The Manual on Uniform Traffic Control Devices (MUTCD) for Streets and Highways recommends hill si... more The Manual on Uniform Traffic Control Devices (MUTCD) for Streets and Highways recommends hill signs be placed in advance of downgrade descent of mountain passes. Mountain passes increase the risk of a runaway, or out of control trucks and so the advance warning signs inform the driver to take special precautions such as reducing speed or using lower gears during the descent. The Wyoming Department of Transportation has installed steep grade advance warning systems on Wyoming mountain passes. However, concerns for out of control trucks on the mountain passes persist. The objective of this study is to evaluate the safety effectiveness of steep grade advance warning signs for trucks on Wyoming mountain passes. The safety evaluation was carried out by implementing a zero-inflated negative binomial modeling technique for predicting truck crashes on mountain passes. The outcome was two models that showed the risk of runaway truck accidents were high at locations where either the grades were steep and long or the grades were long with multiple vertical curves. The analysis showed the current advance warning systems were not significantly impacting truck crash risks at the high risk locations. The study, therefore, recommends some improvements to the current advanced warning signs or implementing an improved Federal Highway Administration Grade Severity Rating System based warning system that will significantly improve truck safety at the hazardous locations. The study informs policy makers on the safety issues on Wyoming Mountain passes with regards to runaway trucks and makes recommendations for reducing the risk of runaway truck crashes on mountain passes.
In the state of Colorado, Colorado Department of Transportation (CDOT) utilizes their Pavement Ma... more In the state of Colorado, Colorado Department of Transportation (CDOT) utilizes their Pavement Management System (PMS) to manage approximately 9,100 miles of Interstate, highways and low volume roads. Three types of deterioration models are currently being used in the existing PMS: site-specific, family and expert opinion curves. These curves are developed using deterministic techniques. In deterministic technique, the uncertainties of pavement deterioration related to traffic and weather are not considered. Probabilistic models that take into account the uncertainties result in more accurate curves. In this study, probabilistic models using the discrete-time Markov process were developed for five distress indices: transverse, longitudinal, fatigue, rut and ride indices as a case study on low volume roads. Regression techniques were used to develop the deterioration paths using the predicted distribution of indices estimated from the Markov process. Results indicated that longitudinal, fatigue and rut indices had very slow deterioration over time, whereas, transverse, and ride indices showed faster deterioration. The developed deterioration models had the coefficient of determination (R2) above 0.84. The models were developed for 15 years to investigate the long-term deterioration. As probabilistic models provide more accurate results, it is recommended that these models be used as the family curves in the CDOT PMS for low volume roads.
Traffic crashes result in a huge cost to society in terms of death, injury and property damage. T... more Traffic crashes result in a huge cost to society in terms of death, injury and property damage. The cost of fatal crashes alone is estimated to be 44 billion dollars a year. Among many factors that can reduce the crash frequency, traffic citations is not well understood and most of the researches carried out so far mostly focused on the number of citations not the specific types of citations. However, certain types of citations may be more likely to reduce the number of crashes and some types are not as effective. This research was set forward to examine the impact of different types of traffic citations on traffic crashes in two main hazardous US highways in Wyoming: US-30 and US-26. The Negative binomial modeling technique was implemented by analyzing four years of citation data and incorporating traffic and geometric features to identify the causal impacts of traffic citations on crash frequency. The modeling results uncover that the higher number of speeding and seat belt citations can reduce the traffic crashes significantly. Traffic counts and number of horizontal curves were also found to be significant in increasing the traffic crashes.
This paper developed a program to implement livability in Wyoming. According to Federal Highway A... more This paper developed a program to implement livability in Wyoming. According to Federal Highway Administration (FHWA), “Livability is about tying the quality and location of transportation facilities to broader opportunities such as access to good jobs, affordable housing, quality schools and safe streets”. Currently, livability is one of the mainstream principles to provide quality of life in our communities. In Wyoming, many initiatives have been taken recently to promote livability. The initiatives include developing a livability program for the Wind River Indian Reservation (WRIR), a pedestrian/bicycle assessment in Laramie and three different livability workshops. This paper demonstrates different initiatives for promoting livability concepts in rural communities.
This paper developed a Traffic Safety Management System (TSMS) for improving safety on county pav... more This paper developed a Traffic Safety Management System (TSMS) for improving safety on county paved roads in Wyoming. A TSMS is a strategic and systematic process to improve safety of a roadway network. When funding is limited, it is important to identify the best mix of safety improvement projects to provide the most benefits to society in terms of crash reduction. The factors included in the proposed optimization model are: annual safety budget, roadway inventory, roadway functional classification, historical crashes, safety improvement countermeasures, cost and Crash Reduction Factors (CRF) associated with safety improvement countermeasures, and ADTs. This paper demonstrated how the proposed model can identify the best mix of safety improvement projects to maximize safety benefits in terms of reducing overall crash frequency. Although that the proposed methodology was implemented on the Wyoming county paved road network, it can be easily modified for potential implementation on the Wyoming state highway system. Other states can also benefit by implementing a similar program within their jurisdictions.
This paper developed a pavement serviceability prediction model for county paved roads. Most coun... more This paper developed a pavement serviceability prediction model for county paved roads. Most county paved roads were built decades ago without following minimum design standards. The recent increase in industrial/mineral activities in the state of Wyoming required developing a Pavement management System (PMS) for local paved roads. The developed PMS used the pavement serviceability index (PSI) as a pavement performance parameter. The proposed PSI model for local roads is based on: international roughness index (IRI), Pavement Condition Index (PCI) and rut depth for flexible pavements only. Ten panelists from Wyoming rated 30 pavement sections that were randomly selected at different distresses levels, using two vehicles (SUV and Sedan). The newly developed model seems to provide more realistic representation of the conditions of county roads than the statewide model used on the state highway system.
Accepted for publication in International Journal of Pavement Engineering, 2015
A Pavement Management System (PMS) is a strategic and systematic process to maintain and upgrade ... more A Pavement Management System (PMS) is a strategic and systematic process to maintain and upgrade the road network. When funding is limited, it is very important to identify the best mix of road preservation projects that provides the most benefits to society in terms of overall life cycle cost of the road network. The most common factors that play an important role for identifying projects are: budget, traffic volume, Present Serviceability Index (PSI) and risk associated with selecting treatment types. This research develops an optimization methodology for county paved roads that identify the best mix of preservation projects within budget, maximizing traffic (passengers and trucks traffic) on treated roads, maximizing the weighted average PSI, and minimizing the risk. This methodology will facilitate a statewide implementation of PMS for counties in the state of Wyoming.
Journal of Transport Literature, Volume 9, Number 2, April 2015, Pages 35–39, Apr 2015
Expansion analyses are performed on a bus transit network in the City of Laramie area in Wyoming.... more Expansion analyses are performed on a bus transit network in the City of Laramie area in Wyoming. Expansion analysis is based on the needs identified by the bus transportation agency and the community. This paper examines the expansions, operations and sustainability of a bus transit in a small city having a population of 30,000 people. When funding is limited, it is very important to identify the best route that provides the services to the more people. Gravity model and ArcGIS software have been used to analyze the data. This paper examines the background of the transportation agency and existing services, finally develops a bus routing model for identifying future expansions. This research identified that one of the existing bus stops account for 1% of the ridership which can be closed. This research also found that adding a new loop considering same number of buses would increase the ridership significantly without increasing headway.
This study examines the interaction between roadway geometric characteristics, adverse weather co... more This study examines the interaction between roadway geometric characteristics, adverse weather conditions on crash occurrence on rural Variable Speed Limit (VSL) freeway corridors through mountainous terrain. On Wyoming Interstate 80, winter crashes are three times higher than summer crashes and adverse weather conditions are a contributing factor for more than 70 percent of the winter crashes. As a quantitative measure of the effect of geometrics in adverse weather conditions, a safety performance function was developed with explanatory variables including snow, ice, frost, wind, horizontal curvature and steep grades. The Generalized Linear Regression Model was used for finding the significance of the explanatory variables. This research concluded that the interaction between grades and horizontal curves with weather variables have a significant impact on crash occurrence. The results from the models suggest that distinct VSL strategies should be implemented on segments with challenging roadway geometry.
COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING Volume 29, Issue 5, May 2014, Pages: 315–329, Oct 31, 2013
The objective of roadway tolling in rural areas is often tied to revenue generation for roadway m... more The objective of roadway tolling in rural areas is often tied to revenue generation for roadway maintenance. Thus, rural pricing models should directly incorporate a pavement deterioration and maintenance model. However, the interactions between these models are not simple, because tolls cause traffic diversion, which in turn affects deterioration rates and forecasted revenue. This paper describes a rural pricing model which calculates diversion endogenously with a network assignment model, and captures both the deterioration rates and pavement condition in the toll-setter’s objective function, maximizing long-run net present value of the highway infrastructure). A novel deterioration model is used which is particularly suitable for computational efficiency. The resulting model is discontinuous and non-differentiable, and involves solving a combinatorial knapsack problem as a subproblem. Thus, a simulated annealing-based algorithm is presented to solve it, in the framework of a new solution method built upon partitioning the feasible region. A demonstration is made using a network representing the state of Wyoming (28 zones, 60 nodes, and 188 links). Sensitivity analyses reveal that while the locations for optimal tolling are relatively stable as demand changes, the revenue collected can vary substantially. Relatively simple models are used throughout for computational reasons, and future research should investigate strategies for incorporating more advanced pavement and network models.
The primary goal of roadway tolling in rural areas is revenue generation rather than elimination ... more The primary goal of roadway tolling in rural areas is revenue generation rather than elimination of congestion externalities, and thus urban pricing models are not directly applicable. In particular, generating funds for roadway maintenance projects is of key interest in rural regions where heavy vehicles and “pass-through” traffic often constitute a large share of roadway volume. At the same time, the lack of congestion in rural areas allows a simplified representation of travel delay. We present a model for finding approximately socially-optimal prices accounting for the value obtained from maintenance projects funded by toll revenue, and the effects of traffic diversion on pavement deterioration and future maintenance expenses. We distinguish between revenue obtained from travelers living within the study area and those living in other regions, and allow differential pricing by vehicle type. Due to the discontinuity of the formulation, simulated annealing is used to find tolls on selected roadway arcs. The numerical results, applied to a network representing the state of Wyoming, verifying its effectiveness and limitations by showing sensitivity analysis for different parameters.
The purpose of this research was to analyze safety and road closure benefits resulting from the i... more The purpose of this research was to analyze safety and road closure benefits resulting from the implementation of Variable Speed Limit (VSL) systems on rural interstates where adverse winter conditions cause high crash rates and frequent road closures. The VSL system provides variable, regulatory speed limits to drivers based on real-time traffic, weather, and roadway conditions. In order to isolate the effects of the VSL system from the effects of mild versus severe winters, it was necessary to perform weather-based safety and road closure analyses. Crashes and road closures for the winter seasons (October 15 to April 15) from 2007 to 2012 and on four VSL corridors along Interstate-80 in the state of Wyoming were analyzed. Negative Binomial (NB) modeling technique was found to be a best regression technique to model the frequency of crash occurrence and road closures separately considering explanatory variables related to weather and the use of the VSL system. The results from the analyses show a significant reduction in winter crashes and road closures due to the use of the VSL systems. A benefit-cost analysis was performed to determine the effectiveness of VSL system in terms of monetary value considering reduced freight truck delay and crash costs.
The purpose of this research was to develop a weather-based safety analysis methodology for deter... more The purpose of this research was to develop a weather-based safety analysis methodology for determining the effectiveness of the Variable Speed Limit (VSL) system. The VSL system provides variable, regulatory speed limits to drivers based on real-time traffic and weather roadway conditions. Crashes for the winter season (October 15 to April 15) from 2007 to 2012 on four VSL corridors along Interstate 80 in the state of Wyoming were analyzed. For establishing the Safety Performance Functions (SPF), a Negative Binomial (NB) modeling technique was found to be the best at modeling the frequency of crash occurrence and explanatory variables related to weather and the use of the VSL system. Weather variables were used to normalize the winter seasons before and after the VSL systems were implemented. The results from the analysis showed a significant reduction in winter crashes due to the use of the VSL systems.
The Manual on Uniform Traffic Control Devices (MUTCD) for Streets and Highways recommends hill si... more The Manual on Uniform Traffic Control Devices (MUTCD) for Streets and Highways recommends hill signs be placed in advance of downgrade descent of mountain passes. Mountain passes increase the risk of a runaway, or out of control trucks and so the advance warning signs inform the driver to take special precautions such as reducing speed or using lower gears during the descent. The Wyoming Department of Transportation has installed steep grade advance warning systems on Wyoming mountain passes. However, concerns for out of control trucks on the mountain passes persist. The objective of this study is to evaluate the safety effectiveness of steep grade advance warning signs for trucks on Wyoming mountain passes. The safety evaluation was carried out by implementing a zero-inflated negative binomial modeling technique for predicting truck crashes on mountain passes. The outcome was two models that showed the risk of runaway truck accidents were high at locations where either the grades were steep and long or the grades were long with multiple vertical curves. The analysis showed the current advance warning systems were not significantly impacting truck crash risks at the high risk locations. The study, therefore, recommends some improvements to the current advanced warning signs or implementing an improved Federal Highway Administration Grade Severity Rating System based warning system that will significantly improve truck safety at the hazardous locations. The study informs policy makers on the safety issues on Wyoming Mountain passes with regards to runaway trucks and makes recommendations for reducing the risk of runaway truck crashes on mountain passes.
In the state of Colorado, Colorado Department of Transportation (CDOT) utilizes their Pavement Ma... more In the state of Colorado, Colorado Department of Transportation (CDOT) utilizes their Pavement Management System (PMS) to manage approximately 9,100 miles of Interstate, highways and low volume roads. Three types of deterioration models are currently being used in the existing PMS: site-specific, family and expert opinion curves. These curves are developed using deterministic techniques. In deterministic technique, the uncertainties of pavement deterioration related to traffic and weather are not considered. Probabilistic models that take into account the uncertainties result in more accurate curves. In this study, probabilistic models using the discrete-time Markov process were developed for five distress indices: transverse, longitudinal, fatigue, rut and ride indices as a case study on low volume roads. Regression techniques were used to develop the deterioration paths using the predicted distribution of indices estimated from the Markov process. Results indicated that longitudinal, fatigue and rut indices had very slow deterioration over time, whereas, transverse, and ride indices showed faster deterioration. The developed deterioration models had the coefficient of determination (R2) above 0.84. The models were developed for 15 years to investigate the long-term deterioration. As probabilistic models provide more accurate results, it is recommended that these models be used as the family curves in the CDOT PMS for low volume roads.
Traffic crashes result in a huge cost to society in terms of death, injury and property damage. T... more Traffic crashes result in a huge cost to society in terms of death, injury and property damage. The cost of fatal crashes alone is estimated to be 44 billion dollars a year. Among many factors that can reduce the crash frequency, traffic citations is not well understood and most of the researches carried out so far mostly focused on the number of citations not the specific types of citations. However, certain types of citations may be more likely to reduce the number of crashes and some types are not as effective. This research was set forward to examine the impact of different types of traffic citations on traffic crashes in two main hazardous US highways in Wyoming: US-30 and US-26. The Negative binomial modeling technique was implemented by analyzing four years of citation data and incorporating traffic and geometric features to identify the causal impacts of traffic citations on crash frequency. The modeling results uncover that the higher number of speeding and seat belt citations can reduce the traffic crashes significantly. Traffic counts and number of horizontal curves were also found to be significant in increasing the traffic crashes.
This paper developed a program to implement livability in Wyoming. According to Federal Highway A... more This paper developed a program to implement livability in Wyoming. According to Federal Highway Administration (FHWA), “Livability is about tying the quality and location of transportation facilities to broader opportunities such as access to good jobs, affordable housing, quality schools and safe streets”. Currently, livability is one of the mainstream principles to provide quality of life in our communities. In Wyoming, many initiatives have been taken recently to promote livability. The initiatives include developing a livability program for the Wind River Indian Reservation (WRIR), a pedestrian/bicycle assessment in Laramie and three different livability workshops. This paper demonstrates different initiatives for promoting livability concepts in rural communities.
This paper developed a Traffic Safety Management System (TSMS) for improving safety on county pav... more This paper developed a Traffic Safety Management System (TSMS) for improving safety on county paved roads in Wyoming. A TSMS is a strategic and systematic process to improve safety of a roadway network. When funding is limited, it is important to identify the best mix of safety improvement projects to provide the most benefits to society in terms of crash reduction. The factors included in the proposed optimization model are: annual safety budget, roadway inventory, roadway functional classification, historical crashes, safety improvement countermeasures, cost and Crash Reduction Factors (CRF) associated with safety improvement countermeasures, and ADTs. This paper demonstrated how the proposed model can identify the best mix of safety improvement projects to maximize safety benefits in terms of reducing overall crash frequency. Although that the proposed methodology was implemented on the Wyoming county paved road network, it can be easily modified for potential implementation on the Wyoming state highway system. Other states can also benefit by implementing a similar program within their jurisdictions.
This paper developed a pavement serviceability prediction model for county paved roads. Most coun... more This paper developed a pavement serviceability prediction model for county paved roads. Most county paved roads were built decades ago without following minimum design standards. The recent increase in industrial/mineral activities in the state of Wyoming required developing a Pavement management System (PMS) for local paved roads. The developed PMS used the pavement serviceability index (PSI) as a pavement performance parameter. The proposed PSI model for local roads is based on: international roughness index (IRI), Pavement Condition Index (PCI) and rut depth for flexible pavements only. Ten panelists from Wyoming rated 30 pavement sections that were randomly selected at different distresses levels, using two vehicles (SUV and Sedan). The newly developed model seems to provide more realistic representation of the conditions of county roads than the statewide model used on the state highway system.
Accepted for publication in International Journal of Pavement Engineering, 2015
A Pavement Management System (PMS) is a strategic and systematic process to maintain and upgrade ... more A Pavement Management System (PMS) is a strategic and systematic process to maintain and upgrade the road network. When funding is limited, it is very important to identify the best mix of road preservation projects that provides the most benefits to society in terms of overall life cycle cost of the road network. The most common factors that play an important role for identifying projects are: budget, traffic volume, Present Serviceability Index (PSI) and risk associated with selecting treatment types. This research develops an optimization methodology for county paved roads that identify the best mix of preservation projects within budget, maximizing traffic (passengers and trucks traffic) on treated roads, maximizing the weighted average PSI, and minimizing the risk. This methodology will facilitate a statewide implementation of PMS for counties in the state of Wyoming.
Journal of Transport Literature, Volume 9, Number 2, April 2015, Pages 35–39, Apr 2015
Expansion analyses are performed on a bus transit network in the City of Laramie area in Wyoming.... more Expansion analyses are performed on a bus transit network in the City of Laramie area in Wyoming. Expansion analysis is based on the needs identified by the bus transportation agency and the community. This paper examines the expansions, operations and sustainability of a bus transit in a small city having a population of 30,000 people. When funding is limited, it is very important to identify the best route that provides the services to the more people. Gravity model and ArcGIS software have been used to analyze the data. This paper examines the background of the transportation agency and existing services, finally develops a bus routing model for identifying future expansions. This research identified that one of the existing bus stops account for 1% of the ridership which can be closed. This research also found that adding a new loop considering same number of buses would increase the ridership significantly without increasing headway.
This study examines the interaction between roadway geometric characteristics, adverse weather co... more This study examines the interaction between roadway geometric characteristics, adverse weather conditions on crash occurrence on rural Variable Speed Limit (VSL) freeway corridors through mountainous terrain. On Wyoming Interstate 80, winter crashes are three times higher than summer crashes and adverse weather conditions are a contributing factor for more than 70 percent of the winter crashes. As a quantitative measure of the effect of geometrics in adverse weather conditions, a safety performance function was developed with explanatory variables including snow, ice, frost, wind, horizontal curvature and steep grades. The Generalized Linear Regression Model was used for finding the significance of the explanatory variables. This research concluded that the interaction between grades and horizontal curves with weather variables have a significant impact on crash occurrence. The results from the models suggest that distinct VSL strategies should be implemented on segments with challenging roadway geometry.
COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING Volume 29, Issue 5, May 2014, Pages: 315–329, Oct 31, 2013
The objective of roadway tolling in rural areas is often tied to revenue generation for roadway m... more The objective of roadway tolling in rural areas is often tied to revenue generation for roadway maintenance. Thus, rural pricing models should directly incorporate a pavement deterioration and maintenance model. However, the interactions between these models are not simple, because tolls cause traffic diversion, which in turn affects deterioration rates and forecasted revenue. This paper describes a rural pricing model which calculates diversion endogenously with a network assignment model, and captures both the deterioration rates and pavement condition in the toll-setter’s objective function, maximizing long-run net present value of the highway infrastructure). A novel deterioration model is used which is particularly suitable for computational efficiency. The resulting model is discontinuous and non-differentiable, and involves solving a combinatorial knapsack problem as a subproblem. Thus, a simulated annealing-based algorithm is presented to solve it, in the framework of a new solution method built upon partitioning the feasible region. A demonstration is made using a network representing the state of Wyoming (28 zones, 60 nodes, and 188 links). Sensitivity analyses reveal that while the locations for optimal tolling are relatively stable as demand changes, the revenue collected can vary substantially. Relatively simple models are used throughout for computational reasons, and future research should investigate strategies for incorporating more advanced pavement and network models.
The primary goal of roadway tolling in rural areas is revenue generation rather than elimination ... more The primary goal of roadway tolling in rural areas is revenue generation rather than elimination of congestion externalities, and thus urban pricing models are not directly applicable. In particular, generating funds for roadway maintenance projects is of key interest in rural regions where heavy vehicles and “pass-through” traffic often constitute a large share of roadway volume. At the same time, the lack of congestion in rural areas allows a simplified representation of travel delay. We present a model for finding approximately socially-optimal prices accounting for the value obtained from maintenance projects funded by toll revenue, and the effects of traffic diversion on pavement deterioration and future maintenance expenses. We distinguish between revenue obtained from travelers living within the study area and those living in other regions, and allow differential pricing by vehicle type. Due to the discontinuity of the formulation, simulated annealing is used to find tolls on selected roadway arcs. The numerical results, applied to a network representing the state of Wyoming, verifying its effectiveness and limitations by showing sensitivity analysis for different parameters.
The purpose of this research was to analyze safety and road closure benefits resulting from the i... more The purpose of this research was to analyze safety and road closure benefits resulting from the implementation of Variable Speed Limit (VSL) systems on rural interstates where adverse winter conditions cause high crash rates and frequent road closures. The VSL system provides variable, regulatory speed limits to drivers based on real-time traffic, weather, and roadway conditions. In order to isolate the effects of the VSL system from the effects of mild versus severe winters, it was necessary to perform weather-based safety and road closure analyses. Crashes and road closures for the winter seasons (October 15 to April 15) from 2007 to 2012 and on four VSL corridors along Interstate-80 in the state of Wyoming were analyzed. Negative Binomial (NB) modeling technique was found to be a best regression technique to model the frequency of crash occurrence and road closures separately considering explanatory variables related to weather and the use of the VSL system. The results from the analyses show a significant reduction in winter crashes and road closures due to the use of the VSL systems. A benefit-cost analysis was performed to determine the effectiveness of VSL system in terms of monetary value considering reduced freight truck delay and crash costs.
The purpose of this research was to develop a weather-based safety analysis methodology for deter... more The purpose of this research was to develop a weather-based safety analysis methodology for determining the effectiveness of the Variable Speed Limit (VSL) system. The VSL system provides variable, regulatory speed limits to drivers based on real-time traffic and weather roadway conditions. Crashes for the winter season (October 15 to April 15) from 2007 to 2012 on four VSL corridors along Interstate 80 in the state of Wyoming were analyzed. For establishing the Safety Performance Functions (SPF), a Negative Binomial (NB) modeling technique was found to be the best at modeling the frequency of crash occurrence and explanatory variables related to weather and the use of the VSL system. Weather variables were used to normalize the winter seasons before and after the VSL systems were implemented. The results from the analysis showed a significant reduction in winter crashes due to the use of the VSL systems.
In the state of Wyoming, there are a total of 27,831 miles of roadway owned and maintained by fed... more In the state of Wyoming, there are a total of 27,831 miles of roadway owned and maintained by federal, state, and local entities. Sixty-three percent of these roads are maintained by local governments. According to Moving Ahead for Progress in the 21st Century Act (MAP-21), each state is required to develop a Pavement Management System (PMS) to improve or preserve the present pavement condition and the performance of the system. Currently, all states have their own pavement management plan. WYDOT utilizes their PMS to maintain 7,402 miles of interstate and state highways . The WYDOT PMS does not include roads maintained by local governments. These local roads include 2,444 miles of county paved roads (approximately 8.8% of total) that are being impacted by modern industrial activities such as oil and gas industry. Many of these county roads were built over 40 years ago and have had inconsistent maintenance, resulting in overall poor road conditions. Moreover, the growth of oil and gas industries has increased truck traffic on many county roads. Increased truck traffic, no maintenance database, and limited funding necessitate the development of an innovative PMS to utilize resources more efficiently for these county paved roads. In the summer of 2014, the WYT2/LTAP center collected the required data for evaluating and assessing the condition of county paved roads. This report provides information about current pavement conditions for Campbell County.
The Wyoming Department of Transportation (WYDOT) installed its first variable speed limit (VSL) c... more The Wyoming Department of Transportation (WYDOT) installed its first variable speed limit (VSL) corridor along Interstate 80 in the Elk Mountain Corridor in the Spring of 2009 in an effort to improve safety and reduce road closures, particularly during winter storm events. Since that time, four additional variable speed limit corridors have been implemented; three additional corridors along segments of Interstate 80 and one on WY 28, a rural two lane highway through the area of South Pass. There were three main objectives to this research effort: develop control strategy for the operation of VSL corridors, analyze the safety effects of the VSL system, and determine the impacts of the VSL on driver speed behavior. For the development of a control strategy, both weather and speed variables were considered. Initially a simple linear regression approach was considered but the complexity of the weather and speed behavior led to a regression tree based control strategy with a self-learning feedback loop using machine learning. For the safety task, descriptive baseline safety was analyzed for all five corridors. Since the Elk Mountain Corridor is the only VSL system in operation for more than two winter seasons, it was used for an Empirical Bayes (EB) before and after analysis, which indicated some statistically significant changes in crash frequency for just a few of the corridor segments. A weather-based safety analysis was performed on the four interstate VSL corridors and results from this analysis indicate a statistically significant reduction in crashes after the VSLs were implemented. Analyses of speed variables indicate a reduction in speed variation with the implementation of the VSL system. Modeling of the difference between observed and posted speeds show a reduction in speed compliance related to large reductions in posted speed limits.
The main objective of rural roadway pricing is revenue generation, rather than elimination of con... more The main objective of rural roadway pricing is revenue generation, rather than elimination of congestion externalities. This report presents a model that provides optimum tolls accounting for pavement deterioration and economic impacts. This model contains multiple components, because imposing tolls creates "ripple effects" on traffic flow: changing traffic movements, which changes pavement deterioration rates, maintenance schedules, and spending in local economies. The model described here also allows differential pricing for different types of vehicle. Due to the discontinuity of the formulation, simulated annealing is used to find tolls on selected roadway arcs. This model is demonstrated on a network representing the state of Wyoming, along with some discussion of the issues raised by the model's recommendations.
The main objective of rural roadway pricing is revenue generation, rather than elimination of con... more The main objective of rural roadway pricing is revenue generation, rather than elimination of congestion externalities. This thesis presents a model which provides optimum tolls accounting for pavement deterioration and economic impacts. Setting tolls changes traffic movements which affects pavement deterioration rates, the benefits of maintenance, and local economies. This model also allows differential pricing for different types of vehicle. Due to the discontinuity of the formulation, simulated annealing is used to find tolls on selected roadway arcs. The numerical results, applied to a network representing the state of Wyoming, verify its effectiveness and limitations by showing sensitivity analysis for different parameters.
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