Entrance Ramp Research Articles

Modeling Wrong-Way Driving Entries at Limited Access Facility Exit Ramps in Florida

Wrong-way driving (WWD) is a dangerous behavior which poses a significant safety risk on limited access facilities. As WWD crashes are rare, it is difficult to build credible statistical models based solely on crashes. Modeling other WWD events, such as citations and 911 calls, can result in more reliable models. Even though these WWD events do not always result in a crash, they can be an effective surrogate for WWD crashes. Analysis of Florida limited access exit ramps found that ramps with multiple WWD crashes from 2011 to 2015 tended to have more WWD citations and 911 calls (WWD entries). Additionally, areas with high WWD crash densities also had high WWD entry densities and 68% of WWD crashes had an associated citation, 911 call, or both. These results show that modeling WWD entries can provide insights into WWD crashes. A model was developed for Florida limited access facilities to identify roadway factors and traffic characteristics of exit ramp terminals that influence WWD entries. This model indicated that interchange type, intersection angle of exit ramp terminals, presence of tolling at the entrance ramp, presence of a channelizing island between the exit ramp lanes, number of lanes on the exit ramp, area (rural or urban), and traffic volumes significantly affect the likelihood of WWD entries at exit ramps. With this model, transportation agencies can better predict WWD entries at exit ramps; identify suitable locations for possible countermeasures; and improve their current design, signing, and pavement marking practices while still following national and state standards.

A study on the CO2 and NOx emissions performance of Euro 6 diesel vehicles under various chassis dynamometer and on-road conditions including latest regulatory provisions

The current study presents a detailed analysis of the gaseous emissions, focusing on CO2 and NOx, of diesel vehicles under several operating conditions. An assessment is also made on the impact and effectiveness of the Real Driving Emissions (RDE) test, which is mandatory by the European Union (EU) type approval regulation for passenger cars since September 2017. The method followed comprises emissions measurement tests on three Euro 6 diesel vehicles, under laboratory and various on-road operation conditions. Chassis dynamometer tests in the laboratory showed that emissions over the current type approval test (World-wide harmonized Light-duty Test Procedure or WLTP), and over the former one (New European Driving Cycle or NEDC), poorly reflect real-world levels. However, the most demanding CADC testing comes closer to real drive emissions. Comparison of driving conditions on the chassis dynamometer over different driving cycles and on the road reveals that the emission performance substantially varies between different tests, even for apparently similar operation conditions. The NOx emissions reduction strategy of pre-RDE monitoring Euro 6 vehicles seems to be optimized for the NEDC driving conditions, which are not representative of the real-world driving conditions. The real-world emissions during normal driving conditions are effectively captured with the new RDE test, however driving the vehicle dynamically, at conditions outside the RDE regulation boundaries, results to disproportional high emissions. This is a significant shortcoming which might be critical for populations living on hilly areas or those close to specific micro-environments, such as highway entrance ramps, traffic lights, etc.

Application of the Highway Safety Manual-2010 to Expect Average Crash Frequency at Full Cloverleaf Interchange

Background: In this study, suggested pattern of HSM-2010 has been developed to expect crashes on Azadegan Interchange in the Tabriz, Iran. IHSDM – HSM software was used to predict and expect the average crash frequency, crash severity, and crash type distributions. Methods: The site that evaluated in this study was a full cloverleaf interchange in an urban area. It is a service Interchange at the junction between a freeway and a minor arterial cross Street. When using the Predictive, the freeways and ramps within the defined project limits were divided into individual sites. A site is a homogeneous freeway segment and homogenous ramp segments. The focus of the discussion in this study is on the sites located in the vicinity of an interchange due to the complexity of interchange roadways. Results: The results of this study showed that the calibration factors obtained for this interchange were 3.68 for FI crashes and 1.35 for property damage only. It was also observed that using accident statistics occurred at the Azadegan interchange by 2016 and 2017 as well as the geometric characteristics of the interchange, the total expected average crash frequency by 2018 is 13.70, of which 7.8 cases were fi crashes, and 5.9 cases are property damages only. It was also observed that in the freeway segment, the severity of the expected fatal injuries, incapacitating injuries and non-incapacitating injuries, decreased by approximately 95, 86 and 4% respectively, and the expected possible injuries and the property damage only ( no injury ) increased by 156% and 239%, respectively. Also, in the entrance and exit ramps of the interchange, the expected severity of the fatal injuries, incapacitating injuries and non-incapacitating injuries, possible injuries and the property damage only ( no injury ), decreased by approximately 98, 94, 53, 24 and 1% respectively. Conclusion: Use of highway safety manual to assess the interchanges, provide useful information to predict and expect the average crash frequency, crash severity, and crash type distributions.

A Study on the Merits for Coordinated Use of Ramp Metering and Variable Speed Limit Traffic Control Systems

Aim:The aim of this research was to investigate the merits for further improvements of traffic operation on freeways and expressways through coordinated use of Ramp Metering and Variable Speed limit (VSL) control systems.Methods:In this research, the widely used ALINEA Ramp Metering strategy was coordinated with a rule-based VSL strategy so that the total flow entered from the upstream freeway and entry ramp is maintained below the merge downstream capacity. The developed algorithm was then examined on a freeway network comprising two merge and one diverge sections, using VISSIM microscopic simulation model. The performance of the simulated network was examined under three scenarios namely, No-control, Ramp Metering only and Ramp Metering plus VSL controls. The network performance under each scenario was then assessed and compared using three measures of performance namely, average travel time, overall delay and freeway throughput. The ANOVA test was used to analyze and compare the impacts of specified scenarios.Results:The results indicated that the best performance is achieved under coordinated Ramp Metering plus VSL scenario as it produced a significantly better performance in comparison with the other two scenarios.Conclusion:The results can be attributed to the synergistic effects of coordinated and integrated use of these control systems on the freeway network and therefore, coordination of such systems is recommended.

High spatio-temporal resolution pollutant measurements of on-board vehicle emissions using ultra-fast response gas analyzers

Abstract. Existing ultra-fast response engine exhaust emissions analyzers have been adapted for on-board vehicle use combined with GPS data. We present, for the first time, how high spatio-temporal resolution data products allow transient features associated with internal combustion engines to be examined in detail during on-road driving. Such data are both useful to examine the circumstances leading to high emissions, and reveals the accurate position of urban air quality “hot spots” as deposited by the candidate vehicle, useful for source attribution and dispersion modelling. The fast response time of the analyzers, which results in 100 Hz data, makes accurate time-alignment with the vehicle's engine control unit (ECU) signals possible. This enables correlation with transient air fuel ratio, engine speed, load, and other engine parameters, which helps to explain the causes of the emissions “spikes” that portable emissions measurement systems (PEMS) and conventional slow response analyzers would miss or smooth out due to mixing within their sampling systems. The data presented is from NO and NOx analyzers, but other fast analyzers (e.g. total hydrocarbons (THC), CO and CO2) can be used similarly. The high levels of NOx pollution associated with accelerating on entry ramps to motorways, driving over speed bumps, accelerating away from traffic lights, are explored in detail. The time-aligned ultra-fast analyzers offer unique insight allowing more accurate quantification and better interpretation of engine and driver activity and the associated emissions impact on local air quality.

2258 - Impact of Different Ramp Metering Strategies on Vehicle Emissions along Freeway Segments

2nd Highest Scoring Abstract: Undergraduate/Masters Background Air pollutants are widely recognized as the substances that adversely affect the global climate, plants and animal species and public health. Certain strategies have been proposed to reduce vehicle emissions, such as the ecology oriented pavement designs and green road operations. A ramp meter is typically installed on a freeway entrance ramp to regulate the traffic flow entering a freeway according to actual traffic conditions. Ramp meters could reduce traffic congestion through adjusting ramp traffic flows to minimize the disruptions on mainline traffic flows. While there is plenty of mobility and safety related research on ramp metering, there are relatively fewer studies on the estimation of specific impacts of ramp metering on freeway emissions. Methods The objective of this research is to estimate emissions while driving along mainline freeways with a series of ramps that are controlled by meters. The vehicle emissions were estimated based on the instant vehicle speed and acceleration rate through dynamic vehicle operating modes defined by EPA MOVES. Real time driving speed and acceleration rate were measured from a test vehicle driving along the freeway I-45 in Houston, TX, where five on-ramps were placed with three control mode: (1) no metering, (2) isolated metering, and (3) integrated metering. Results During rush hours of a weekday, the isolated and integrated ramp metering strategies could improve the mobility, therefore reducing travel delay; and prevent harder acceleration and deceleration from being operated. The integrated metering strategy is more beneficial to the mobility improvement and smooth vehicle maneuver than the isolated one, which is reflected by the dominant distribution of the operational mode IDs as well. However, the ramp metering control strategy is not always favorable to vehicle emissions. The total mainline freeway emissions estimated under the isolated ramp metering strategy are higher than the no metering strategy. Conclusions Isolated and integrated ramp metering control strategies could improve mobility and enhance smooth vehicle maneuver in the mainline of a freeway. In the mean time, only when the mobility is significantly improved, such as the one in the integrated ramp metering control strategy, the total emissions are tremendously reduced for the shorter emission duration. Therefore, the integrated ramp metering control strategy is superior to the isolated control strategy, in terms of both mobility and vehicle emissions.

2258 - Impact of Different Ramp Metering Strategies on Vehicle Emissions Along Freeway Segments

Air pollutants are widely recognized as the substances that adversely affect the global climate, plants and animal species and public health. Certain strategies have been proposed to reduce vehicle emissions, such as the ecology oriented pavement designs and green road operations. A ramp meter is typically installed on a freeway entrance ramp to regulate the traffic flow entering a freeway according to actual traffic conditions. Ramp meters could reduce traffic congestion through adjusting ramp traffic flows to minimize the disruptions on mainline traffic flows. While there is plenty of mobility and safety related research on ramp metering, there are relatively fewer studies on the estimation of specific impacts of ramp metering on freeway emissions. The objective of this research is to estimate emissions while driving along mainline freeways with a series of ramps that are controlled by meters. The vehicle emissions were estimated based on the instant vehicle speed and acceleration rate through dynamic vehicle operating modes defined by EPA MOVES. Real time driving speed and acceleration rate were measured from a test vehicle driving along the freeway I-45 in Houston, TX, where five on-ramps were placed with three control mode: (1) no metering, (2) isolated metering, and (3) integrated metering. During rush hours of a weekday, the isolated and integrated ramp metering strategies could improve the mobility, therefore reducing travel delay; and prevent harder acceleration and deceleration from being operated. The integrated metering strategy is more beneficial to the mobility improvement and smooth vehicle maneuver than the isolated one, which is reflected by the dominant distribution of the operational mode IDs as well. However, the ramp metering control strategy is not always favorable to vehicle emissions. The total mainline freeway emissions estimated under the isolated ramp metering strategy are higher than the no metering strategy. Isolated and integrated ramp metering control strategies could improve mobility and enhance smooth vehicle maneuver in the mainline of a freeway. In the mean time, only when the mobility is significantly improved, such as the one in the integrated ramp metering control strategy, the total emissions are tremendously reduced for the shorter emission duration. Therefore, the integrated ramp metering control strategy is superior to the isolated control strategy, in terms of both mobility and vehicle emissions.

Using Naturalistic Driving Study Data to Evaluate the Effects of Intersection Balance on Driver Behavior at Partial Cloverleaf Interchange Terminals

Past studies showed that poor intersection balances at partial cloverleaf (parclo) interchange terminals significantly impact traffic safety and sight distance of drivers making left turns to entrance ramps. Some state traffic agencies have recommended a “balance” guideline that the length between the left-turn stop line on crossroads to the middle of the intersection should not be greater than 60% of the entire length of the intersection. However, a scarcity of research exists on how the balance of an intersection affects driver behavior, which has been identified as a critical contributing factor to intersection-related crashes. This study utilizes the Naturalistic Driving Study (NDS) data to evaluate the effects of intersection balance on driver behavior at parclo interchange terminals for proof-of-concept. A small but representative data sample was collected from the second Strategic Highway Research Program’s (SHRP 2) NDS dataset. It demonstrates statistical characteristics and overall trends of driver speed, acceleration/deceleration rates, and risk perception with the changing of intersection balances. Conclusions provide guidance on optimal intersection balance design that may help drivers make smoother and safer transitions from crossroads to entrance ramps at parclo interchange terminals.

Methods of dropping auxiliary lanes at freeway weaving segments

ABSTRACTAuxiliary lanes connecting freeway entrance and exit ramps provide additional space for entering and exiting vehicles to change lanes. The method of dropping auxiliary lanes is critical in the design of freeway auxiliary lanes. This study investigates the performance of different methods of dropping auxiliary lanes. Case studies were conducted at two selected freeway segments with successive entrance or exit ramps in the City of Houston. Traffic simulation analysis results of these two case studies show that additional operational benefits can be achieved by extending an auxiliary lane beyond the freeway weaving segment. The study also found that if the weaving segment is followed by an entrance/exit ramp and this ramp has high traffic volume, it can be less operationally favorable to extend and terminate the auxiliary lane at this entrance/exit ramp location. Instead, dropping the auxiliary lane before this entrance/exit ramp represents a more operationally effective option.

Feasibility of Using a Constant Acceleration Rate for Freeway Entrance Ramp Acceleration Lane Length Design

AbstractWhen estimating the required acceleration length of vehicles accelerating from a stopped position, a constant acceleration rate is sometimes assumed for the sake of simplicity. Nevertheless...

Early ramp warning using vehicle behavior analysis

The ramp entrance connects the main road and the ramp and is the merging zone for vehicles from main road and ramp. As ramp entrance is considered to be the most accident-prone area, this paper focuses on the early warning to avoid collision of vehicles for the ramp entrance on freeway. Firstly, we studied the relation between the vehicle speed and collision risk by analyzing the vehicle trajectories. Secondly, the risk grades were defined based on the lag of the time when vehicles enter into the merging zone from the main road and the ramp. Finally, the risk grade was released by the information board and vehicle terminal to make driver aware of it, so that the vehicles can pass the merging zone in sequence rather than collide with each other. Theoretical analysis and experiment results show that the proposed method could realize early warning for the ramp entrance, reducing the possible traffic accidents.

Improve Sight Distance at Signalized Ramp Terminals of Partial-Cloverleaf Interchanges to Deter Wrong-Way Entries

AbstractProviding drivers with open sight distance on entrance ramps can help prevent wrong-way entries at interchange terminals. For partial-cloverleaf (parclo) interchange terminals with close-sp...

The Pennsylvania Turnpike, the Nation's First Superhighway at The State Museum of Pennsylvania

<i>The Pennsylvania Turnpike, the Nation's First Superhighway</i> at The State Museum of Pennsylvania

Right Here, Right Here

Right Here, Right Here Shibasaki Tomoka (bio) Translated by Kendall Heitzman From the time I got off the bus to the time I reached the foot of the bridge, I met almost no one. I was at last standing right in front of it, and the opening segment didn't appear to be as steep a climb as I had imagined. Maybe the steep part came after the tollgate, which the car that had just zipped past me was about to pass through. I couldn't find the entrance to the pedestrian walkway, so I walked down the sidewalk that ran alongside the IKEA that had been built right next to the bridge. The IKEA parking lot was mostly empty, but I could see the figures of people on the store's shuttle bus when it came by. The bridge was almost two kilometers long, leading to the Ōsakakō area on the other side. I had taken the city bus across it many times. It was neither a suspension nor a truss bridge, but rather was entirely supported by an alarmingly small number of piers; from certain angles, the roadbed appeared to be hovering in midair. Every time the bus climbed that sharp gradient, I would feel a sense of elation just as though I were lifting off on the Railroad to the Milky Way. Whoooaaa, just like a sightseeing plane! At its highest point, the bridge is 45 meters above the water. There aren't any tall buildings around it, and the fencing is low, so there is nothing at all to get in the way of the view—you can see all of Osaka from the top. The view is probably even better than the ones from the observation decks on towers and skyscrapers that you have to pay to get into. [End Page 80] I knew that you could walk across it. All of the bridges around here were more than 30 meters above the water, so that the ships could get to the industrial areas, but if you were looking to go to the top of one of them, this was the tallest and longest. The sky was overcast in a mottled pattern, to the point that I didn't know where the sun was. The low-slung clouds were the very ones that brought the rains of winter. Ahead was the entrance ramp to the pedestrian walkway, in a fenced-in area underneath the bridge where it started to rise above the ground. The wire fencing had turned black from rust and exhaust fumes. There was no crosswalk leading from here to the pedestrian entrance facing the other side of the road, but there was also virtually no traffic down here. I walked across to the entrance to the ramp, where I took my camera out of my backpack and took off my gloves. The pedestrian ramp snaked this way and that under the rise of the bridge. It felt familiar to me. When I was a child, I would make my way to swimming classes every week via a pedestrian walkway under the Hanshin Expressway that connected to a different ward of Osaka on the other side of the water, and a little farther upstream from that was a bridge I would occasionally cross on my way home from high school. With my nylon bag from the swimming school on my back, I would peer over the railing at the surface of the water far below. The green river didn't offer the least bit of visibility, but still I would see the scary dark shadows of fish; they looked like they were monsters from Ultraman, creatures with the power to suddenly change shape. Their black legion whorled in continuous pursuit of itself. Underneath that ramp were abandoned bicycles and a scrapyard. The factories close by either side of the highway were always dimly lit, and there were almost never other people there. Compared to that, the view from here—of a parking lot down below with brand-spanking-new cars, and an endless expanse of empty land on both sides—was already a good deal happier. The pedestrian ramp twisted right and left...

Study on Interval Optimal Control Method for Ramp’s Merging Areas in Urban Expressway

How to solve the problem of urban expressway traffic congestion is an urgent problem for the government and the transportation department. Ramp’s merging areas, as the interaction link between internal and external traffic of expressway system, is the main research object of this paper. Taking Hangzhou Qiushi expressway on the road section of the entrance ramp as the target section , the interval optimal control model considering vehicle speed, time occupancy and vehicle spacing as interval variables is proposed, and the single dynamic adjustment algorithm of on-ramp is given.

이산 슬라이딩모드 제어를 이용한 램프 미터링 제어

Ramp metering is one of the most efficient and widely used control methods for an intelligent transportation management system on a freeway. Its objective is to control and upgrade freeway traffic by regulating the number of vehicles entering the freeway entrance ramp, in such a way that not only the alleviation of the congestion but also the smoothing of the traffic flow around the desired density level can be achieved for the maintenance of the maximum mainline throughput. When the cycle of the signal detection is larger than that of the system process, the density tracking problem needs to be considered in the form of the discrete-time system. Therefore, a discrete-time sliding mode control method is proposed for the ramp metering problem in the presence of both input constraint in the on-ramp and exogenous disturbance in the off-ramp considering the random behavior of the driver. Simulations were performed using a validated second-order macroscopic traffic flow model in Matlab environment and the simulation results indicate that proposed control method can achieve better performance than previously well-known ALINEA strategy in the sense that mainstream flow throughput is maximized and congestion is alleviated even in the presence of input constraint and exogenous disturbance.

Model-based airflow controller design for fire ventilation in road tunnels

This paper describes a new approach to design the proportional-integral-derivative (PID) controller of the longitudinal airflow velocity in road tunnels for fire situations. Our work shows clearly that the use of a proper model provides valid data for model-based tuning of tunnel controllers, which is demonstrated by real tunnel tests. The design uses the simplified mathematical model of airflow dynamics based on Bernoulli and continuity equations, which describe the airflow dynamics in one dimension. Optimizing controller parameters on site is very time consuming and this problem increases in the case of complex tunnels with several entrance and exit ramps, which typically have occurrences of traffic congestion. Our approach is based on the design of the controller through simulations, which use the mathematical model of airflow velocity in the tunnel. This approach spares a lot of work and time with the controller tuning within tunnel tests. Moreover, it can discover potential problems, which can occur during real instances of fire in the tunnel. The additional advantage of this approach is a possibility to simulate a scenario of errors and failures of some devices, which are important for reliable control of longitudinal airflow velocity. Although this approach is focused primarily on complex road tunnels, due to their complexity and significant time savings with the controller tuning, it can be also used for simpler tunnels with no ramps (usually highway tunnels) where the design of the airflow controller is not as complex compared to the case of road tunnels. This paper also includes a case study of the airflow controller design for the Blanka tunnel complex in Prague, Czech Republic, which is the largest city tunnel in Central Europe.

Intravital imaging of T and B cell migration across high endothelial venules in lymph node

Abstract High endothelial venules (HEVs) in lymph node (LN) facilitate an effective recruitment of circulating lymphocytes from the blood. HEVs have distinctive cuboidal-shaped endothelial cells and prominent perivascular sheaths consisting of fibroblastic reticular cells (FRCs). Yet, detailed dynamic behaviors of lymphocytes during trans-endothelial migration, intra-perivascular channel crawling and trans-FRC migration in HEV are still poorly understood. In this work, we adapted a custom-design confocal microscope to visualize T and B cell migration across HEV in real time in vivo. Actin-DsRed transgenic mice were used to visualize HEV-endothelial cells and T or B cells obtained from actin-GFP mice were adoptively transferred. At the same time, FRCs were labeled in vivo by injecting anti-ER-TR7 antibody conjugated with far-red fluorophore to the footpad. T and B cells squeezed in between endothelial cells (ECs) and then migrated along the perivascular channel, narrow space between ECs and FRCs, for searching a proper site to exit by trans-FRC migration. Interestingly, B cells spent twice longer time in the perivascular channel than T cells although their total moving distances in the perivascular channel were similar. In addition, we observed that there existed preferred exit sites (“exit ramps”) from the perivascular channel for both of T and B cell. To observe whether T and B cell exit through the same exit ramp, we simultaneously transferred DsRed+ T and GFP+ B cells into wild type mouse. Indeed, T and B cells followed each other though the same exit ramp from the perivascular channel. There also existed “entrance ramps” into the perivascular channel; preferred sites for trans-endothelial migration for both of T and B cells.

A Study of Collision Risk Estimation and Users Evaluation at Merging Section of Urban Expressway in Japan

For usability of urban expressway in Japan, there are some problems due to the limitation of spatial con-straint. As the result of the limitation, there are merging sections that do not have enough length and set a right-side entrance ramp which is connected to the passing lane, directly. Therefore, unfamiliar drivers such as female and/or elderly drivers are subjected to stress and aware of danger when they merge onto the expressway and it is necessary to measure these situations quantitatively from the viewpoints of both traffic conflict risk and users evaluation. The purpose of this study is to estimate collision risk by using Surrogate Safety Measure and evaluate Quality of Service for drivers at merging sections of urban expressway in Japan. We focused on each ve-hicle merging movements and traffic conflicts at three on-ramps, which has different geometries, by im-age processing technology. First, in order to elucidate the occurrences of collision risk in merging section, we analyzed the collision risk between a merging vehicle and a main lane vehicle by using the Possibility Index for Collision with Urgent Deceleration (PICUD) index. It is shown that the position of conflicts is affected by the amount of traffic volume. Second, we conducted discriminant analyses for the results of the PICUD estimation in order to reveal the influence factors of collision risk at each merging section. As the result of discriminant analyses, it is found that the percentage of merging position and traffic volume of main lane have a huge effect on collision risk for merging movement. In addition, both the percentage of heavy vehicles and the existence of other merging vehicle at a time trigger rear-end collision risk. Fur-thermore, we examined some countermeasures to reduce collision risk in objective merging sections by sensitivity analysis and proposed a Level of Service index which is based on the rank of rear-end collision risk considering users’ subjective evaluation.

New Applications for Polymer Overlays

Polymer concrete (PC) overlays have proven to be a very effective method of extending the lives of bridge decks and improving skid resistance. Many states in the U.S have specifications and have used overlays on hundreds of bridge decks. Multiple-layer epoxy, epoxy and methacrylate slurry, and polyester premixed overlays have been widely used. One of the keys to successful performance is surface preparation. The very light weight, water tightness, good skid resistance, excellent bond to concrete, and excellent durability have made PC overlays a very sustainable solution for increasing the life of bridges and parking garages, But in recent years very thin overlays referred to as high-friction surface treatments (HFST) have been widely used to provide skid resistance for asphalt pavements in high accident zones, particularly on horizontal curves. Several state departments of transportation (DOTs) have reported very significant reductions in accidents after HFST have been applied. The total length of the application is often only a few hundred meters or less. The cost, when compared to other remedial measures, has been very competitive. The treatments are very similar to very thin slurry overlays. The purpose is not to structurally rehabilitate the pavement, but to provide increased skid resistance for safety. There is also an increased use of thin overlays to provide color for applications including pedestrian and bicycle lanes, bus lanes, entrance and exit ramps, cross walks, and rail road crossings. There are few standards in the U.S. for colors in various applications or for where color should be used. But these thin overlays provide high visibility, skid resistance, and long life. A discussion of these applications, materials and installation methods, and where available, costs, will be presented.