The opening of the Panama Canal in 1913 increased the availability of internationally traded goods and transformed ocean-shipping by shortening travel time between the Atlantic Ocean and Pacific Ocean. The canal spark...The opening of the Panama Canal in 1913 increased the availability of internationally traded goods and transformed ocean-shipping by shortening travel time between the Atlantic Ocean and Pacific Ocean. The canal sparked the growth of port authorities and increased ship tonnage on both coasts of Panama. Since the construction of the Panama Canal, in the 1910s, pesticides, herbicides and chemicals, including arsenic, have been essential for controlling wetland vegetation, including hyacinth, which blocked rivers, lakes, and the canal as well as managing mosquitoes. Pesticides and chemicals flowed into Lake Gatun (reservoir) either attached to sediment or in solution during the monsoon season. Lake Gatun was the drinking water source for most of the people living in the Panama Canal Zone. The United States military base commanders had the ability to order and use cacodylic acid (arsenic based) from the Naval Depot Supply Federal and Stock Catalog and the later Federal Supply Catalog on the military base grounds in the Panama Canal Zone. Cacodylic acid was shipped to Panama Canal Zone ports, including Balboa and Cristobal, and distributed to the military bases by rail or truck. The objective of this study is to determine the fate of arsenic: 1) applied between 1914 and 1935 to Panama Canal shipping lane hyacinth and other wetland vegetation and 2) cacodylic acid (arsenic) sprayed from 1948 to 1999 on the US military base grounds in the Panama Canal Zone.展开更多
Road Diets are far from a new technique for designers to apply to roadways. Yet after over 50 years of implementation and countless studies into their effectiveness, it is only relatively recently that the process is ...Road Diets are far from a new technique for designers to apply to roadways. Yet after over 50 years of implementation and countless studies into their effectiveness, it is only relatively recently that the process is gaining widespread recognition and implementation. Each year, more states and countries are examining potential road diets and putting them into place. Still, there remains great skepticism and opposition in many corners. In addition, cities and states may be drawing from many of the same sources in how to go about the process of a road diet and evaluate them, yet their methodology, goals, and even terminology can vary from region to region. This study analyzes the implementation of a road diet along a one-way arterial road, in Newark, Delaware. The primary aim of this analysis is to evaluate the feasibility of introducing a dedicated bicycle infrastructure to enhance local accessibility and to quantify its potential impacts on traffic flow, parking availability, and loading logistics within the vicinity. While the reduction of one lane could be perceived as a constraint on traffic management, the investigation revealed that E Main Street, the roadway analyzed, for the most part, can adequately accommodate its traffic load with a single lane. Detailed findings underscore the notable enhancement in level of service and subsequent reduction in delay times across most surveyed approaches.展开更多
This paper introduces a new two-lane high-order continuum model by embedding the two delay time scales con- tinuum traffic model presented by Xue （2003 Phys. Rev. E 68 066123） into the multi-lane model proposed by D...This paper introduces a new two-lane high-order continuum model by embedding the two delay time scales con- tinuum traffic model presented by Xue （2003 Phys. Rev. E 68 066123） into the multi-lane model proposed by Daganzo （1997 Transpn. Res. B 31 83） with the consideration of the coupling effect between the vehicles of two lanes in instantaneous traffic situation and lane-change effect. In the novel model, the coupling effect of two lanes and phenomena of lane change, which were not discussed in Daganzo＇s model and Xue＇s model, are taken into account. Numerical simulation shows that it is in accordance with real traffic flow. This obviously indicates that the new phenomenon and behaviour are analogous results as single lane presented by Xue, and the proposed model is more reasonable on two lanes. Furthermore, the generation rate between two lanes is also investigated. The results show that the formation and diffusion of traffic shock wave can be better simulated on two lanes.展开更多
Along with the rapid globalization and urbanization,primitive ecological environment and cultural life atmosphere of urban streets and lanes have degraded,memories of the city have been lost,and cities have shown the ...Along with the rapid globalization and urbanization,primitive ecological environment and cultural life atmosphere of urban streets and lanes have degraded,memories of the city have been lost,and cities have shown the tendency of convergence and homogenization.Taking the Confucius Temple Block for example,this paper applied cognitive map,oral interview and GIS spatial statistics to study residents' col ective memories of urban street and lane spaces,and found that the locals' collective memories of streets and lanes in the Confucius Temple Block declined gradually in the sequence of "aura area" → "secondary aura area" → "buffer area" → "blind spot area",and "civilian" urban design concept was claimed as the major incentive of the decline.Streets and lanes as important components of urban public spaces have specific historical connotations and genius loci,and they deserve wide concern from the academic circle and the society for their function of protecting collective memories of residents.展开更多
To explore the potential capacity of dual-fight-turn lanes at signalized intersections under mixed traffic conditions, we defined two conflict zones between right turn vehicles and through bicycle corresponding to dif...To explore the potential capacity of dual-fight-turn lanes at signalized intersections under mixed traffic conditions, we defined two conflict zones between right turn vehicles and through bicycle corresponding to different right turn flows from dual-right-turn lanes. Relationships between the arrival rate of bicycle group at each conflict zone and the saturation flow rate of right turn movement were investigated. A model based on gap acceptance theory was adopted to estimate the capacity of dual-right-turn lanes under mixed traffic conditions. An analysis was carried out using the collected data from three four-leg signalized intersections in Beijing, China, where the dual-right-turn lanes were used. In addition, we also discussed the patterns of bicycle lane in the urban area of Beijing, and classified it based on its characteristics in use. It is concluded that the two lanes of dual-fight-turn lanes produce different capacities under mixed traffic conditions, and the analysis on scenarios of dual-right-turn movement traversing bicycle traffic plays a key role in explaining the different capacity performance of the two right turn lanes. Error analysis of the model indicated that the model was rational.展开更多
Crash prediction models are commonly used for network screening in highway safety management process,where potential impacts of highway safety treatments are quantified.The Highway Safety Manual(HSM)provides crash pre...Crash prediction models are commonly used for network screening in highway safety management process,where potential impacts of highway safety treatments are quantified.The Highway Safety Manual(HSM)provides crash prediction models for various types of highway facilities that are often referred to as safety performance functions(SPFs).Freeway facility SPFs in the HSM were developed using data gathered from the states of California,Maine,and Washington.When applying these HSM-default SPFs to a local jurisdiction,the HSM recommends calibration of HSM-default SPFs or development of jurisdiction-specific SPFs to improve the accuracy of crash predictions.This study first calibrated the HSM-default freeway SPFs and for further accuracy and comparison purposes calibration functions were developed using Kansas freeway data.The performance of calibrated HSM-default SPFs was then compared with developed calibration functions concerning the accuracy in crash prediction.Freeway facility calibration dataset included521 freeway segments,351 entrance-related speed-change lanes,and 366 exit-related speed-change lanes.Cumulative residual plots and several other goodness-of-fit measures were used to assess the quality of calibrated HSM-default SPFs and calibration functions.Calibration functions fitted better compared to calibrated HSM-default SPFs for Kansas freeway data.The methodology used in this study could be beneficial and practiced to any jurisdiction.Calibration functions could be used as an alternative to jurisdiction-specific SPFs or a replacement for HSM-default SPFs,which are frequently used in comparing alternatives,in calculating economic benefits of project improvements,and in estimating economic effectiveness of crash reduction in highway safety-related decision making.展开更多
Considering the effects that the probability of traffic interruption and the friction between two lanes have on the car-following behaviour, this paper establishes a new two-lane microscopic car-following model. Based...Considering the effects that the probability of traffic interruption and the friction between two lanes have on the car-following behaviour, this paper establishes a new two-lane microscopic car-following model. Based on this microscopic model, a new macroscopic model was deduced by the relevance relation of microscopic and macroscopic scale parameters for the two-lane traffic flow. Terms related to lane change are added into the continuity equations and velocity dynamic equations to investigate the lane change rate. Numerical results verify that the proposed model can be efficiently used to reflect the effect of the probability of traffic interruption on the shock, rarefaction wave and lane change behaviour on two-lane freeways. The model has also been applied in reproducing some complex traffic phenomena caused by traffic accident interruption.展开更多
Traffic management aims to ensure a high quality of service for most users by decreasing congestion and increasing safety. However, uncertainty regarding travel time decreases the quality of service and leads end-user...Traffic management aims to ensure a high quality of service for most users by decreasing congestion and increasing safety. However, uncertainty regarding travel time decreases the quality of service and leads end-users to change their routes and schedules even when the average travel time is low, Indicators describing travel time reliability are being developed and should be used in the future both for the optimization and the assessment of active traffic management operation. This paper describes a managed lane experience on a motorway weaving section in France - hard shoulder running operation in rush hours. The paper is focused on travel time reliability indicators and their use for reliability assessment. It provides some discussions about the advantages and drawbacks of reliability indicators under different traffic conditions. It particularly shows the difference between using buffer times and buffer indexes. The paper also discusses the difficulty of interpreting the skew of travel time distribution for travel reliability,展开更多
Particulate matter(PM), one of the most important pollutants of traffic emission, threatens the health of urban ecosystems and citizens. Roadside trees play an important role in trapping PM, and the foliar PM load is ...Particulate matter(PM), one of the most important pollutants of traffic emission, threatens the health of urban ecosystems and citizens. Roadside trees play an important role in trapping PM, and the foliar PM load is a useful indicator for air PM pollution in road systems. To detect the relationships of foliar PM load with road structures, urbanization, and meteorology in road systems, we studied a widely-planted tree Sophora japonica L. in 100 roads and 10 yards of Beijing, China, and found that the foliar PM loads increased with the distances from the urban centre(DUC) linearly, while decreased with the road density. All-subsets regression analysis indicated that DUC, average monthly relative humidity, average monthly wind speed, and mean annual wind speed were the most important factors in predicting foliar PM load, rather than general situation of buildings and road cleanliness. The monthly relative humidity and monthly wind speed had a negative correlation to foliar PM, while the annual relative humidity and annual wind speed had a positive correlation to foliar PM. Suburban areas and these effective factors should be highlighted in PM control in Beijing.展开更多
The use of managed lanes to control and maximize freeway throughput is increasing. One way of encouraging more managed lane use is through the implementation of incentives. In the Dallas-Fort Worth area, a managed lan...The use of managed lanes to control and maximize freeway throughput is increasing. One way of encouraging more managed lane use is through the implementation of incentives. In the Dallas-Fort Worth area, a managed lane is being added to the I-30 (Tom Landry freeway) and incentives to maximize the use of this lane were planned. Since the managed lanes were not yet open and the incentives were hypothetical, a stated preference survey was used to gauge the potential impact of the incentives on traveler behavior. The stated preference questions were designed using Db-efficient and random adaptive designs. The incentives were chosen by looking at other programs around the country and through discussion with transportation experts. Once ready, the survey was administered online to travelers in the area and a total of 898 usable responses were gathered. From the responses, a mixed-logit model was developed to describe and predict traveler behavior. From the model, elasticities were calculated to predict the impact of the incentives on mode choice. The model found that incentives with discounts and free trips (a transit fare discount, express bus service to downtown, a free trip for every X number of paid trips, and a discount offered to select businesses) were more effective at encouraging managed lane use. The other incentives (gift card worth $5 for every X number of trips and $5 in credit for every X number of trips taken by transit) had less of an impact.展开更多
Traditional block of Xin’gan South Road in Ganzhou City is taken as the research object.Using urban design techniques,spatial structure,spatial interface,scale,ratio and spatial node of traditional streets and lanes ...Traditional block of Xin’gan South Road in Ganzhou City is taken as the research object.Using urban design techniques,spatial structure,spatial interface,scale,ratio and spatial node of traditional streets and lanes are controlled and processed,and spatial image is analyzed.Moreover,the strategic transformation proposal is put forward.It promotes the renewal of traditional streets and lanes in urban renewal,and realizes the historical continuation of spatial image of traditional streets and lanes,thereby protecting the historical features of the ancient city.展开更多
It is summer and Xiamen, China's famed coastal city in southeast Fujian Provinee that played a key role in Chinese going out to explore opportunities abroad, has its dog days’ features on full display. It is hot ...It is summer and Xiamen, China's famed coastal city in southeast Fujian Provinee that played a key role in Chinese going out to explore opportunities abroad, has its dog days’ features on full display. It is hot and humid despite the sea breeze, lush ripe man goes dangle tan talizi ngly from bent tree branches, and the bike lanes are deserted except for a stream of diehard afternoon runners since Xiamen, after all, is also famous for its marathons.展开更多
文摘The opening of the Panama Canal in 1913 increased the availability of internationally traded goods and transformed ocean-shipping by shortening travel time between the Atlantic Ocean and Pacific Ocean. The canal sparked the growth of port authorities and increased ship tonnage on both coasts of Panama. Since the construction of the Panama Canal, in the 1910s, pesticides, herbicides and chemicals, including arsenic, have been essential for controlling wetland vegetation, including hyacinth, which blocked rivers, lakes, and the canal as well as managing mosquitoes. Pesticides and chemicals flowed into Lake Gatun (reservoir) either attached to sediment or in solution during the monsoon season. Lake Gatun was the drinking water source for most of the people living in the Panama Canal Zone. The United States military base commanders had the ability to order and use cacodylic acid (arsenic based) from the Naval Depot Supply Federal and Stock Catalog and the later Federal Supply Catalog on the military base grounds in the Panama Canal Zone. Cacodylic acid was shipped to Panama Canal Zone ports, including Balboa and Cristobal, and distributed to the military bases by rail or truck. The objective of this study is to determine the fate of arsenic: 1) applied between 1914 and 1935 to Panama Canal shipping lane hyacinth and other wetland vegetation and 2) cacodylic acid (arsenic) sprayed from 1948 to 1999 on the US military base grounds in the Panama Canal Zone.
文摘Road Diets are far from a new technique for designers to apply to roadways. Yet after over 50 years of implementation and countless studies into their effectiveness, it is only relatively recently that the process is gaining widespread recognition and implementation. Each year, more states and countries are examining potential road diets and putting them into place. Still, there remains great skepticism and opposition in many corners. In addition, cities and states may be drawing from many of the same sources in how to go about the process of a road diet and evaluate them, yet their methodology, goals, and even terminology can vary from region to region. This study analyzes the implementation of a road diet along a one-way arterial road, in Newark, Delaware. The primary aim of this analysis is to evaluate the feasibility of introducing a dedicated bicycle infrastructure to enhance local accessibility and to quantify its potential impacts on traffic flow, parking availability, and loading logistics within the vicinity. While the reduction of one lane could be perceived as a constraint on traffic management, the investigation revealed that E Main Street, the roadway analyzed, for the most part, can adequately accommodate its traffic load with a single lane. Detailed findings underscore the notable enhancement in level of service and subsequent reduction in delay times across most surveyed approaches.
基金supported by the National High Tech Research and Development (863) Program of China (Grant No 511-0910-1031)the National ‘10th Five-year’ Science and Technique Important Program of China (Grant No 2002BA404A07)
文摘This paper introduces a new two-lane high-order continuum model by embedding the two delay time scales con- tinuum traffic model presented by Xue （2003 Phys. Rev. E 68 066123） into the multi-lane model proposed by Daganzo （1997 Transpn. Res. B 31 83） with the consideration of the coupling effect between the vehicles of two lanes in instantaneous traffic situation and lane-change effect. In the novel model, the coupling effect of two lanes and phenomena of lane change, which were not discussed in Daganzo＇s model and Xue＇s model, are taken into account. Numerical simulation shows that it is in accordance with real traffic flow. This obviously indicates that the new phenomenon and behaviour are analogous results as single lane presented by Xue, and the proposed model is more reasonable on two lanes. Furthermore, the generation rate between two lanes is also investigated. The results show that the formation and diffusion of traffic shock wave can be better simulated on two lanes.
基金Sponsored by Youth Program of National Natural Science Foundation of China(41401152)Humanities and Social Science Youth Program of the Ministry of Education(14YJCZH228)+1 种基金"Qing-Lan"Project of Excellent Young Teachers’Training Program of Jiangsu Provincial Colleges and UniversitiesScientific Research Fund for the Fifth Session of Jiangsu Provincial"333"Project(Level 3)
文摘Along with the rapid globalization and urbanization,primitive ecological environment and cultural life atmosphere of urban streets and lanes have degraded,memories of the city have been lost,and cities have shown the tendency of convergence and homogenization.Taking the Confucius Temple Block for example,this paper applied cognitive map,oral interview and GIS spatial statistics to study residents' col ective memories of urban street and lane spaces,and found that the locals' collective memories of streets and lanes in the Confucius Temple Block declined gradually in the sequence of "aura area" → "secondary aura area" → "buffer area" → "blind spot area",and "civilian" urban design concept was claimed as the major incentive of the decline.Streets and lanes as important components of urban public spaces have specific historical connotations and genius loci,and they deserve wide concern from the academic circle and the society for their function of protecting collective memories of residents.
文摘To explore the potential capacity of dual-fight-turn lanes at signalized intersections under mixed traffic conditions, we defined two conflict zones between right turn vehicles and through bicycle corresponding to different right turn flows from dual-right-turn lanes. Relationships between the arrival rate of bicycle group at each conflict zone and the saturation flow rate of right turn movement were investigated. A model based on gap acceptance theory was adopted to estimate the capacity of dual-right-turn lanes under mixed traffic conditions. An analysis was carried out using the collected data from three four-leg signalized intersections in Beijing, China, where the dual-right-turn lanes were used. In addition, we also discussed the patterns of bicycle lane in the urban area of Beijing, and classified it based on its characteristics in use. It is concluded that the two lanes of dual-fight-turn lanes produce different capacities under mixed traffic conditions, and the analysis on scenarios of dual-right-turn movement traversing bicycle traffic plays a key role in explaining the different capacity performance of the two right turn lanes. Error analysis of the model indicated that the model was rational.
基金supported by the Kansas Department of Transportation(KDOT)under the K-TRAN program.
文摘Crash prediction models are commonly used for network screening in highway safety management process,where potential impacts of highway safety treatments are quantified.The Highway Safety Manual(HSM)provides crash prediction models for various types of highway facilities that are often referred to as safety performance functions(SPFs).Freeway facility SPFs in the HSM were developed using data gathered from the states of California,Maine,and Washington.When applying these HSM-default SPFs to a local jurisdiction,the HSM recommends calibration of HSM-default SPFs or development of jurisdiction-specific SPFs to improve the accuracy of crash predictions.This study first calibrated the HSM-default freeway SPFs and for further accuracy and comparison purposes calibration functions were developed using Kansas freeway data.The performance of calibrated HSM-default SPFs was then compared with developed calibration functions concerning the accuracy in crash prediction.Freeway facility calibration dataset included521 freeway segments,351 entrance-related speed-change lanes,and 366 exit-related speed-change lanes.Cumulative residual plots and several other goodness-of-fit measures were used to assess the quality of calibrated HSM-default SPFs and calibration functions.Calibration functions fitted better compared to calibrated HSM-default SPFs for Kansas freeway data.The methodology used in this study could be beneficial and practiced to any jurisdiction.Calibration functions could be used as an alternative to jurisdiction-specific SPFs or a replacement for HSM-default SPFs,which are frequently used in comparing alternatives,in calculating economic benefits of project improvements,and in estimating economic effectiveness of crash reduction in highway safety-related decision making.
基金Project supported by the National High Tech Research and Development Program of China (Grant No. 511-0910-1031)
文摘Considering the effects that the probability of traffic interruption and the friction between two lanes have on the car-following behaviour, this paper establishes a new two-lane microscopic car-following model. Based on this microscopic model, a new macroscopic model was deduced by the relevance relation of microscopic and macroscopic scale parameters for the two-lane traffic flow. Terms related to lane change are added into the continuity equations and velocity dynamic equations to investigate the lane change rate. Numerical results verify that the proposed model can be efficiently used to reflect the effect of the probability of traffic interruption on the shock, rarefaction wave and lane change behaviour on two-lane freeways. The model has also been applied in reproducing some complex traffic phenomena caused by traffic accident interruption.
文摘Traffic management aims to ensure a high quality of service for most users by decreasing congestion and increasing safety. However, uncertainty regarding travel time decreases the quality of service and leads end-users to change their routes and schedules even when the average travel time is low, Indicators describing travel time reliability are being developed and should be used in the future both for the optimization and the assessment of active traffic management operation. This paper describes a managed lane experience on a motorway weaving section in France - hard shoulder running operation in rush hours. The paper is focused on travel time reliability indicators and their use for reliability assessment. It provides some discussions about the advantages and drawbacks of reliability indicators under different traffic conditions. It particularly shows the difference between using buffer times and buffer indexes. The paper also discusses the difficulty of interpreting the skew of travel time distribution for travel reliability,
基金Under the auspices of National Natural Science Foundation of China(No.41430638)Special Found for Beijing Common Construction Project for Beijing Laboratory of Urban and Rural Ecological Environment(No.PXM2015_014207_000014)Grants from the Beijing Municipal Education Commission(No.PXM2019_014207_000099)
文摘Particulate matter(PM), one of the most important pollutants of traffic emission, threatens the health of urban ecosystems and citizens. Roadside trees play an important role in trapping PM, and the foliar PM load is a useful indicator for air PM pollution in road systems. To detect the relationships of foliar PM load with road structures, urbanization, and meteorology in road systems, we studied a widely-planted tree Sophora japonica L. in 100 roads and 10 yards of Beijing, China, and found that the foliar PM loads increased with the distances from the urban centre(DUC) linearly, while decreased with the road density. All-subsets regression analysis indicated that DUC, average monthly relative humidity, average monthly wind speed, and mean annual wind speed were the most important factors in predicting foliar PM load, rather than general situation of buildings and road cleanliness. The monthly relative humidity and monthly wind speed had a negative correlation to foliar PM, while the annual relative humidity and annual wind speed had a positive correlation to foliar PM. Suburban areas and these effective factors should be highlighted in PM control in Beijing.
文摘The use of managed lanes to control and maximize freeway throughput is increasing. One way of encouraging more managed lane use is through the implementation of incentives. In the Dallas-Fort Worth area, a managed lane is being added to the I-30 (Tom Landry freeway) and incentives to maximize the use of this lane were planned. Since the managed lanes were not yet open and the incentives were hypothetical, a stated preference survey was used to gauge the potential impact of the incentives on traveler behavior. The stated preference questions were designed using Db-efficient and random adaptive designs. The incentives were chosen by looking at other programs around the country and through discussion with transportation experts. Once ready, the survey was administered online to travelers in the area and a total of 898 usable responses were gathered. From the responses, a mixed-logit model was developed to describe and predict traveler behavior. From the model, elasticities were calculated to predict the impact of the incentives on mode choice. The model found that incentives with discounts and free trips (a transit fare discount, express bus service to downtown, a free trip for every X number of paid trips, and a discount offered to select businesses) were more effective at encouraging managed lane use. The other incentives (gift card worth $5 for every X number of trips and $5 in credit for every X number of trips taken by transit) had less of an impact.
文摘Traditional block of Xin’gan South Road in Ganzhou City is taken as the research object.Using urban design techniques,spatial structure,spatial interface,scale,ratio and spatial node of traditional streets and lanes are controlled and processed,and spatial image is analyzed.Moreover,the strategic transformation proposal is put forward.It promotes the renewal of traditional streets and lanes in urban renewal,and realizes the historical continuation of spatial image of traditional streets and lanes,thereby protecting the historical features of the ancient city.
文摘It is summer and Xiamen, China's famed coastal city in southeast Fujian Provinee that played a key role in Chinese going out to explore opportunities abroad, has its dog days’ features on full display. It is hot and humid despite the sea breeze, lush ripe man goes dangle tan talizi ngly from bent tree branches, and the bike lanes are deserted except for a stream of diehard afternoon runners since Xiamen, after all, is also famous for its marathons.
