Work Zone Length Research Articles

Development and Evaluation of Statistical and Machine-Learning Models for Queue-Length Estimation for Lane Closures in Freeway Work Zones

Freeway maintenance and rehabilitation work usually require closing one or multiple lanes, interrupting traffic flows, and creating queues upstream of the work zone. Public agencies can use queue length as a criterion to determine the maximum duration of lane closures and necessary traffic diversions. Previous studies of estimating queue length due to work zone lane closures are data- and time-intensive. This study presents an efficient approach for estimating queue length estimation due to work zone lane closures by developing various statistical and machine-learning models. The inputs for these queue length estimation models were vehicle demand, lane closure duration, active work zone length, and heavy vehicle percentage. The extent of the queues caused by short-term work zones on freeways for 2-to-1 (one-lane closure on a two-lane freeway), 3-to-1 (one-lane closure on a three-lane freeway), and 3-to-2 (two-lane closure on a three-lane freeway) lane-closure configurations can be estimated with these models. The primary scientific contribution of this study is the applicability of the queue length estimation models in any freeway network with work zone configurations and geometric features such as those used for model development. This research evaluated the efficacy of both statistical and machine-learning models for estimating the queue length considering different work zone scenarios. The accuracy of the queue length estimation models was evaluated for a different network that the original models had not seen previously. Among the statistical models, the quantile regression model had the best accuracy based on mean absolute percentage error (MAPE) for the 2-to-1 lane-closure configuration (88%), and the multiple linear regression had the best accuracy for the 3-to-1 (76%) and 3-to-2 (72%) lane-closure configurations. Among the machine-learning models, the stacking regressor model had the best accuracy for 2-to-1 (95%), 3-to-1 (90%), and 3-to-2 (89%) lane-closure configurations. Based on the analysis, it was observed that machine-learning models performed better than the traditional statistical models in estimating queue lengths.

Comparison of Analytical and Simulation Results for One-Lane Operation on Low-Volume Two-Lane Highway

Work zones on two-lane highways with one lane closed require sharing the open lane with traffic from the closed directions. In such work zones, traffic control resembles operating a two-phase traffic signal and, in rare cases, a three-phase traffic signal. Temporary traffic signals (or flaggers) allow the open lane to be used in an alternating manner. Signal timing (green times and cycle length) of the temporary traffic lights directly affects the delay and queue in the work zones. Delay and queue computations must consider queue build up that often happens in oversaturated conditions. Another influential variable is the average operating speed of the work zone. The operating speed is affected by the work zone speed limit, work intensity, speed control technique, lane and shoulder widths, acceleration capability of vehicles, and work zone length. WorkZoneQ-Pro (WZQ-Pro) is developed with a new signal timing method that considers the above-mentioned factors. The procedure can handle multiple hours of analysis with two- or three-phase signal operations. Test scenarios are real-world work zone examples from three different U.S. states that were used to compute signal time variables and use them to compute queue and delay. These values were also computed using Highway Capacity Manual (HCM) 2016 procedures and are compared. In addition, the computed values were input into Vissim simulation software, and the results were compared. It showed that the WZQ-Pro results are reasonably close to Vissim simulation results, and that further validated that an acceptable agreement existed between the analytical and simulation results.

Determining the Most Economical Work Zone Lengths for Rural Highway Rehabilitation Projects

Despite the wealth of research that has sought to understand the effects of highway work zones, very little definitive information is available concerning the determination of work zone length (WZL) of rural highway rehabilitation projects. Despite its significant impact, adaptive models that holistically estimate reasonable WZLs are very rare. To fill this gap, this study first created a high-confidence data set through a series of scheduling and traffic simulations and subsequently identified critical factors affecting WZL through a descriptive factor analysis. Based on these data sets and findings, a novel decision support framework was developed to determine the most economical WZL in a balanced trade-off between motorists’ inconvenience level induced by traffic disruption and their opportunity cost. The practical applications of the WZL determination framework were then demonstrated through a systematic eight-step procedure, followed by an illustrative use case of an actual project. The results revealed that traffic loading and work zone duration are critical factors, with an important benchmarking point being traffic loading at approximately 41,000 vehicles per day. As the first of its kind, this study will help state transportation agencies devise sounder construction phasing plans by providing a means of establishing WZL that strikes a balance between travelers’ inconvenience and constructability.

Quantifying Operational Impacts of Variations in Work Zone Setups, Traffic Demand, and Traffic Composition: A Case Study

The presence of work zones due to pavement repair and rehabilitation is very common in highway facilities. Lane closures associated with work zones result in capacity reduction, which, in turn, often leads to increased congestion at such locations. This paper documents findings from a study that investigated the performance of freeway facilities in the presence of work zones under various Temporary Traffic Control (TTC) and lane closure scenarios while taking under consideration traffic composition and driving behaviors. The study site was an approximately 10-mile freeway segment of Interstate 65 (I-65) located in Birmingham, AL. The testbed was coded in PTV VISSIM, a microscopic simulation analysis platform, for: 1) baseline conditions (i.e., no work zone presence) and 2) work zone conditions with single lane closure (i.e., 3-to-2 lane closure). Work zone scenarios were coded for two TTC strategies, namely, early merge and late merge control and for three different positions of the lane closure (i.e., left, right, and center lane closures). The length of the work zones varied from 1000 to 2000, and 3000 ft. Sensitivity analysis was performed to document the operational impacts of varying heavy vehicle percentages, changes in drivers’ aggressiveness, and projected traffic demand changes. The impacts were quantified using linked-based measures of effectiveness (MOEs) such as travel time, and travel time index. The study results show that there is no significant change in travel time index due to the variation of work zone length across the study corridor. Under similar traffic control and demand conditions, a center lane closure consistently results in significantly higher travel time index than a left or right lane closure and should be avoided. Consideration of operational impacts of changes in truck percentage indicates that the corridor can absorb an increase in truck percentage from 10% to 15%, while performance rapidly deteriorates when a higher percentage of trucks is present in the traffic stream. The study findings can be used to guide transportation agencies in their future efforts to develop strategic lane closure plans that minimize congestion.

The Influence of Work Zone Management on User Carbon Dioxide Emissions in Life Cycle Assessment on Highway Pavement Maintenance

The higher contribution of traffic delay to environmental impacts is urging the highway agencies to take work zone management into the maintenance schemes decision-making. Aiming to understand the role of work zone management in user CO2 emissions reduction, this paper firstly developed a practical methodological framework of traffic delay-related CO2 emissions caused by highway maintenance based on a popular life cycle user cost analysis approach in regard of the microscopic vehicle operation analysis. The method was applied in an actual freeway flexible pavement with 15-year design life in Shaanxi Province, China, covering three types of preventive maintenance, correction maintenance, and rehabilitation. In addition, the impacts of key inputs of proposed method on work zone user CO2 emissions results were checked. The results show that traffic delay attributes to 29.4% of total CO2 emissions of the life cycle of highway pavement maintenance, and 51.8% of work zone user CO2 emissions result from preventive maintenance, especially from micro vehicle operations including speed change and queue near work zone (62% of total work zone user CO2 emissions). The work zone management alternative strategies related to less traffic volume or higher highway capacity including vehicle type limitation and the limited work zone speed have an advantage in reducing the work zone CO2 emissions over changing work zone length or work zone timing. The findings in this paper may present a useful tool and reference for robustly supporting the decision-making on highway maintenance carbon mitigation in work zone traffic.

A method to estimate urban work zone intersection capacity under multiple influencing factors

Work zones generate significant congestion in urban centers, yet the influence of various capacity factors in urban arterials and intersections are poorly understood. This paper analyzes the influence of the following factors on urban arterial and intersection work zone capacity from 22 intersections: heavy vehicle flow, heavy vehicle percentage, work zone length, maximum speed limit, entrance lane width, left turn volumes, entrance and exit lane width reductions, and intersection length and width. An urban work zone was modeled using VISSIM simulation software, and regression models were developed based on the reduction coefficients with MATLAB software for fitting analysis. The results show that the proposed model estimated work zone capacity with high accuracy. Urban work zones were found to reduce capacity by 64% in the selected arterial and by 35% in the selected intersection, with corresponding increases in delay and queue length. The model also estimates the capacity improvement that can be expected given various mitigation factors. Transportation agencies may find work zone capacity estimates useful when planning construction in critical urban centers.

Probabilistic speed–flow models in highway construction work zones

Since variations in exogenous factors could cause unpredictable fluctuations/variability of the speed–flow relationship, the aim of this study was to develop probabilistic speed–flow relationships in a work zone (i.e. a segment of road in which maintenance or construction operations affect the operational characteristics of traffic flow). With observed traffic data from six highway work zones in Shanghai, China, lognormally distributed speed–flow functions were established to formulise probabilistic speed–flow relationships under uncongested and congested traffic conditions. A work zone capacity distribution model was then derived based on these probabilistic speed–flow relationships. The modelling results showed that work zone length, percentage of heavy vehicles and road roughness had strong effects on the probabilistic speed–flow relationships in work zones. A smaller mean work zone capacity was strongly associated with a long work zone length, a large proportion of heavy vehicles and poor road conditions. The models developed in this study could help traffic engineers evaluate the variability of work zone traffic states and the reliability of traffic management strategies.

Optimisation of pavement maintenance and rehabilitation activities, timing and work zones for short survey sections and multiple distress types

ABSTRACTExisting pavement management systems (PMSs) aggregate short survey sections into long homogeneous sections (typically 1–5 km), aiming to reduce the amount of data and formulate a tractable optimisation problem. However, assuming that sections in a similar condition will undergo a similar deterioration of this condition is incorrect, resulting in imprecise predictions and violations of thresholds. Thus, any maintenance and rehabilitation (M&R) optimisation approach based on long road sections and a single condition indicator (aggregated or not) cannot provide applicable results at the project level. This paper provides a holistic model framework and consistent methodology for a new PMS, abolishing the need for composite condition indices, data aggregation and homogeneous sections in the M&R optimisation process. The proposed bottom-up optimisation is based on short survey sections (25–50m) and solves for optimal treatment type, timing, work-zone length and layout, minimising agency, road user and environmental life cycle costs. Instead of using just one condition indicator, the method models the effects of each treatment on multiple distress types and their combinations. Moreover, the short survey sections are grouped into larger work zones based on purely economic criteria (i.e. economies-of-scale costs). Treatment cost, temporary traffic control cost, and work-zone user cost models are derived as a function of the project size and calibrated for actual prices in Austria. Genetic algorithms are employed as a part of the solution algorithm, being capable of handling an unlimited number of road sections. Furthermore, the approach can be extended to account for budget restrictions, risk and cross-asset allocation of funds for any aging repairable infrastructure system.

Optimization of Work Zone Segments on Urban Roads Using Cellular Automata Model in Mixed Traffic

Increased delays and reduced speeds in work zones leads to congestion. This can be improved by optimizing the work zone length. The focus of this study is to model work zones using cellular automata model and to find the effects of work zones on traffic flow. The methodology adopted in the study involved creating work-zone on the road by blocking some of the cells and then determining traffic characteristics such as delay and queue lengths for model validation. For this the lateral movement rules of the existing Cellular Automata model were modified in order to replicate the traffic movement near work zones. This model is calibrated and validated using data from work zone observed near a metro rail station in Delhi. From the analysis it was evident that the queue length increased with increase in the length of work zone. Several relationships were tried between delay and work zone length. Among them the rational form was found suitable.

Meta-analysis of the effect of road work zones on crash occurrence

There is strong evidence that work zones pose increased risk of crashes and injuries. The two most common risk factors associated with increased crash frequencies are work zone duration and length. However, relevant research on the topic is relatively limited. For that reason, this paper presents formal meta-analyses of studies that have estimated the relationship between the number of crashes and work zone duration and length, in order to provide overall estimates of those effects on crash frequencies. All studies presented in this paper are crash prediction models with similar specifications. According to the meta-analyses and after correcting for publication bias when it was considered appropriate, the summary estimates of regression coefficients were found to be 0.1703 for duration and 0.862 for length. These effects were significant for length but not for duration. However, the overall estimate of duration was significant before correcting for publication bias. Separate meta-analyses on the studies examining both duration and length was also carried out in order to have rough estimates of the combined effects. The estimate of duration was found to be 0.953, while for length was 0.847. Similar to previous meta-analyses the effect of duration after correcting for publication bias is not significant, while the effect of length was significant at a 95% level. Meta-regression findings indicate that the main factors influencing the overall estimates of the beta coefficients are study year and region for duration and study year and model specification for length.

A simulator-based approach for modeling longitudinal driving behavior in construction work zones: Exploration and assessment

The essential need to maintain roadway structures makes encountering work zones an inevitable part of today’s driving. The corresponding changes in traffic dynamics directly affect the drivers’ mobility and safety. Accordingly, a closer look into driver’s interaction with work zones’ geometrics and activity features may be helpful. The overall objective of this study is to examine the longitudinal characteristics of driver behavior in different work zone conditions. Based on existing literature, the variables defining these work zone conditions were specified as the work zone length, the barrier type and the level of activity. Eight different scenarios were designed by changing these three variables in a driving simulator and 40 trajectory data sets were recorded. Using a genetic algorithm, these data sets were used to calibrate a prospect theory-based acceleration model. The calibrated parameter values helped quantify the driver’s perception of the surrounding environment, his/her risk-attitudes and the corresponding judgment process.

Delay and queue lengths at stop/go control during half-width construction

It is common practice in South Africa that road reseal projects, road reconstruction projects or road upgrade projects on two-lane, two-way roads are constructed in half-widths, resulting in a situation where traffic on the remaining roadway is reduced to one-way operation. There is currently no method for determining a suitable length of work zone for half-width construction based on traffic volumes, and also no method for determining waiting time for the vehicle in the front of the stationary queue at the STOP/GO control, and of the back-of-queue position at such a work zone. An Excel-based calculation sheet for determining the back-of-queue position and the maximum waiting time, was developed. This was used to develop design tables, graphs and equations that can be used by designers and contractors to estimate the back-of-queue position and maximum waiting time. Based on the conclusions of this paper and the fact that this project was largely based on literature studies of traffic conditions not related to work zones for half-width construction, the main recommendation of the study is that all the input parameters which were investigated need to be verified and calibrated specifically for work zones for half-width construction.

Feasibility of shoulder use for highway work zone optimization

Highway maintenance, often requiring lane closure, is very expensive in terms of the costs associated with transportation agencies (i. e. work zone setups) and road users (i. e. delay). Longer work zones tend to increase the user delay but will be efficient because of fewer repeated setups. To increase road capacity and mitigate congestion impact for a short-term work zone, temporary shoulder use may be applied. This study develops an analytical model to optimize work zone length on a multi-lane highway considering time-varying traffic volume and road capacity affected by light condition, heavy vehicle percentage, and lane width. The results can be used to evaluate the work zone impact (i. e. delay and cost) and assist engineers/planners to prepare and develop a cost-effective highway maintenance plan. A case study for a highway work zone in New Jersey has been conducted, in which the optimized solution is found. A guideline of using road shoulder under various circumstances is developed. Language: en

Incorporating work zone configuration factors into speed‐flow and capacity models

SummaryThis study aims to develop work zone speed‐flow and capacity models, which incorporate work zone configuration factors including the number of work zones, geometrical alignment, work zone speed limit, and work zone length. On the basis of the traffic data from six work zone sites with various work zone configurations, two nonlinear traffic speed and flow models including work zone configuration factors are developed for the uncongested and congested traffic conditions, respectively. A work zone capacity model is proposed on the basis of the two models. The three models can further be used to examine the effects of work zone configuration factors on the speed‐flow relationship and capacity at work zones. Results show that traffic speed, traffic flow, and work zone capacity increase with the posted speed limit. Traffic speed under uncongested conditions decreases with the geometric alignment, the number of work zones, work zone length, and heavy vehicle percentage. Under congested conditions, the increase of the number of work zones is found to exhibit a larger negative impact on the traffic flow than the increase of geometric alignment. The number of work zones is also found to have the largest negative impacts on work zone capacity, followed by the geometric alignment. Short work zone length exhibits a relatively minor contribution to increasing work zone capacity. Copyright © 2014 John Wiley & Sons, Ltd.

Simulation-based model for optimizing highways resurfacing operations

Work zone length in the highways’ resurfacing is an important factor that should be determined before the start of work. This factor influences the time and cost of the project. This paper presents a framework that is dedicated for determining the optimum length of highway resurfacing work zone. The framework estimates the total duration and total cost of resurfacing by conducting simulation analysis to model the resurfacing operations of highways to account associated uncertainties. The framework analyzes resurfacing of highways and divides them into zones. The lengths of these zones depend on minimum total cost and minimum duration. The framework consists of two modules; simulation and optimization. Simulation module is responsible for estimating total duration for each work zone. Whereas, optimization module optimizes the total cost including direct resurfacing operation, indirect/overhead costs, and the impact of work on road users’ costs. The latter costs include queuing delay cost, moving delay cost, accident cost. A numerical example is presented to illustrate the practical use of the framework.

A Method for Determining Length of Freeway Work Zone Based on Classification of Service Level

based on the relationship between speed and density according to the classification criteria of freeway service level when the design speed is 80km/h in Highway capacity manual, the method of microscopic traffic flow simulation supported by VISSIM software is adopted, such that, in the situation the capacity and desired speed are guaranteed to be consistent with the reality, the proposed values of the length of work zone under different traffic composition and traffic volume are given in the condition that a 2-way-8-lane freeway is half closed for construction with 2-way-4-lane being left open for traffic.

Modeling work zone crash frequency by quantifying measurement errors in work zone length

Work zones are temporary traffic control zones that can potentially cause safety problems. Maintaining safety, while implementing necessary changes on roadways, is an important challenge traffic engineers and researchers have to confront. In this study, the risk factors in work zone safety evaluation were identified through the estimation of a crash frequency (CF) model. Measurement errors in explanatory variables of a CF model can lead to unreliable estimates of certain parameters. Among these, work zone length raises a major concern in this analysis because it may change as the construction schedule progresses generally without being properly documented. This paper proposes an improved modeling and estimation approach that involves the use of a measurement error (ME) model integrated with the traditional negative binomial (NB) model. The proposed approach was compared with the traditional NB approach. Both models were estimated using a large dataset that consists of 60 work zones in New Jersey. Results showed that the proposed improved approach outperformed the traditional approach in terms of goodness-of-fit statistics. Moreover it is shown that the use of the traditional NB approach in this context can lead to the overestimation of the effect of work zone length on the crash occurrence.

The Rational Construction Length Alternately by Subsections of the Reconstruction Project of Freeway

In order to ensure the quality of the reconstruction project of freeway as well as the traffic efficiency without breaking down the traffic, it is crucially important to arrange the work zone length alternately by sub-ways and subsections. The simulation method of transportation is adopted for Microscopic of the transportation situation under various length of work zone. Based on the results of the simulation, the stability, efficiency and safety of traffic flow are evaluated and analyzed comprehensively. The balance point among these three factors is determinated by the method of fuzzy comprehensive evaluation. Combined with the project cost, construction cost saving and other factors. to get the reasonable construction segment length reference value. Finally, G4 freeway (Beijing to Hong Kong and Macao) is selected as a case study.

Estimation of Effectiveness of a Vehicle-Actuated Signal Control System on Work Zone Operations for a Two-Lane Highway

Korean two-lane highways take charge of a function to connect arterial roads with major national roads and provide efficient mobility. However, the number of work zones for road construction and expansion is constantly increasing owing to increment of traffic volume. Therefore the number of maintenance projects is also growing to meet the increased need for road maintenance. All projects that require full or partial closure of a two-lane highway create safety problems, because of two-way delays and poor traffic control, especially at night. Flagging is typically used to control traffic in work zones on two-lane highways by closing one lane and alternating traffic movements. Generally, there is a flagger or Time of Day (hereinafter TOD) control and a one- or two-way delay occurs. Poor safety control in work zones can result in a serious accident if a driver has poor visibility. In this study, to diminish these problems, some alternative traffic control systems are indicated such as actuated signal control with fixed all red (hereinafter AFAR) and actuated signal control with dynamic all red (hereinafter ADAR). And the comparison with each traffic control methods is analyzed focused on average control delay and the number of conflicts which take into account various situations as the length of work zone and traffic volume. The signal control methods under investigation were TOD, AFAR, and ADAR. The average control delay per vehicle was used to evaluate the effectiveness of each method, and work zone conflict was used to evaluate safety. ADAR was found to be the most efficient signal control method under most conditions examined, in terms of safety and mobility in work zones on two-lane highways.

Bayesian Belief Network Model for Decision Making in Highway Maintenance: Case Studies

This paper presents two case studies that were conducted to illustrate the functionality and application of a decision support system for predicting the influence of decisions made by state highway agencies regarding important work zone project variables such as work window, work zone length, lane closure strategy, and contract incentives on the cost, duration, quality, safety, and public satisfaction of a particular project under consideration. The first case study describes in detail the operation and function of the three major levels of the proposed framework using a completed project, whereas the second case study provides an opportunity for the application of the decision support system to a work zone project in the planning stages using the input of the actual decision maker for the project.