1,721,187 research outputs found
Quantifying the role of disturbances and speeds on separated bicycle facilities
Full text linkAs cities aim to spur cycling, a key issue revolves around the location and quality of separated bicycle facilities. However, sometimes owing to impedances, these facilities fail to have the desired overall utility for cyclists. This study focuses on the role of non-stationary disturbances, i.e., the presence of users of other modes. The aim is to quantify the effects and frequencies of disturbances on off-street bicycle facilities (from other cyclists and pedestrians) and compare them to disturbances (from motorized vehicles) while cycling in mixed traffic. Using three segments in Bologna, Italy, we measured the frequency, type, and speed reduction attributed to different types of disturbances. We analyzed speed and likelihood of events to calculate a weighted average of the cyclists’ speed for separated bicycling facilities and on the roadway. For two of the segments, weighted speed reductions were minimal. However, in a third segment—one with considerably more disturbances—speed reductions were considerable: 20 percent for the separated facility and 40 percent for the mixed traffic. When married with cycling use patterns along the facilities, the notable speed reductions point to a possible trade-off cyclists make in choosing between different routes. The results help quantify relationships between cyclists and non-stationary disturbances; they also caution transport officials about possible unintended outcomes for separated bicycle facilities.Bernardi, Silvia; Krizek, Kevin J.; Rupi, Federico. (2016). Quantifying the role of disturbances and speeds on separated bicycle facilities. Retrieved from the University Digital Conservancy, 10.5198/jtlu.2015.715
Performance Evaluation of Extreme Bicycle Scenarios
No full textAbstractThis present work evaluates the performance of extreme bike scenarios for partners-cities of the Central Europe project “BICY”. With extreme bike scenarios we mean that a city has implemented the best possible conditions for cycling. Our analyses confirm that approximately half of all urban trips are less than five km and could be done by bike. Some cities in the Netherlands have shown that bike mode shares of 40% and higher can be achieved. The question is how much cycling infrastructure and investments are required to convert a city into a top cycling city and what would be the benefits?For the purpose of establishing a quantitative relation between infrastructure investments, increase in cycling and effects on the environment and health, we reduce the cycling conditions to the presence of cycling infrastructure. It is shown that such a reduction is a conservative assumption as promotion, mobility management and education are low cost measures to increase bike mode share even without expanding the cycling network. The health benefits have been calculated using the HEAT framework developed by the World Health Organization. This is a standard to determine the costs of lives saved due to reduced mortality as a consequence of more physical exercise.Gathering official data and detailed information from mobility surveys in 13 central European cities with low to medium-high cycling levels, we have estimated the potential bike share with an average of approximately 50%, the required cycling infrastructure necessary to reach the potential between 30 and 370km of exclusive bikeways and cycling infrastructure costs between 10-60Million. The expected benefits/cost ratios have been found between 1.2 and 15, average 5.7. However, analyse of current stated preferences show that the share of persons willing to start cycling is far less than the potential, even if ideal cycling conditions were provided
Caratteristiche generali del sistema di trasporto aereo e potenziali fattori di sviluppo degli aeroporti regionali italiani
No full textNegli ultimi cinquanta anni il traffico aereo mondiale ha conosciuto un incremento elevatissimo, nettamente superiore, in termini di tasso di crescita, rispetto a quello degli altri sistemi di trasporto. La domanda di trasporto aereo mondiale ha costantemente seguito lo sviluppo economico: registrando tassi di crescita mediamente doppi rispetto a quelli del prodotto interno lordo mondiale. La crescita economica determina un aumento degli scambi di merce e di servizi, inoltre con l’aumento del reddito pro-capite crescono i viaggi per svago. Il sistema di trasporto aereo ha inoltre conosciuto un tasso di evoluzione tecnologica superiore a quello degli altri sistemi di trasporto: questo ha permesso di diminuire i costi di produzione del servizio. Un’influenza, forse ancora maggiore, sulla diminuzione dei costi, e delle tariffe, è stata determinata, a partire dagli anni 80, dell’avanzamento del processo di liberalizzazione del mercato del trasporto aereo, e, più recentemente, dall’entrata nel mercato di compagnie caratterizzate da nuove modalità di gestione: le compagnie “low-cost”. Le compagnie “low-cost” sono da molti considerate il migliore “prodotto” del processo di liberalizzazione e la loro affermazione è considerata una “rivoluzione” nei servizi di trasporto aereo. La nota mette in evidenza come il mercato del trasporto aereo italiano abbia seguito sostanzialmente l’evoluzione di quello mondiale: più che triplicando i passeggeri negli ultimi venti anni. Inoltre deve essere rilevato che nel caso italiano il rapporto tra il tasso di crescita della domanda di trasporto aereo e quello del PIL è stato pari a circa 3. .
Successivamente nella nota sono esaminate le caratteristiche del servizio di trasporto offerto dalle compagnie aeree tradizionali e da quelle di tipo “low-cost”. Le prime sono caratterizzate da un servizio basato su reti di tipo “hub-and-spoke”, le seconde da un servizio basato su reti di tipo punto-punto. La nota descrive le caratteristiche principali del servizio offerto agli utenti dalle compagnie “low- cost” a proposito di: tariffe, vendita biglietti, servizi a bordo, frequenza e puntualità dei voli. Sono quindi esaminate le caratteristiche delle compagnie low- cost da un punto di vista operativo a proposito di: aeromobili utilizzati, tratta di servizio, aeroporti utilizzati, gestione del personale. Le compagnie di tipo “low-cost” puntano a servire soprattutto passeggeri con bassa disponibilità di spesa per i quali il confort di viaggio non risulti un attributo chiave del servizio. Il successo del modello di “business” delle compagnie di tipo “low-cost” è ormai fuori discussione : anche negli anni caratterizzati da una congiuntura sfavorevole, queste compagnie sono state in grado di produrre profitti. Nella memoria sono quindi affrontate le caratteristiche delle reti di tipo “hub–and-spoke” . Questo tipo di rete si è affermato, fra le compagnie tradizionali, negli anni 80 in seguito alla deregolamentazione del mercato del trasporto aereo. Un rete di tipo “hub-and-spoke” richiede: un elevato grado di concentrazione spaziale della struttura di rete; il coordinamento temporale dell’orario dei voli all’”hub” secondo il sistema delle onde; l’integrazione dei servizi via “hub”. I principali requisiti che deve possedere un “hub” sono: centralità geografica rispetto al mercato da servire; elevata capacità fisica del sistema delle piste; elevata capacità ambientale del sistema delle piste; condizioni meteo che consentono un elevato livello di utilizzazione dello scalo; elevato domanda in origine e destinazione da/per l’”hub”; presenza di una compagnia che decida di operare con servizio ad “onde” Nella nota è quindi definita l’”onda ideale” : complesso di voli in arrivo ed in partenza, entro una determinata fascia oraria, tale che ciascun volo in arrivo possa stabilire una connessione, con ciascun volo in partenza, che possa essere effettivamente prenotata dai passeggeri. Nel lavoro sono quindi esaminati i vantaggi delle reti “hub-and spoke” e di quelle punto-punto. Il principali vantaggi di una rete “hub-and-spoke”, in un ambiente competitivo, sono: l’alto numero di coppie O/D che possono essere servite, rispetto ad una rete punto-punto, a parità di voli; la possibilità di esercitare potere monopolistico agli aeroporti “hub” (si parla a questo proposito di hub “fortificati”). Rispetto alle reti punto-punto quelle “hub-and spoke” hanno il problema di elevati picchi di domanda che provocano un aumento dei costi dell’utilizzo delle risorse infrastrutturali e umane. L’aumento dei costi è messo in evidenza dal fatto che le compagnie “low-cost” non praticano l’”hubbing”. Nella memoria è anche affrontato la novità in campo aeronautico rappresentata de “regional jet”. Questo tipo di aereo, da 30-100 posti, ha una velocità più elevata ed un impatto acustico minore rispetto ai turboelica che precedentemente costituivano la tipologia più diffusa di aerei “regional”. I “regional jet” inoltre possono operare su piste corte.
La memoria si conclude con l’osservazione che, nel quadro di evoluzione dei servizi di trasporto aereo descritto, possono essere individuate le opportunità di sviluppo degli aeroporti regionali, ed, in particolare, di quelli italiani. Infatti le compagnie aeree tradizionali, grazie anche alla diffusone dei “regional jet”, vedono nello sviluppo degli aeroporti regionali il modo di alimentare il traffico, in particolare a lunga percorrenza, sui loro grandi aeroporti “hub”. D’altra parte le compagnie “low- cost” trovano negli aeroporti regionali dei terminali di viaggio fondamentali in quanto: non congestionati, poco costosi e con domanda di trasporto aereo non soddisfatta. Lo sviluppo degli aeroporti regionali permetterebbe una maggiore diffusione del trasporto aereo nel territorio e perciò un aumento dell’accessibilità; inoltre permetterebbe una più equa distribuzione dei traffici tra grandi aeroporti, che sono quasi tutti al limite della saturazione, in particolare da un punto di vista ambientale, e scali secondari che molto spesso hanno riserve di capacità fisica ed ambientale. Inoltre una più capillare diffusione del servizio aereo nel territorio italiano può condurre ad importanti occasioni di sviluppo di aree territoriali marginali. In questo quadro, di evoluzione e di opportunità, concludono gli autori della nota, appare particolarmente opportuna la messa a punto di metodi e modelli quantitativi finalizzati alla programmazione ed allo sviluppo dei sistemi aeroportuali regionali ed in particolare di quello italiano
Map-matching algorithm applied to bicycle global positioning system traces in Bologna
No full textA novel map-matching algorithm is proposed, implemented and applied to global positioning system (GPS) traces which have been recorded by cyclists in Bologna, a medium-sized city in the North of Italy. The algorithm has been developed to match geo-referenced traces to a sequence of edges of a given road network model. Map-matching for bike trips is particularly challenging as cyclists often use footpath or parks which are not necessarily represented by the road network model. The matching algorithm should smartly tolerate the lack of network information. The algorithm should also be fast and capable of processing thousands of GPS traces in a reasonable time. The proposed probability-based method, which also exploits information on various network attributes, allows a reliable and fast map matching, even in dense street networks and with interrupted GPS data streams. In fact, one serious issue is to find a reliability measure which allows to verify the matched routes, without the knowledge of the real routes, as the available cyclist traces are anonymous. In addition to the reliability check, a sensitivity analyses with respect to the most relevant parameters has been conducted. The advantages of the proposed map-matching algorithm are quantified through a direct comparison with a topology-based map-matching algorithm from literature
Traffic surveys and GPS traces to explore patterns in cyclist’s in-motion speeds
Full text linkSpeed and travel time of cyclists play important roles in the cyclist’s route choice and therefore there is a growing need on estimating the dynamic attributes of cyclists. Being able to quantify bicycle speeds on various facilities can help provide suitable accessibility measures based on estimates of travel time by bicycle and to calibrate and validate microsimulation models of cyclist’s behavior. Route choice and speed profiles may vary significantly among cyclists, depending on infrastructure characteristics as well as their personal characteristics (e.g., physical fitness and risk perception). The aim of this paper is to quantify how the personal and network attributes influence the cyclist’s speed, combining a big data sample of 270,000 GPS traces recorded in the city of Bologna, Italy, with a manual traffic survey. The novelty of the study regards the application to the data set of an algorithm that estimates travel times from map matched GPS traces and associates them with infrastructure attributes, after a successful validation of the data sample with manual observations and after testing its representativeness. The algorithm first estimates cyclist’s trip waiting times and those recorded on specific infrastructure elements from the GPS traces – which represents an innovation in the literature - and then obtains travel time as a difference with the trip duration. Results are sometimes different from those obtained in other studies, show a high correlation between the cyclist’s dynamic attributes and both cyclist’s typology and infrastructure attributes. The most interesting results are that average travel speed increases with road width, the number of lanes, road length and road priority. In the case study, average speeds on larger roads shared with motorized vehicles are even greater than those on separate level bikeways, which contradict previous studies. Male cyclists record on average an 11% higher speed than women, and faster cyclists have an age between 25 and 35 years old. Frequent cyclists are on average 5% faster than infrequent cyclists and cyclists even increase the average speed during rush hour of approximately 2%, without being affected by traffic congestion
A macroscopic analysis of transport networks: the influence of network design on urban transportation performance
No full textThis research aims at investigating the direct and indirect influence of network structures on urban transportation performance with a macroscopic perspective. Transport systems are complex – the functional properties of a transportation network can affect mobility patterns which in turn changes the network performance. Understanding the topology of transportation networks is important in order to upgrade transport network design and to improve transportation performance. This paper attempts to determine important network indicators such connectivity, centrality and clustering measures for different network types (road, rail and bike) from 86 urban areas and 32 countries, based on compa- rable, directly observable open-source data such as OpenStreetMap (OSM) and the TomTom congestion database. Relations between indicators are identified through correlation measures. In addition, regression models are calibrated which quantify the relations between infrastructure accessibility (IA) and network indicators and average traffic delay times. The indicator average road connectivity over average road circuity (RCRC), which is proposed in this study, has not been cited before in literature. The main results suggest that the determination of distance-based connectivity of networks is an important proxy to understand road transportation performance. Consequently, two main results were obtained: (1) an increase in average short-distance connectivity of road networks (average closeness centrality and RCRC) eases road congestion, presumably because the network distributes road traffic more homogenously while decreasing low-permeability choke points, (2) an increase of the average short-distance connectivity of networks of alternative modes such as rail or bike (average weighted rail clustering coefficient and average cycle closeness centrality) does alleviate road congestion. In particular, for cities with over 0.4 km per km2 cycleway density, an increase in cycleway closeness centrality decreases road congestion and it does so almost as efficiently as an increase in road infrastructure accessibility. Presumably, well-connected, alternative networks with short and direct routes convince car users to shift to the alternative mode, which decreases road traffic volumes
Cyclist gaze behavior in urban space: An eye-tracking experiment on the bicycle network of Bologna
No full textThe increase of cyclist presence in urban areas and of the number of cyclist accidents on roads lead
researchers to explore the in-traffic visual behavior and hazard perception of cyclists.
In this study the actual cyclist gaze behavior while cycling on bicycle tracks—exclusive or shared with
pedestrians is analyzed. The intent is to allow a better comprehension of those elements representing
interferences, which can influence user’s trip.
Field tests were performed in the urban center of Bologna, Italy. 16 participants were asked to wear
mobile eye tracking glasses and cycle along a defined route. From gaze data recorded by the mobile eye
detector, we analyzed which visual information are detected. By applying fixations detection algorithm
and then a frame-by-frame analysis we calculated the proportion of fixations—number and durationacross
different areas of interest. Proportion of fixations and fixation time are assumed as a proxy of
visual workload. Thus, the relative frequency of fixation has been used to rank those elements that draw
cyclist attention.
Three are the main outcomes: first, an equilibrium of attention location between the central
(trajectory) and lateral parts of the visual scene can be assumed as the optimal cycling visual condition.
This condition results compromised when the presence of pedestrians is high. Second, discontinuities of
the path (like intersections and crosswalks) and the presence of pedestrians are the elements requiring
more attention. Third, the absence of physical and visual separation between cyclists and pedestrians
seems to lead to a lack of attention to these risk elements.
These outcomes about cyclists’ visual behavior allowed to recommend design measures to increase
comfort and safety on shared-with pedestrian-cycling paths. Thus, suggestions are addressed in the
conclusions
Comparing practice-ready forecast models for weekly and monthly fluctuations of average daily traffic and enhancing accuracy by weighting methods
Full text linkKnowing daily traffic for the current year is recognized as being essential in many fields of transport analysis and practice, and short-term forecasting models offer a set of tools to meet these needs. This paper examines and compares the accuracy of three representative parametric and non-parametric prediction models, selected by the analysis of the numerous methods proposed in the literature for their good combination of forecast accuracy and ease of calibration, using real-life data on Italian motorway stretches. Non-parametric K-NN regression model, Gaussian maximum likelihood model and double seasonality Holt–Winters exponential smoothing model confirm their goodness to predict the weekly and monthly fluctuations of average daily traffic with varying degrees of performance, while maintaining an easy use in professional practice, i.e. requiring ordinary professional skills and conventional analysis tools. Since combining several prediction models can give, on average, more accuracy than that of the individual models, the paper compares two weighting methods of easy implementation and susceptible to a direct use, namely the widely used information entropy method and the less widespread Shapley value method. Despite being less common than the information entropy method, the Shapley value method proves to be more capable in better combining single forecasts and produces improvements in the predictions for test data. With these remarks, the paper might be of interest to traffic technicians or analysts, in various and not uncommon tasks they might find in their work. Keywords: Short-term traffic forecasting, Non-parametric regression, Gaussian maximum likelihood, Double seasonal Holt–Winters exponential smoothing, Entropy weighting method, Shapley value weighting metho
Lane-Distribution Models and Related Effects on the Capacity for a Three-Lane Freeway Section: Case Study in Italy
No full textTraffic flow, its characteristics, and road quality service are usually estimated by using aggregated and averaged data from multiple lanes; however, in real experiences, there is significant variability in traffic-flow parameters across the different freeway lanes. Among the numerous factors that affect traffic distribution are vehicular composition, driver behavior, regulations about passing and overtaking, lane discipline, and designated lanes. Because these factors are very specific, the models and values for traffic distribution in a multilane freeway segment are highly sensitive to their national context. This study starts from an analysis of the capacity of a three-lane test segment within the Italian freeway system, and then examines the manner in which the flow and density vary across the freeway lanes. The analysis is restricted to up-to-capacity conditions and nonlinear regression models of the distribution relationships are calibrated for each lane, for both flow and density ratios, as a function of the total flow. The nonhomogeneous use of freeway lanes in Italy can be qualified and quantified through the trends found in these ratios, and then compared with similar internationally focused studies. This provides a useful interpretation of driver behavior, and is also a reference for calibrating traffic models, supporting design and operational processes and the implementation of intelligent transportation systems (ITSs) that are consistent with the national context
Evaluating cyclist patterns using GPS data from smartphones
No full textGPS traces from cyclists are used to retrieve their path by matching the traces to a detailed, attribute-rich urban road
network. The main objective of this research is to explore the influence of road network characteristics on the cyclist's path choice behaviour. The dataset used in this study consists of ∼27,500 GPS traces, which cyclists have recorded in Bologna, Italy, over a period of 4 weeks using a special smartphone application. Work trips are extracted from all traces by selecting only straight trips during the mornings of work days. After matching the traces to a specially prepared road map, the distributions of trip length, trip time and trip speed are determined. The shortest possible path between origin and destination of each trip is determined and compared with the chosen path. Results show that most cyclists tend to use the shortest path and accept only small detours. However, comparing the shortest path with the chosen path for each trip, it is possible to identify the network characteristics causing the cyclists to deviate from the shortest path. The main results of this study indicate that the chosen paths contain more cycleways and less intersections compared with the respective shortest paths
- …
