Dynamic loss balancing and sequential enhancement for road-safety assessment and traffic scene classification

Road-safety inspection is an indispensable instrument for reducing road-accident fatalities contributed to road infrastructure. Recent work formalizes road-safety assessment in terms of carefully selected risk factors that are also known as road-safety attributes. In current practice, these attributes are manually annotated in geo-referenced monocular video for each road segment. We propose to reduce dependency on tedious human labor by automating recognition with a two-stage neural architecture. The first stage predicts more than forty road-safety attributes by observing a local spatio-temporal context. Our design leverages an efficient convolutional pipeline, which benefits from pre-training on semantic segmentation of street scenes. The second stage enhances predictions through sequential integration across a larger temporal window. Our design leverages per-attribute instances of a lightweight bidirectional LSTM architecture. Both stages alleviate extreme class imbalance by incorporating a multi-task variant of recall-based dynamic loss weighting. We perform experiments on the iRAP-BH dataset, which involves fully labeled geo-referenced video along 2,300 km of public roads in Bosnia and Herzegovina. We also validate our approach by comparing it with the related work on two road-scene classification datasets from the literature: Honda Scenes and FM3m. Experimental evaluation confirms the value of our contributions on all three datasets.Comment: This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

Expression of GNSS Positioning Error in Terms of Distance

This manuscript analyzes two methods for Global Navigation Satellite System positioning error determination for positioning performance assessment by calculation of the distance between the observed and the true positions: one using the Cartesian 3D rectangular coordinate system, and the other using the spherical coordinate system, the Cartesian reference frame distance method, and haversine formula for distance calculation. The study shows unresolved issues in the utilization of position estimates in geographical reference frame for GNSS positioning performance assessment. Those lead to a recommendation for GNSS positioning performance assessment based on original WGS84-based GNSS position estimates taken from recently introduced data access from GNSS software-defined radio (SDR) receivers

Traffic flow modelling on the road network in the cities

Planiranje cestovne prometne infrastrukture je složen proces. Jedan od najvećih problema je određivanje projektnih elemenata cestovne infrastrukture (vrsta ceste i broj prometnih traka, poprečni profil i sl). Za potrebe dimenzioniranja prometnica koriste se parametri iz strane literature s vrijednostima koje su empirijskim metodama derivirane iz lokalnih podataka o prometnom toku (najčešće sjevernoamerički gradovi). Cilj ovog rada bio je istraživanje prometnih tokova radi izrade modela koji će pružiti mogućnost egzaktnijeg opisa lokalnih karakteristika prometnih tokova na području srednjoeuropskih gradova. Istraživanje osnovnih parametara prometnog toka sastojalo se od izbora lokacije cesta, vremena snimanja, snimanja prometa, analize video zapisa istatističke analize i proračuna osnovnih parametara prometnog toka. Posebnost provedenog istraživanja sadržana je u načinu prikupljanja i analizi podataka za svaki prometni trak (ili kolnik) radi uočavanja razlike u vrijednostima osnovnih parametara prometnih tokova. Istraživanje je obavljeno na različitim gradskim prometnicama i u različitim prometnim uvjetima te su dobiveni osnovni parametri prometnog toka. Pomoću tih parametara napravljeni su dijagrami odnosa brzine, gustoće i propusne moći i dobivene su kumulativne funkcije parametara prometnih tokova za cjelokupnu prometnu mrežu grada. Time je omogućeno da se izrade nove jednadžbe pomoću kojih je moguće teoretski odrediti kapacitet, brzinu i gustoću toka prometnice.Razvijena metoda kao i rezultat ovog znanstvenog istraživanja pouzdan je, koristan i primjenljiv alat za određivanje kriterija propusne moći ceste i proračun vrijednosti relevantnih koeficijenata mjerodavnih za dimenzioniranje poprečnog presjeka cesta u urbanim sredinama, ali i svih ostalih kategorija cesta.Planning of road transport infrastructure is a complex process. One of the major issues is determining the design elements of road infrastructure (road type and number of traffic lanes, cross-sectional profile, etc.). When designing roads, parameters from the international literature are used, containing values derived empirically from local data on traffic flow (mostly from northern American cities). The goal of this paper was to explore traffic flows for the purpose of developing a model that will enable scientifically exact description of traffic flows in urban areas of Central Europe. Study of basic parameters of traffic flow included the selection of road location, survey time, traffic survey, analysis of video recordings, as well as statistical analysis and calculation of basic parameters of traffic flow. Added value of this research is demonstrated through the method of collecting and analysing the data for each lane (or roadway) separately in order to detect the difference in the values of the basic parameters of traffic flows. The research was conducted on various urban roads and in various traffic conditions and in this way the basic parameters of traffic flow were obtained. These parameters were used to develop diagrams of relations between speed, traffic density and volume, resulting in cumulative functions of traffic flow parameters for the entire urban traffic network. This made it possible to develop new equations enabling theoretical determination of flow volume, speed and density for a given road. Methods established in this work and the results of the research present a useful and applicable tool for benchmarking road capacity and finding relevant coefficients significant for dimensioning the road cross-sections in urban areas, but also on all other categories of roads

Harmonization and synchronization model of interrupted traffic flows on motorways

The research in this paper focuses on harmonization and synchronization of traffic flows in the period of application of zonal temporary traffic regulation. The specific case scenario addressed in this research implicates that on both carriageways no vehicles were allowed to reside in the work zones for a significant time interval in the same time periods on both sections. In order to solve this problem, the model for harmonization of the traffic flows on dual carriageway motorways with synchronization of opposing traffic flows on both carriageways in special traffic conditions is presented. Actual traffic situation that occurred is presented in order to demonstrate the model, where intensive traffic flows were interrupted on both carriageways during extensive road works on two nearby sections. The model described in this paper has several stages. The first stage implies detailed analysis of traffic flows with computation of expected number of vehicles in the queue. The next stage in the modelling process is to calculate the queue discharge time for both directions and propose measures to optimise operating speed in order to maximize capacity. Then, a graphical method by means of two-way coordination diagram is used to synchronise stop signal timings on all closed sections. This paper shows results of a new model that was developed and implemented in real situations in most complex conditions that can occur on motorways. The research findings have shown the suitability of the proposed model. First published online 24 October 201

The Concept of Sustainable Traffic System Development in the Bjelovar-Bilogora County

Kreiranje dugoročne strategije razvoja prometa uspostavljanjem održivog prometnog sustava strateški je interes svake države, njezinih regija te svakog naselja i grada. U središtu mora biti podizanje kvalitete života građana i posjetitelja uz osiguravanje bolje mobilnosti svim korisnicima prometnog sustava. Grad Bjelovar i Bjelovarsko-bilogorska županija geoprometno su vrlo povoljno smješteni, ali razvoj prometnog sustava nije iskoristio pun potencijal te pozicije, tako da strateški i ekonomski važni prometni pravci u smjeru istok – zapad te u smjeru od sjevera prema jugu ne prolaze kroz tu regiju. U ovom radu analizirane su prostorno-prometne karakteristike Grada Bjelovara i Bjelovarsko-bilogorske županije uz spoznaju potencijala za održivi prometni razvoj i kvalitetniju integraciju na okolnu prometnu mrežu. Zaključci provedene analize predstavljaju osnovne postavke za definiranje daljnjeg razvoja održivog prometnog sustava Grada Bjelovara i Bjelovarsko-bilogorske županije. Ekonomski i društveni razvoj Grada Bjelovara i Bjelovarsko-bilogorske županije uvjetovani su kvalitetnim cestovnim i željezničkim vezama te je nužno realizirati nove i poboljšati postojeće pravce u smjeru istok – zapad i sjever – jug. Uz povezivanje Bjelovarsko-bilogorske županije s državnim i međunarodnim prometnim pravcima prioritetno je unaprijediti unutarnji prometni sustav Županije. Važno je kvalitetno i na održiv način povezati Grad Bjelovar s ostalim županijskim gradskim središtima u skladu s postojećom i budućom prometnom potražnjom. Grad Bjelovar, kao sjedište Županije, mora biti primjer ostalim gradskim središtima načinom upravljanja prometnim sustavom s ciljem razvitka samoga grada i cijele Bjelovarsko-bilogorske županije.Creating a long-term traffic development strategy by introducing a sustainable traffic system represents a strategic interest of any country, its regions, settlements, towns and cities. In the focus thereof ought to be raising the quality of life of inhabitants and visitors, and ensuring a better mobility for all the users of the traffic system. The City of Bjelovar and the Bjelovar-Bilogora County are very favourably positioned in the geographical and traffic-related sense; nevertheless, the process of the development of the traffic system has not used the full potential of this position. Hence, the strategically and economically important traffic lines oriented East–West and North–South detour this region. This paper analyses the spatial and traffic features of the City of Bjelovar and the Bjelovar-Bilogora County, taking thereby into consideration the potentials for sustainable traffic development and higher-quality integration in relation to the traffic web surrounding this area. The conclusions reached as a result of the conducted analysis present basic tenets needed for defining the follow-up development of a sustainable traffic system of the City of Bjelovar and the Bjelovar-Bilogora County. Since the economic and social development of the City of Bjelovar and the Bjelovar-Bilogora County has been enabled by quality road and railway connections, it is necessary to launch new and improve the present traffic lines oriented East–West and North–South. In addition to connecting the Bjelovar-Bilogora County with national and international traffic lines, the priority lies in improving the internal County traffic system. It is crucial to solidly and sustainably connect the City of Bjelovar with other towns in the County, depending on and in relation to the existing and future traffic-related demand. The City of Bjelovar, being the County centre, ought to set an example for other towns by choosing the best way to manage the traffic system, aimed at achieving the development of the city itself and of the whole Bjelovar-Bilogora County

Using IRAP methodology when selecting traffic accidents caused by road vehicles driver fatigue

SAŽETAK: Korištenjem samo klasičnih metoda zasnovanih na izračunu objektivnog statističkog rizika nakon ekspertiza prometnih nesreća vrlo je teško pouzdano izdvojiti one za koje je mogući uzrok umor vozača cestovnih vozila. IRAP metodologija može bitno pomoći u boljem izdvajanju prometnih nesreća za koje je vjerojatni uzrok umor vozača, jer se iRAP metodologijom može brzo i objektivno procijeniti statička sigurnost prometne infrastrukture, a onda i isključiti kao mogući uzrok. Prema dinamičkom otvorenom Fullerovom TCI modelu „zahtjev zadaće-sposobnost vozača“, vozači dominantno određuju željenu razinu težine zadaće tijekom vožnje odabirom brzine, što u slučaju odabira nedopuštene brzine ili brzine neprilagođene uvjetima na cesti između ostaloga može ovisiti i o tome je li vozač umoran ili ne. Na primjeru šest prometnih nesreća na autocestama u Republici Hrvatskoj, izdvojenih statističkom obradom prema karakterističnim kriterijima iz recentne znanstvene literature, pokazat će se kako se primjenom iRAP metodologije odrednice prometne infrastrukture iz skupine čimbenika „prometni okoliš“ mogu potpuno isključiti kao uzrok prometne nesreće. Što točnije izdvajanje prometnih nesreća cestovnih vozila za koje je mogući uzrok umor pomoći će kolegama istraživačima iz ostalih znanstvenih područja istražiti karakteristične čimbenike prometnih nesreća povezanih s umorom, a zbog predlaganja mjera za smanjivanje utjecaja umora na izvedbu vozača.Using only classical methods based on the calculation of objective statistical risk after the traffic accident expertise, it is very difficult to select the traffic accidents that were probably caused by fatigue of road vehicle drivers. The iRAP methodology can significantly assist in the selection of road traffic accidents which were probably caused by the driver\u27s fatigue, because by using the iRAP methodology the static safety of road infrastructure elements can be quickly and objectively evaluated, and then excluded as a possible cause of a traffic accident. According to dynamic and open TCI Fuller\u27s model “task demand - driver\u27s capability”, drivers dominantly influence the desired level of task demand while driving by choosing the speed, which in the case of choosing the unacceptable speed or speed unsuited for the environmental conditions on the road, among the rest, may depend on whether the driver is under the influence of fatigue. On the example of six traffic accidents that occurred on motorways in the Republic of Croatia and were selected for statistical analysis by characteristic criteria from the recent scientific literature, it will be presented how by using the iRAP methodology the factors of road infrastructure from the group of “traffic environment” factors can be completely excluded as the cause of traffic accidents. The more accurate selection of road traffic accidents that were caused by driver’s fatigue will help researchers from other scientific fields to select and explore the characteristic factors of fatigue-related traffic accidents in order to suggest measures to reduce the fatigue effect on the driver\u27s performance

Analytic Determination of Reference Passenger Car Size for Parking Space Dimensioning in Croatia

Dimensions of parking spaces have been subject to standardization in recent decades in the world. Different state institutions and standardization committees regulated parking space sizes based on typical passenger car size and ergonomic conditions. Most of these regulations are not following the notable growth in size of passenger cars that has been the case in the past 30 years. In that period in Croatia, a significant increase was also observed in the number of passenger cars in mid-sized and large passenger car classes thus emphasising the problem of outdated and inadequate parking space dimension standard. In this paper an analytic procedure is presented that takes into account the number and types of passenger cars registered in Croatia that leads to the determination of reference passenger car size. This reference values, as well as other relevant ergonomic standards are used to calculate the recommended parking space dimensions in Croatia. The purpose of this analysis is to produce new recommendations and suggest new design standards for parking spaces in Croatia as well as to provide analytic procedures to conduct similar researches in other areas

Transportation Costs and Subsidy Distribution Model for Urban and Suburban Public Passenger Transport

Public transport (PT) subsidy provides the means to impose the optimal combination of fare and Level of Service (LoS) offered to passengers. In regions where one PT operator services multiple local communities on multiple lines it becomes hard to uniformly link the actual cost of a line and thus the LoS offered, to a particular local community. This leads to possible disproportions in the overall subsidy distribution that can result in being unfair to some local communities, mainly the ones that are sparsely populated or geographically isolated. In order to extricate this problem the appropriate level of PT subsidisation according to the average values in the European cities was investigated and the current subsidy policies in Croatia were investigated. Based on this research and the hypothesis that the offered LoS must be reflected in the subsidy amount a new subsidy distribution model was established that involves a series of analytical procedures and processes. This model introduces several factors used for the calculation of the actual share in costs. Thus, the amount of subsidies for individual lines in a region can be determined based on the actual service offered to the local community, The proposed model has been tested and successfully implemented in the Dubrovnik-Neretva County in the Republic of Croatia

Conceptual Model for Determining the Statistical Significance of Predictive Indicators for Bus Transit Demand Forecasting

This article addresses the possibility of improving the traditional bus passenger demand forecasting models by leveraging additional data from relevant big data systems and proposes a conceptual framework for developing big data-based forecasting models. Based on the data extracted from available big data systems, the authors have developed a conceptual procedural framework for determining the significance of statistical indicators that can potentially be used as predictor variables for forecasting future passenger demand. At the first stage of the proposed framework, the statistical significance of partial linear correlations between observed statistical indicators and bus ridership demand are determined. All statistical indicators identified as potentially significant are further tested for multicollinearity, homoscedasticity, autocorrelation and multivariate normality to determine the suitability of their inclusion in the final equation of the prediction model. The final formulation of the predictive model was developed using stepwise regression. The R programming language was used to implement the proposed procedural framework to develop a model suitable for predicting passenger demand on the Prizren-Zagreb international bus route. Two predictor variables identified as the most statistically significant are the population of Kosovo and the annual number of Kosovo citizens crossing the Croatian border by bus