Article
Engineering, Industrial
Bekir Bartin, Kaan Ozbay, Chuan Xu
Summary: This paper presents the calibration and development process of safety performance function for undivided two-lane urban and suburban arterial segments in New Jersey. Various statistical models were generated and compared using likelihood ratio test, AIC, BIC, Vuong test, and rootograms. The results showed that the negative binomial and hurdle models exhibited better performance in terms of absolute residuals and absolute Pearson residual statistics.
Article
Ergonomics
Vikash V. Gayah, Eric T. Donnell
Summary: The relationship between expected crash frequency and traffic volume is non-linear, with a proposed alternative functional form allowing for different elasticities within different traffic volume ranges. The new model, applied to two-lane rural roadways in Pennsylvania, offers improved fit and predictive performance compared to traditional and Hoerl functional forms, potentially for future SPF development.
ACCIDENT ANALYSIS AND PREVENTION
(2021)
Article
Ergonomics
Heesub Rim, Mohamed Abdel-Aty, Nada Mahmoud
Summary: This study develops Safety Performance Functions (SPFs) for freeway weaving segments, which are known for their higher crash probability due to multiple movements of traffic. Lane-level traffic data was utilized to analyze detailed traffic conditions and Poisson Lognormal (PLN) regression model technique was used to develop SPFs. The results found significant traffic parameters based on different crash types, providing important insights for safety evaluation and operational strategies on freeway weaving segments.
ACCIDENT ANALYSIS AND PREVENTION
(2023)
Article
Green & Sustainable Science & Technology
Nopadon Kronprasert, Katesirint Boontan, Patipat Kanha
Summary: This study aims to develop crash prediction models using Safety Performance Functions (SPFs) to examine the risk factors of two-lane rural horizontal curve segments. The results showed that lane width is the most significant parameter influencing crash frequency.
Article
Ergonomics
Zihe Zhang, Jun Liu, Xiaobing Li, Xing Fu, Chenxuan Yang, Steven Jones
Summary: Safety Performance Functions (SPFs) are used to predict the number of crashes on highways based on site characteristics. Traditional approaches assume that the relationships between safety performance and observed factors are stationary, but there may be unobserved factors that significantly affect roadway safety. This study uses a spatial modeling approach to incorporate spatial heterogeneity into SPF model estimation.
ACCIDENT ANALYSIS AND PREVENTION
(2023)
Article
Engineering, Civil
Taha Saleem, Raghavan Srinivasan
Summary: This paper describes the evaluation of safety impacts of increasing the speed limit from 55 mph to 60 mph on selected state highway road segments in Minnesota, U.S. The analysis showed a minor effect on overall crashes and operating speeds, with a slight increase in total crashes and injury crashes, and a slight reduction in injury crashes.
TRANSPORTATION RESEARCH RECORD
(2023)
Article
Transportation
Syeda Rubaiyat Aziz, Sunanda Dissanayake
Summary: To improve accuracy in results, Kansas developed specific safety performance functions (SPFs) for local conditions. Through calibration and validation, these new SPFs were found to more accurately predict crashes than the HSM-provided models.
JOURNAL OF TRANSPORTATION SAFETY & SECURITY
(2021)
Article
Green & Sustainable Science & Technology
Paolo Intini, Nicola Berloco, Stefano Coropulis, Roberta Gentile, Vittorio Ranieri
Summary: This study aims to develop a predictive framework for estimating crash frequencies and determining priority areas for interventions by establishing SPFs at the macro-level. The study used a province-wide database and divided cities and towns into census macro-zones based on different safety performance indicators and basic predictors.
Article
Construction & Building Technology
H. R. Pasindu, R. K. T. K. Ranawaka, R. M. K. Sandamal, T. W. K. I. M. Dias
Summary: This study proposes a methodology to incorporate road safety performance in rural roads in maintenance planning using a multi-objective optimisation approach. The developed model has been demonstrated from the illustrative example of a rural road network, showing that roads with safety issues can also be prioritised in budget allocation.
INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING
(2021)
Article
Engineering, Civil
Anik Das, Mohamed M. Ahmed
Summary: This study proposes a methodology to develop weather-specific microsimulation models based on different freeway facilities by updating lane-change parameters. The study finds that adverse weather conditions result in increased conflicts, decreased average speed, and increased total travel time and delay.
TRANSPORTATION RESEARCH RECORD
(2022)
Article
Transportation
Subasish Das, Xiaoduan Sun, Ming Sun
Summary: The study analyzed roadway departure crash data and specifically focused on rural two-lane roads in Louisiana, finding that the Cubist model performed well in estimating these accidents.
INTERNATIONAL JOURNAL OF TRANSPORTATION SCIENCE AND TECHNOLOGY
(2021)
Article
Transportation
Subasish Das, Ioannis Tsapakis, Ali Khodadadi
Summary: The study developed safety performance functions (SPFs) for rural minor collector two-lane roadways using crash data from Texas from 2015 to 2019, improving prediction accuracies.
Article
Engineering, Civil
Kirolos Haleem, Mehdi Hosseinpour
Summary: The main objective of this study was to develop a safety performance function (SPF) tool for predicting CMV crashes occurring on interchange ramp segments. Four count models were used and compared in fitting CMV crash-specific SPFs along interchange ramp segments in Kentucky. The HTCMP model significantly outperformed the other three models in crash prediction accuracy and goodness-of-fit statistics. Potential safety countermeasures were proposed based on the SPF model results using the HTCMP approach.
TRANSPORTATION RESEARCH RECORD
(2023)
Article
Engineering, Civil
Arastoo Karimi, Amin Mirza Boroujerdian
Summary: The study found that increasing the length of passing zones can reduce the rate of passing maneuvers ending in no-passing zones, and that passing rate is also influenced by lane width, the percentage of heavy vehicles in the subject direction, and directional split. Under certain conditions, the passing rate reaches a peak and then decreases.
TRANSPORTATION RESEARCH RECORD
(2021)
Article
Ergonomics
Panagiotis Lemonakis, Nikolaos Eliou, Theodoros Karakasidis
Summary: This study investigates the behavior of motorcyclists on curved road sections, finding that they tend to ride closer to the centerline of the road, neglect hazards associated with dim lighting conditions, and maintain constant speed in both left and right-hand horizontal curves.
JOURNAL OF SAFETY RESEARCH
(2021)
Article
Engineering, Civil
Anshu Bamney, Hisham Jashami, Sarvani Sonduru Pantangi, Jayson Ambabo, Megat-Usamah Megat-Johari, Qiuqi Cai, Nischal Gupta, Peter T. Savolainen
Summary: The COVID-19 pandemic has had significant impacts on public health, economics, and transportation systems. Stay-at-home orders and travel restrictions have led to a substantial reduction in vehicle miles traveled (VMT), although this effect diminishes over time.
TRANSPORTATION RESEARCH RECORD
(2023)
Article
Engineering, Civil
Meghna Chakraborty, Md Shakir Mahmud, Timothy J. Gates, Subhrajit Sinha
Summary: This study uses linear regularization algorithms to analyze the factors influencing human mobility during the COVID-19 pandemic in the United States, and predicts human mobility based on these factors. The results show that multiple factors have a significant impact on daily trips.
TRANSPORTATION RESEARCH RECORD
(2023)
Article
Engineering, Civil
Jonathan Kay, Timothy J. Gates, Peter T. Savolainen, Md Shakir Mahmud
Summary: Alternative intersection designs, such as median U-turn intersections, can offer safety and operational benefits with potentially lower costs. However, research specific to unsignalized reduced left-turn conflict intersections is limited. This study evaluated historical traffic crashes and volume data at 95 unsignalized intersections in Michigan and provided crash modification factors for future conversions.
TRANSPORTATION RESEARCH RECORD
(2022)
Article
Public, Environmental & Occupational Health
Sarvani Sonduru Pantangi, Grigorios Fountas, Md Tawfiq Sarwar, Abhishek Bhargava, Satish B. Mohan, Peter Savolainen, Panagiotis Ch Anastasopoulos
Summary: This study examines the performance of different PPP contracting approaches in terms of transportation safety, revealing variations in the determinants of crash frequencies and their impacts across different types of PPP. Contracts with higher costs, shorter durations, fewer lane-miles to be covered, more asset work activities, better pavement and drainage conditions, low to medium AADT, and higher width of shoulder tend to observe fewer crashes. Correlated random parameter models are used to show the heterogeneous patterns underlying the safety performance of different PPP approaches.
ANALYTIC METHODS IN ACCIDENT RESEARCH
(2022)
Article
Engineering, Civil
Md Shakir Mahmud, Anshu Bamney, Megat Usamah Megat Johari, Hisham Jashami, Timothy J. Gates, Peter Tarmo Savolainen
Summary: This study investigated the effectiveness of a dynamic speed feedback sign (DSFS) as a speed reduction measure on horizontal curves of rural highways. The results showed that the DSFS was more effective when installed near the advance curve warning sign, especially at curves with sharper curvature. The continued use of DSFSs on rural horizontal curves is recommended.
TRANSPORTATION RESEARCH RECORD
(2023)
Article
Engineering, Civil
Nischal Gupta, Md Shakir Mahmud, Hisham Jashami, Peter T. Savolainen, Timothy J. Gates
Summary: This study examines the effects of the increase in maximum speed limits on rural freeways in Michigan on traffic speed characteristics. The results consistently show increases in speed metrics, ranging from 1.1 to 3.2 mph depending on the specific metric and data source. Limited spillover effects were observed at sites where speed limits were not changed. Various site-specific characteristics were found to be correlated with speed selection, with differences depending on the data source.
TRANSPORTATION RESEARCH RECORD
(2023)
Article
Engineering, Civil
Meghna Chakraborty, Timothy Gates
Summary: Previous research on urban roadway safety has focused on high functional classification roadways, but this study examines low functional classification roadways and finds that speed limits and driveway density have significant impacts on roadway safety performance.
TRANSPORTATION RESEARCH RECORD
(2023)
Article
Engineering, Civil
Megat Usamah Megat Johari, Nusayba Megat Johari, Peter T. Savolainen, Timothy J. Gates
Summary: This study aims to evaluate the impact of the differential between the mainline speed limit and the lower exit ramp advisory speeds on safety. Analyses were conducted using data from 187 exit ramps in Michigan, and random effects negative binomial regression models were estimated. The results show that crashes increased as the difference between mainline and ramp speed increased. Additionally, crashes decreased on ramps with longer upstream deceleration lane lengths.
TRANSPORTATION RESEARCH RECORD
(2022)
Article
Engineering, Civil
Ehsan Kamjoo, Ramin Saedi, Ali Zockaie, Mehrnaz Ghamami, Timothy Gates, Alireza Talebpour
Summary: This study investigates the impact of snowplows on car-following behavior and compares car-following models with and without a collision avoidance system. The results show that snowplows significantly affect car-following behavior, while the improvement in behavior from the collision avoidance system is not statistically significant. Additionally, considering driving behavior heterogeneity leads to more accurate prediction of car-following behavior. Developing specific models for winter maintenance operations helps in the development of microsimulation models for adverse weather conditions.
TRANSPORTATION RESEARCH RECORD
(2023)
Article
Engineering, Civil
Nusayba Megat-Johari, Megat-Usamah Megat-Johari, Peter Savolainen, Timothy J. Gates
Summary: This paper examines cell phone use rates in the United States and analyzes related enforcement activities and safety information dissemination. The results show that enforcement activities and cell phone-specific safety messages can indeed reduce cell phone use rates. The study also finds that use rates vary by age, gender, and race, suggesting the need for targeted awareness campaigns. Additionally, use rates differ at different types of intersections.
TRANSPORTATION RESEARCH RECORD
(2022)
Article
Engineering, Civil
Md Shakir Mahmud, Timothy J. Gates, Peter Tarmo Savolainen, Babak Safaei
Summary: This research evaluated the effectiveness of dynamic speed feedback signs (DSFSs) as a speed reduction measure at a freeway exit ramp with horizontal curvature. The study found that installing a DSFS near the start of the curve resulted in an average reduction of 3.5 mph in curve entry speeds. The best speed reduction was achieved when the message activated within 250 to 400 ft of the curve. The lateral position and display panel size of the DSFS did not significantly impact curve entry speeds, but adding a yellow sign border enhanced the speed reduction effects.
TRANSPORTATION RESEARCH RECORD
(2023)
Article
Engineering, Civil
Md Shakir Mahmud, Megat Usamah Megat Johari, Anshu Bamney, Hisham Jashami, Timothy J. Gates, Peter T. Savolainen
Summary: The study found that using dynamic speed feedback signs (DSFS) can effectively reduce vehicle speeds in speed transition zones entering communities on high-speed rural roadways. The closer the DSFS is to the motorists, the greater the speed reduction effect. Continued use of DSFS in these areas is recommended for speed management.
TRANSPORTATION RESEARCH RECORD
(2023)
