46 research outputs found
Track Gauge Degradation Modelling on Small Urban Rail Networks: Zagreb Tram System Case Study
Track gauge is the most significant tram track geometry parameter. Its degradation, which manifests as gradual increase of gauge deviation from prescribed values during track exploitation, causes poor ride quality, reduces safety and triggers most of the maintenance activities. To optimize tram track maintenance procedures, it is necessary to increase the proportion of preventive maintenance at the expense of corrective maintenance. This requires creation of physical model of track degradation. Conducted survey of conventional track degradation models showed that, in order to quantify the influence of track design, construction and exploitation characteristics on gauge degradation, it is most favourable to adopt the mechanisticāempirical modelling approach. Zagreb highācapacity tram network presents an optimal testing ground for exploration of the possibilities for tram track gauge degradation model development. Analysis of modelling results gave new, practical insights about the effects of tram track design and construction elements and exploitation characteristics on gauge degradation. These models represent the first step towards predictive maintenance system establishment on Zagreb tram tracks
Analysis of Vehicle Vibrations ā New Approach to Rating Pavement Condition of Urban Roads
Urban road infrastructure is daily burdened by heavy traffic volume. Pavement structure roughness observations are significantly more difficult in urban agglomerations than on roads in unpopulated areas. Roughness, expressed by IRI (International Roughness Index), directly affects the quality and safety of road traffic. Within the framework of the pavement management in relation to safety and the achievement of the best possible ride comfort, it is very important to foresee when a road should be reconstructed. The method for quality evaluations of safety and ride comfort on urban roads presented in this paper is based on vehicle vibrations measurements. In the article, measuring of vehicle vibrations was performed on the main urban roads in Zagreb (Croatia). Measurements covered roads with different pavement surface roughness. This method can be simply and very easily used in pavement management aimed at achieving road safety and better ride comfort. The results of measurements according to this method could be used by traffic and civil engineering experts as an indication for the roads that require reconstruction or maintenance.
KEY WORDS: urban roads, traffic flow, safety, vehicle vibrations, road surface roughness (IRI
Razvoj Centra za istraživanje i razvoj sigurnog i održivog izgraÄenog okoliÅ”a GraÄevinskog fakulteta u Zagrebu
GraÄevinski fakultet pokrenuo je osnivanje centra izvrsnosti pod nazivom āāCentar za istraživanje i razvoj sigurnog i održivog izgraÄenog okoliÅ”aāā
u SveuÄiliÅ”nom kampusu Borongaj u Zagrebu. U Centru Äe se stvoriti uvjeti za znanstvena istraživanja u svim granama graÄevinarstva te Äe se omoguÄiti znaÄajno poboljÅ”anje znanstvenog i istraživaÄkog rada GraÄevinskog fakulteta. Isto tako, važnu kariku u razvoju graÄevinske struke i novih tehnologija te njihove primjene predstavlja suradnja fakulteta s gospodarstvom. Sudjelovanje u rjeÅ”avanju najzahtjevnijih inženjerskih zadaÄa u graÄevinarstvu stvara uvjete za stjecanje novih struÄnih znanja i iskustava koja se dalje prenose na studente te pružaju snažnu osnovu za prijenos inovativnih rjeÅ”enja u graÄevinsku praksu
Tram track maintenance-planning by gauge degradation modelling
Tram track system management is a complex, costly and interdisciplinary process. It involves construction, monitoring and maintenance of track infrastructure and rolling stock, and public transport organization. Track management cost reduction requires development of a modern management system that is based on integration and mutual complementarity of engineering and maintenance activities. The first step of its establishment is increasing the proportion of planned predictive-preventive track maintenance at the expense of corrective maintenance. This requires creation of a maintenance-planning model. Its basic prerequisite is the development of a mathematical model of tram track degradation during exploitation. The research presented in this paper describes the creation of mechanisticempirical models for tram tracks (narrow) gauge degradation by adopting the modelling methodology used on the classic railway constructions. Two types of tram tracks are observed: tracks with indirect elastic rail fastening system and stiffer direct elastic rail fastening system. These models represent the first step towards establishing a predictive maintenance system on Zagreb tram tracks
RUCONBAR betonske barijere za zaŔtitu od buke s recikliranom gumom
RUCONBAR predstavlja novo, ekoāinovativno rjeÅ”enje betonskih barijera za zaÅ”titu od buke. Inovativan sastav i postupak dobivanja apsorbirajuÄeg sloja izraÄenog od reciklirane otpadne gume razvijen je i patentiran na GraÄevinskom fakultetu u Zagrebu, a cjelokupna proizvodnja izvediva je u hrvatskim pogonima. Ovaj tip barijera se zasniva na ideji upotrebe recikliranih materijala u novom proizvodu, Äime se donosi dobrobit u tri podruÄja: (1) zaÅ”titi od buke, (2) gospodarenju otpadom te (3) smanjenoj upotrebi prirodnih resursa
Noise level determination in train station zones
OdreÄivanja stanja buÄnosti u zonama željezniÄkih kolodvora svodi se na izradu modela proraÄuna Å”to je zahtjevan postupak zbog potrebnog prikupljanja velikog broja podataka o utjecajnim parametrima. Opisan je postupak optimizacije izrade modela. UsporeÄeni su rezultati proraÄuna prema mjerenjima na terenu na dva reprezentativna primjera. Rezultati dobiveni opisanim postupkom u odnosu na mjerenja na terenu pouzdani su, Å”to je nužno za donoÅ”enje odluke o mjerama zaÅ”tite od buke.Determination of noise levels in train station zones is based on preparation of analysis models, which is a very demanding procedure because of a multitude of parameters that have to be collected in the process. The model optimization procedure is described. Calculation results are compared with on site measurements using two representative examples. In comparison with on site measurements, results obtained using the described procedure have proven to be reliable, which is indispensable for making appropriate decisions on measures to be taken in the sphere of noise protection
Hardness distribution over cross-section of grooved rails
Radi produljenja ciklusa zamjene traÄnica na zagrebaÄkim je tramvajskim kolosijecima uvedena primjena traÄnica s poveÄanom tvrdoÄom glave. Prilikom savijanja takvih traÄnica, za potrebe ugradnje u krivinama, doÅ”lo je do njihova pucanja. Kako bi se utvrdilo leži li razlog u neuobiÄajenim mehaniÄkim karakteristikama Äelika traÄnica, provedena su mjerenja tvrdoÄe temeljem kojih se proraÄunski definirala vlaÄna ÄvrstoÄa. Ispitivanja su pokazala da su izmjerene vrijednosti tvrdoÄe, iako znatno variraju duž popreÄnog presjeka traÄnice, veÄe od propisanih minimalnih vrijednosti. Može se pretpostaviti da problemi vezani uz ove traÄnice mogu biti posljedica promjena u mikrostrukturi Äelika zbog poveÄanja tvrdoÄe glave traÄnice njezinom termiÄkom obradom.Head hardened rails have been introduced In order to extend the rail-replacement cycles for Zagreb tram tracks. During their precurving, the rail cracking occurred. Hardness tests were performed and tensile strength was calculated to establish whether unusual mechanical properties of rail steel are responsible for the cracking. Tests have shown that hardness values, despite significant variation over the rail cross-section, are higher than the prescribed minimum. It is assumed that rail problems encountered may be due to changes in rail steel microstructure resulting from an increase in rail head hardness during its thermal treatment
Rail traffic noise and vibration mitigation measures in urban areas
Smanjenje buke i vibracija od traÄniÄkog prometa pojmovi su koji se danas najviÅ”e koriste vezano za ugodno življenje u podruÄjima smjeÅ”tenih neposredno uz željezniÄke pruge. PoviÅ”ene razine buke i vibracija glavni su faktor nezadovoljstva, posebno stanovnika urbanih sredina. U radu je dan pregled i uÄinak mjera za smanjenje buke i vibracija koje se u najveÄoj mjeri primjenjuju na mreži europskih traÄniÄkih sustava, a koje bi se uvelike mogla primijeniti i na mreži hrvatskih željeznica, gdje se problemu buke i vibracija do sada nije pridavala velika pažnja. TakoÄer, prikazani su rezultati istraživanja uÄinka primjene nekolicine mjera provedenih od strane Zavoda za prometnice GraÄevinskog fakulteta u cilju preciznijeg definiranja njihovog uÄinka u lokalnim uvjetima.Today, reduction of rail traffic noise and vibration is a widely used concept for improving the life standard in vicinity of railway lines. Elevated levels of noise and vibration are the main factors of dissatisfaction, especially in urban areas. The paper reviews the effectiveness of noise and vibration mitigation measures applied to the network of European railway systems. These measures could also be applied to Croatian railways network where the issue of noise and vibration has not been addressed so far. Also, the paper presents research results of the application of several mitigation measures performed by the Department for Transportation at the Faculty of Civil Engineering, aimed at increasing the impact definition of their performance in local conditions
RUCONBAR betonske barijere za zaŔtitu od buke s recikliranom gumom
RUCONBAR predstavlja novo, ekoāinovativno rjeÅ”enje betonskih barijera za zaÅ”titu od buke. Inovativan sastav i postupak dobivanja apsorbirajuÄeg sloja izraÄenog od reciklirane otpadne gume razvijen je i patentiran na GraÄevinskom fakultetu u Zagrebu, a cjelokupna proizvodnja izvediva je u hrvatskim pogonima. Ovaj tip barijera se zasniva na ideji upotrebe recikliranih materijala u novom proizvodu, Äime se donosi dobrobit u tri podruÄja: (1) zaÅ”titi od buke, (2) gospodarenju otpadom te (3) smanjenoj upotrebi prirodnih resursa