scholarly journals Developing a New Surrogate Safety Indicator Based on Motion Equations

2014 ◽  
Vol 26 (5) ◽  
pp. 371-381 ◽  
Author(s):  
Hamid Behbahani ◽  
Navid Nadimi ◽  
Hooman Alenoori ◽  
Mina Sayadi
Keyword(s):  
Collision Avoidance ◽  
Safety Measure ◽  
Safety Measures ◽  
Motion Equations ◽  
Time To Collision ◽  
Safety Indicator ◽  
Probability Of Collision ◽  
Collision Avoidance System ◽  
Surrogate Measures ◽  
Surrogate Safety Measures

Collision avoidance system (CAS), with the help of surrogate safety measures is a beneficial tool for reducing driver errors and preventing rear-end collisions. One of the most well-known surrogate safety measures to detect rear-end conflicts is Time-to-collision (TTC). TTC refers to the time remaining before the rear-end accident if the course and the speed of vehicles are maintained constant. Different surrogate measures have been derived from TTC; however, the most important are Time Exposed Time-to-collision (TET) and Time Integrated Time-to-collision (TIT). In this paper a new surrogate safety measure based on TTC notion has been developed. This new indicator merges TET and TIT into one measure and gives a score between 0 and 100%, as the probability of collision. Applying this indicator in CAS as a safety measure will be more useful than TET&TIT, to reduce driver errors and rear-end collisions.

Probability of Collision in a Model Collision Avoidance System

1974 ◽  
Vol 27 (4) ◽  
pp. 496-509
Author(s):  
K. Hara
Keyword(s):  
Statistical Analysis ◽  
Collision Avoidance ◽  
Basic Concept ◽  
Queuing Theory ◽  
Marine Traffic ◽  
Traffic Environment ◽  
Model Collision ◽  
Probability Of Collision ◽  
Collision Avoidance System

A basic concept for estimating the probability of collision for a ship navigating through a seaway with congested marine traffic can be derived by applying queuing theory to the relation between collision avoidance manœuvres and the traffic environment. Ships usually perform various ‘services’, such as altering course or collision avoidance, to other ships and geographical obstacles; the analogy of the collision avoidance system to queuing is that each arrival of another ship represents a ‘customer’ and each manœuvre of own ship corresponds to a ‘service’. A model for a collision-avoidance system was constructed analytically from queuing theory and expressed numerically, under assumptions based on traffic surveys and the statistical analysis of collision avoidance procedures at sea, in order to study the feasibilities of the model.

scholarly journals The evaluation of the surrogate safety measures along a pedestrian confined ramp of an old bridge

2020 ◽  
pp. 1-13
Author(s):  
Chiara Gruden
Keyword(s):  
Road Traffic ◽  
Travel Speed ◽  
Point Of View ◽  
Urban Context ◽  
Safety Level ◽  
Safety Measures ◽  
Pedestrian Bridges ◽  
Surrogate Measures ◽  
Surrogate Safety Measures ◽  
Behavioural Aspects

Pedestrians walk daily to meet their basic needs. Therefore, over the years it has been attempted to make urban context more livable, respecting the needs of weak road users. Pedestrian mobility is also growing strongly from the point of view of tourism, especially in the areas where government measures are taken to reduce vehicular flow in order to let the architectural and landscape assets more usable. Often tourist itineraries are made of narrow areas crossed by numerous pedestrians, leading to possible critical circumstances. The criticality is connected to a likely reduction of safety and use (comfort and possible delays). Confined spaces such as small streets or pedestrian bridges well exemplify the described situation. Particularly, pedestrian bridges are often composed of ramps with variable slopes and consist of different floors, making walking difficult and therefore reducing travel speed and limiting the mobility of users such as handicapped or elderly people. Starting from the geometrical evaluation of the old bridge of Mostar (BIH), this article provides some ideas for evaluating the safety of pedestrians during the journey on the bridge, under different flow conditions. The analyses were carried out starting from an estimate of pedestrian flows from video monitoring. Safety was then assessed thanks to the calculation of surrogate measures, based on the trajectories of individuals, obtained through tracking tools. Camera monitoring and inspections to survey infrastructure’s geometric features ease the procedure of data entering into image processing software. The evaluation of individual pedestrian trajectories and/or their interactions allows to estimate the movement variations through the study of parameters such as speed variation, pedestrian density and surrogate safety factors. Surrogate safety measures, indeed, are indicators calculated for a chosen pair of users interacting in the detected scene. Among these factors there are: relative speed (Delta-V), Time-To-Collision (TTC), Time Advantage (TAdv) and T2. All the above-mentioned kinds of measures are interesting to study generally the behavioural aspects of road traffic and, specifically, safety level and factors influencing it. The purpose of this work is to estimate the effects of induced pedestrian mobility on Mostar’s Ottoman bridge in terms of safety, with the aim of preventing negative scenarios that could lead to a bad infrastructural level of service. Keywords: road safety; pedestrian trajectories; surrogate safety measures.

Assessing Surrogate Safety Measures using a Safety Pilot Model Deployment Dataset

2018 ◽  
Vol 2672 (38) ◽  
pp. 1-11 ◽  
Author(s):  
Zhaoxiang He ◽  
Xiao Qin ◽  
Pan Liu ◽  
Md Abu Sayed
Keyword(s):  
Goodness Of Fit ◽  
Big Data Analytics ◽  
Model Performance ◽  
Safety Analysis ◽  
Trajectory Data ◽  
Safety Measures ◽  
Great Opportunity ◽  
Time To Collision ◽  
Pilot Model ◽  
Surrogate Safety Measures

Emerging data sources such as Safety Pilot Model Deployment (SPMD) provide a great opportunity to gain a better understanding of collision mechanisms and to develop novel safety metrics. The SPMD program was a comprehensive data collection effort under real-world conditions in Ann Arbor, Michigan, covering over 73 lane-miles and including approximately 3,000 pieces of onboard vehicle equipment and 30 pieces of roadside equipment. In-vehicle data (e.g., speed, location) collected by the SPMD program can potentially be an important supplement to traditional crash data-oriented safety analysis. The goal of this study was to assess roadway link-level surrogate safety measures using the vehicle trajectory data from SPMD. The study’s objectives included: 1) developing a framework to process the SPMD dataset using big-data analytics; 2) converting raw vehicle motion data from SPMD to surrogate safety measures; and 3) analyzing the statistical relationship between crash records and the calculated safety index. The statistical models showed that modified time to collision (MTTC) outperforms time to collision (TTC) and deceleration rate to avoid collision (DRAC) with respect to its goodness of fit. The findings are promising in that augmenting safety analysis with surrogate measures and vehicle performance (e.g., speed and brake duration from connected vehicles) improves the overall model performance. Such information is vital for safety analysis, especially in the absence of detailed roadway and traffic data.

scholarly journals Surrogate Safety Measures from Traffic Simulation: Validation of Safety Indicators with Intersection Traffic Crash Data

2020 ◽  
Vol 12 (17) ◽  
pp. 6974
Author(s):  
Vittorio Astarita ◽  
Ciro Caliendo ◽  
Vincenzo Pasquale Giofrè ◽  
Isidoro Russo
Keyword(s):  
Crash Risk ◽  
Safety Measures ◽  
Traffic Crash ◽  
Crash Data ◽  
Time To Collision ◽  
Vehicle Trajectories ◽  
Simulation Validation ◽  
Black Spots ◽  
Single Vehicle ◽  
Surrogate Safety Measures

The traditional analysis of road safety is based on statistical methods that are applied to crash databases to understand the significance of geometrical and traffic features on safety, or in order to localize black spots. These classic methodologies, which are based on real crash data and have a solid background, usually do not explicitly consider the trajectories of vehicles at any given location. Moreover, they are not easily applicable for making comparisons between different traffic network designs. Surrogate safety measures, instead, may enable researchers and practitioners to overcome these limitations. Unfortunately, the most commonly used surrogate safety measures also present certain limits: Many of them do not take into account the severity of a potential collision and the dangers posed by road-side objects and/or the possibility of drivers being involved in a single-vehicle crash. This paper proposes a new surrogate safety indicator founded on vehicle trajectories, capable also of considering road-side objects. The validity of the proposed indicator is assessed by means of comparison between the calculation of surrogate safety measures on micro-simulated trajectories and the real crash risk obtained with data on real crashes observed at several urban intersection scenarios. The proposed experimental framework is also applied (for comparison) to classical indicators such as TTC (time to collision) and PET (post-encroachment time).

Sign in / Sign up

Export Citation Format

Share Document