The document is the culmination of the first offering of an innovative transportation engineering... more The document is the culmination of the first offering of an innovative transportation engineering graduate course at Texas A and M University entitled, Traffic Information and Control Systems Design. The course was presented during the summer 1991 term. As part of the course, a Practitioner-In-Residence program was initiated as a means of providing the students with unique learning experiences. Five top-level managers/practitioners from city and state transportation departments and from transportation consulting firms were invited to Texas A and M University to present a 2-day Symposium on Advanced Traffic Management Systems at the beginning of the summer term. Immediately following the Symposium, the students enrolled in the course participated in a Workshop with the transportation managers/practitioners and course instructors. Based on mutual interests, each student was assigned to one of the managers/practitioners who served as a mentor (along with the course instructors) to the ...
Abstract: The economic strength of rural areas in America requires dependable transportation, oft... more Abstract: The economic strength of rural areas in America requires dependable transportation, often over sparsely settled lands in all types of weather conditions. This dependency on safe and reliable mobility is certainly true for rural school bus operations ...
This volume, the fourth of a four-volume final report, provides the specific sites initially stud... more This volume, the fourth of a four-volume final report, provides the specific sites initially studied for possible geometric design inconsistencies, laboratory experimental methods and a detailed step-by-step cost-effectiveness procedure. The cost-effectiveness procedure follows closely those recommended by AASHTO in its publication-"A Manual of User Benefit Analysis of Highway and Bus Transit Improvements." A total of 148 sites located in Texas and Georgia were inventoried using videotape, Super-8 film and 35 mm color slides. These sites provided the base from which the 12 most critical basic geometric features were identified as having the highest average potential for violating driver expectancy based on subjective rating procedures. This volume is the fourth in a series. The others in the series are: Volume 1-FHWA/RD-81/035 Executive Summary; Volume 2-FHWA/RD-81/036 Research Report; and Volume 3-FHWA/RD-81/037 Design Procedure. (FHWA)
This volume, the third of a four-volume final report, presents a procedure for evaluating and imp... more This volume, the third of a four-volume final report, presents a procedure for evaluating and improving the geometric design consistency of rural highways. The procedure is based on basic driver behavior principles, a sound conceptual approach and considerable empirical evidence. Basic geometric design objectives, a procedure and examples and remedial countermeasures are presented to aid the designer in applying the procedure. Both 2-lane and 4-lane highways in flat or rolling terrain can be evaluated with this procedure. A detailed step-by-step procedure is presented for evaluating the geometric design inconsistency of proposed or existing rural highways. Two case studies are presented to illustrate the evaluation procedure. (FHWA)
The state of the practice in highway geometric design consistency was determined through a review... more The state of the practice in highway geometric design consistency was determined through a review of U.S. and foreign geometric design policy, practice, and research. Models, and a menu-driven microcomputer procedure for their use, were developed for operating-speed and driver-workload consistency evaluations of rural two-lane highway horizontal alignments. The operating-speed model was calibrated based upon speed and geometry data for 138 horizontal curves and 78 of their approach tangents in 5 States. The driver workload model was calibrated based upon 2 occluded vision test studies on a total of 55 subjects. The operating-speed data suggest that 85th percentile speeds generally exceed the design speed of horizontal curves whose design speed is less than drivers' desired speed (i.e., 85th percentile speed on long tangents). A preliminary evaluation comparing model-estimated operating-speed reductions versus degree of curvature as predictors of accident experience was conducted using a data base of 1,126 curve sites in 3 States. The evaluation suggests that accident experience increases as the required speed reduction from an approach tangent to a horizontal curve increases.
This study addresses the question of the amount of bulb loss that can be tolerated in an electron... more This study addresses the question of the amount of bulb loss that can be tolerated in an electronic motorist-information sign before the message becomes illegible, misunderstood, or misinterpreted. A representative group of traffic-descriptor and advisory words and route numerals were displayed on a real-time matrix sign. Selected percentages (10 to 50) of bulbs were failed in a random pattern, and slides were taken of the resulting displays. These slides were shown to subjects who were instructed to respond by writing the word if it was legible. From these data, specifications for 85th and 95th percentile correct comprehension were determined for both familar and unfamiliar motorists.
This report is the user's manual for a software package called "RAMBO" ( Ramp Adapt... more This report is the user's manual for a software package called "RAMBO" ( Ramp Adaptive Metering Bottleneck Optimization). Developed as a practical ramp metering system, RAMBO consists of two complimentary programs. RAMBO I employs interactive graphic screens to assist the traffic engineer in evaluating local ramp traffic conditions. It generates ramp metering plans and Transition Point Patterns for each metering level. RAMBO II is a system ramp metering package that evaluates ramp metering plans based on forecasted traffic conditions along an extended section of freeway containing up to 12 metered entrance ramps and 12 exit ramps.
This study is concerned with the evaluation of real-time changeable message signs that inform mot... more This study is concerned with the evaluation of real-time changeable message signs that inform motorists of freeway traffic conditions. Included in the study is an evaluation of the use of a letter-grade rating scale for indicating freeway conditions. Evaluation was accomplished through the use of a questionnaire survey and a traffic operations analysis. The study results showed that the changeable message signs were effective in providing information to the motorist. Considerable motorist diversion was noted during analysis incidents which were accompanied by a "LANE BLOCKED" display. The signs were highly visible, generally understood, and useful within the constraints of corridor geometry. Lack of understanding of the letter-grade rating scale employed was attributed to the fact that the scale was not anchored to a readily understandable base. Questionnaire results showed that a vast majority of the respondents found the system useful.
LANE OCCUPANCY WAS EVALUATED AS A TRAFFIC VARIABLE FOR DIGITAL COMPUTER CONTROL OF A SAFETY WARNI... more LANE OCCUPANCY WAS EVALUATED AS A TRAFFIC VARIABLE FOR DIGITAL COMPUTER CONTROL OF A SAFETY WARNING SYSTEM FOR URBAN FREEWAYS. PERFORMANCE CHARACTERISTICS WERE STUDIED OF MEASURED LANE OCCUPANCY AS AN INDICATOR OF SHOCK WAVES RESULTING FROM FREEWAY INCIDENTS. A CONTROL STRATEGY WAS DEVELOPED, PROGRAMMED, AND EVALUATED FOR DIGITAL COMPUTER OPERATION OF THE WARNING SYSTEM. COMPARISONS WERE MADE WITH ENERGY AS A CONTROL VARIABLE. BASED ON THE RESULTS OF THIS RESEARCH A NEW CONTROL ALGORITHM WAS DEVELOPED INCORPORATING THE BEST PERFORMANCE FEATURES OF OF BOTH ENERGY AND LANE OCCUPANCY.
Traffic incidents, whether due to accidents also create safety hazards on the freeway. To enhance... more Traffic incidents, whether due to accidents also create safety hazards on the freeway. To enhance safety and to provide assistance and security to motorists, District 12 of the Texas State Department of Highways and Public Transportation has been operating a motorist courtesy patrol on some Houston freeways. A questionnaire study and a cost- effectiveness analysis were used to evaluate the operation of the patrol. The questionnaire study indicated that motorists aided by the patrol were overwhelmingly in favor of continuation of the program. The cost-effectiveness analysis showed the patrol to have a benefit-cost ratio of 2 to 1. Several additional qualitative benefits are discussed. /Author/
This paper examines the effects of minimum phase length and variations in the spatial arangement ... more This paper examines the effects of minimum phase length and variations in the spatial arangement of ramp intersections on the capacity of diamond interchanges operated with 4-phase-overlap signalization. The introduction of practical minimum constraints on phase lenghts can significantly alter the performance characteristics of this type of interchange. This paper also illustrates a method by which interchange design can be assessed in terms of quality-of-service measures. A computer program, written in FORTRAN IV, was developed to speed up the analysis. Examination of some typical cases illustrates that an efficient design can be selected if one uses the program for a given set of minimum green-phase lengths and traffic demands.
The development of a research study conducted by the Texas Transportation Institute entitled &quo... more The development of a research study conducted by the Texas Transportation Institute entitled "Reduced-Delay Optimization and Other Enhancements to PASSER II-80" is summarized. The research was sponsored by the Texas State Department of Highways and Public Transportation (SDHPT) in cooperation with the FHWA, U.S. Department of Transportation. The brief 6-month research effort was directed toward several topic areas including development of a reduced-delay optimization procedure that could fine tune the offsets of traffic signals to reduce total arterial system delay and maximize arterial progression, development of methods that can better estimate vehicular delay in a nearly saturated traffic system, and development of methods to estimate fuel consumption for arterial traffic movements in an urban network. Significant enhancements have been made to the popular PASSER II program. This study also demonstrated the practical combination of the maximum bandwidth procedure and th...
Abstract: Engineering factors affecting traffic signal change interval (yellow and all-red) are r... more Abstract: Engineering factors affecting traffic signal change interval (yellow and all-red) are reviewed, particularly in terms of drivers' perception and brake reaction time (t), and deceleration rate (d). Using driver behavior data collected from time-lapse cameras, two ...
... 1987 6. Performing Organi tation Coda 7-Author's) Vergil G. Stover, JL Gattis, and C... more ... 1987 6. Performing Organi tation Coda 7-Author's) Vergil G. Stover, JL Gattis, and Carroll J.Messer í. ... Abilene, Bryan, College Station, Denton, Garland, Georgetown, Huntsville, Lancaster, McKinney, New Braunfels, Orange, Rockwall, Round Rock, San Marcos, and Wichita ...
MAXBAND 86 is the only operational traffic signal program that allows progression bandwidth optim... more MAXBAND 86 is the only operational traffic signal program that allows progression bandwidth optimization in multiarterial, closed-loop traffic signal networks. The program formulates the problem as a mixed integer linear program and is capable of optimizing network-wide cycle length, signal offsets, and signal phasing sequences. However, hours of computer time may be required to optimize a medium-sized network problem, even on a mainframe computer. This computational inefficiency of MAXBAND 86 makes it impractical for use by the traffic engineering community. However, two heuristic methods efficiently optimize network signal timing problems modeled by MAXBAND 86. The experimental results demonstrate that these heuristic methods produce tremendous savings in the computer time required to solve optimization problems in traffic network signal timing. In addition, computational benefits are achieved by explicitly modeling one-way arterials in a network rather than as two-way arterials, as used in MAXBAND 86.
Freeway ramp metering systems are being used to alleviate urban freeway congestion. This report p... more Freeway ramp metering systems are being used to alleviate urban freeway congestion. This report presents a methodology for determining the distance requirements for ramp metering for a wide range of traffic volume and freeway geometric conditions. The distance requirement for ramp metering consists of distance required for queue storage and distance required for the freeway merging operation. A queue storage model has been developed to determine distance required for queue storage. The constant acceleration models of linear motion have been used to determine distance required for the freeway merging operation. A methodology for determining the optimal placement of the ramp meter signal has been presented. Guidelines for effecting a trade-off between queue storage and freeway merging distance requirements have also been presented. A sample problem demonstrates the use of the presented methodology.
Abstract: This report is the user's manual for a software package called" RAMBO"(R... more Abstract: This report is the user's manual for a software package called" RAMBO"(Ramp Adaptive Metering Bottleneck Optimization). RAMBO is the end product of research conducted within SPR research project 1232 entitled" Urban Highway Operations Research and Implementation". It was developed by the Texas Transportation Institute for the Texas Department of Transportation (TxDOT) as a practical ramp metering system, primarily for Texas applications. RAMBO consists of two complimentary programs, RAMBO I and ...
The document is the culmination of the first offering of an innovative transportation engineering... more The document is the culmination of the first offering of an innovative transportation engineering graduate course at Texas A and M University entitled, Traffic Information and Control Systems Design. The course was presented during the summer 1991 term. As part of the course, a Practitioner-In-Residence program was initiated as a means of providing the students with unique learning experiences. Five top-level managers/practitioners from city and state transportation departments and from transportation consulting firms were invited to Texas A and M University to present a 2-day Symposium on Advanced Traffic Management Systems at the beginning of the summer term. Immediately following the Symposium, the students enrolled in the course participated in a Workshop with the transportation managers/practitioners and course instructors. Based on mutual interests, each student was assigned to one of the managers/practitioners who served as a mentor (along with the course instructors) to the ...
Abstract: The economic strength of rural areas in America requires dependable transportation, oft... more Abstract: The economic strength of rural areas in America requires dependable transportation, often over sparsely settled lands in all types of weather conditions. This dependency on safe and reliable mobility is certainly true for rural school bus operations ...
This volume, the fourth of a four-volume final report, provides the specific sites initially stud... more This volume, the fourth of a four-volume final report, provides the specific sites initially studied for possible geometric design inconsistencies, laboratory experimental methods and a detailed step-by-step cost-effectiveness procedure. The cost-effectiveness procedure follows closely those recommended by AASHTO in its publication-"A Manual of User Benefit Analysis of Highway and Bus Transit Improvements." A total of 148 sites located in Texas and Georgia were inventoried using videotape, Super-8 film and 35 mm color slides. These sites provided the base from which the 12 most critical basic geometric features were identified as having the highest average potential for violating driver expectancy based on subjective rating procedures. This volume is the fourth in a series. The others in the series are: Volume 1-FHWA/RD-81/035 Executive Summary; Volume 2-FHWA/RD-81/036 Research Report; and Volume 3-FHWA/RD-81/037 Design Procedure. (FHWA)
This volume, the third of a four-volume final report, presents a procedure for evaluating and imp... more This volume, the third of a four-volume final report, presents a procedure for evaluating and improving the geometric design consistency of rural highways. The procedure is based on basic driver behavior principles, a sound conceptual approach and considerable empirical evidence. Basic geometric design objectives, a procedure and examples and remedial countermeasures are presented to aid the designer in applying the procedure. Both 2-lane and 4-lane highways in flat or rolling terrain can be evaluated with this procedure. A detailed step-by-step procedure is presented for evaluating the geometric design inconsistency of proposed or existing rural highways. Two case studies are presented to illustrate the evaluation procedure. (FHWA)
The state of the practice in highway geometric design consistency was determined through a review... more The state of the practice in highway geometric design consistency was determined through a review of U.S. and foreign geometric design policy, practice, and research. Models, and a menu-driven microcomputer procedure for their use, were developed for operating-speed and driver-workload consistency evaluations of rural two-lane highway horizontal alignments. The operating-speed model was calibrated based upon speed and geometry data for 138 horizontal curves and 78 of their approach tangents in 5 States. The driver workload model was calibrated based upon 2 occluded vision test studies on a total of 55 subjects. The operating-speed data suggest that 85th percentile speeds generally exceed the design speed of horizontal curves whose design speed is less than drivers' desired speed (i.e., 85th percentile speed on long tangents). A preliminary evaluation comparing model-estimated operating-speed reductions versus degree of curvature as predictors of accident experience was conducted using a data base of 1,126 curve sites in 3 States. The evaluation suggests that accident experience increases as the required speed reduction from an approach tangent to a horizontal curve increases.
This study addresses the question of the amount of bulb loss that can be tolerated in an electron... more This study addresses the question of the amount of bulb loss that can be tolerated in an electronic motorist-information sign before the message becomes illegible, misunderstood, or misinterpreted. A representative group of traffic-descriptor and advisory words and route numerals were displayed on a real-time matrix sign. Selected percentages (10 to 50) of bulbs were failed in a random pattern, and slides were taken of the resulting displays. These slides were shown to subjects who were instructed to respond by writing the word if it was legible. From these data, specifications for 85th and 95th percentile correct comprehension were determined for both familar and unfamiliar motorists.
This report is the user's manual for a software package called "RAMBO" ( Ramp Adapt... more This report is the user's manual for a software package called "RAMBO" ( Ramp Adaptive Metering Bottleneck Optimization). Developed as a practical ramp metering system, RAMBO consists of two complimentary programs. RAMBO I employs interactive graphic screens to assist the traffic engineer in evaluating local ramp traffic conditions. It generates ramp metering plans and Transition Point Patterns for each metering level. RAMBO II is a system ramp metering package that evaluates ramp metering plans based on forecasted traffic conditions along an extended section of freeway containing up to 12 metered entrance ramps and 12 exit ramps.
This study is concerned with the evaluation of real-time changeable message signs that inform mot... more This study is concerned with the evaluation of real-time changeable message signs that inform motorists of freeway traffic conditions. Included in the study is an evaluation of the use of a letter-grade rating scale for indicating freeway conditions. Evaluation was accomplished through the use of a questionnaire survey and a traffic operations analysis. The study results showed that the changeable message signs were effective in providing information to the motorist. Considerable motorist diversion was noted during analysis incidents which were accompanied by a "LANE BLOCKED" display. The signs were highly visible, generally understood, and useful within the constraints of corridor geometry. Lack of understanding of the letter-grade rating scale employed was attributed to the fact that the scale was not anchored to a readily understandable base. Questionnaire results showed that a vast majority of the respondents found the system useful.
LANE OCCUPANCY WAS EVALUATED AS A TRAFFIC VARIABLE FOR DIGITAL COMPUTER CONTROL OF A SAFETY WARNI... more LANE OCCUPANCY WAS EVALUATED AS A TRAFFIC VARIABLE FOR DIGITAL COMPUTER CONTROL OF A SAFETY WARNING SYSTEM FOR URBAN FREEWAYS. PERFORMANCE CHARACTERISTICS WERE STUDIED OF MEASURED LANE OCCUPANCY AS AN INDICATOR OF SHOCK WAVES RESULTING FROM FREEWAY INCIDENTS. A CONTROL STRATEGY WAS DEVELOPED, PROGRAMMED, AND EVALUATED FOR DIGITAL COMPUTER OPERATION OF THE WARNING SYSTEM. COMPARISONS WERE MADE WITH ENERGY AS A CONTROL VARIABLE. BASED ON THE RESULTS OF THIS RESEARCH A NEW CONTROL ALGORITHM WAS DEVELOPED INCORPORATING THE BEST PERFORMANCE FEATURES OF OF BOTH ENERGY AND LANE OCCUPANCY.
Traffic incidents, whether due to accidents also create safety hazards on the freeway. To enhance... more Traffic incidents, whether due to accidents also create safety hazards on the freeway. To enhance safety and to provide assistance and security to motorists, District 12 of the Texas State Department of Highways and Public Transportation has been operating a motorist courtesy patrol on some Houston freeways. A questionnaire study and a cost- effectiveness analysis were used to evaluate the operation of the patrol. The questionnaire study indicated that motorists aided by the patrol were overwhelmingly in favor of continuation of the program. The cost-effectiveness analysis showed the patrol to have a benefit-cost ratio of 2 to 1. Several additional qualitative benefits are discussed. /Author/
This paper examines the effects of minimum phase length and variations in the spatial arangement ... more This paper examines the effects of minimum phase length and variations in the spatial arangement of ramp intersections on the capacity of diamond interchanges operated with 4-phase-overlap signalization. The introduction of practical minimum constraints on phase lenghts can significantly alter the performance characteristics of this type of interchange. This paper also illustrates a method by which interchange design can be assessed in terms of quality-of-service measures. A computer program, written in FORTRAN IV, was developed to speed up the analysis. Examination of some typical cases illustrates that an efficient design can be selected if one uses the program for a given set of minimum green-phase lengths and traffic demands.
The development of a research study conducted by the Texas Transportation Institute entitled &quo... more The development of a research study conducted by the Texas Transportation Institute entitled "Reduced-Delay Optimization and Other Enhancements to PASSER II-80" is summarized. The research was sponsored by the Texas State Department of Highways and Public Transportation (SDHPT) in cooperation with the FHWA, U.S. Department of Transportation. The brief 6-month research effort was directed toward several topic areas including development of a reduced-delay optimization procedure that could fine tune the offsets of traffic signals to reduce total arterial system delay and maximize arterial progression, development of methods that can better estimate vehicular delay in a nearly saturated traffic system, and development of methods to estimate fuel consumption for arterial traffic movements in an urban network. Significant enhancements have been made to the popular PASSER II program. This study also demonstrated the practical combination of the maximum bandwidth procedure and th...
Abstract: Engineering factors affecting traffic signal change interval (yellow and all-red) are r... more Abstract: Engineering factors affecting traffic signal change interval (yellow and all-red) are reviewed, particularly in terms of drivers' perception and brake reaction time (t), and deceleration rate (d). Using driver behavior data collected from time-lapse cameras, two ...
... 1987 6. Performing Organi tation Coda 7-Author's) Vergil G. Stover, JL Gattis, and C... more ... 1987 6. Performing Organi tation Coda 7-Author's) Vergil G. Stover, JL Gattis, and Carroll J.Messer í. ... Abilene, Bryan, College Station, Denton, Garland, Georgetown, Huntsville, Lancaster, McKinney, New Braunfels, Orange, Rockwall, Round Rock, San Marcos, and Wichita ...
MAXBAND 86 is the only operational traffic signal program that allows progression bandwidth optim... more MAXBAND 86 is the only operational traffic signal program that allows progression bandwidth optimization in multiarterial, closed-loop traffic signal networks. The program formulates the problem as a mixed integer linear program and is capable of optimizing network-wide cycle length, signal offsets, and signal phasing sequences. However, hours of computer time may be required to optimize a medium-sized network problem, even on a mainframe computer. This computational inefficiency of MAXBAND 86 makes it impractical for use by the traffic engineering community. However, two heuristic methods efficiently optimize network signal timing problems modeled by MAXBAND 86. The experimental results demonstrate that these heuristic methods produce tremendous savings in the computer time required to solve optimization problems in traffic network signal timing. In addition, computational benefits are achieved by explicitly modeling one-way arterials in a network rather than as two-way arterials, as used in MAXBAND 86.
Freeway ramp metering systems are being used to alleviate urban freeway congestion. This report p... more Freeway ramp metering systems are being used to alleviate urban freeway congestion. This report presents a methodology for determining the distance requirements for ramp metering for a wide range of traffic volume and freeway geometric conditions. The distance requirement for ramp metering consists of distance required for queue storage and distance required for the freeway merging operation. A queue storage model has been developed to determine distance required for queue storage. The constant acceleration models of linear motion have been used to determine distance required for the freeway merging operation. A methodology for determining the optimal placement of the ramp meter signal has been presented. Guidelines for effecting a trade-off between queue storage and freeway merging distance requirements have also been presented. A sample problem demonstrates the use of the presented methodology.
Abstract: This report is the user's manual for a software package called" RAMBO"(R... more Abstract: This report is the user's manual for a software package called" RAMBO"(Ramp Adaptive Metering Bottleneck Optimization). RAMBO is the end product of research conducted within SPR research project 1232 entitled" Urban Highway Operations Research and Implementation". It was developed by the Texas Transportation Institute for the Texas Department of Transportation (TxDOT) as a practical ramp metering system, primarily for Texas applications. RAMBO consists of two complimentary programs, RAMBO I and ...
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