Lane Length Research Articles

Multi-class traffic flow on a partially space-shared road

ABSTRACTScarce urban space makes urban streets have to be partly shared by cars and cyclists. Traffic flow can be considerably influenced by cyclists, which are comparatively slower than cars. The fundamental diagram (FD) can change greatly, correlating to bike lane length and the cyclist flow. Models for the traffic dynamics on the space-shared streets are still lacking. This work fills the gap. This paper starts from proposing analytic formulas for the capacity, free-flow speed and critical density on a one-lane road, which together characterize the FD. The sensitivity of the FD to the bike lane length as well as the cyclist flow, using the analytical formulas, are presented. The given FD is satisfactory, compared with microscopic simulation results. Finally, we extend the research scope to a multi-lane road. It is expected that this work can benefit city designs and traffic operations.

Delays of Shared-Short Lanes at Unsignalized Intersections

At unsignalized intersections, both on the major street and on the minor street, there may be short turning lanes alongside the through lanes following downstream from one single lane. This combined system is termed a shared-short lane (SSL). Up to now it has only been possible to calculate the capacity of these lanes at the stop line and the capacity of the diverging point, where the turning lane diverges from the through lane. For the total average delay of the involved individual movements, there is no applicable estimation procedure. As a special case, the shared lane (SL), which is used by several movements without a separate turning lane, must also be reconsidered. This paper presents a new model for the estimation of average delays of SSL with SL as a special case at unsignalized intersections. The model is based on the analogy to standard queuing systems. The results depend on the length of the short lane. The model is validated by simulation. The results demonstrate that the outcome of the models in current highway capacity manuals may be misleading, with the risk of inaccurately classifying the level of service of an intersection. Therefore, there is an urgent need to complete the relevant procedures in highway capacity manuals by more realistic estimation procedures for the total delay at an SSL or an SL. The methods in this paper—even if they are rather complex—are recommended to be incorporated into future versions of highway capacity manuals using some simplifications.

Cellular automaton simulation of vehicles in the contraflow left‐turn lane at signalised intersections

To improve the capacity of signalised intersections for left-turn vehicles, an unconventional left-turn design named the contraflow left-turn lane is applied at intersections in several cities of China. The main concept of the design is to provide more capacity for left-turn vehicles by dynamically making use of the adjacent opposite lanes. In this study, a cellular automaton model that simulates left-turn traffic flow at a signalised intersection with a contraflow left-turn lane was developed and verified by field data. Rules for vehicles entering the contraflow left-turn lane were proposed, and various factors including the vehicle type, driver type, and the ratio of U-turn vehicles were considered. The simulation results showed that the contraflow left-turn lane could increase the capacity of the intersection and decrease the delay of left-turn vehicles. Also, the optimal match between the length of the contraflow left-turn lane and the duration of the pre-signal green light can be evaluated via simulation. This study can provide a reference for the actual application of contraflow left-turn lanes.

Passing lane optimum length on two-lane highways

An investigation into the optimum length of passing lanes on rural two-lane highways is presented in this paper. A passing lane is a short length of added lane to improve passing opportunities on two-lane two-way highways. The study utilized field data and traffic simulation in this investigation, with field data primarily used in calibrating and validating the traffic simulation program. A sensitivity analysis was conducted using traffic level and length of passing lane as the primary variables. The level of association between the reduction in platooning and study variables was examined. Study results showed that, within the range of passing lane length investigated in this study (0.5 mi to 3.0 mi), traffic performance continued to improve with the increase in passing lane length. Moreover, for the same target improvement in performance, the required passing lane length increases with the increase in traffic volume. The passing lane optimum lengths developed in this study all varied in the range between 0.80 and 2.0 miles depending on traffic volume.

An exploratory investigation of the impact of ramp metering on driver acceleration behavior

Ramp metering has been proven as an effective freeway management strategy; however, the impact of ramp metering on drivers' acceleration behavior has not been fully investigated. A better understanding of acceleration behavior changes with ramp metering is critical to the adequate design of ramp metering facilities. In this study, drivers' speed and acceleration data were collected at two representative metered ramps in Los Angeles, California. The speed and acceleration profiles under meter-on and meter-off scenarios were compared. Statistical results demonstrated that ramp metering affects drivers' acceleration behavior at ramp acceleration lane. It was found that at the metered ramp with short existing acceleration length, the average acceleration rate from ramp meter stop bar to 500 ft downstream under meter-on scenario (4.72 ft./s2) is approximately 40% higher than when meter-off (3.18 ft./s2). The design of acceleration lane length for metered on-ramps should therefore take into account the potential impacts of ramp metering on driver acceleration behavior.

Driver Behavior Analyses of 2+1 Roads based on a Driving Simulation Experiment

The Korean government has moved forward with the application of 2+1 roads to mitigate traffic delays and offer safety improvements relative to the two-lane highway. Before beginning construction of the first 2+1 road in Korea, calls have been made to conduct driver behavior studies prior to implementing these roadway types within the existing road network. In this study, experiments using a driving simulator were conducted to assess driver behavior on 2+1 roads. The study results suggest several concepts to be integrated into 2+1 road design in Korea. First, drivers tended to decrease speed suddenly in both critical and noncritical transition zones so that lane changing information system is significantly important in 2+1 roads. Second, the speed change patterns on the 2+1 roads were different for driver ages, with greater variations in speed by older drivers. Third, the locations of speed reductions are related to the passing lane lengths. Sufficient passing lane length is necessary to increase capacity and may offer safety benefits based on the driver behavior analyses. Fourth, inappropriate design of a passing lane can lead to traffic operational problems, especially for older drivers. Finally, safety treatments including median-delineators should be considered in bad weather conditions including snow.

Effect of centerline marking on lane changing behavior of drivers

Background: Traffic accidents are in continuous rise on Sri Lankan roads. According to the records available at traffic headquarters, one death is reported at every 3 hour or less on Sri Lankan roads. Similar to the rest of the world, driver misbehavior contribute heavily on those road mishaps among identified reasons for common road traffic accidents in Sri Lanka, careless overtaking has recorded as the number one reason. Therefore, this paper is about a study carried out to study the effect of centerline markings on lane changing behavior of drivers. Methods: Three road segments from the Sri Lankan main roads were selected for this study. All the roads were single carriageways with one lane per direction. Out of three road segments, two were mountainous and winding and one is flat and rolling. No Road type Nature Total length (km) Percentage non lane changeable length 1 A Class Mountainous – Winding 15 74.6 2 AB Class Flat and Rolling 16.6 57.8 3 A Class Mountainous – Rolling 15.3 32.7 For each road segment, non-lane changeable segments were divided into three types. They were Length less than 100 m ( L1), Length between 100 m and 300 m ( L2) and length greater than 300 m ( L3). Vehicle movement behavior were observed using video cameras and number of overtaking were collected after the field surveys of one hour each for each kind of non- changeable lane segments. Video cameras were installed to observe vehicle movement at non- lane changeable as well as legally acceptable lane changes. With respect to non- lane changeable segments, both the beginning of non-lane changeable areas as well as the ending of non – lane changeable segments were observed. Results: Following tables are the summary of observations made based on video recordings. The next table is the summary of overtaking observed at the beginning and the end of non- lane changeable segments; According to the field measurements, it was clear that there is a high tendency for drivers to overtake when the continuous length of non-changeable road segments (single line or double line divided) is longer than 300 m. Further, chances were slightly higher when there is a bunching. Bunching is due to slow moving vehicle controlling the optimum speed of most of the other vehicles in the bunch. Non lane changeable type Road segment – 1 Road segment – 2 Road segment – 3 L1 L2 L3 L1 L2 L3 L1 L2 L3 Nature of lane changing Legally acceptable 20 8 16 12 35 18 31 17 13 Non – lane changeable- without vehicle bunching 6 13 21 5 7 13 6 11 13 Non – lane changeable – with vehicle bunching 3 11 24 2 5 17 4 3 15 Road segment 1 Road Segment 2 Road Segment 3 L1 L2 L3 L1 L2 L3 L1 L2 L3 Begin 3 5 20 2 5 11 5 4 15 End 6 19 25 5 7 19 5 10 13 Conclusion: From the summarized results of this study, it is evident that drivers are forced to change the lane to overtake vehicle in front of them when the length of the non- lane changeable lane length is longer. More frequent when there is a bunching effect due to slow moving vehicles. Further, lane changing to overtake vehicles is more prominent towards the latter part of the non-lane changeable section than the beginning. It may be an indication that all the drivers are not really indiscipline in changing the lane and overtaking but they may be frustrated after driving a long distance without having opportunity to go at their comfortable speed. Therefore, introducing the overtaking lanes at regular intervals or any other such suitable measures can be an answer to such illegal lane changing to overtaking. Though there are no adequate details to prove, such overtaking may lead to a traffic accident.

Estimating Acceleration and Deceleration Lane Lengths by Analyzing Vehicle Speed Variation of Rest Areas for Drowsy Drivers

Estimating Acceleration and Deceleration Lane Lengths by Analyzing Vehicle Speed Variation of Rest Areas for Drowsy Drivers

The influence of constructional and operational factors on indicators of maneuverability of the metrobus

Metrobuses in their design are similar to two-lane and three-lane freight vehicles, the study of maneuverability of which a significant number of works is devoted to. Therefore, in order to assess the maneuverability of the metrobus, it is necessary to use two, namely, the overall traffic lane and the possibility of reverse movement.The least studied for today is the question of the possibility of moving backwards of auto trains. However, this question regarding metrobuses is not decisive, since metrobuses move along separate allocated lanes.In the article, the indicators of maneuverability of the metrobus were determined on the elastic wheels in the lateral direction with the help of a system of equations, which allowed to investigate the behavior of the three-block metrobus in both stationary and non-stationary modes of motion. The solution of the system of equations is carried out with the help of the Maple 14 software. The calculations are made for a three-lane metrobus consisting of a three-axle bus with a total weight of 24 tons and combinations of two-axis unmanaged and triple controlled trains with a total weight of 16 tons.It is established that the reduction of the parameter c i.e. the distance from the point of the coupling of the bus with the first trailer from 1.0 m to 4.0 m leads to improved metrobus maneuverability. Changing the length of the drawbar of the first trailer is similar to changing the point of the coupling of the bus with the drawbar of first trailer.It is shown in the conclusions that the auto train № 2 (the first trailer with spaced axles and the front axle control, the second trailer is with approximate axles) is considerably better compared to the auto train № 3 (two trailers with approximated axles) and complies with the requirements of DIRECTIVE 2002/7 / EC . Thus, the overall length of the traffic lane in motion by circular trajectory of the auto train № 2 is 6,98 m, while the auto train № 3 is 7,43 m, which does not meet the requirements of DIRECTIVE 2002/7 / EC.

Optimal Type-2 Fuzzy System For Arterial Traffic Signal Control

Arterial traffic is the artery of urban transport and loads huge traffic pressure. In order to alleviate its traffic pressure effectively, a coordinated arterial traffic type-2 fuzzy logic control (FLC) method is proposed. First, arterial traffic flow model and evaluation index model are set up, in which the turning vehicles and lane length are given full consideration. The traditional queue spillover phenomenon in the traffic models can be prevented here. Second, aiming at the coordination and dynamic uncertainty problem in arterial traffic, a coordinated arterial traffic type-2 fuzzy coordination control method is put forward. It consists of two-layer type-2 fuzzy controller, the basic control layer and the coordination layer. The former allocates green time according to the traffic situation of each intersection, while the latter adjusts each intersection’s green time on basis of the vehicles between the intersection and the downstream intersections for the purpose of enlarging green wave band. Finally, in order to configure the high-dimensional complex parameters of the coordinated two-layer type-2 FLC effectively, the parameters of membership function and the rules of the two controllers are optimized alternately by gravitational search algorithm. The simulation results verify the effectiveness of the proposed method from several aspects.

A Simplified Simulation Model to Estimate the Storage Length of the Right-Turn Lane in Left-Hand Traffic at Signalised Intersections for Different Signal Phases and Cycle Timings

Introduction: A large number of the current guidelines and models are used to estimate the right-turn lane (RTL) length in left-hand traffic at signalised intersections under split phase, in which the movement of traffic in the right-turn lane and through lane happen concurrently. There is a need to examine other phase types and timings as a part of the RTL design. This is particularly significant in the case of established intersections that cannot be modified due to physical constraints. Methods: A MATLAB based simulation programme was developed to provide an estimate of the right-turn lane storage length for different traffic volumes in order to avoid the problems associated with blockage and overflow of the right turn vehicles in 95% of the traffic signal cycles. The model enhances flexibility when dealing with the complexity of the design of the storage length taking into account different signal phases and timings to overcome the aforementioned problems. The simulation model also takes into consideration the left-over queue from the previous cycle which was ignored by most of the previous studies. Results and Conclusion: The model input includes as a configuration matrix containing the sequence of operational states of the intersection. This ensures the flexibility and the simplicity of manipulating the data to reflect all phase types and timings. The model results have been compared against a recently developed analytical model in which similar signal phases and timings were investigated. The outcomes agree to the results that are obtained from the analytical model in most of the signal phases. The developed simulation model is flexible enough to be used further to simulate the situation when there is a large difference between the approaching and opposing traffic volumes and optimise the green time in case of split phase. In this study, the simplified simulation model for estimating the RTL storage length has been developed for the left-hand traffic countries; however, the study is equally applicable to the left-turn lane (LTL) in right-hand traffic countries.

Factors associated with productivity on automatic milking system dairy farms in the Upper Midwest United States

The objective of this study was to identify housing and management factors associated with productivity on automatic milking system (AMS) dairy farms measured as daily milk yield/AMS and daily milk yield/cow. Management, housing, and lameness prevalence data were collected from 33 AMS farms in Minnesota and Wisconsin during a farm visit. All farms in the study used free-flow cow traffic. Mixed model analysis of cross-sectional data showed that farms with automatic feed push-up via a robot produced more milk per AMS/day and per cow/day than farms where feed was pushed up manually. New versus retrofitted facility, freestall surface, manure removal system, and the number of AMS units/pen were not associated with daily milk yield per AMS or per cow. Cow comfort index (calculated as number of cows lying down in stalls divided by total number of cows touching a stall) was positively associated with daily milk yield/cow. Prevalence of lameness and severe lameness, number of cows per full-time employee, depth of the area in front of the AMS milking station, and length of the exit lane from the AMS milking station were not associated with daily milk yield per AMS or per cow. Multivariable mixed model analysis of longitudinal AMS software data collected daily over approximately an 18-mo period from 32 of the farms found a positive association between daily milk yield/AMS and average age of the cows, cow milking frequency, cow milking speed, number of cows/AMS, and daily amount of concentrate feed offered/cow in the AMS. Factors negatively associated with daily milk yield/AMS were number of failed and refused cow visits to the AMS, treatment time (the time spent preparing the udder before milking and applying a teat disinfectant after milking), and amount of residual concentrate feed/cow. Similar results were also found for daily milk yield on a per cow basis; however, as it would be expected, average days in milk of the herd were also negatively associated with daily milk yield/cow. These findings indicate that several management and cow factors must be managed well to optimize AMS productivity.

Model of Parallel-Type Acceleration Lane Length

A model of a parallel-type acceleration lane length based on the dynamic merging process is established in this study to determine the need for parallel-type acceleration lane length of merging vehicles. The model considers road operation and design attributes, driver attributes, vehicle attributes, and several random attributes in the insertion process, and sets random attributes as the breakthrough point. Furthermore, Monte Carlo simulation is used to solve the model. The case study introduces the use of the model and proves its applicability.

Safety evaluation of discontinuous lane design of intersection approach in China

ABSTRACTA special kind of road marking design denoted as discontinuous lane design is prevailing in most cities of China, in which a changeover portion between the upstream road segment and the approach of intersection is void of road markings. This article evaluates the road safety and traffic efficiency of the discontinuous lane design for the most typical case that three lanes upstream are followed by four approaching lanes to the intersection. A safety risk comparison was made between the discontinuous lane design and its counterpart continuous lane design by index of postencroachment time (PET). Then, using an ordered probit model, the PETs, representing the severity of traffic conflict, were linked to relevant variables including the traffic volume, the queue length of target lane on the approach, the queue length of the neighboring target lane, the upstream lane used by the vehicle, the vehicle speed before entering the discontinuous zone, and so on. It was found that the upstream lane has an important effect on traffic safety under discontinuous lane design. Continuous lane design is only recommended for intersection approaches with relatively stable right and left turning flows, and not appropriate for specific cases when the turning flows fluctuate significantly in daily periods.

Safety evaluation of freeway acceleration lanes based on crashes and simulated conflicts

Crash-based safety performance functions (SPFs) typically cannot account for all design and operational factors that contribute to crash frequency in assessing the safety impacts of these factors. An approach using surrogate safety measures can address this issue, providing these measures can be linked to crashes. This approach was explored by using microsimulation to generate and analyze conflicts for merge areas on Ontario freeways. Crash–conflict integrated SPFs with different time to collision thresholds were then developed and compared. The results of the conflict-based SPFs are in agreement with those from crash-based SPFs developed for the same sample, with logically negative coefficients for acceleration lane length and positive coefficients for traffic volumes. This suggests that the crash–conflict approach is a reasonable substitute for conventional crash prediction models in assessing the safety effects of design changes, especially for those changes that cannot be captured in the conventional models.

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...

Safety assessment of passing relief lanes using microsimulation-based conflicts analysis

The paper target is to analyze the influence of passing lane section and merging area lengths, which represent a critical part in the geometric design of passing lanes. The lack of observed data and the still limited implementation of short passing 2+1 lane in Poland do not allow to perform a reliable performance-based design of their length to balance context and economical restrains with operational and safety performances. Besides, defining the optimum geometric design from observed data is a reactive approach which require detailed observations and evaluations of the safety and operational performances for different geometric configurations. The present research work aims to fill the gap by performing an evaluation of optimal length, based on microsimulation analysis. Particular attention was paid to the calibration and validation of microsimulation models using real data of traffic characteristics and crash history. The assessment was conducted using simulation models in VISSIM and Surrogate Safety Assessment Model (SSAM) software and comparison based on simulated results at different lengths of passing lane, merging area in a wide range of AADT values. The results suggested not only that conflicts can be a surrogate measure of safety but also that the influence of geometric parameter, such as the length of the additional lane, plays a fundamental role in the safety performance of the 2+1 short passing lane.

Optimizing signal phase plan, green splits and lane length for isolated signalized intersections

At an isolated signalized intersection, short left-turn lanes may be provided to enhance intersection capacity and level of service. The capacity of an entire intersection depends not only on the effective green time per phase and the length of each short left-turn lane but also on the selected signal phase plan. This paper enumerates 16 typical signal phase plans for a four-leg intersection with protected left-turn phases. Given the existence of short left-turn lanes and the freedom to select signal phase plans, two optimization models are formulated. Numerical examples are carried out to illustrate the application of these models and show the sensitivity of the outcomes to impact factors. The orthogonal experiments show that the primary factor is whether a short left-turn lane is added on an approach and the demand distribution is the secondary factor in determining an optimal allocation of the time-space resources of an intersection. To analyse traffic flow operations under different signal phase sequences, the simulation tests are fulfilled using VISSIM under the assumption that the components of a signal phase plan and green splits are all identical. The simulated results indicate that the signal phase sequence for a specified approach may greatly affect traffic movements at an approach, and the leading green phasing is better than the lagging one for a specified approach when the left-turn bay length is short at the approach. Finally, two variations of the developed models are recommended for use and the procedure for the model application is provided in practice.

Safety audit for weaving maneuver: A driver simulation safety analysis

ABSTRACTWeaving lanes are designed to ensure the crossing of two or more traffic streams traveling in the same direction along stretch of road without the aid of traffic control devices. Weaving lanes assume a key role in roundabouts characterized by wide inscribed circle diameter, where the weaving maneuver represents a crucial aspect for safety. This is confirmed by several findings that demonstrate as the weaving maneuver is one of the most difficult operation to analyze in terms of road safety. Many studies report that the combination between the length of weaving lanes and the traffic volume is a key factor to explain high accident rate along interchange zones. Bearing in mind this facet, this article proposes an analysis of driver behavior on different weaving lanes in various traffic conditions performed on an interactive driving simulator. Different lengths of weaving lane combined with different traffic flow conditions were simulated, and the different drivers' performance have been analyzed. A risk assessment has been conducted by analyzing driver's behavior as a function of driver's risk perception. It has been observed that the increase of weaving lane length is effective only when the traffic flow conditions exceed a certain threshold.

Exploring the impact of walk–bike infrastructure, safety perception, and built-environment on active transportation mode choice: a random parameter model using New York City commuter data

This study estimates a random parameter (mixed) logit model for active transportation (walk and bicycle) choices for work trips in the New York City (using 2010–2011 Regional Household Travel Survey Data). We explored the effects of traffic safety, walk–bike network facilities, and land use attributes on walk and bicycle mode choice decision in the New York City for home-to-work commute. Applying the flexible econometric structure of random parameter models, we capture the heterogeneity in the decision making process and simulate scenarios considering improvement in walk–bike infrastructure such as sidewalk width and length of bike lane. Our results indicate that increasing sidewalk width, total length of bike lane, and proportion of protected bike lane will increase the likelihood of more people taking active transportation mode This suggests that the local authorities and planning agencies to invest more on building and maintaining the infrastructure for pedestrians. Further, improvement in traffic safety by reducing traffic crashes involving pedestrians and bicyclists, will increase the likelihood of taking active transportation modes. Our results also show positive correlation between number of non-motorized trips by the other family members and the likelihood to choose active transportation mode. The model would be an essential tool to estimate the impact of improving traffic safety and walk–bike infrastructure which will assist in investment decision making.