At the core of ITRE’s mission is transportation research. Staff and graduate students conduct a variety of surface and air transportation studies that address today’s — and tomorrow’s — complex issues, many of which are best management practices.

Aviation

 

Considerations for Effective Lidar Deployment by Transportation Agencies

Light Detection and Ranging (LiDAR) is becoming increasingly popular across the United States, and state transportation agencies are adopting practical use of the technology for transportation related applications. The methodology presented in this paper aims to
provide guidance on how agencies may determine whether or not LiDAR can be practically utilized within their organizations. It is recommended that interested parties systematically consider the aspects and performance measures outlined for effective deployment of LiDAR equipment or contracted services.

Paper

Bike / Ped

 

Behavioral Effects of Completing a Critical Link on the American Tobacco Trail: A Look at Impacts on Health, Transportation and the Economy

This study responded to a unique opportunity to determine behavioral changes that resulted from the construction of a critical link of the American Tobacco Trail (ATT). Observational data were collected both before and after construction of a bicycle and pedestrian bridge that linked two separate segments of the regional greenway. Prior to construction of the bridge and trail connections, the two segments of the ATT were separated by Interstate 40. Heavy traffic on local streets, as well as a lack of bicycle and pedestrian facilities in the area provided additional barriers to active travel between the two ATT segments. ITRE conducted surveys and counts on the two trail segments before and after construction of the bridge. The before and after data were compared to determine the changes that occurred in use of the ATT and accompanying social, public health, transportation, and economic effects.

Brochure | Report | Paper (Coming Soon)

Non-Motorized Volume Data

ITRE explores research questions related to counting bicyclists and pedestrians and the development of traffic monitoring programs. Two outcomes of this research are shared below. Learn more about this project.

Video | Paper

North Carolina Pedestrian Crossing Guidance

This research provides guidance to NCDOT for when to consider marking crosswalks at uncontrolled approches for pedestrians, installing pedestrian signal heads at existing signalized intersections, or providing supplemental treatments at a crossing location. The crossing assessment flowchart is intended to be a self-contained, wall-mounted poster that fully describes most aspects of the evaluation and decision-making process. The report supplements the flowchart, providing background with references to research and underlying data used to develop the guidance.

Report | Flowchart

Rumble Strip Gaps for High Speed Bicycles on Downgrades

Shoulder rumble strips (SRS) are a proven safety countermeasure that reduce motor vehicle lane departures; however, they may be seen as an impediment to bicycle travel as they decrease comfort for bicyclists and can impact one’s control while bicycling. Roads with SRS along long, steep grades presenta unique set of risks for cicylists due to the capacity for higher bicycle speeds. This study evaluates how variations in SRS gap lengths and shoulder widths affect a bicyclist’s ability to maneuver through these gaps when riding at higher than average bicycle speeds.

Report | Paper

Economic Impact of Investments in Bicycle Facilities: Case Study of North Carolina’s Northern Outer Banks

The northern Outer Banks coastal area in North Carolina is well suited to drawing bicycle tourism because of its geography, climate, and attractions.   This study examines the value of public investment in bicycle facilities in the area over a 10-year period by collecting data to determine the economic impact of bicycling visitors to the area. Data were collected two ways: cyclists were intercepted using the facilities or they filled out a self-administered tourist survey at a visitor center. Data were analyzed based on the amount and nature of bicycling activity indicated and on the spending patterns of bicyclists in the area.

Report | BrochurePaper | Research Pays Off

Simulator Study of Driver Responses to Pedestrian Treatments at Multilane Roundabouts

In this study, a driving simulator was used to assess three different treatments in regard to their propensity for increasing the driver yielding rate. These treatments were the relocation of the stop bar and crosswalk away from the beginning of the exit leg and two types of beacons, namely a pedestrian hybrid beacon (PHB) and a rectangular rapid flashing beacon (RRFB).

Paper

Development and Implementation of a Conflict-based Assessment of Pedestrian Safety (CAPS) to Evaluate Accessibility of Complex Intersections

In past years, a significant research has been done on pedestrian access to modern roundabouts and other complex intersection forms, including a significant focus on the accessibility for pedestrians who are blind. A majority of these studies have relied on actual street crossings by study participants under supervision of trained Orientation and Mobility (O&M) Specialist. This paper develops and implements the Conflict-based Assessment of Pedestrian Safety (CAPS) methodology for evaluating pedestrian accessibility at complex intersections.

Paper

Nonvisual Cues for Maintaining Heading During Street Crossings

Five cues were evaluated with respect to their usefulness in directing the headings of pedestrians who were blind during street crossings. The study was conducted at a simulated crosswalk, with the angle of the crosswalk varied relative to the approach and direction of the slope of the ramp. Three cues worked well over the distance equivalent to the width of a six-lane road.

Paper

Nonvisual Cues for Aligning to Cross Streets

Accurately aligning to the crosswalk is an important component of safe street crossing for pedestrians who are blind. Six alignment cues were evaluated in a simulated crosswalk environment in which crosswalk angle was not always in line with ramp slope. The effectiveness of each cue is reported and implications are discussed.

Paper

User Perceptions of the Quality of Service on Shared Paths

The purpose of this project is to develop level-of-service estimation methods for shared use paths that overcome current limitations. The focus of this paper is on the collection of the perceptions of shared-use path users, and the development of a model relating those perceptions to operationl and path variables. Perceptions from 105 volunteers viewing 36 video clips of 10 locations was collected. A statistically sound model estimating LOS includes variables for path width, number of meeting and passing events, and presence of a center line.

Paper

Public Perception of Double Crossover Diamond Interchanges

A double crossover diamond (DCD) interchange is designed is to accommodate left-turning movements onto arterials and limited-access highways while eliminating the need for a left turn bay and signal phase at the ramp terminals. During a large study sponsored by the Federal Highway Administration, the research team examined how users perceived new DCD interchanges using focus groups formed at three DCD sites with 20 total participants and attitudes summarized from surveys conducted at two DCD sites with a total of 1,649 participants. The results from both the focus groups and surveys revealed that DCD interchanges operated properly, but there is room for improvement in how these interchanges might be more readily accepted by the public. The most frequently reported issues are summarized for further consideration in outreach, education, planning, or design.

Paper

 

Econ & Policy

 

Considerations for Effective Lidar Deployment by Transportation Agencies

Light Detection and Ranging (LiDAR) is becoming increasingly popular across the United States, and state transportation agencies are adopting practical use of the technology for transportation related applications. The methodology presented in this paper aims to
provide guidance on how agencies may determine whether or not LiDAR can be practically utilized within their organizations. It is recommended that interested parties systematically consider the aspects and performance measures outlined for effective deployment of LiDAR equipment or contracted services.

Paper

Behavioral Effects of Completing a Critical Link on the American Tobacco Trail: A Look at Impacts on Health, Transportation and the Economy

This study responded to a unique opportunity to determine behavioral changes that resulted from the construction of a critical link of the American Tobacco Trail (ATT). Observational data were collected both before and after construction of a bicycle and pedestrian bridge that linked two separate segments of the regional greenway. Prior to construction of the bridge and trail connections, the two segments of the ATT were separated by Interstate 40. Heavy traffic on local streets, as well as a lack of bicycle and pedestrian facilities in the area provided additional barriers to active travel between the two ATT segments. ITRE conducted surveys and counts on the two trail segments before and after construction of the bridge. The before and after data were compared to determine the changes that occurred in use of the ATT and accompanying social, public health, transportation, and economic effects.

Brochure | Report | Paper (Coming Soon)

Economic Impact of Investments in Bicycle Facilities: Case Study of North Carolina’s Northern Outer Banks

The northern Outer Banks coastal area in North Carolina is well suited to drawing bicycle tourism because of its geography, climate, and attractions.   This study examines the value of public investment in bicycle facilities in the area over a 10-year period by collecting data to determine the economic impact of bicycling visitors to the area. Data were collected two ways: cyclists were intercepted using the facilities or they filled out a self-administered tourist survey at a visitor center. Data were analyzed based on the amount and nature of bicycling activity indicated and on the spending patterns of bicyclists in the area.

Report | BrochurePaper | Research Pays Off

Nonvisual Cues for Maintaining Heading During Street Crossings

Five cues were evaluated with respect to their usefulness in directing the headings of pedestrians who were blind during street crossings. The study was conducted at a simulated crosswalk, with the angle of the crosswalk varied relative to the approach and direction of the slope of the ramp. Three cues worked well over the distance equivalent to the width of a six-lane road.

Paper

Nonvisual Cues for Aligning to Cross Streets

Accurately aligning to the crosswalk is an important component of safe street crossing for pedestrians who are blind. Six alignment cues were evaluated in a simulated crosswalk environment in which crosswalk angle was not always in line with ramp slope. The effectiveness of each cue is reported and implications are discussed.

Paper

User Perceptions of the Quality of Service on Shared Paths

The purpose of this project is to develop level-of-service estimation methods for shared use paths that overcome current limitations. The focus of this paper is on the collection of the perceptions of shared-use path users, and the development of a model relating those perceptions to operationl and path variables. Perceptions from 105 volunteers viewing 36 video clips of 10 locations was collected. A statistically sound model estimating LOS includes variables for path width, number of meeting and passing events, and presence of a center line.

Paper

Resident, Commuter, and Business Perceptions of New Superstreets

Superstreets are an unconventional at-grade intersection design that have significant potential to help with safety and delay. The purpose of this paper is to formally evaluate residential, commuter, and business owner opinions of superstreets across North Carolina through feedback from three separate surveys.

Paper

Public Opinions of Roadway Assets – Roadway Review as a New Survey Method

In October 2011, the North Carolina Department of Transportation conducted a roadway review with a randomly recruited sample of North Carolina residents and community leaders. The purpose of the roadway review was twofold: to determine
the expectations for the condition of North Carolina highways and to identify the features that North Carolinians believe are most important on different types of highways. This paper discusses the findings from the roadway review.

Paper

Business Perceptions of Access Management Techniques

Transportation agencies have made significant strides to reduce collisions and increase capacity along strategic highway corridors. Efforts have led to the implementation of many different access management techniques along corridors, such as installing medians versus two-way left-turn lanes and closing median openings. Businesses along these corridors have indicated their concern that these new designs will have a negative economic impact on their business because of the lack of direct access to their properties. The objective of this study was to quantify the business perceptions of median treatments on businesses adjacent to multilane highways.

Paper

Structural and Safety Investigation of Statewide Weathered Steel Beam Guardrail Performance in North Carolina

Weathered steel beam guardrail (WSBG) is a popular alternative to galvanized steel guardrail (GSG) in that it is an aesthetic solution that blends in with the surrounding natural environment. This paper evaluates the structural integrity and safety performance of WSBG in North Carolina.

Paper

Is TACT Effective in Changing Driver Behavior:Evidence from North Carolina TACT III Effort

Ticketing Aggressive Cars and Trucks (TACT) is a federally-funded effort to develop a model program of enhanced enforcement, education/media, and program evaluation that can be implemented at the state level. The goal of TACT is to reduce the contribution of aggressive driving behaviors to commercial motor vehicle (CMV)-involved crashes. This paper presents work conducted as part of North Carolina’s evaluation of its Highway Patrol TACT III operation (Ticketing Aggressive Cars and Trucks).

Paper

Traffic Operational Impacts of Contemporary Multi-Pump Island Fuel Centers

Many contemporary fueling centers are much larger and offer more services than traditional gas stations. For these fueling stations, the information contained in the Institute of Transportation Engineers (ITE) Trip Generation Handbook for gasoline stations may not be applicable. This paper highlights a study that was conducted to investigate the importance of site and variable selection in developing an improved trip generation model for fueling centers.

Paper

Evaluating the Effectiveness of Red Light Running Camera Enforcement in Raleigh, North Carolina

This research analyzes the safety effects of an automated red-light running (RLR) program in Raleigh, North Carolina. It expands on a previous research effort funded by the North Carolina Governor’s Highway Safety Program, by providing a more robust dataset of 46 months, compared to the original dataset of five months. The strength of this study, versus others of its kind, is in the selection of treatment and comparison sites, and the volume of data collected.

Paper

An Analysis of Automated Speed Enforcement Cameras in Charlotte, NC

This paper examines the effects of a mobile automated speed enforcement system in Charlotte, North Carolina. Limited focus groups were conducted
to characterize resident and professional attitudes, opinions, and beliefs regarding such a speed program.

Paper

Reasonable Speeds on Suburban Multilane Highways with Curbs

in this research the team collected relevant data such as speeds and collisions on four-lane road sections with curbs that have 45 or 55 mph speed limits and nontraversable medians or two-way left-turn lanes. The team found that the speed limit does not seem to make an important difference in collision rates or severities for the roads the team examined. The higher speed limit also made relatively small differences in the mean speeds and speed variances observed.

Paper

Effects of License Plate Attributes on Automatic License Plate Recognition.

The objective of this experiment was to develop a thorough understanding of the readability of North Carolina license plate systems with automatic license plate recognition systems. The research focused on law enforcement applications and used infrared cameras on more than 900 plates in a controlled environment. Plates with blue ink had the highest capture and read rates while personalized and specialty plates had reduced rates.

Paper

Public Perception of Double Crossover Diamond Interchanges

A double crossover diamond (DCD) interchange is designed is to accommodate left-turning movements onto arterials and limited-access highways while eliminating the need for a left turn bay and signal phase at the ramp terminals. During a large study sponsored by the Federal Highway Administration, the research team examined how users perceived new DCD interchanges using focus groups formed at three DCD sites with 20 total participants and attitudes summarized from surveys conducted at two DCD sites with a total of 1,649 participants. The results from both the focus groups and surveys revealed that DCD interchanges operated properly, but there is room for improvement in how these interchanges might be more readily accepted by the public. The most frequently reported issues are summarized for further consideration in outreach, education, planning, or design.

Paper

Highway Systems

 

Considerations for Effective Lidar Deployment by Transportation Agencies

Light Detection and Ranging (LiDAR) is becoming increasingly popular across the United States, and state transportation agencies are adopting practical use of the technology for transportation related applications. The methodology presented in this paper aims to
provide guidance on how agencies may determine whether or not LiDAR can be practically utilized within their organizations. It is recommended that interested parties systematically consider the aspects and performance measures outlined for effective deployment of LiDAR equipment or contracted services.

Paper

North Carolina Pedestrian Crossing Guidance

This research provides guidance to NCDOT for when to consider marking crosswalks at uncontrolled approches for pedestrians, installing pedestrian signal heads at existing signalized intersections, or providing supplemental treatments at a crossing location. The crossing assessment flowchart is intended to be a self-contained, wall-mounted poster that fully describes most aspects of the evaluation and decision-making process. The report supplements the flowchart, providing background with references to research and underlying data used to develop the guidance.

Report | Flowchart

Rumble Strip Gaps for High Speed Bicycles on Downgrades

Shoulder rumble strips (SRS) are a proven safety countermeasure that reduce motor vehicle lane departures; however, they may be seen as an impediment to bicycle travel as they decrease comfort for bicyclists and can impact one’s control while bicycling. Roads with SRS along long, steep grades presenta unique set of risks for cicylists due to the capacity for higher bicycle speeds. This study evaluates how variations in SRS gap lengths and shoulder widths affect a bicyclist’s ability to maneuver through these gaps when riding at higher than average bicycle speeds.

Report | Paper

Simulator Study of Driver Responses to Pedestrian Treatments at Multilane Roundabouts

In this study, a driving simulator was used to assess three different treatments in regard to their propensity for increasing the driver yielding rate. These treatments were the relocation of the stop bar and crosswalk away from the beginning of the exit leg and two types of beacons, namely a pedestrian hybrid beacon (PHB) and a rectangular rapid flashing beacon (RRFB).

Paper

Development and Implementation of a Conflict-based Assessment of Pedestrian Safety (CAPS) to Evaluate Accessibility of Complex Intersections

In past years, a significant research has been done on pedestrian access to modern roundabouts and other complex intersection forms, including a significant focus on the accessibility for pedestrians who are blind. A majority of these studies have relied on actual street crossings by study participants under supervision of trained Orientation and Mobility (O&M) Specialist. This paper develops and implements the Conflict-based Assessment of Pedestrian Safety (CAPS) methodology for evaluating pedestrian accessibility at complex intersections.

Paper

Nonvisual Cues for Maintaining Heading During Street Crossings

Five cues were evaluated with respect to their usefulness in directing the headings of pedestrians who were blind during street crossings. The study was conducted at a simulated crosswalk, with the angle of the crosswalk varied relative to the approach and direction of the slope of the ramp. Three cues worked well over the distance equivalent to the width of a six-lane road.

Paper

Nonvisual Cues for Aligning to Cross Streets

Accurately aligning to the crosswalk is an important component of safe street crossing for pedestrians who are blind. Six alignment cues were evaluated in a simulated crosswalk environment in which crosswalk angle was not always in line with ramp slope. The effectiveness of each cue is reported and implications are discussed.

Paper

User Perceptions of the Quality of Service on Shared Paths

The purpose of this project is to develop level-of-service estimation methods for shared use paths that overcome current limitations. The focus of this paper is on the collection of the perceptions of shared-use path users, and the development of a model relating those perceptions to operationl and path variables. Perceptions from 105 volunteers viewing 36 video clips of 10 locations was collected. A statistically sound model estimating LOS includes variables for path width, number of meeting and passing events, and presence of a center line.

Paper

Lane Utilization at Two-Lane Arterial Approaches to Double Crossover Diamond Interchanges

This study examined lane utilization factors provided in the Highway Capacity Manual 2010 (HCM) for conventional diamond interchanges and found that they are not generally applicable to DCD interchanges. The study then proposed a lane utilization model calibrated with field data obtained at three DCD sites. The new model fit observed conditions at the DCD sites better than previously developed HCM factors. The model was then validated with three additional DCD interchanges, and validation results confirmed that the new model adequately predicted DCD lane utilization. The authors recommend that DCD interchange designers and analysts use the new model where it is applicable but also that more research be conducted to find lane utilization factors for other DCD configurations.

Paper

Resident, Commuter, and Business Perceptions of New Superstreets

Superstreets are an unconventional at-grade intersection design that have significant potential to help with safety and delay. The purpose of this paper is to formally evaluate residential, commuter, and business owner opinions of superstreets across North Carolina through feedback from three separate surveys.

Paper

Public Opinions of Roadway Assets – Roadway Review as a New Survey Method

In October 2011, the North Carolina Department of Transportation conducted a roadway review with a randomly recruited sample of North Carolina residents and community leaders. The purpose of the roadway review was twofold: to determine
the expectations for the condition of North Carolina highways and to identify the features that North Carolinians believe are most important on different types of highways. This paper discusses the findings from the roadway review.

Paper

Business Perceptions of Access Management Techniques

Transportation agencies have made significant strides to reduce collisions and increase capacity along strategic highway corridors. Efforts have led to the implementation of many different access management techniques along corridors, such as installing medians versus two-way left-turn lanes and closing median openings. Businesses along these corridors have indicated their concern that these new designs will have a negative economic impact on their business because of the lack of direct access to their properties. The objective of this study was to quantify the business perceptions of median treatments on businesses adjacent to multilane highways.

Paper

Structural and Safety Investigation of Statewide Weathered Steel Beam Guardrail Performance in North Carolina

Weathered steel beam guardrail (WSBG) is a popular alternative to galvanized steel guardrail (GSG) in that it is an aesthetic solution that blends in with the surrounding natural environment. This paper evaluates the structural integrity and safety performance of WSBG in North Carolina.

Paper

Is TACT Effective in Changing Driver Behavior:Evidence from North Carolina TACT III Effort

Ticketing Aggressive Cars and Trucks (TACT) is a federally-funded effort to develop a model program of enhanced enforcement, education/media, and program evaluation that can be implemented at the state level. The goal of TACT is to reduce the contribution of aggressive driving behaviors to commercial motor vehicle (CMV)-involved crashes. This paper presents work conducted as part of North Carolina’s evaluation of its Highway Patrol TACT III operation (Ticketing Aggressive Cars and Trucks).

Paper

Operational Effects of Signalized Superstreets in North Carolina

Arterials across the United States are operating inefficiently and are becoming increasingly congested because of growing traffic demand. Agencies tasked with improving these arterials are running out of good solutions. Superstreets, called restricted crossing U-turns by FHWA, are part of a menu of unconventional arterial designs that may provide promising solutions. The purpose of this research was to determine the operational effects of the superstreet treatment on existing signalized arterials in North Carolina.

Paper

Safety Effects of Unsignalized Superstreets in North Carolina

Arterials across the United States are experiencing far too many collisions. Agencies tasked with improving these arterials have few available effective solutions. Up to this point, there is little valid information available on the safety effects of superstreets, as study results have been from basic analyses that only account for traffic volume changes. The purpose of this research was to determine the safety effects of the unsignalized superstreet countermeasure on existing arterials in North Carolina.

Paper

Traffic Operational Impacts of Contemporary Multi-Pump Island Fuel Centers

Many contemporary fueling centers are much larger and offer more services than traditional gas stations. For these fueling stations, the information contained in the Institute of Transportation Engineers (ITE) Trip Generation Handbook for gasoline stations may not be applicable. This paper highlights a study that was conducted to investigate the importance of site and variable selection in developing an improved trip generation model for fueling centers.

Paper

Evaluating the Effectiveness of Red Light Running Camera Enforcement in Raleigh, North Carolina

This research analyzes the safety effects of an automated red-light running (RLR) program in Raleigh, North Carolina. It expands on a previous research effort funded by the North Carolina Governor’s Highway Safety Program, by providing a more robust dataset of 46 months, compared to the original dataset of five months. The strength of this study, versus others of its kind, is in the selection of treatment and comparison sites, and the volume of data collected.

Paper

An Analysis of Automated Speed Enforcement Cameras in Charlotte, NC

This paper examines the effects of a mobile automated speed enforcement system in Charlotte, North Carolina. Limited focus groups were conducted
to characterize resident and professional attitudes, opinions, and beliefs regarding such a speed program.

Paper

Reasonable Speeds on Suburban Multilane Highways with Curbs

in this research the team collected relevant data such as speeds and collisions on four-lane road sections with curbs that have 45 or 55 mph speed limits and nontraversable medians or two-way left-turn lanes. The team found that the speed limit does not seem to make an important difference in collision rates or severities for the roads the team examined. The higher speed limit also made relatively small differences in the mean speeds and speed variances observed.

Paper

Safety Evaluation of Seven of the Earliest Diverging Diamond Interchanges Installed in the US

The objective of this work was to conduct a broader safety evaluation of DDIs and recommend a crash modification factor (CMF) for the conversion of a conventional diamond to a DDI. The results showed that crashes were reduced at most of the sites, and the team recommended a CMF of 0.67, meaning that installation of a DDI to replace a diamond should reduce all crashes by 33 percent. The reduction in injury crashes was even larger, with the team recommending a CMF of 0.59. Other analyses indicated that DDI installation should mean a substantial reduction of angle and turning crashes with some reduction in rear end crashes as well, although rear end crashes will still be the dominant crash types after DDI installation.

Paper

Effects of License Plate Attributes on Automatic License Plate Recognition.

The objective of this experiment was to develop a thorough understanding of the readability of North Carolina license plate systems with automatic license plate recognition systems. The research focused on law enforcement applications and used infrared cameras on more than 900 plates in a controlled environment. Plates with blue ink had the highest capture and read rates while personalized and specialty plates had reduced rates.

Paper

Collecting Horizontal Curve Data: Mobile Asset Vehicles and Other Techniques.

Horizontal curves are an important roadway element that are difficult to collect data on. A mobile collection system would cut down on costs and efforts related to collecting horizontal curve data. Length and radius data from three commercial vendors was tested on a 24 mile course in central North Carolina. The results helped better understand the limitations of mobile data collection for horizontal alignments.

Paper

Public Perception of Double Crossover Diamond Interchanges

A double crossover diamond (DCD) interchange is designed is to accommodate left-turning movements onto arterials and limited-access highways while eliminating the need for a left turn bay and signal phase at the ramp terminals. During a large study sponsored by the Federal Highway Administration, the research team examined how users perceived new DCD interchanges using focus groups formed at three DCD sites with 20 total participants and attitudes summarized from surveys conducted at two DCD sites with a total of 1,649 participants. The results from both the focus groups and surveys revealed that DCD interchanges operated properly, but there is room for improvement in how these interchanges might be more readily accepted by the public. The most frequently reported issues are summarized for further consideration in outreach, education, planning, or design.

Paper

Modeling & Computation

 

Simulator Study of Driver Responses to Pedestrian Treatments at Multilane Roundabouts

In this study, a driving simulator was used to assess three different treatments in regard to their propensity for increasing the driver yielding rate. These treatments were the relocation of the stop bar and crosswalk away from the beginning of the exit leg and two types of beacons, namely a pedestrian hybrid beacon (PHB) and a rectangular rapid flashing beacon (RRFB).

Paper

Lane Utilization at Two-Lane Arterial Approaches to Double Crossover Diamond Interchanges

This study examined lane utilization factors provided in the Highway Capacity Manual 2010 (HCM) for conventional diamond interchanges and found that they are not generally applicable to DCD interchanges. The study then proposed a lane utilization model calibrated with field data obtained at three DCD sites. The new model fit observed conditions at the DCD sites better than previously developed HCM factors. The model was then validated with three additional DCD interchanges, and validation results confirmed that the new model adequately predicted DCD lane utilization. The authors recommend that DCD interchange designers and analysts use the new model where it is applicable but also that more research be conducted to find lane utilization factors for other DCD configurations.

Paper

Operational Effects of Signalized Superstreets in North Carolina

Arterials across the United States are operating inefficiently and are becoming increasingly congested because of growing traffic demand. Agencies tasked with improving these arterials are running out of good solutions. Superstreets, called restricted crossing U-turns by FHWA, are part of a menu of unconventional arterial designs that may provide promising solutions. The purpose of this research was to determine the operational effects of the superstreet treatment on existing signalized arterials in North Carolina.

Paper

Safety Effects of Unsignalized Superstreets in North Carolina

Arterials across the United States are experiencing far too many collisions. Agencies tasked with improving these arterials have few available effective solutions. Up to this point, there is little valid information available on the safety effects of superstreets, as study results have been from basic analyses that only account for traffic volume changes. The purpose of this research was to determine the safety effects of the unsignalized superstreet countermeasure on existing arterials in North Carolina.

Paper

Traffic Operational Impacts of Contemporary Multi-Pump Island Fuel Centers

Many contemporary fueling centers are much larger and offer more services than traditional gas stations. For these fueling stations, the information contained in the Institute of Transportation Engineers (ITE) Trip Generation Handbook for gasoline stations may not be applicable. This paper highlights a study that was conducted to investigate the importance of site and variable selection in developing an improved trip generation model for fueling centers.

Paper

Effects of License Plate Attributes on Automatic License Plate Recognition.

The objective of this experiment was to develop a thorough understanding of the readability of North Carolina license plate systems with automatic license plate recognition systems. The research focused on law enforcement applications and used infrared cameras on more than 900 plates in a controlled environment. Plates with blue ink had the highest capture and read rates while personalized and specialty plates had reduced rates.

Paper

Transit

Public Perception of Double Crossover Diamond Interchanges

A double crossover diamond (DCD) interchange is designed is to accommodate left-turning movements onto arterials and limited-access highways while eliminating the need for a left turn bay and signal phase at the ramp terminals. During a large study sponsored by the Federal Highway Administration, the research team examined how users perceived new DCD interchanges using focus groups formed at three DCD sites with 20 total participants and attitudes summarized from surveys conducted at two DCD sites with a total of 1,649 participants. The results from both the focus groups and surveys revealed that DCD interchanges operated properly, but there is room for improvement in how these interchanges might be more readily accepted by the public. The most frequently reported issues are summarized for further consideration in outreach, education, planning, or design.

Paper