Transportation Research Record: Journal of the Transportation Research Board, 2016
Research into the operation of traffic flow at high volumes reveals that the capacity of freeways... more Research into the operation of traffic flow at high volumes reveals that the capacity of freeways is not a fixed number but is rather a random variable. Since traditional operational performance measures for the analysis of traffic flow on freeways typically disregard the randomness of capacity, new approaches to make use of the concept of randomness for freeway operation analysis are required. To address that need, this paper introduces a new indicator of freeway performance based solely on a stochastic approach to capacity computation. With this new indicator, the maximum reliable volume that can be carried by a freeway over prolonged time periods was derived from parameters of capacity distribution functions. The breakdown probability corresponding to the optimum volume can be used to select a single value from the capacity distribution function. To explore the empirical relationship between expected values of capacity and the optimum volumes calculated from this new computationa...
PDFTech Report06-2SSHurricanesEvacuationRoutes and routingTraffic congestionTraffic flowTransport... more PDFTech Report06-2SSHurricanesEvacuationRoutes and routingTraffic congestionTraffic flowTransportation planningData collectionSurveysRevealed preferencesTime dependenceBehaviorNew Orleans (Louisiana)Louisiana Transportation Research CenterWilmot, ChesterLouisiana Transportation Research CenterLouisiana. Dept. of Transportation and DevelopmentLouisiana State University (Baton Rouge, La.)NTL-PLANNING AND POLICY-SurveysUS Transportation CollectionCurrent hurricane evacuation transportation modeling uses an approach fashioned after thetraditional four-step procedure applied in urban transportation planning. One of the limitingfeatures of this approach is that it models traffic in a static manner. That is, link flows aremodeled as the total flow occurring on a link during an analysis period, such as a morningpeak, with no indication of the variation in traffic flow during the period. In addition, static tripassignment assumes that trips complete the journey from origin to destination during theanalysis period. During a hurricane evacuation, trips can take up to 20 hours, necessitatinglong analysis periods if static assignment is used. These two features, long analysis periodsand no indication of the variation in traffic flow during these periods, are serious limitations onthe integrity of the modeling process. Congestion is critical in estimating evacuationclearance time, evacuation efficiency, and the proportion of evacuees evacuated. Otherdifferences between ordinary day-to-day urban travel and evacuation travel include uncertaintyof road conditions, the possibility that destinations may change due to road closures or lack ofaccommodation, and the fact that an evacuation trip is mandatory rather than discretionary
016097422017PDFTech Report17-01-TA-SSConsumer preferencesEvaluationField studiesHighway safetyPas... more 016097422017PDFTech Report17-01-TA-SSConsumer preferencesEvaluationField studiesHighway safetyPassenger vehiclesPassingRural highwaysSurveysTraffic platooningTraffic speedTrucksTwo lane highwaysVariable speed limitsHighwaysMotor CarriersOperations and Traffic ManagementSafety and Human FactorsLouisianaUnited StatesLouisiana. Department of Transportation and DevelopmentDavis, HaggaiGudishala, RavindraZeringue, Kirk M.Wilmot, ChesterCodjoe, JuliusRoberts, MatthewLouisiana Transportation Research CenterLouisiana. Department of Transportation and DevelopmentNTL-OPERATIONS AND TRAFFIC CONTROLS-OPERATIONS AND TRAFFIC CONTROLSUS Transportation CollectionThis report addresses the matter of differential and uniform speed limits and their application at the state level. It was prepared in response to a request in the 2017 session of the Louisiana House of Representatives where the Louisiana Department of Transportation and Development (DOTD) was asked to \u201cstudy the safety and operational impacts of differential speed limits on interstate highways\u201d (House Concurrent Resolution 112). Thus, the purpose of this study is to inform the Louisiana Legislature about the documented various benefits and costs of a differential speed limit for passenger cars versus larger vehicles specifically with regards to the topics of Safety, Mobility and Operations, Fuel Consumption and Emissions, and Truck Determination as outlined in HCR 112. The majority of research into this topic has not been able to conclusively determine which speed limit system is safer, a uniform speed limit (USL) or a differential speed limit (DSL). There is uncertainty amongst the literature as to which is better, USL or DSL. The uncertainty is due to several factors that work against each other. Changes in observed speed are usually less than the changes in the posted speed, which dulls the impact of a DSL. If the posted speed limit is too low, many drivers will ignore it leading to low compliance rates. A slower speed reduces the severity of crashes; however, a greater speed variance increases the opportunity for crashes. Almost 75% of the nation\u2019s truck fleet cannot travel above a preset speed because they have speed limiters built in. In other countries, the limiter is mandatory, but no study has attempted to quantify the safety. In America, the current trend has states moving toward a USL. Passenger car drivers tend to prefer a DSL, but less strongly than truck drivers prefer a USL. The time and cost to fully implement a speed limit regime change can be substantial. With the lack of strong evidence in the existing published research in either direction, this paper cannot conclude which method is better than the other. Further research (on a much larger scale than this literature review) would be necessary to conclude which speed limit arrangement is better
This paper describes a number of individual-choice models of work-trip mode-choice, calibrated in... more This paper describes a number of individual-choice models of work-trip mode-choice, calibrated in the course of a bus study in two communities of Metropolitan Johannesburg. First, it is found to be useful to reduce the alternative set from eight modes to four modes, without loss of estimation power. Second, a number of alternative specifications of costs and times are examined, from which the chosen model is selected as one containing five such variables. In addition, a variable of car competition is found to add significantly to the explanatory power of the model. Finally, recently-documented procedures are applied to the selected model specification to pool the results of two random subsamples and to correct the choice-based biases in the alternative-specific constants. It is found that the coefficients of the South African model fall well within the range of coefficients determined in the U.S.
International Choice Modelling Conference 2017, Mar 28, 2017
In this study a joint mode and destination type choice model was developed based on evacuation be... more In this study a joint mode and destination type choice model was developed based on evacuation behavior captured in a post hurricane Irene behavior survey. A Nested Logit model specification was used with destination type being modeled in the upper nest and mode choice in the lower nest. As anticipated, the estimated model showed significant dependence between mode and destination type choice. Variables in the model included household socio-demographic characteristics, measures of social connectivity within communities, and a proxy variable of the level of transit service provided in each zone. The study provides insight into some of the factors affecting mode and destination type choice of residents during hurricane evacuation.
The objective of this study was to investigate the feasibility of using a Bluetooth Probe Detecti... more The objective of this study was to investigate the feasibility of using a Bluetooth Probe Detection System (BPDS) to estimate travel time in an urban area. Specifically, the study investigated the possibility of measuring overall congestion, the trend in congestion, the location of congestion “hotspots,” and finally measurement of the level of congestion at the hotspots using a BPDS. A secondary objective was to assess the possibility of obtaining travel time from other quicker and cheaper methods such as simply purchasing it from a commercial vendor. The findings of the study indicate that a BPDS can reliably be used to measure travel time and estimate congestion in terms of indices such as travel delay, planning time index, and travel time index. However, the acquisition of a BPDS includes certain overheads such as installation costs, maintenance costs and monitoring costs. Purchase of travel time from a commercial vendor might be a viable option if the travel time data is not nee...
This paper examines the impact of time-dependent travel cost on hurricane evacuation destination ... more This paper examines the impact of time-dependent travel cost on hurricane evacuation destination choice models based on post hurricane Floyd survey data collected in South Carolina in 1999. The network condition for destination choice model is represented by time dependent origin-destination travel cost. Multinomial logit models were applied for models with travelers evacuating to friends and relatives. The models were applied for all period, peak period and off-peak period. The results show that the dynamic model has less impact overall than the static model with static shortest path travel cost. The travelers have better knowledge of travel cost in off-peak period than in peak period and as a result, the time-dependent travel cost to the destination becomes less important in the peak period model.
The Louisiana Department of Transportation and Development (DOTD) Outsourcing Decision Assistance... more The Louisiana Department of Transportation and Development (DOTD) Outsourcing Decision Assistance Model was developed to assist officials of the DOTD to assess the outsourcing potential of individual activities or functions in the department. The model consists of both a qualitative and a quantitative assessment process which is conducted interactively by a user on a personal computer. The qualitative portion of the model uses the subjective judgment of one or more persons on a set number of perspectives, where each perspective is aimed at a different aspect of the potential for outsourcing. The quantitative portion of the model consists of the comparison of the cost of insourcing or outsourcing the activity. This manual describes how to install and use the computer program that executes both the qualitative and quantitative portions of the model.
AbstractIn this research, the factors affecting route choice in hurricane evacuation are investig... more AbstractIn this research, the factors affecting route choice in hurricane evacuation are investigated. Two hypotheses are tested. First, it is hypothesized that contrary to common practice where travel time is considered the sole or main determinant of route choice, other variables such as familiarity with the route, availability of fuel and shelter, road type, and accessibility of the route have an effect on an evacuees’ route choice as well. The second hypothesis is that as time passes and storm conditions change, the impact each variable has on route choice changes. That is, it is hypothesized that the importance evacuees assign to the factors determining route choice is not static but varies with time. The logit structure was used for modeling the choice process and stated choice data previously collected from the New Orleans area on hypothetical storms was used to calibrate the model. The study found that accessibility to a route, familiarity with the route, road type, length of a route, and availabi...
Page 1. Two dynamic travel demand models for hurricane evacuation based on survival analysis are ... more Page 1. Two dynamic travel demand models for hurricane evacuation based on survival analysis are presented: a Cox proportional hazards model and a piecewise exponential model. ... DemandModels for Hurricane Evacuation Haoqiang Fu and Chester G. Wilmot ...
Transportation Research Record: Journal of the Transportation Research Board, 2016
Research into the operation of traffic flow at high volumes reveals that the capacity of freeways... more Research into the operation of traffic flow at high volumes reveals that the capacity of freeways is not a fixed number but is rather a random variable. Since traditional operational performance measures for the analysis of traffic flow on freeways typically disregard the randomness of capacity, new approaches to make use of the concept of randomness for freeway operation analysis are required. To address that need, this paper introduces a new indicator of freeway performance based solely on a stochastic approach to capacity computation. With this new indicator, the maximum reliable volume that can be carried by a freeway over prolonged time periods was derived from parameters of capacity distribution functions. The breakdown probability corresponding to the optimum volume can be used to select a single value from the capacity distribution function. To explore the empirical relationship between expected values of capacity and the optimum volumes calculated from this new computationa...
PDFTech Report06-2SSHurricanesEvacuationRoutes and routingTraffic congestionTraffic flowTransport... more PDFTech Report06-2SSHurricanesEvacuationRoutes and routingTraffic congestionTraffic flowTransportation planningData collectionSurveysRevealed preferencesTime dependenceBehaviorNew Orleans (Louisiana)Louisiana Transportation Research CenterWilmot, ChesterLouisiana Transportation Research CenterLouisiana. Dept. of Transportation and DevelopmentLouisiana State University (Baton Rouge, La.)NTL-PLANNING AND POLICY-SurveysUS Transportation CollectionCurrent hurricane evacuation transportation modeling uses an approach fashioned after thetraditional four-step procedure applied in urban transportation planning. One of the limitingfeatures of this approach is that it models traffic in a static manner. That is, link flows aremodeled as the total flow occurring on a link during an analysis period, such as a morningpeak, with no indication of the variation in traffic flow during the period. In addition, static tripassignment assumes that trips complete the journey from origin to destination during theanalysis period. During a hurricane evacuation, trips can take up to 20 hours, necessitatinglong analysis periods if static assignment is used. These two features, long analysis periodsand no indication of the variation in traffic flow during these periods, are serious limitations onthe integrity of the modeling process. Congestion is critical in estimating evacuationclearance time, evacuation efficiency, and the proportion of evacuees evacuated. Otherdifferences between ordinary day-to-day urban travel and evacuation travel include uncertaintyof road conditions, the possibility that destinations may change due to road closures or lack ofaccommodation, and the fact that an evacuation trip is mandatory rather than discretionary
016097422017PDFTech Report17-01-TA-SSConsumer preferencesEvaluationField studiesHighway safetyPas... more 016097422017PDFTech Report17-01-TA-SSConsumer preferencesEvaluationField studiesHighway safetyPassenger vehiclesPassingRural highwaysSurveysTraffic platooningTraffic speedTrucksTwo lane highwaysVariable speed limitsHighwaysMotor CarriersOperations and Traffic ManagementSafety and Human FactorsLouisianaUnited StatesLouisiana. Department of Transportation and DevelopmentDavis, HaggaiGudishala, RavindraZeringue, Kirk M.Wilmot, ChesterCodjoe, JuliusRoberts, MatthewLouisiana Transportation Research CenterLouisiana. Department of Transportation and DevelopmentNTL-OPERATIONS AND TRAFFIC CONTROLS-OPERATIONS AND TRAFFIC CONTROLSUS Transportation CollectionThis report addresses the matter of differential and uniform speed limits and their application at the state level. It was prepared in response to a request in the 2017 session of the Louisiana House of Representatives where the Louisiana Department of Transportation and Development (DOTD) was asked to \u201cstudy the safety and operational impacts of differential speed limits on interstate highways\u201d (House Concurrent Resolution 112). Thus, the purpose of this study is to inform the Louisiana Legislature about the documented various benefits and costs of a differential speed limit for passenger cars versus larger vehicles specifically with regards to the topics of Safety, Mobility and Operations, Fuel Consumption and Emissions, and Truck Determination as outlined in HCR 112. The majority of research into this topic has not been able to conclusively determine which speed limit system is safer, a uniform speed limit (USL) or a differential speed limit (DSL). There is uncertainty amongst the literature as to which is better, USL or DSL. The uncertainty is due to several factors that work against each other. Changes in observed speed are usually less than the changes in the posted speed, which dulls the impact of a DSL. If the posted speed limit is too low, many drivers will ignore it leading to low compliance rates. A slower speed reduces the severity of crashes; however, a greater speed variance increases the opportunity for crashes. Almost 75% of the nation\u2019s truck fleet cannot travel above a preset speed because they have speed limiters built in. In other countries, the limiter is mandatory, but no study has attempted to quantify the safety. In America, the current trend has states moving toward a USL. Passenger car drivers tend to prefer a DSL, but less strongly than truck drivers prefer a USL. The time and cost to fully implement a speed limit regime change can be substantial. With the lack of strong evidence in the existing published research in either direction, this paper cannot conclude which method is better than the other. Further research (on a much larger scale than this literature review) would be necessary to conclude which speed limit arrangement is better
This paper describes a number of individual-choice models of work-trip mode-choice, calibrated in... more This paper describes a number of individual-choice models of work-trip mode-choice, calibrated in the course of a bus study in two communities of Metropolitan Johannesburg. First, it is found to be useful to reduce the alternative set from eight modes to four modes, without loss of estimation power. Second, a number of alternative specifications of costs and times are examined, from which the chosen model is selected as one containing five such variables. In addition, a variable of car competition is found to add significantly to the explanatory power of the model. Finally, recently-documented procedures are applied to the selected model specification to pool the results of two random subsamples and to correct the choice-based biases in the alternative-specific constants. It is found that the coefficients of the South African model fall well within the range of coefficients determined in the U.S.
International Choice Modelling Conference 2017, Mar 28, 2017
In this study a joint mode and destination type choice model was developed based on evacuation be... more In this study a joint mode and destination type choice model was developed based on evacuation behavior captured in a post hurricane Irene behavior survey. A Nested Logit model specification was used with destination type being modeled in the upper nest and mode choice in the lower nest. As anticipated, the estimated model showed significant dependence between mode and destination type choice. Variables in the model included household socio-demographic characteristics, measures of social connectivity within communities, and a proxy variable of the level of transit service provided in each zone. The study provides insight into some of the factors affecting mode and destination type choice of residents during hurricane evacuation.
The objective of this study was to investigate the feasibility of using a Bluetooth Probe Detecti... more The objective of this study was to investigate the feasibility of using a Bluetooth Probe Detection System (BPDS) to estimate travel time in an urban area. Specifically, the study investigated the possibility of measuring overall congestion, the trend in congestion, the location of congestion “hotspots,” and finally measurement of the level of congestion at the hotspots using a BPDS. A secondary objective was to assess the possibility of obtaining travel time from other quicker and cheaper methods such as simply purchasing it from a commercial vendor. The findings of the study indicate that a BPDS can reliably be used to measure travel time and estimate congestion in terms of indices such as travel delay, planning time index, and travel time index. However, the acquisition of a BPDS includes certain overheads such as installation costs, maintenance costs and monitoring costs. Purchase of travel time from a commercial vendor might be a viable option if the travel time data is not nee...
This paper examines the impact of time-dependent travel cost on hurricane evacuation destination ... more This paper examines the impact of time-dependent travel cost on hurricane evacuation destination choice models based on post hurricane Floyd survey data collected in South Carolina in 1999. The network condition for destination choice model is represented by time dependent origin-destination travel cost. Multinomial logit models were applied for models with travelers evacuating to friends and relatives. The models were applied for all period, peak period and off-peak period. The results show that the dynamic model has less impact overall than the static model with static shortest path travel cost. The travelers have better knowledge of travel cost in off-peak period than in peak period and as a result, the time-dependent travel cost to the destination becomes less important in the peak period model.
The Louisiana Department of Transportation and Development (DOTD) Outsourcing Decision Assistance... more The Louisiana Department of Transportation and Development (DOTD) Outsourcing Decision Assistance Model was developed to assist officials of the DOTD to assess the outsourcing potential of individual activities or functions in the department. The model consists of both a qualitative and a quantitative assessment process which is conducted interactively by a user on a personal computer. The qualitative portion of the model uses the subjective judgment of one or more persons on a set number of perspectives, where each perspective is aimed at a different aspect of the potential for outsourcing. The quantitative portion of the model consists of the comparison of the cost of insourcing or outsourcing the activity. This manual describes how to install and use the computer program that executes both the qualitative and quantitative portions of the model.
AbstractIn this research, the factors affecting route choice in hurricane evacuation are investig... more AbstractIn this research, the factors affecting route choice in hurricane evacuation are investigated. Two hypotheses are tested. First, it is hypothesized that contrary to common practice where travel time is considered the sole or main determinant of route choice, other variables such as familiarity with the route, availability of fuel and shelter, road type, and accessibility of the route have an effect on an evacuees’ route choice as well. The second hypothesis is that as time passes and storm conditions change, the impact each variable has on route choice changes. That is, it is hypothesized that the importance evacuees assign to the factors determining route choice is not static but varies with time. The logit structure was used for modeling the choice process and stated choice data previously collected from the New Orleans area on hypothetical storms was used to calibrate the model. The study found that accessibility to a route, familiarity with the route, road type, length of a route, and availabi...
Page 1. Two dynamic travel demand models for hurricane evacuation based on survival analysis are ... more Page 1. Two dynamic travel demand models for hurricane evacuation based on survival analysis are presented: a Cox proportional hazards model and a piecewise exponential model. ... DemandModels for Hurricane Evacuation Haoqiang Fu and Chester G. Wilmot ...
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