Intersection Types Research Articles

Investigating the role of exiting vehicles and turn indicator usage in gap acceptance at single-lane roundabouts

Roundabouts are becoming a preferred form of intersection control type due to their safety and capacity benefits. Yield control at roundabout entries inherently reduces fuel consumption and emissions when compared to other conventional intersection types. However, these benefits can be limited by poor driver behavior and judgment when entering the roundabout. This research addresses the nature of gap distributions and use of turn indicators by exiting vehicles at three single-lane roundabouts in Vermont, New York, and Alaska. Presented here is a comparison of vehicle headways measured at two different locations in each roundabout. Rejected headways are analyzed in the context of priority abstaining events when entering drivers yield to vehicles exiting on the same leg of the roundabout suggesting that “true” critical gaps are being overestimated. Results indicate that exiting vehicles, particularly those that do not use their turn indicators when departing from the major-stream of traffic have an influence on the entry decision of drivers on the same approach. This behavior is of particular concern for intersection efficiency (i.e., delay) and sustainability (i.e., excess fuel consumption and emissions). Results prompt the consideration of more consistent guidance on and enforcement of turn indicator use during roundabout negotiations.

Experimental study on the mechanism of hydraulic fracture growth in a glutenite reservoir

Glutenite reservoirs are frequently significantly heterogeneous because of their unique depositional environment. The presence of gravel in this type of formation complicates the growth path of hydraulic fracture (HF). In this study, laboratory fracturing experiments were conducted on six large natural glutenite specimens (300 mm × 300 mm × 300 mm) using a true triaxial hydraulic fracturing system to investigate the growth law of HF in glutenite reservoirs. Before the experiments were performed, the rock properties of the gravel particles and matrix in the glutenite specimens were determined using various apparatuses. The effects of gravel size, horizontal differential stress, fracturing fluid type (or viscosity), and flow rate on the HF growth pattern, fracture width, and injection pressure were examined in detail. Similar to previous studies, four types of HF intersections with gravel particles, namely, termination, penetration, deflection, and attraction, were observed. The HF growth path in the glutenite specimens with large gravel (40 mm–100 mm) is likely branched and tortuous even under high horizontal differential stress. The HF growth path in the glutenite specimens with small gravel (less than 20 mm) is simple, but a process zone with multiple thin fractures may be created. Breakdown pressure may increase significantly when HF initiates from high-strength gravel particles, which are mainly composed of quartz. HF propagation is likely limited within high-strength gravel particles, thereby resulting in narrow fractures and even termination. The use of low-viscosity fluids, such as slickwater, and the low injection rate can further limit HF growth, particularly its width. As a response, high extension pressure builds up during fracturing.

Evaluation of the effects of in‐vehicle traffic lights on driving performances for unsignalised intersections

Ground traffic lights are essential for maintaining traffic efficiency and safety at intersections. However, unsignallised intersections are still frequent in actual traffic environments. With the development of new forms of vehicular communication, in-vehicle traffic lights can assist drivers at unsignallised intersections. The authors proposed two types of in-vehicle traffic lights to assist drivers; these corresponded to two-way and all-way stop-controlled intersections. They adopted gap acceptance theory and a first-come-first-served strategy to determine passing priority for the two types of intersections, respectively. They then conducted a driving simulator experiment involving 23 participants, to investigate driver behaviours elicited by the proposed system. They prepared four experimental conditions with combinations of in-vehicle traffic lights and auditory warnings. The authors’ experimental results indicated that in-vehicle traffic lights were associated with significantly longer post-encroachment times and a significantly shorter maximum brake stroke. In terms of eye-gaze behaviours, the percentage of gaze concentration to the road centre area and mean glance durations were deemed acceptable for the avoidance of visual distraction, when in-vehicle traffic lights were presented via a head-up display. Therefore, their analysis of driver behaviours indicates that in-vehicle traffic lights can effectively provide driver assistance at unsignallised intersections.

Retractions in Intersection Types

This paper deals with retraction - intended as isomorphic embedding - in intersection types building left and right inverses as terms of a lambda calculus with a bottom constant. The main result is a necessary and sufficient condition two strict intersection types must satisfy in order to assure the existence of two terms showing the first type to be a retract of the second one. Moreover, the characterisation of retraction in the standard intersection types is discussed.

Intersection Types and Counting

We present a new approach to the following meta-problem: given a quantitative property of trees, design a type system such that the desired property for the tree generated by an infinitary ground lambda-term corresponds to some property of a derivation of a type for this lambda-term, in this type system. Our approach is presented in the particular case of the language finiteness problem for nondeterministic higher-order recursion schemes (HORSes): given a nondeterministic HORS, decide whether the set of all finite trees generated by this HORS is finite. We give a type system such that the HORS can generate a tree of an arbitrarily large finite size if and only if in the type system we can obtain derivations that are arbitrarily large, in an appropriate sense; the latter condition can be easily decided.

Proceedings Eighth Workshop on Intersection Types and Related Systems

Proceedings Eighth Workshop on Intersection Types and Related Systems

Intersection Types, Quantitative Semantics and Linear Logic

Intersection Types, Quantitative Semantics and Linear Logic

Intersections and Unions of Session Types

Prior work has extended the deep, logical connection between the linear sequent calculus and session-typed message-passing concurrent computation with equi-recursive types and a natural notion of subtyping. In this paper, we extend this further by intersection and union types in order to express multiple behavioral properties of processes in a single type. We prove session fidelity and absence of deadlock and illustrate the expressive power of our system with some simple examples. We observe that we can represent internal and external choice by intersection and union, respectively, which was previously suggested by Padovani for a different language of session types motivated by operational rather than logical concerns.

Intersection Types for Real Number Computation

Intersection Types for Real Number Computation

Characterisation of Approximation and (Head) Normalisation for λμ using Strict Intersection Types

We study the strict type assignment for lambda-mu that is presented in [van Bakel'16]. We define a notion of approximants of lambda-mu-terms, show that it generates a semantics, and that for each typeable term there is an approximant that has the same type. We show that this leads to a characterisation via assignable types for all terms that have a head normal form, and to one for all terms that have a normal form, as well as to one for all terms that are strongly normalisable.

Micromotion Feature Extraction and Distinguishing of Space Group Targets

Traditional micro-Doppler (m-D) analysis theories largely focus on isolated targets, making these theories difficult to utilize in monitoring and recognizing space group targets. This letter proposes an algorithm for separating ballistic group targets based on the extraction of micromotion features. Modeling the ballistic targets as cone-cylinder models, the skeleton extraction method in morphology image processing is first utilized to suppress the sidelobes of range profiles. A sliding window whose length of frames can be adaptively changed according to the curve characteristics is established to separate the m-D curves. Then, different recording criteria are adopted considering different types of intersections. After separating the m-D curves, the group targets are distinguished by extracting the different tendency gradients of group targets. In addition to being capable of distinguishing group targets, the proposed algorithm is robust to influences from noise. Simulations are performed to validate the effectiveness of the proposed method.

Execution time of λ-terms via denotational semantics and intersection types

The multiset-based relational model of linear logic induces a semantics of the untyped λ-calculus, which corresponds with a non-idempotent intersection type system, System R. We prove that, in System R, the size of type derivations and the size of types are closely related to the execution time of λ-terms in a particular environment machine, Krivine's machine.

Intersection type calculi of bounded dimension

A notion of dimension in intersection typed λ-calculi is presented. The dimension of a typed λ-term is given by the minimal norm of an elaboration (a proof theoretic decoration) necessary for typing the term at its type, and, intuitively, measures intersection introduction as a resource. Bounded-dimensional intersection type calculi are shown to enjoy subject reduction, since terms can be elaborated in non-increasing norm under β-reduction. We prove that a multiset interpretation (corresponding to a non-idempotent and non-linear interpretation of intersection) of dimensionality corresponds to the number of simultaneous constraints required during search for inhabitants. As a consequence, the inhabitation problem is decidable in bounded multiset dimension, and it is proven to be EXPSPACE-complete. This result is a substantial generalization of inhabitation for the rank 2-fragment, yielding a calculus with decidable inhabitation which is independent of rank. Our results give rise to a new criterion (dimensional bound) for subclasses of intersection type calculi with a decidable inhabitation problem, which is orthogonal to previously known criteria, and which should have immediate applications in synthesis. Additionally, we give examples of dimensional analysis of fragments of the intersection type system, including conservativity over simple types, rank 2-types, and normal form typings, and we provide some observations towards dimensional analysis of other systems. It is suggested (for future work) that our notion of dimension may have semantic interpretations in terms of of reduction complexity.

A diverging diamond interchange (DDI) in conditions of road network in Slovakia

This article focuses on the comparison of the current uncontrolled intersection and the new type of intersection. To obtain the most accurate results the intersection is simulated in the Aimsun software. The intersection is situated in Bratislava. It is formed by exits and entrances to the highway D2. The new type of the intersection is denoted as a Diverging diamond interchange (DDI) which increases the safety and fluency of the road traffic. It is most used in the interchanges.

Empirical Study and Modeling of Vehicular Communications at Intersections in the 5 GHz Band

Event warnings are critical in the context of ITS, being dependent on reliable and low-delay delivery of messages to nearby vehicles. One of the main challenges to address in this context is intersection management. Since buildings will severely hinder signals in the 5 GHz band, it becomes necessary to transmit at the exact moment a vehicle is at the center of an intersection to maximize delivery chances. However, GPS inaccuracy, among other problems, complicates the achievement of this goal. In this paper we study this problem by first analyzing different intersection types, studying the vehicular communications performance in each type of intersection through real scenario experiments. Obtained results show that intersection-related communications depend on the distances to the intersection and line-of-sight (LOS) conditions. Also, depending on the physical characteristics of intersections, the presented blockages introduce different degrees of hampering to message delivery. Based on the modeling of the different intersection types, we then study the expected success ratio when notifying events at intersections. In general, we find that effective propagation of messages at intersections is possible, even in urban canyons and despite GPS errors, as long as rooftop antennas are used to compensate for poor communication conditions.

Junction parameter calibration for mesoscopic simulation in Vissim

Abstract: In this paper, we present a mesoscopic simulation method with a special focus on the calibration of the junction control parameters. Mesoscopic simulation methods are popular for their fast run times compared to microscopic simulations methods. However, there are some simpler behavioral assumptions in the mesoscopic simulation, which will be described in the paper along with the basic algorithms of the mesoscopic simulation. Hereby, we also describe the main differences in the implementations of microscopic and mesoscopic simulation as being implemented in the traffic simulator software PTV Vissim. The main focus of this paper is directed towards parameter calibration for junctions. The influence of parameter variation is demonstrated for different types of intersections and ranks of movements, namely this concerns the follow-up and critical gap and the maximum waiting time. More specifically, it can be shown that adjusting these three parameters allows to closely match illustrative exhibits between conflicting volumes and the potential capacity in the Highway Capacity Manual (HCM). Due to the simplifications compared to microscopic algorithms junction modelling in mesoscopic simulation is based on the same gap parameters as the analytic approach in the HCM. Consequently, default values for these parameters in Vissim form a suitable basis for parameter calibration to local situations.

Turbo – Roundabouts and their Basic Evaluation at Realized Constructions in Czech Republic

The article deals with an operation issues and traffic evaluation at selected turbo-roundabouts realized in Czech Republic. Also describes redevelopment possibility of existing roundabouts with classic layout to the roundabouts with spiral arrangement of the traffic lanes on the circulatory roadway. Described are advantages and disadvantages of the spiral arrangement in compare with normal roundabouts. The article evaluates Czech methodology of turbo - roundabout design, which was published in 2015 and compares its findings with foreign methodologies, especially Dutch and Slovakian standards. Presented are basic divisions of turbo - roundabouts and how the single types of layout are different from the point of view of number of traffic lanes and estimated capacity. There is shown the list of realized turbo - roundabouts on which is made a comparison of identity of the selected parameters of geometric elements defined in the Czech methodology with the foreign standards. Evaluation criteria of realized constructions are basic design elements of turbo-roundabouts, traffic lane (roadway) width and layout and design arrangement with aiming on problematic design features.The article also briefly deals with the evaluation of effectiveness from the point of view of capacity and traffic accidents, when are compared traffic accidents data at selected locations in Czech Republic where redevelopment of conventional types of intersections to turbo-roundabouts were made.

Evaluation of Safety Performance Functions Based on Experimental Design Using a Cross-Validation Method

The Highway Safety Manual (HSM) Part C provides a series of safety performance functions (SPFs) for different roadway conditions. The SPFs suggested in the HSM are formulated on the basis of exposure variables: the logarithms of the annual average daily traffic (AADT) on the major road and on the minor road under the base condition. In this research, data from 7,802 intersections in Florida were collected and processed. These intersections were categorized into seven types based on area type (rural or urban), number of legs (three or four), and number of approaches controlled by stop signs. Twenty-two SPF formulations, including the one suggested by the HSM, were developed for each intersection type for examination of the goodness-of-fit measures of the SPFs. In addition, the goodness of fit of each model of the 22 SPFs in each category was examined with 10-fold leave-one-out cross-validation (LOOCV). With a comparison of the delta values generated with the LOOCV method, it is suggested that the SPF with the logarithm of the total entering vehicle volume and the ratio of the AADT on the minor road and the AADT on the major road are important. In addition, the SPFs with the AADT on the major road and the AADT on the minor road and their logarithmic transformations are also important. Therefore, it is suggested that the future HSM compare these two SPF formulations—as suggested in the current research, along with the original SPF formulation in the manual—and select the one with the best model fit on the basis of the delta value using LOOCV.

Empirical Analysis and Modeling of Stop-Line Crossing Time and Speed at Signalized Intersections.

In China, a flashing green (FG) indication of 3 s followed by a yellow (Y) indication of 3 s is commonly applied to end the green phase at signalized intersections. Stop-line crossing behavior of drivers during such a phase transition period significantly influences safety performance of signalized intersections. The objective of this study is thus to empirically analyze and model drivers’ stop-line crossing time and speed in response to the specific phase transition period of FG and Y. High-resolution trajectories for 1465 vehicles were collected at three rural high-speed intersections with a speed limit of 80 km/h and two urban intersections with a speed limit of 50 km/h in Shanghai. With the vehicle trajectory data, statistical analyses were performed to look into the general characteristics of stop-line crossing time and speed at the two types of intersections. A multinomial logit model and a multiple linear regression model were then developed to predict the stop-line crossing patterns and speeds respectively. It was found that the percentage of stop-line crossings during the Y interval is remarkably higher and the stop-line crossing time is approximately 0.7 s longer at the urban intersections, as compared with the rural intersections. In addition, approaching speed and distance to the stop-line at the onset of FG as well as area type significantly affect the percentages of stop-line crossings during the FG and Y intervals. Vehicle type and stop-line crossing pattern were found to significantly influence the stop-line crossing speed, in addition to the above factors. The red-light-running seems to occur more frequently at the large intersections with a long cycle length.

Associations between the characteristics of intersections and the risk of red-light-running crashes

ABSTRACTMany studies have focused on the effects of drivers and the characteristics of signals on crashes involving automobiles running red-lights (referred to as ‘RLR’ in this paper). However, very little work has been conducted to quantify the effect of the geometric design of intersections on the risk of RLR crashes. This study investigates signalized intersections in Alabama to examine how RLR crashes differ from other types of crashes at these intersections. The analysis results indicate that four-way intersections showed a higher susceptibility of RLR crashes than other intersection types. Some other comparisons that showed a higher susceptibility of RLR crashes were intersections on straight roadways compared to curved roads, level roads compared to downhill or uphill, crest or sag, and intersections having two-lane cross streets compared to those with wider cross streets. Also, installing a left-turn lane can reduce the proportion of RLR crashes compared to others at the signalized intersections.