Four-lane Roadways Research Articles

버스베이 설치에 따른 통행시간비용 절감효과 분석 : 왕복 4차로 도로를 중심으로

버스베이 설치에 따른 통행시간비용 절감효과 분석 : 왕복 4차로 도로를 중심으로

Temporal instability and differences in injury severity between restrained and unrestrained drivers in speeding-related crashes

Upon detecting a crash impact, the vehicle restraint system locks the driver in place. However, external factors such as speeding, crash mechanisms, roadway attributes, vehicle type, and the surrounding environment typically contribute to the driver being jostled within the vehicle. As a result, it is crucial to model unrestrained and restrained drivers separately to reveal the true impact of the restraint system and other factors on driver injury severities. This paper aims to explore the differences in factors affecting injury severity for seatbelt-restrained and unrestrained drivers involved in speeding-related crashes while accounting for temporal instability in the investigation. Utilizing crash data from Thailand between 2012 and 2017, mixed logit models with heterogeneity in means and variances were employed to account for multi-layered unobserved heterogeneity. For restrained drivers, the risk of fatal or severe crashes was positively associated with factors such as male drivers, alcohol influence, flush/barrier median roadways, sloped roadways, vans, running off the roadway without roadside guardrails, and nighttime on unlit or lit roads. For unrestrained drivers, the likelihood of fatal or severe injuries increased in crashes involving older drivers, alcohol influence, raised or depressed median roadways, four-lane roadways, passenger cars, running off the roadway without roadside guardrails, and crashes occurring in rainy conditions. The out-of-sample prediction simulation results are particularly significant, as they show the maximum safety benefits achievable solely by using a vehicle's seatbelt system. Likelihood ratio test and predictive comparison findings highlight the considerable combined impact of temporal instability and the non-transferability of restrained and unrestrained driver injury severities across the periods studied. This finding also demonstrates a potential reduction in severe and fatal injury rates by simply replicating restrained driver conditions. The findings should be of value to policymakers, decision-makers, and highway engineers when developing potential countermeasures to improve driver safety and reduce the frequency of severe and fatal speeding-related single-vehicle crashes.

Development of Road Diet Segment and Intersection Crash Modification Factors

Road diets can offer potential safety improvements for both pedestrians and vehicles. The additional space provided by reducing the number of vehicular through lanes can be reallocated to other uses such as bicycle lanes, parking, sidewalks, transit use, turn lanes, curb extensions, parklets, or pedestrian refuge islands. This study evaluated the safety effectiveness of road diets in Virginia using the empirical Bayes method, focusing on the common road diet conversion from a four-lane roadway to a three-lane roadway with added bike lanes. A total of 36 segment sites and 39 intersections were identified in Virginia where road diet installations were implemented between the years 2009 to 2018. The analysis showed segment crash modification factors (CMFs) of 0.62 for total crashes and 0.36 for fatal and injury (FI) crashes. Across all intersection types, the CMFs were 0.65 for total crashes and 0.54 for FI crashes. All CMFs were found to be statistically significant at a 95% confidence level. When intersections were separated into signalized and unsignalized intersections, no significant safety benefit was found for unsignalized intersections. Based on the results, it was concluded that road diets can potentially reduce crashes, and public agencies should consider the safety benefits of road diets when justifying roadway improvements.

Bayesian Approach to Developing Context-Based Crash Modification Factors for Medians on Rural Four-Lane Roadways

Rural four-lane roadways provide important transportation accessibility and mobility to populations in rural areas. It is a challenge for practitioners to determine cross-section types when both benefits and costs need to be considered. Crash Modification Factors (CMFs) are developed to evaluate the safety effectiveness of alternative designs. However, safety effectiveness could vary significantly across contexts. Thus, this study aims to estimate CMFs for alternative cross sections of rural four-lane roadways under different contexts characterized by traffic volume, truck percentage, and access point density. Using Georgia state-wide crash data, this study developed Safety Performance Functions (SPFs) to predict crash frequencies for different contexts. Considering linearity and independence assumptions of traditional negative binomial SPFs, this study adopts Bayesian generalized negative binomial modeling approaches to relax those assumptions and only follows the Bayes rule to form SPFs for CMF estimation. This study focuses on four typical cross-sections including: (1) non-traversable medians; (2) two-way-left-turn lanes; (3) 4-ft flush medians; and (4) undivided roadways with double-yellow lines (the base cross-section design). The results show that CMFs vary significantly across different contexts. Compared with the base cross-section design, safety benefits of the other three designs can be either positive or negative under different traffic or road conditions. For example, 4-ft flush medians are found to have positive safety benefits (CMF < 1) under lower average daily traffic volumes (e.g., ≤ 6,000) and negative benefits (CMF > 1) under greater average daily traffic volumes (e.g., ≥ 15,000). The findings suggest that, to enhance roadway safety, practitioners should vary cross-section designs for different rural contexts.

Assessing driving behavior upstream of work zones by detecting response points in speed profile: A naturalistic driving study

Objective: To assess driving behavior when presented with different work zone features such as signs. Driving behavior upstream of a work zone is of interest since this is the point where drivers need to slow or react to upcoming conflicts such as lane closures, congested traffic, or presence of workers and equipment.Methods: Using 299 time series traces from four-lane roadways with both shoulder and lane closure scenario from the naturalistic driving study, this study analyzed driving behavior by detecting response points within the advance warning area from the first sign to the start of work zone. Response point was defined as the point where drivers reduced speed by a certain threshold. A mixed effect logistic model was developed to assess the relationship between driver response and work zone characteristics.Results: Results indicated the first work zone sign a driver encountered in the immediate area upstream of the work zone was not significantly likely to elicit a driver response. The model found lane ends, speed limit, and active changeable message signs (CMS) as statistically significant. Since more than one sign can be legible to the driver at the same time, the effect of overlapping signs was evaluated, but was not found to have significant effect on the driver response. In general, drivers were more likely to show a response to the signs the closer they got to the start of the work zone. Static work zone speed limit and dynamic speed feedback signs were both found to be more likely to elicit a response as compared to normal speed limit signs (non-work zone related). Drivers who were traveling over the posted speed limit were more likely to show response at any given work zone signs with the exception of the first sign. In addition, driver distraction, and driver information like age, gender, experience and other environmental factors were not found to be significant in the model.Conclusions: Overall, drivers were likely to show a response at the lane ends, work zone speed limit signs, and speed feedback signs.

Queue-Based Guidance for Signalization Consideration at Two and Three-Legged Intersections

This research collected and analyzed gap acceptance in North Carolina to develop a data-driven method for determining the need for considering additional signalization analysis at intersections with fewer than four legs. This method can be used for movements that merge with or cross two lanes of oncoming traffic. It is intended to provide guidance and support to traffic engineers in their decision-making process. Charts are provided to determine the expected 95th percentile queue lengths for left-turn, right-turn, and U-turn movements crossing or merging with two lanes of conflicting traffic. This situation is typically present along four-lane roadways where a one-way primary movement opposes either a minor road right-turn movement or a left-turn movement, or in the case of a median U-turn opening. Adjustment factors to the conflicting flowrate were developed to account for the presence of upstream signalized intersections. This method less frequently recommends further signal consideration when compared with the Manual on Uniform Traffic Control Devices peak hour warrant, but is similar to the delay-based level of service D/E threshold for two-way stop-controlled intersections in HCM6 Chapter 19.

Sustainable design of rural roads with 2+1 road design: Levels of service and traffic flow performance

This paper provides research results of a study to assess the driver performance levels of a 2+1 road, a special type of road involving intermediate cross section that is applied where a four-lane roadway construction is unjustifiable and the use of a two-lane road design may not provide the desired level of mobility. Despite increased driver safety, the use of the 2+1 road involves a problem that the South Korean government cannot assess the mobility effects of 2+1 roads, because the current Korean Highway Capacity Manual lacks the level of service procedure for 2+1 roads. Hence, research is required to provide potential measures of effectiveness for describing traffic flows in 2+1 roads and establish a reliable level of service analysis procedure. To address this issue, we applied the following approach: (1) existing research concerning 2+1 road design and flow performance was reviewed; (2) a field study was conducted in 2+1 roads with video cameras and traffic detectors to investigate traffic flow conditions; (3) candidate measures of effectiveness for describing traffic flow in 2+1 roads were identified based on field study results as well as TWOPAS simulation efforts; and (4) an analysis procedure applicable to determine levels of traffic flow service for 2+1 roads was proposed. We also examined how our proposed procedure would perform based on a case study. It was found that the percent time spent following would represent the most appropriate measures of effectiveness and that realistic output may be produced with our proposed procedure.

Assessing the safety effects of multiple roadside treatments using parametric and nonparametric approaches

This study evaluates the safety effectiveness of multiple roadside elements on roadway segments by estimating crash modification factors (CMFs) using the cross-sectional method. To consider the nonlinearity in crash predictors, the study develops generalized nonlinear models (GNMs) and multivariate adaptive regression splines (MARS) models. The MARS is one of the promising data mining techniques due to its ability to consider the interaction impact of more than one variables and nonlinearity of predictors simultaneously. The CMFs were developed for four roadside elements (driveway density, poles density, distance to poles, and distance to trees) and combined safety effects of multiple treatments were interpreted by the interaction terms from the MARS models. Five years of crash data from 2008 to 2012 were collected for rural undivided four-lane roadways in Florida for different crash types and severity levels. The results show that the safety effects decrease as density of driveways and roadside poles increase. The estimated CMFs also indicate that increasing distance to roadside poles and trees reduces crashes. The study demonstrates that the GNMs show slightly better model fitness than negative binomial (NB) models. Moreover, the MARS models outperformed NB and GNM models due to its strength to reflect the nonlinearity of crash predictors and interaction impacts among variables under different ranges. Therefore, it can be recommended that the CMFs are estimated using MARS when there are nonlinear relationships between crash rate and roadway characteristics, and interaction impacts among multiple treatments.

Assessment of safety effects for widening urban roadways in developing crash modification functions using nonlinearizing link functions

Since a crash modification factor (CMF) represents the overall safety performance of specific treatments in a single fixed value, there is a need to explore the variation of CMFs with different roadway characteristics among treated sites over time. Therefore, in this study, we (1) evaluate the safety performance of a sample of urban four-lane roadway segments that have been widened with one through lane in each direction and (2) determine the relationship between the safety effects and different roadway characteristics over time. Observational before–after analysis with the empirical Bayes (EB) method was assessed in this study to evaluate the safety effects of widening urban four-lane roadways to six-lanes. Moreover, the nonlinearizing link functions were utilized to achieve better performance of crash modification functions (CMFunctions). The CMFunctions were developed using a Bayesian regression method including the estimated nonlinearizing link function to incorporate the changes in safety effects of the treatment over time. Data was collected for urban arterials in Florida, and the Florida-specific full SPFs were developed and used for EB estimation.The results indicated that the conversion of four-lane roadways to six-lane roadways resulted in a crash reduction of 15 percent for total crashes, and 24 percent for injury crashes on urban roadways. The results show that the safety effects vary across the sites with different roadway characteristics. In particular, LOS changes, time changes, and shoulder widths are significant parameters that affect the variation of CMFs. Moreover, it was found that narrowing shoulder and median widths to make space for an extra through lane shows a negative safety impact. It was also found that including the nonlinearizing link functions in developing CMFunctions shows more reliable estimates, if the variation of CMFs with specific parameters has a nonlinear relationship. The findings provide insights into the selection of roadway sites for adding through lanes.

EVALUATION OF I-75 LANE CLOSURES

A spot pavement replacement and joint sealing project on I-75 in southern Kentucky during the 1986 construction season involved numerous lane closures. Traffic congestion caused by heavy volumes and late merges resulted in the use of the following traffic control devices to supplement standard lane closure devices: variable message signs, supplemental lane closure warning signs, and rumble strips placed in the lane to be closed in advance of the taper. Because the devices were not typical applications for work zones and because of the potential for applications at other sites, an evaluation study was conducted. Results showed a decrease in the percentage of traffic in the lane to be closed with each successive traffic control device in addition to the standard lane closure devices. There was a general decrease in speeds as traffic approached the taper. The percentage of trucks in the lane to be closed was lower than the percentage in the open lane when the closure was a left lane. Hourly traffic volumes observed in this study (800 to 1,300 vph) did not appear to influence the percentage of traffic in the lane to be closed. The percentage of trucks in both lanes (8.5 to 14.7 percent) did not influence the percentage of traffic in the lane to be closed either. Recommendations from the study included the following: (a) supplemental signs for all long-term closures on high-volume, high-speed four-lane roadways, (b) variable message signs when one-way hourly volumes exceed 1,000 (ADT exceeds 20,000), and (c) application of rumble strips if other devices do not reduce late merges and there is excessive congestion.

Four-Lane to Five-Lane Urban Roadway Conversions for Safety

Undivided roadways have consistently exhibited low safety performance, particularly in urban or suburban areas where roadside development is relatively intense. Changing a four-lane undivided road to a divided roadway by either building a boulevard cross-section or installing a physical barrier is a desirable option to improve safety performance of an undivided roadway, but it requires significant resources. This article introduces a crash countermeasure successfully implemented on two different segments of undivided roadways in Louisiana. This crash countermeasure is to change an undivided four-lane roadway to a five-lane roadway with a center lane for left turns by restriping pavement markings without increasing pavement width. Although the five-lane roadway is no longer an acceptable roadway type in Louisiana, the impressive crash reductions on both roadway segments demonstrate it is a feasible solution under constrained conditions. Based on the statistical analysis with 6 years of crash data (3 years before and 3 years after excluding the implementation year), the crash modification factors for both roadways are estimated to be less than 0.5 with a standard deviation less than 0.07. Although it is not surprising to see the biggest crash reduction comes from the rear-end collisions, the other types of collision are also reduced.

Development of Left-Turn Lane Warrants for Unsignalized Intersections

Left-turn movements at intersections, including driveways—especially movements that are made from lanes that are shared with through traffic—cause delays and adversely affect safety. Although some left-turn warrants have been updated, many agencies still use research performed by M. D. Harmelink in the mid-1960s. Most states use procedures that are based on Harmelink's work, but several limitations have been identified. Economic analysis can provide a useful method for combining traffic operations and safety benefits of left-turn lanes to identify situations in which left-turn lanes either are or are not justified economically. This project used a benefit–cost approach to determine when a left-turn lane would be justified. The steps included simulation to determine delay savings from installing a left-turn lane, crash costs and crash reduction savings determined from safety performance functions and crash modification factors available in the Highway Safety Manual, and construction costs. Left-turn lane warrants were developed for rural two-lane highways, rural four-lane highways, and urban and suburban roadways. In addition, warrants for bypass lanes were developed for rural two-lane highways.

도시지역 우수유출 저감을 위한 식재박스형 침투시설의 개발

우수유출저감과 건전한 도시 물순환 환경의 구축을 위하여 다양한 침투시설들의 개발 및 적용이 점점 중요해지고 있다. 본 연구에서는 도시에서 가로수목공간으로 사용되는 식재박스를 활용하여, 우수유출의 저감, 도시내 물순환 체계 개선 및 친환경적인 기능을 수행할 수 있는 침투시설을 개발하였다. 개발된 시설은 작은 규모로도 설치할 수 있어 광로, 대로, 중로, 소로 및 보행도로나 좁은 공간의 구분없이 설치가 가능하여, 기존 도시 및 신도시 등에 광범위하게 적용할 수 있다. 개발된 기술을 4차로에 적용할 경우 식수대의 설치간격을 6m미만으로 유지한다면, 98%의 호우사상에 대하여 우수의 유출을 65% 이상 저감할 수 있는 것으로 나타났다. 본 연구에서 개발된 가로수목공간 조성기술 적용을 통하여, 우수유출 저감에 따른 치수효과와 더불어 녹색도시의 구현이 가능할 것으로 기대된다. It becomes more and more important to develop various infiltration facilities for healthy water cycle and reduction of urban storm water runoff. In this study, a infiltration facility by utilizing tree box was developed. The developed facility is capable of reducing storm water road runoff, improving urban water cycle, and performing other sustainable and environmental functions. Because the facility can be manufactured to a smaller size than an existing runoff reduction facility, it can be installed at various road types of not only existing urban areas, but new developed areas. If the facility is applied to four-lane roadways, it is expected to reduce 65% of rainfall runoff discharge. Urban flood control improvement can be accomplished by a wide application of the developed technique.

Safety Impacts of Design Element Trade-Offs for Multilane Rural Highways

Roadway designs intend to provide a safe facility addressing mobility concerns, accommodating the physical and social environment and within financial constraints. Sometimes, trade-offs among these may be needed to deliver the desired project and designers need tools to estimate the safety implications from such decisions. The work completed here aimed to develop a set of recommendations to be used in evaluating safety implications from design element trade-offs. The effort focused on developing crash-prediction models and accident modification factors (AMFs) for multilane rural roads regarding lane width, shoulder width, and median width and type. The available data limited these models to four-lane roadways with 12-ft lanes. Separate models were developed for divided and undivided facilities as well as for single-vehicle, multivehicle, and all crashes involving both total and injury crashes. The AMF values recommended here were compared to those proposed in the Highway Safety Manual. Most of the proposed values are in accordance with previous work and demonstrate the effect of these elements on crash occurrence.

Red Retroreflective Raised Pavement Markings

Research was conducted to evaluate drivers’ understanding of red retroreflective raised pavement markers (RRPMs) on two-lane and four-lane undivided and divided roadways. The study included 191 participants, equally divided between three participant groups: drivers from countries with left-hand drive (e.g., Australia, United Kingdom, and Japan), drivers from Hawaii, and drivers from the continental United States. Five typical roadway configurations were tested by means of a laptop survey. For each roadway configuration, standard pavement markings were shown as a baseline condition. Three alternate marking treatments were shown for each typical roadway configuration. Two of the alternative marking treatments consisted of different combinations of supplemental RRPMs, and the third alternative treatment consisted of supplemental pavement marking arrows without RRPMs. The general findings were that red RRPMs on one-way divided roadways to indicate the wrong direction of travel helped drivers realize when they were going in the wrong direction; red RRPMs on undivided roadways can improve understanding of drivers from countries with left-hand drive without reducing the understanding of drivers from Hawaii and the continental United States; and replacing supplemental RRPMs with supplemental arrows always improved the rates of correct responses for all roadway configurations and for all participant groups.

Effect on Utilization of Auxiliary through Lanes of Downstream Right-Turn Volume

To increase the capacity of through traffic at signalized intersections, additional lanes with limited lengths—called auxiliary lanes—are usually added to the roadway at the intersection. Because of their limited length, as well as other factors, these lanes are not fully utilized as other continuous through lanes. The objectives of this research were (1) to identify the level of utilization of auxiliary through lanes added at intersections of four-lane roadways with right-turn driveways and/or side streets present within the downstream length of the auxiliary lane; and (2) to study the effect of auxiliary lane length, right-turn volume existing downstream into driveways/side streets, and through/right-turn lane group delay on the level of their utilization. Lane-use and right-turning volume data collected during 866 saturated cycles at eight signalized intersections with different auxiliary lane lengths and right-turn volumes were used to accomplish the research objectives. Auxiliary lane length and right-turn volume downstream were found to significantly contribute to the use of auxiliary lanes at the 0.01 level of significance. Lane-use of nearly 0.4–1.9 straight-through vehicles per cycle, depending on lane length and downstream right-turn volume, was observed at the study locations. Though not directly comparable to this study, previous studies had indicated lane-use values within this range. Longer auxiliary lanes and lower downstream right-turn volumes encouraged the use of auxiliary lanes by straight-through vehicles. The range of lane utilization adjustment factors (\If\DLU\N-factors) calculated from field data was 0.72–0.80, which is lower than the 1997 U.S. Highway Capacity Manual default value of 0.91 for a three-lane through/right-turn group.

Design and Construction of Smart Road over Wilson Creek: Montgomery County, Virginia

The Smart Road over Wilson Creek, located in Montgomery County, Virginia, is the primary bridge project on a future four-lane divided roadway between Blacksburg, Virginia, and Interstate 81. The road was given the name Smart because it will be used as a test bed for research in such areas as variable weather and lighting conditions, communications systems, and experimental pavements. Figg Bridge Engineers, Inc., designed the bridge for the Virginia Department of Transportation (Virginia DOT) and provided construction engineering and inspection services on site. Aesthetics were a major concern for the Virginia DOT and the local community because of the natural beauty of the surroundings. Long spans were used to minimize the number of piers. The 605-m five-span structure has three interior spans of 144 m (472 ft) and end spans of 86.5 m (284 ft). The variable-depth concrete box girder superstructure was built by using cast-in-place balanced cantilever segmental construction with form travelers. The cast-in-place piers are conventionally reinforced voided rectangular sections with variable slopes in both directions. With pier heights varying up to 41.4 m (135 ft), the bridge deck is a maximum of approximately 53 m (175 ft) above the valley floor, making the Smart Road the tallest bridge in Virginia. Other aesthetic enhancements implemented on this project include monolithic connections between the piers and the superstructure, the use of natural stone treatments on the piers and railing terminal walls, an open bridge railing, and a concrete surface coating.

Paris–Lexington Road Project: Project Report

The Paris-Lexington Road Project is the four-lane roadway reconstruction project of the two-lane Paris Pike, a 19-plus-km (12-plus-mi) section of US-27/58. This section of highway has been dedicated as a historic corridor and has had its share of archeological and environmental sensitive sites along the corridor. In addition, Paris Pike is one of the major thoroughfares through picturesque horse farms that make up the prosperous Kentucky thoroughbred industry. Over the years, safety and traffic operations problems had become noticeable to the Kentucky Transportation Cabinet (KyTC). However, when KyTC attempted to use standard department procedures to study, plan, design, and construct a solution to rectify these problems, they found that the special circumstances of Paris Pike required something innovative. Some background is given on the circumstances that KyTC had to consider: historic, environmental, and political. To ensure compliance with the historic and environmental preservation requirements of this project, KyTC used innovative approaches in contracting the design segments. Preliminary findings are reported on the effectiveness of the construction phase of the first three of five design segments that have been contracted. Although further investigation is ongoing, a comparison can be made of the results observed and the typical results achieved for highway construction projects performed under traditional design-bid-build contracting methods.

SuperJet Grouting: New Technology for In Situ Soil Improvement

The New Jersey Department of Transportation solicited a request for proposal for a design-construct bid to extend the Atlantic City Expressway to the marina district and Brigantine. This would service a developing area for casino construction as well as greatly improve access to the beachfront towns north of Atlantic City. The preliminary proposal required approximately 0.8 km (0.5 mi) of four-lane roadway to go underground, eliminating traffic noise, and to pass under US-30. The prime and specialist contractors, in concert with intuitive engineering support, developed an in situ installation of a subgrade bottom-strut bracing system for a cut-and-cover tunnel installation. This concept offered many advantages, including months of schedule savings, reduced sheet-pile cost, and much-reduced wall-anchoring requirements. To economically install this bottom strut, the new system of SuperJet grouting was used. This grouting system offers several key advancements over conventional jet grouting and allows the construction of columns up to 5 m (16 ft) in diameter. This new technology, the method of installation, difficulties overcome, and the quality-assurance and quality-control elements of this portion of the project are presented. Future applications are also proposed.

Safety Effects of the Conversion of Rural Two-Lane to Four-Lane Roadways Based on Cross-Sectional Models

As congestion on two-lane rural roads increases, there is increasing interest in conversion to a four-lane undivided or four-lane divided facility within the same corridor. There is a surprising lack of research aimed at precisely estimating the safety benefits of these conversions. This lack is due in large part to the difficulty of conducting such research, because the best answer would result from analysis of a large sample of converted locations covering many different before-and-after configurations. The authors have attempted to estimate the benefits of such conversions by developing cross-sectional models producing crash rates for typical sections of two- and four-lane roadways in four different states. Predicted crash reductions for conversion from most typical two- to four-lane divided sections ranged from 40 to 60 percent. The reduction due to conversion to a four-lane undivided configuration is much less well defined, ranging from no effect to perhaps a 20 percent reduction. Continuing research needs include ( a) verification of the undivided four-lane results, ( b) additional information on the effects of driveways, ( c) estimates for higher levels of two-lane average daily traffic, ( d) expansion of the outcome variable to include crash severity, and ( e) verification of all results by before-and-after studies of actual conversions.