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Francesco Bella - One of the best experts on this subject based on the ideXlab platform.
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interaction driver bicyclist on Rural Roads effects of cross sections and road geometric elements
Accident Analysis & Prevention, 2017Co-Authors: Francesco Bella, Manuel SilvestriAbstract:Abstract The interaction of motorists and bicyclists, particularly during passing maneuvers, is cited as one of the primary causes of bicyclist fatalities. This paper reports the results of a driving simulator study, which sought to analyze the effects that three cross-section configurations of a two-lane Rural road and four geometric elements of the road have on driver behavior, during the interaction with a cyclist. A two-lane Rural road, about 11 km long, was designed and implemented in an advanced-interactive driving simulator. Three different cross-sections (all with same width, but with and without a bicycle lane and for different widths of bicycle lane) were tested. Forty participants carried out three driving sessions (one for each road alignment with different cross-section) and were exposed to the condition of bicycle traffic along four geometric elements of the alignment (2 tangents with different lengths, right curve and left curve). The driving simulator experiments were designed in such a way that, along the sections where the driver–cyclist interactions occurred, the oncoming traffic was absent. Overall, 468 speed profiles and 468 lateral position profiles were plotted to obtain the descriptive variables of the driver behavior during the interaction with the cyclist. The influences of cross-sections, geometric elements and bicycle traffic conditions on driver behavior were evaluated by a multivariate variance analysis. The presence of the cyclist determined different levels of influence on driver’s trajectory for the three cross-sections. A wider bicycle lane ensured a higher later clearance distance between driver and cyclist, allowing safer overtaking maneuver. The interferences of the cyclist on driver’s behavior depended on the geometric elements. On tangents, the lowest lateral clearances were recorded and no speed reduction was observed, compared to the cyclist absence condition. On the left curve, the higher lateral clearance was recorded, due to the concordant tendencies of the driver to move away from the cyclist and to cut the curve. This determined an excessive and risky displacement of the vehicle to the opposing lane, whose criticality was also emphasized by the high speed adopted by the driver. On the right curve, the lateral clearance was higher than that recorded on the tangents, probably due to the necessity of the driver to perform the demanding maneuver of entering in the right curve, which also determined a speed reduction compared to the cyclist absence condition. The obtained results provide suggestions for the most efficient cross-section reorganization of existing two-lane Rural Roads in order to improve the road safety.
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driver perception of Roadside configurations on two lane Rural Roads effects on speed and lateral placement
Accident Analysis & Prevention, 2013Co-Authors: Francesco BellaAbstract:Abstract This paper reports the results of a driving simulator study which sought to analyze the effect that: (a) three Roadside configurations on a two-lane Rural road lined with trees have on speed and lateral position of the driver, depending on different cross-sections as well as geometric elements; (b) the beginning of the guardrail barrier has upon the driver's behavior whenever this occurs on the left curve, right curve or tangent. A two-lane Rural road lined with trees was designed and implemented in an advanced-interactive driving simulator. Two different cross-sections (with and without a shoulder), which were combined with three Roadside configurations (only trees, trees and barriers, trees and barriers having undergone a treatment), were tested. Six road scenarios were then analyzed. Thirty-six drivers (33 were deemed to be valid and used for the analysis) drove in the simulator using these scenarios and the speed and lateral placement values were collected. Statistical analysis showed that the driver behavior was only affected by the cross-sections and geometric elements but not by Roadside configurations. Although the presence of trees along the road represents a factor that increases the severity of run-off-road accidents, drivers do not change their behavior when barriers are not present. Concerning the effects of the beginning of the barrier, MANOVA revealed a main effect for Roadside configuration on lateral position but not on speed. There was also a clear tendency of drivers to “cut” both the right curves as well as the left curves in order to minimize the speed reduction in the tangent–curve–tangent transition. These main results allow useful suggestions to be made as regards safety measures for improving road safety on two-lane Rural Roads lined with trees.
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driving simulator for speed research on two lane Rural Roads
Accident Analysis & Prevention, 2008Co-Authors: Francesco BellaAbstract:The paper reports on a validation study of the interactive fixed-base driving simulator of Inter-University Research Center for Road Safety (CRISS) that was effectuated in order to verify the CRISS driving simulator's usefulness at a tool for speed research on two-lane Rural Roads. Speeds were recorded at eleven measurement sites with different alignment configurations on a two-lane Rural road near Rome. The real world was reproduced in the CRISS driving simulator. Forty drivers drove the simulator. The results of the comparative and statistical analysis established the relative validity and also revealed that absolute validity was obtained in nine measurements sites. Only in two non-demanding configurations, were the speeds in simulator significantly higher than those recorded in the field. In these sites the mean speed in simulator was equal to or greater than 94 km/h. For these configurations, the higher speeds recorded in simulator appeared to stem from the different risk perception on the simulated road as opposed to that on the real road. The study's results should be considered for driving speed behavior research, in which simulator equipment with similar features of the CRISS driving simulator is used.
Eric T. Donnell - One of the best experts on this subject based on the ideXlab platform.
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Safety performance functions for horizontal curves and tangents on two lane, two way Rural Roads.
Accident; analysis and prevention, 2018Co-Authors: Jeffrey P. Gooch, Vikash V. Gayah, Eric T. DonnellAbstract:Horizontal curves on two-way, two-lane Rural Roads pose critical safety concerns. Accurate prediction of safety performance at these locations is vital to properly allocate resources as a part of any safety management process. The current method of predicting safety performance on horizontal curves relies on the application of a safety performance function (SPF) developed using only tangent sections and adjusting this value using a crash modification factor (CMF). However, this process inherently assumes that safety performance on curves and tangent sections share the same general functional relationships with variables included in the SPF, notably traffic volumes and segment length, even though research suggests otherwise. In light of this, the goal of this paper is to systematically study the relationship between safety performance and traffic volumes on horizontal curves of two-lane, two-way Rural Roads and to compare this to the safety performance of tangent sections. The propensity scores-potential outcomes framework is used to help ensure similarity between tangent and curve sections considered in the study, while mixed-effects negative binomial regression is used to quantify safety performance. The results reveal that safety performance on horizontal curves differs significantly from that on tangent sections with respect to both traffic volumes and segment length. Significant differences were also found between the safety performance on tangents and curves relative to other roadway features. These results suggest that curve-specific SPFs should be considered in the next edition of the Highway Safety Manual.
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development of regionalized spfs for two lane Rural Roads in pennsylvania
Accident Analysis & Prevention, 2017Co-Authors: Vikash V. Gayah, Eric T. DonnellAbstract:Abstract The American Association of State Highway and Transportation Officials’ Highway Safety Manual (HSM) contains safety performance functions (SPFs) to predict annual crash frequencies for several roadway types. When applying these SPFs in a jurisdiction whose data were not used to develop the SPF, a calibration factor can be applied to adjust the expected crash frequency estimate to statewide or local conditions. Alternatively, the HSM suggests that transportation agencies may develop their own SPFs in lieu of applying the calibration factor to the HSM SPFs. However, the HSM does not provide guidance on the appropriate level of regionalization that should be adopted for either method, even though safety performance may vary considerably within a state. In light of this, the present study considers the development of local or regionalized SPFs for two-lane Rural highways within the Commonwealth of Pennsylvania. Three regionalization levels were considered: statewide, engineering district and individual counties. The expected crash frequency for each level of regionalization was compared to the reported crash frequency over an eight-year analysis period. The results indicate that district-level SPFs with county-level adjustment factors provide better predictive accuracy than the development of a statewide SPF or application of the HSM-calibrated SPF. The findings suggest that there are significant differences in safety performance across engineering districts within Pennsylvania. As such, other state transportation agencies developing SPFs or using calibration factors may also consider how variations across jurisdictions will affect predicted crash frequencies.
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quantifying the safety effects of horizontal curves on two way two lane Rural Roads
Accident Analysis & Prevention, 2016Co-Authors: Jeffrey P. Gooch, Vikash V. Gayah, Eric T. DonnellAbstract:The objective of this study is to quantify the safety performance of horizontal curves on two-way, two-lane Rural Roads relative to tangent segments. Past research is limited by small samples sizes, outdated statistical evaluation methods, and unreported standard errors. This study overcomes these drawbacks by using the propensity scores-potential outcomes framework. The impact of adjacent curves on horizontal curve safety is also explored using a cross-sectional regression model of only horizontal curves. The models estimated in the present study used eight years of crash data (2005–2012) obtained from over 10,000 miles of state-owned two-lane Rural Roads in Pennsylvania. These data included information on roadway geometry (e.g., horizontal curvature, lane width, and shoulder width), traffic volume, Roadside hazard rating, and the presence of various low-cost safety countermeasures (e.g., centerline and shoulder rumble strips, curve and intersection warning pavement markings, and aggressive driving pavement dots). Crash prediction is performed by means of mixed effects negative binomial regression using the explanatory variables noted previously, as well as attributes of adjacent horizontal curves. The results indicate that both the presence of a horizontal curve and its degree of curvature must be considered when predicting the frequency of total crashes on horizontal curves. Both are associated with an increase in crash frequency, which is consistent with previous findings in the literature. Mixed effects negative binomial regression models for total crash frequency on horizontal curves indicate that the distance to adjacent curves is not statistically significant. However, the degree of curvature of adjacent curves in close proximity (within 0.75 miles) was found to be statistically significant and negatively correlated with crash frequency on the subject curve. This is logical, as drivers exiting a sharp curve are likely to be driving slower and with more awareness as they approach the next horizontal curve.
Gayatri B Koolwal - One of the best experts on this subject based on the ideXlab platform.
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estimating the long term impacts of Rural Roads a dynamic panel approach
Social Science Research Network, 2011Co-Authors: Shahidur R Khandker, Gayatri B KoolwalAbstract:Infrastructure investments are typically long-term. As a result, observed benefits to households and communities may vary considerably over time as short-term outcomes generate or are subsumed by longer-term impacts. This paper uses a new round of household survey as part of a local government engineering department's Rural road improvement project financed by the World Bank in Bangladesh to compare the short-term and long-term effects of Rural Roads over eight years. A dynamic panel model, estimated by generalized method of moments, is applied to estimate the varying returns to public road investment accounting for time-varying unobserved characteristics. The results show that the substantial effects of Roads on such outcomes as per capita expenditure, schooling, and prices as observed in the short run attenuate over time. But the declining returns are not common for all outcomes of interest or all households. Employment in the Rural non-farm sector, for example, has risen more rapidly over time, indicating increasing returns to investment. The very poor have failed to sustain the short-term benefits of Roads, and yet the gains accrued to the middle-income groups are strengthened over time because of changing sectors of employment, away from agriculture toward non-farm activity. The results also show that initial state dependence -- or initial community and household characteristics as well as road quality -- matters in estimating the trajectory of road impacts.
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the poverty impact of Rural Roads evidence from bangladesh
Social Science Research Network, 2006Co-Authors: Shahidur R Khandker, Zaid Bakht, Gayatri B KoolwalAbstract:The rationale for public investment in Rural Roads is that households can better exploit agricultural and nonagricultural opportunities to use labor and capital more efficiently. But significant knowledge gaps remain as to how opportunities provided by Roads actually filter back into household outcomes and their distributional consequences. This paper examines the impacts of Rural road projects using household-level panel data from Bangladesh. Rural road investments are found to reduce poverty significantly through higher agricultural production, higher wages, lower input and transportation costs, and higher output prices. Rural Roads also lead to higher girls' and boys' schooling. Road investments are pro-poor, meaning the gains are proportionately higher for the poor than for the non-poor.
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the poverty impact of Rural Roads evidence from bangladesh
Economic Development and Cultural Change, 2006Co-Authors: Shahidur R Khandker, Zaid Bakht, Gayatri B KoolwalAbstract:This brief summarizes the results of a gender impact evaluation study, entitled The poverty impact of Rural Roads : evidence from Bangladesh, conducted during the time period 1995 to 1996 in Bangladesh. The study observed that a rationale for public investment in Rural Roads is that households can better exploit agricultural and nonagricultural opportunities to employ labor and capital more efficiently. Significant knowledge gaps persist, however, as to how opportunities provided by Roads actually filter back into household outcomes as well as distributional consequences. Rural road investments are found to reduce poverty significantly through higher agricultural production, higher wages, lower input and transportation costs, and higher output prices. Road investments are pro-poor, meaning the gains are proportionately higher for the poor than for the non-poor.
Salvatore Cafiso - One of the best experts on this subject based on the ideXlab platform.
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new approach to defining continuous speed profile models for two lane Rural Roads
Transportation Research Record, 2012Co-Authors: Salvatore Cafiso, Gianluca CerniAbstract:Despite a large body of research on operating speeds, there is still much to learn about the factors that affect free-flow speeds, especially with regard to the development of a continuous speed profile for two-lane Rural highways. This paper presents a new approach to modeling driver speed profile along two-lane Rural Roads. Speed data regarding individual drivers traveling on selected two-lane Rural Roads were sampled during a naturalistic experiment that used an onboard Global Positioning System (GPS). GPS devices facilitate the collecting and processing of continuous speed data. Unlike spot speed measurements, which have typically been collected in similar studies, continuous speed data are useful for studying the actual speed profile with regard to acceleration-deceleration behavior and maximum speed on tangents and curves. New variables are used in the regression equation. These variables refer to the horizontal curvature and the vertical grade as weighted values of the geometric features of the ali...
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performance of safety indicators in identification of black spots on two lane Rural Roads
Transportation Research Record, 2011Co-Authors: Salvatore Cafiso, Giacomo Di SilvestroAbstract:Defining a black spot is not as perceptual as it may appear. Unusually high crash counts do not necessarily indicate a real safety problem. When black spots on two-lane Rural Roads with low and medium traffic volumes are being identified, a reduced number of observed crashes is a critical issue that can emphasize weak results obtained with various safety indicators and checks. It is generally assumed that an empirical Bayesian (EB) estimate represents the best approach for the identification of black spots, but it is difficult to define quantitatively the precision of estimates that are arrived at with different procedures. Because traffic volume, segment length, and crash observation period are critical issues in the identification of black spots and can emphasize the quality of the results obtained with safety indicators and checks, definition is needed of the limits and errors that can be expected when inadequate indicators and procedures are used to identify black spots on two-lane Rural Roads. A Monte Carlo simulation was used to produce theoretical crash data similar to empirical data, and the data were used to define a priori hazardous sites and, therefore, to assess whether a method could correctly identify such sites. The accuracy and efficiency of procedures are compared on the basis of observed frequency of crashes, crash rate, EB estimation, and the potential for safety improvement (PSI). As a general rule, even if some arrangements can mitigate the lower performance of some indicators, the best practice is to use the indicators based on the EB estimation PSI to identify true positives.
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revisiting variability of dispersion parameter of safety performance for two lane Rural Roads
Transportation Research Record, 2010Co-Authors: Salvatore Cafiso, Bhagwant Persaud, Giacomo Di Silvestro, Morjina Ara BegumAbstract:Safety performance functions (SPFs) are commonly calibrated with negative binomial regression in which a dispersion parameter that represents extra-Poisson variation is estimated. The primary use of this parameter is in empirical Bayes estimation for safety management applications such as treatment evaluation and network screening. It stands to reason that the importance of precise estimation of the dispersion parameter should be established. Recent research has suggested that the dispersion parameter is not constant but actually varies from site to site, depending on site characteristics such as segment length. In revisiting the dispersion parameter issue in this empirical investigation, previous research on this issue is reinforced by filling a number of knowledge gaps. First, light is cast on the dispersion parameter variation for SPFs for two-lane Rural Roads, an important entity type for which there is little or no knowledge in this regard. In this study, more precise model forms are investigated to represent the variation with respect to the key variable, segment length. This investigation confirms that the dispersion parameter is inversely related to segment length but reveals that it is not inversely proportional to segment length, as suggested in other research. Second, it was found that the dispersion parameter is smaller and the variation less pronounced with better-specified models. Finally, additional evidence is provided to suggest that dispersion parameter variation matters more for shorter segment lengths.
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safety evaluation process for two lane Rural Roads a 10 year review
Transportation Research Record, 2002Co-Authors: Ruediger Lamm, Basil Psarianos, Salvatore CafisoAbstract:A practical procedure was developed that explicitly considers the driving behavioral and safety rules of a horizontal alignment for the evaluation of roadway new designs; redesigns; and projects of rehabilitation, restoration, and resurfacing. Design classes were developed to classify, from a traffic safety point of view, roadway sections as good, fair, or poor; these design classes are associated with three safety criteria to develop an overall quantitative safety evaluation procedure for two-lane Rural Roads. The safety criteria are introduced to analyze and evaluate by (a) Safety Criterion (SC) I: the difference between design speed and actual driving behavior as expressed by variations in observed 85th percentile speed; (b) SC II: the difference between observed 85th percentile speeds on successive design elements; and (c) SC III: the difference between side-friction assumed and side-friction demanded at the 85th percentile speed level on curves. Furthermore, the issues discussed include design speed,...
Susanne Van Dillen - One of the best experts on this subject based on the ideXlab platform.
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on the way to good health Rural Roads and morbidity in upland orissa
Journal of transport and health, 2018Co-Authors: Clive Bell, Susanne Van DillenAbstract:Abstract This paper investigates the effects of India's Rural Roads programme (PMGSY) on morbidity, using data on 279 households drawn from 30 villages in upland Orissa. The households were surveyed in 2010 and 2013, yielding an unbalanced panel of 1580 individuals, 1076 of whom were present in both years. Ten of the villages had received a direct all-weather road connection between 2004 and 2013. To estimate the programme's effects, the villages were treated as units within the whole network of Roads and medical facilities. The provision of a connection, whether direct or in the neighbourhood, was associated with the following reductions in morbidity (random-effects estimates): for each km of unpaved track so replaced, an inhabitant's probability of suffering a bout of incapacitating illness fell by 4.5 percentage points and the expected duration of such illness by 0.53 days. The village fixed-effects estimates are qualitatively the same, but smaller and less precise. A simple indicator variable for the presence or absence of such a connection yields qualitatively similar estimates, but with very large standard errors, which confirms the importance of employing fine measures of the network regressors.
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on the way to good health Rural Roads and morbidity in upland orissa
Research Papers in Economics, 2015Co-Authors: Clive Bell, Susanne Van DillenAbstract:This paper investigates the effects of India’s Rural Roads program (PMGSY) on morbidity, using data on 279 households drawn from 30 villages in a region of upland Orissa. The households were surveyed in 2010 and 2013, yielding an unbalanced panel of 1580 individuals, 1076 of whom were present in both years. Ten villages had received a direct all-weather road connection by 2013. Treating the village as a unit within the whole road network, the provision of a connection, whether direct or in the neighbourhood, is estimated to have reduced an inhabitant’s probability of falling sick by an estimated 3.6 percentage points, and the expected duration of incapacitating illness by 0.46 days, for each km. of unpaved track so replaced.
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how does india s Rural Roads program affect the grassroots findings from a survey in orissa
Social Science Research Network, 2012Co-Authors: Clive Bell, Susanne Van DillenAbstract:This paper analyzes the effects of all-weather Rural Roads on households' net output prices, education and health in a poor, drought-prone region of India. Of 30 villages originally surveyed in 2001-02, when two had such Roads, a further nine received them between January 2007 and December 2009 under the program Pradhan Mantri Gram Sadak Yojana. Cross-section comparisons involving all villages and 'before and after' comparisons in the nine yielded these findings: (i) net output prices were 5 percent or more higher; (ii) substantially fewer days of schooling were lost due to bad weather, largely because teachers had fewer absences; (iii) the acutely sick received more timely treatment and were more likely to be treated in a hospital than in the nearest primary health clinic; and (iv) the respondents ranked the resulting benefits in the domains of health and education at least as highly as the 'commercial' ones.
