Entrance Ramp Research Articles

Accommodation of Wheelchair-Reliant Individuals by Community Fitness Facilities

Adhering to recommended healthy physical activity guidelines can be difficult for individuals with spinal cord injury, stroke or other paralytic conditions. Ordinary community structures such as curbs, stairs and narrow passageways can present as major obstacles for individuals who are wheelchair-reliant. The Americans with Disabilities Act of 1990 mandates that public facilities including community fitness centers be accessible to everyone equally. PURPOSE: To determine the level of compliance with ADA accessibility and accommodation of wheelchair-reliant individuals in the Hattiesburg, MS metropolitan area. METHODS: Ten facilities consented to unfettered access allowing evaluation using an 82-item checklist. An ADA Accessibility Stick (Access, Inc., Lawrence, KS) was used to check ADA compliance. Measurements were conducted for parking areas, entrance ramps, exterior door entrances, path of travel throughout the public area, elevators, restrooms and locker rooms, drinking fountains and accessibility to and around exercise equipment. For information concerning accommodation of wheelchair-reliant individuals beyond ADA accessibility, the facility managers were questioned about the training of facility staff and available adaptive equipment. RESULTS: All surveyed facilities were found to be partially compliant, with none of the facilities being 100% compliant. The areas of least compliance were access to and free movement around exercise equipment and full access to restrooms. Beyond ADA accessibility, only 20% of the participating facilities provided suitable adaptive equipment and no facilities employed staff trained in the special needs of those with paralytic conditions. CONCLUSIONS: It remains important for healthcare professionals and other advocacy groups to stress the need for inclusion and accommodation of individuals with disabilities to community fitness facilities allowing wellness needs to be met.

A network model for capped link-based tolls

Toll road operators and other toll facility stakeholders require analysis tools to estimate the ridership and projected income for an increasing variety of tolling schemes. Some tolling schemes commonly considered include link-based tolls as well as derived schemes, such as charging both a minimum and a maximum toll (or cap) for the use of the facility. In addition, different entry ramps may incur different tolls, which may be added to a link-based toll and subject the total toll to a toll cap value. Network equilibrium models that consider such tolls result in non-additive costs on the modeled network due to the capping. To obtain a more tractable equivalent model, a network transformation is used. The model uses the addition of a set of temporary links to the network, which inherit the delays and tolls of the original links. It considers the toll cost per link, as well as minimum and a maximum value of the tolls paid. It is shown that the modified and the original network formulations are equivalent. To solve the resulting multi-class network equilibrium model, a multi-threaded bi-conjugate variant of the linear approximation method has been adapted for the particular network model used. The method is illustrated with a small example as well as an instance of capped link-based toll modeling on a network originating from practice that employs the toll structure considered.

Development of Freeway and Interchange Safety Performance Functions with Respect to Roadway Lighting

The absence of roadway lighting during the night results in a disproportionally large number of traffic crashes and fatalities. Past research on safety effects of roadway lighting involved mostly qualitative studies and focused on intersections and rural roads rather than freeways and interchanges. However, it is desirable to quantify the safety benefits of lighting for cost–benefit analysis and eventual decision making on lighting installations. This paper aims to develop nighttime crash prediction models for roadway lighting in the form of safety performance functions (SPFs). A pilot study on all freeways and expressways in the jurisdiction of Dane County, Wisconsin, was conducted. The crash data collection covered five years' nighttime crashes on all freeways, expressways, and interchanges in Dane County. Nighttime crashes were identified and light-pole data were collected along with traffic and geometry data. On the basis of the data, six SPFs were developed for freeway segments and interchange ramps under lighted and unlighted conditions. Results showed that the number of lanes was a significant factor for interchange ramps. Entry ramps had significantly higher numbers of crashes than did exit ramps under unlighted conditions. Similar results were observed for interchange freeway segments and noninterchange freeway segments. The international roughness index, used as a surrogate for pavement friction values, was significant for all freeway segments' SPFs. Severity distribution functions were also developed. Results showed that the largest safety benefit could be achieved by installing lighting at interchange segments, entry ramps, or exit ramps with annual average daily traffic greater than 10,000 vehicles per day.

Developing a Traffic Management Framework for Coastal Expressway Bridges under Adverse Weather Conditions: Case Study of Rain Day in Shenzhen, China

Adverse weather can reduce visibility and road surface friction, lower vehicle maneuverability, and increase crash frequency and injury severity. The impacts of adverse weather and its interactions with drivers and roadway on the operation and management of expressway or expressway bridges have drawn the researchers’ and managers’ attention to develop traffic management frameworks to mitigate the negative influence. Considering the peculiar geographical location and meteorological conditions, the Guangshen Coast Expressway-Shenzhen Segment (GSCE-SS) was selected as a case in this study to illustrate the proposed traffic management framework on rain days. Conditions categorized by rainfall intensity and traffic flow were the main precondition to make the management decisions. CORSIM simulator was used to develop the alternate routes choice schemes, providing reference for other systems in the proposed traffic management framework. Maps of (a) entrance ramp control (ERC) strategies; (b) mainline control strategies; (c) alternate routes choice; (d) information release schemes, under scenarios of different volume and rainstorm warning grades (BLUE to RED), were drawn to present a reference or demonstration for managers of long-span expressway bridges not only in China, but even in the world.

Prediction of Potential Wrong-Way Entries at Exit Ramps of Signalized Partial Cloverleaf Interchanges

Background: Several previous studies, based upon wrong-way driving (WWD) crash history, have demonstrated that partial cloverleaf (parclo) interchanges are more susceptible to WWD movements than others. Currently, there is not a method available to predict WWD incidents and to prioritize parclo interchanges for implementing safety countermeasures for reducing WWD crashes.Objectives: The focus of this manuscript is to develop a mathematical method to estimate the probability of WWD incidents at exit ramp terminals of this type of interchange.Methods: VISSIM traffic simulation models, calibrated by field data, are utilized to estimate the number of potential WWD maneuvers under various traffic volumes on exit ramps and crossroads. The Poisson distribution model was implemented without field observation and crash data.Results: A comparison between the field data and simulation outputs revealed that the developed model enjoys an acceptable level of accuracy. The proposed model is largely sensitive to left-turn volume toward an entrance ramp (LVE) than stopped vehicles at an exit ramp (SVE). The results indicated that potential WWD events increase when LVEs increase and SVEs decrease. Also, the probability of WWD event decreases as road users are more familiar with the facility.Conclusion: The proposed method can diminish one of the challenges in front of transportation engineers, which is to identify high WWD crash locations due to insufficient information in crash reports. The results are helpful for transportation professionals to take proactive steps to identify locations for implementing safety countermeasures at high risk signalized parclo interchanges.

HMM and HSS Based Social Behavior of Intelligent Vehicles for Freeway Entrance Ramp

In this paper, a novel approach of intelligent vehicle to interact and cooperate with other human driving vehicles is proposed at the freeway entrance ramp scenario. The system consists of a Safety Alert Module and Vehicle Control Module. The Safety Alert System module includes intention estimation and conflict judgment. A two dimension Hidden Markov Model (2DHMM) is used to estimate social vehicle’s driving intention in the intention estimation module. Then the conflict judgment module predicts the potential conflicts between the intelligent vehicle and social vehicle. Moreover, the hybrid state system (HSS) is introduced to control the intelligent vehicle while considering its decision making, states and dynamics. Co-simulation using PreScan and Simulink is conducted. The experiment results show that the intelligent vehicle performs well with a commendable social behavior in the freeway entrance ramp.

Study of Dynamic Adjustment to the Freeway Entrance Ramp Based on VISSIM

This paper aimed at the freeway entrance ramp control principles, through introduction of dynamic adjustment system of the entrance ramp and the control algorithm of the difference between traffic demand and capacity, a problem of the dynamic adjustable rate’s selection was proposed, then used the micro-simulation tool VISSIM to analysis the influence of dynamic adjustable rate that under different capacity reduction factors, choosing delay time and travel time as the standard of entrance ramp control system. At last, this paper concludes that the best reduction factor is 0.98 times the capacity.

Design of an Experimental Tensegrity Pedestrian Bridge

This paper presents the design of an experimental tensegrity pedestrian bridge. The structure is designed as a permanent three-span bridge with spans of 105 m. The bridge has two entrance ramps, three ground supports and one water support. The main structure of the bridge is designed as a light transparent structure based on the tensegrity principle using membranes.

Study on the Traffic Behavior of On-Ramp System Considering Driver Behavior

based on the main road into a two lane entrance ramp system the open boundary conditions, using the asymmetric lane changing rules, considering driver behavior characteristics, from standpoint of safety driving ,simulate the entrance ramp system. We get a basic road map different entrance probability of flow, velocity, and analyze the driving safety.compared with reference, and the reference results show that after considering driver behavior, in the ramp at the interface, reduce the interaction with the main ramp,not only the system traffic flow in each section is improved, and but also improve the driving safety.Considering the entrance ramp system driver behavior can be simulated more in line with the running state of the vehicle in real life.

Radio Channel Properties for Vehicular Communication: Merging Lanes Versus Urban Intersections

Vehicle-to-vehicle (V2V) communication is a challenging but fast-growing technology. It has the potential to enhance road safety by helping the driver to avoid collisions during basic maneuvers such as crossing street intersections, changing lanes, merging on a highway, and driving safely in blind turns. The significance of V2V safety applications increases further where the visual line-of-sight (LOS) is unavailable because of buildings, roadside sound berms, or small hills at an intersection point of two or more roads intersecting at a certain angle, e.g., merging lanes, the entrance or exit ramps on a highway, or four-way street intersections. The reliability of V2V safety applications, which use IEEE 802.11p [1] as the underlying communication technology, highly depends on the quality of the communication link, which relies on the properties of the propagation channel. Therefore, understanding the properties of the propagation channel becomes extremely important.

Research on Driving Risk Model of Freeway Interchange Entrance Area for Accident Prevention

Based on analysis of traffic characteristics of freeway interchange entrance area, Collision Risk Index (CRI) is put forward to evaluate driving risk. Possibility of collision coefficient, speed difference between two colliding vehicles, colliding speed and acceleration of the following car on the target lane are took into consideration in the risk assessment model of CRI. Traffic collisions that may occur in the entrance area are divided into five kinds. The occurrence conditions and risk assessment models of 5 cases are studied correspondingly. Finally, against running speed of main line, distance headway, running speed of vehicle on entrance ramp (front vehicle), three-dimensional numerical simulation has been carried out and driving risk variation laws have been obtained.

Balance Lane Use with VMS to Mitigate Motorway Traffic Congestion

This paper is focused on an application and evaluation of a lane use balancing measure with the variable message signs (VMS) installed on both sides of a carriageway in a bottleneck of a 3-lane section in one direction on a motorway. This is achieved by providing keep-left related messages on the roadside VMS or on the VMS on both sides, and on the entrance ramp to persuade drivers to use the left hand lanes as much as possible. The VMS resulted in slightly more balanced lane use across the carriageway. As a result, it increased the mean capacity and reduced the breakdown probability at the bottleneck.

Study on Control Design of Interchange Entrance Congestion Zone

Interchange entrance area is the key point which affects the overall operational reliability of an Interchange. In order to alleviate the crowded ramp merging area, improve the overall reliability of the interchange and improve traffic safety, when traffic demand increases to a certain extent, traffic control strategies should be used. According of the characteristics of the interchange ramp entrance area, the control strategy of interchange and the mainline which affect the reliability of high-speed road network most has been researched. Analyzing the geometric and traffic characteristics of the ramp merging area, different control strategies on the ramp and the mainline are proposed, that is ramp access control strategy and the main line lane running constraint strategy.

Assessing mobile food vendors (a.k.a. street food vendors)—methods, challenges, and lessons learned for future food-environment research

ObjectivesMobile food vendors (also known as street food vendors) may be important sources of food, particularly in minority and low-income communities. Unfortunately, there are no good data sources on where, when, or what vendors sell. The lack of a published assessment method may contribute to the relative exclusion of mobile food vendors from existing food-environment research. A goal of this study was to develop, pilot, and refine a method to assess mobile food vendors. Study designCross-sectional assessment of mobile food vendors through direct observations and brief interviews. MethodsUsing printed maps, investigators canvassed all streets in Bronx County, NY (excluding highways but including entrance and exit ramps) in 2010, looking for mobile food vendors. For each vendor identified, researchers recorded a unique identifier, the vendor's location, and direct observations. Investigators also recorded vendors answers to where, when, and what they sold. ResultsOf 372 identified vendors, 38% did not answer brief-interview questions (19% were ‘in transit’, 15% refused; others were absent from their carts/trucks/stands or with customers). About 7% of vendors who ultimately answered questions were reluctant to engage with researchers. Some vendors expressed concerns about regulatory authority; only 34% of vendors had visible permits or licenses and many vendors had improvised illegitimate-appearing set-ups. The majority of vendors (75% of those responding) felt most comfortable speaking Spanish; 5% preferred other non-English languages. Nearly a third of vendors changed selling locations (streets, neighbourhoods, boroughs) day-to-day or even within a given day. There was considerable variability in times (hours, days, months) in which vendors reported doing business; for 86% of vendors, weather was a deciding factor. ConclusionsMobile food vendors have a variable and fluid presence in an urban environment. Variability in hours and locations, having most comfort with languages other than English, and reluctance to interact with individuals gathering data are principal challenges to assessment. Strategies to address assessment challenges that emerged form this project may help make mobile-vendor assessments more routine in food-environment research.

A real-time crash prediction model for the ramp vicinities of urban expressways

Ramp vicinities are arguably the known black-spots on urban expressways. There, while maintaining high speed, drivers need to respond to several complex events such as maneuvering, reading road signs, route planning and maintaining safe distance from other maneuvering vehicles simultaneously which demand higher level of cognitive response to ensure safety. Therefore, any additional discomfort caused by traffic dynamics may induce driving error resulting in a crash. This manuscript presents a methodology for identifying these dynamically forming hazardous traffic conditions near the ramp vicinities with high resolution real-time traffic flow data. It separates the ramp vicinities into four zones – upstream and downstream of entrance and exit ramps, and builds four separate real-time crash prediction models. Around two year (December 2007 to October 2009) crash data as well as their matching traffic sensor data from Shibuya 3 and Shinjuku 4 expressways under the jurisdiction of Tokyo Metropolitan Expressway Company Limited have been utilized for this research. Random multinomial logit, a forest of multinomial logit models, has been used to identify the most important variables. Finally, a real-time modeling method, Bayesian belief net (BBN), has been employed to build the four models using ramp flow, flow and congestion index in the upstream and flow and speed in the downstream of the ramp location as variables. The newly proposed models could predict 50%, 42%, 43% and 55% of the future crashes with around 10% false alarm for the downstream of entrance, downstream of exit, upstream of entrance and upstream of exit ramps respectively. The models can be utilized in combination with various traffic smoothing measures such as ramp metering, variable speed limit, warning messages through variable message signs, etc. to enhance safety near the ramp vicinities.

Speed Synchronization Process of Merging Vehicles from the Entrance Ramp

This paper explores the “lane-changing preparation process,” defined as the synchronization process, from a new, integrated perspective. A comprehensive study was conducted to analyze the behavioral characteristics of the speed synchronization process of merging vehicles from entrance ramps by tracking their trajectories in the merge lanes. On the basis of gap selection, merging vehicles were classified as either original gap type or overtaking type, and the existence of speed synchronization was proved by comparing the speed differences of merging vehicles in relation to the putative leader (PL) and the putative follower (PF) vehicles. Several rules of merging vehicles during speed synchronization were established in the behavioral study. The merging vehicles tended to maintain a speed 5 to 7 m/s higher than the speed of the PL so as to overtake unsatisfied gaps in the adjacent through lane. When those vehicles intended to accept a gap, they first adjusted their speeds to be within a 2-m/s difference from their PL and PF vehicles and then merged into the targeted gap within 2 to 3 s. Factors affecting drivers' tolerance of their speed with PL and PF vehicles were modeled with the multiregression method. Significant effects in speed synchronization include the number of rejected gaps, acceleration or deceleration, the speed difference between the PL and the PF, the time headway, the remaining distance in the auxiliary lane, and whether the PL is a merged vehicle. Results from this study may contribute to the understanding of the complex lane-changing behavior in microscopic traffic flow modeling.

Relationship between Rider Trajectory and Injury Outcome in Motorcycle-to-Barrier Crashes

In collisions with traffic barriers, motorcyclists have a much higher risk of fatality than other road users. Many databases focus on the vehicle when reporting the sequence of events; however, in motorcycle collisions, the vehicle and rider often separate and follow different trajectories. The aim of this study was to determine how rider trajectory influences injury outcome. Rider trajectories in barrier collisions were determined through an analysis of police accident reports from New Jersey (2007 to 2011). Seven trajectories were identified: upright, sliding, vaulting, ejected (same side landing), ejected (side unknown), ejected into barrier, and separated before barrier impact. Google Earth Street View was used to verify the barrier type in each collision. Of the 442 single-vehicle motorcycle-to-barrier collisions reported in New Jersey, police accident reports were analyzed for 430 crashes and the barriers were identified for 342 of these crashes (77.4% of all crashes). In the analyzed crashes, 361 riders and passengers were involved. In these crashes, riders most often struck the barrier upright without being ejected from the motorcycle. Barrier type and occurrence on an entrance or exit ramp were found to have a significant effect on the distribution of rider trajectory outcomes. Additionally, being ejected from the motorcycle after striking the barrier increased the odds of serious injury by 2.91 times (95% confidence interval: 1.31 to 6.46).

Enhancing Roundabout Operations via Vehicle Connectivity

With in-vehicle automation and vehicle connectivity gaining momentum, cooperative adaptive cruise control (CACC) systems are expected to enter the market in the near future. Given that the number of roundabouts in the United States has increased significantly, this research effort investigated the potential benefits of the use of CACC systems and vehicle-to-infrastructure connectivity to optimize the trajectories of vehicles approaching a single-lane roundabout. The optimization ensures that vehicles can enter the roundabout when gaps in the circulating roadway are available. The proposed idea is generally similar to the concept of metering single-lane entrance ramps. The system is simulated on a single-lane roundabout for different traffic demands and CACC market penetration levels. The study demonstrates that CACC systems can produce savings in total delay and fuel consumption levels of up to 80% and 40%, respectively, relative to the levels for traditional roundabout control. Further benefits are also achievable if one considers the potential to reduce the time headway between CACC-equipped vehicles and thus increase lane capacity.

Analysis Framework for Evaluation of Traffic Compliance Measures

Agencies and practitioners often test innovative strategies for improving driver compliance with traffic regulations. However, in evaluating these strategies, researchers often rely on simple before-and-after methods that suffer from several flaws and that can result in misleading results and an inaccurate assessment of a strategy's effectiveness. This paper examines these flaws, proposes a framework that avoids or corrects for them, and then uses it to analyze the effectiveness of a common strategy: installation of larger signage (at a freeway entrance ramp). The framework described in this paper can be applied to a wide range of driver compliance situations. Among them are yielding at pedestrian crossings, speed limit obedience, and proper anticipation of roadway features such as speed humps or intersections.

On-Ramp Fuzzy Metering and Simulation in Urban Expressway

In view of the high complexity and uncertain characteristics of traffic flow in urban expressway, a fuzzy logic approach is proposed to adjust the number of vehicles entering a mainline of urban expressway via entrance ramp during rush traffic times. Taking account of the combine influence of traffic state on mainline and the on-ramp queue at Surface Street, the on-ramp fuzzy controller of urban expressway is designed based on such traffic information as the speed downstream mainline, time occupancy upstream mainline, and on-ramp queue length at the Surface Street. Simulation research based on MATLAB toolbox is carried out and the results show that the fuzzy controller is feasible and reasonable to confirm the number of vehicles entering the mainline of urban expressway.