticare da merodavne protoke analiziraju po klasama, sto je veoma retko rađeno u dosadasnjoj praksi. Iz tog razloga, u ovom radu je sprovedena generalna analiza merodavnih saobracajnih protoka na mreži puteva u Republici Srbiji za period od 2011. do 2015. godine. Poseban akcenat je stavljen na karakter saobracajnih tokova, vremenske neravnomernosti, distribuciju protoka po klasama i analizu eksploatacionih brzina u zavisnosti od merodavnih protoka i klasa casovnih protoka. Rezultati ovog rada bi trebalo da omoguce sprovođenje argumentovanijih analiza u fazama projektovanja, saobracajnom i ekonomskom vrednovanju putnih projekata.