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 mechanistic‐empirical modelling approach. Zagreb high‐capacity 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 – 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 izgrađenog okoliša Građevinskog fakulteta u Zagrebu

Građevinski fakultet pokrenuo je osnivanje centra izvrsnosti pod nazivom ‘’Centar za istraživanje i razvoj sigurnog i održivog izgrađenog okoliša’’ u Sveučilišnom kampusu Borongaj u Zagrebu. U Centru će se stvoriti uvjeti za znanstvena istraživanja u svim granama građevinarstva te će se omogućiti značajno poboljšanje znanstvenog i istraživačkog rada Građevinskog fakulteta. Isto tako, važnu kariku u razvoju građevinske struke i novih tehnologija te njihove primjene predstavlja suradnja fakulteta s gospodarstvom. Sudjelovanje u rješavanju najzahtjevnijih inženjerskih zadaća u građevinarstvu stvara uvjete za stjecanje novih stručnih znanja i iskustava koja se dalje prenose na studente te pružaju snažnu osnovu za prijenos inovativnih rješenja u građevinsku 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 zaštitu od buke s recikliranom gumom

RUCONBAR predstavlja novo, eko‐inovativno rješenje betonskih barijera za zaštitu od buke. Inovativan sastav i postupak dobivanja apsorbirajućeg sloja izrađenog od reciklirane otpadne gume razvijen je i patentiran na Građevinskom fakultetu u Zagrebu, a cjelokupna proizvodnja izvediva je u hrvatskim pogonima. Ovaj tip barijera se zasniva na ideji upotrebe recikliranih materijala u novom proizvodu, čime se donosi dobrobit u tri područja: (1) zaštiti od buke, (2) gospodarenju otpadom te (3) smanjenoj upotrebi prirodnih resursa

Noise level determination in train station zones

Određivanja stanja bučnosti u zonama željezničkih kolodvora svodi se na izradu modela proračuna što je zahtjevan postupak zbog potrebnog prikupljanja velikog broja podataka o utjecajnim parametrima. Opisan je postupak optimizacije izrade modela. Uspoređeni su rezultati proračuna prema mjerenjima na terenu na dva reprezentativna primjera. Rezultati dobiveni opisanim postupkom u odnosu na mjerenja na terenu pouzdani su, što je nužno za donošenje odluke o mjerama zaštite 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 tračnica na zagrebačkim je tramvajskim kolosijecima uvedena primjena tračnica s povećanom tvrdoćom glave. Prilikom savijanja takvih tračnica, za potrebe ugradnje u krivinama, došlo je do njihova pucanja. Kako bi se utvrdilo leži li razlog u neuobičajenim mehaničkim karakteristikama čelika tračnica, provedena su mjerenja tvrdoće temeljem kojih se proračunski definirala vlačna čvrstoća. Ispitivanja su pokazala da su izmjerene vrijednosti tvrdoće, iako znatno variraju duž poprečnog presjeka tračnice, veće od propisanih minimalnih vrijednosti. Može se pretpostaviti da problemi vezani uz ove tračnice mogu biti posljedica promjena u mikrostrukturi čelika zbog povećanja tvrdoće glave tračnice njezinom termičkom 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

Overview of modern track structures on solid basesIt is emphasized that the development of track structures on concrete and asphalt bases has mostly been motivated by the demand for higher speed, greater load capacity and better quality of geometrical relationships in the track. Track structures on solid bases, which are presently increasingly used in tunnels, on bridges and on high-speed railways, are analyzed. These tracks are compared with traditional track structures from the technical, economic and environmental aspects.

Istaknuto je da je razvoj kolosiječnih konstrukcija na betonskim i asfaltnim podlogama najviše potaknut zahtjevima za povećanjem brzina, opterećenja i kvalitetom geometrijskih odnosa u kolosijeku. Analiziraju se kolosiječne konstrukcije na čvrstim podlogama, koje se danas sve više primjenjuju na dijelovima kolosijeka u tunelima, na mostovima i na prugama za velike brzine. Uspoređene su s klasičnim kolosiječnim konstrukcijama s obzirom na tehničke, ekonomske i ekološke aspekte

Rail traffic noise and vibration mitigation measures in urban areas

Smanjenje buke i vibracija od tračničkog prometa pojmovi su koji se danas najviše koriste vezano za ugodno življenje u područjima smještenih neposredno uz željezničke pruge. Povišene razine buke i vibracija glavni su faktor nezadovoljstva, posebno stanovnika urbanih sredina. U radu je dan pregled i učinak mjera za smanjenje buke i vibracija koje se u najvećoj mjeri primjenjuju na mreži europskih tračničkih 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. Također, prikazani su rezultati istraživanja učinka primjene nekolicine mjera provedenih od strane Zavoda za prometnice Građevinskog fakulteta u cilju preciznijeg definiranja njihovog učinka 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 zaštitu od buke s recikliranom gumom

RUCONBAR predstavlja novo, eko‐inovativno rješenje betonskih barijera za zaštitu od buke. Inovativan sastav i postupak dobivanja apsorbirajućeg sloja izrađenog od reciklirane otpadne gume razvijen je i patentiran na Građevinskom fakultetu u Zagrebu, a cjelokupna proizvodnja izvediva je u hrvatskim pogonima. Ovaj tip barijera se zasniva na ideji upotrebe recikliranih materijala u novom proizvodu, čime se donosi dobrobit u tri područja: (1) zaštiti od buke, (2) gospodarenju otpadom te (3) smanjenoj upotrebi prirodnih resursa