Engineering Commons^™

The Effectiveness Of Regulatory School Flashers In Reducing Vehicle Speeds, Charles V. Zegeer, Robert C. Deen

Kentucky Transportation Center Research Report

Pedestrian safety for school-age children has been a growing problem in recent years. Children between the ages of five and nine represent less than 10 percent of Kentucky's population but over 16 percent of all pedestrian fatalities. A study was conducted to evaluate the effectiveness of regulatory school flashers used in school zones to reduce vehicle speeds and alert motorists of pedestrian activity and to determine measures which promote safety in school zones.

Speed studies were conducted during flashing and non-flashing periods at 48 school zones where regulatory school flashers were used. The locations involved a variety of speed limits …

Fatigue Damage Of Flexible Pavements Under Heavy Loads, James H. Havens, Herbert F. Southgate, Robert C. Deen

Kentucky Transportation Center Research Report

A modified Chevron N-Layer computer program has the capability of calculating the "work" done by the total load on a given load group. Earlier analyses of AASHO Road Test sections and test vehicles had permitted the development of damage factor relationships. This paper presents seven, namely two-tire and four-tire single axles, tandems, triaxles, and four-axle, five-axle, and six-axle groups. The two-tire axle (front or steering axle) has the most severe damage relationship. The 80-kN (18-kip) four-tire single axle was used as the reference axle and was assigned a damage factor of 1.0 for a specific amount of "work". Other axle …

Interstate Safety Improvement Program, Jerry G. Pigman, Kenneth R. Agent, Charles V. Zegeer

Kentucky Transportation Center Research Report

A previous report dealt with development of procedures for preparation of an Interstate Safety Improvement Program. The purpose of this report was to prepare prioritized rankings of recommended improvements which could be implemented for the Interstate Safety Improvement Program. Together, these two reports include logical and comprehensive procedures for the selection, scheduling, construction, and evaluation of highway safety improvement projects.

Considerable detail is presented which documents analysis procedures used to determine sites, sections, and elements of the roadway in need of improvement. The average number of accidents per interchange, bridge, 1.0-mile (1.6-km) section, and 0.3-mile (0.48-km) spots were summarized for …

Use Of Economic Analyses And Dynamic Programming In The Selection Of Projects For Resurfacing, Charles V. Zegeer, Kenneth R. Agent, Rolands L. Rizenbergs

Kentucky Transportation Center Research Report

The objective of this study was to develop a dynamic programming procedure using economic analyses to assist in optimizing expenditures in the pavement resurfacing program in Kentucky. Benefit relationships were determined from expected accident reduction, improved comfort, time savings, fuel savings, and maintenance savings. The only cost input to the program was the resurfacing cost of each project.

Dynamic programming was adapted to the selection of projects for resurfacing. Over $8.4 million of additional user benefits would have been realized in 1976 if dynamic programming had been used in selecting projects. The benefit-cost ratio of sections selected for resurfacing was …

Acoustic Emission Monitoring Of Weldments, Theodore Hopwood Ii, James H. Havens

Kentucky Transportation Center Research Report

Weld tests were performed on low-carbon and high-strength, low-alloy steel weldments. The weldments were monitored with an acoustic emission detector during both the 'in-process' and the 'in-cooling' phases of the welding operation. Artificial defects were induced in several of the welds to promote cracking. Some high-strength weldments were designed to produce welds subject to high restraint.

Nondestructive and destructive evaluation of the completed weldments revealed that high acoustic emission activity 'in-cooling' could be correlated with embedded defects and cold-cracking. Copious emission activity was also detected from unflawed weldments. Acoustic emissions were detected in high-strength steel weldments for periods up to …

Low-Void Concrete Mixtures, Assaf S. Rahal, James H. Havens

Kentucky Transportation Center Research Report

The purpose of this study was to modify concrete mix-design formulas to supplant all water over and above that needed for hydration with a non-evaporable liquid material and(or) a super-water-reducer or plasticizer -- thus producing a low-void concrete. A water-cement ratio of 0.244 - 0.30 was presumed minimal for hydration of the cement. Several polymeric materials, asphalts, oils, and superplasticizers were used. Success was achieved with two latexes, one epoxy, and several superplasticizers. The use of these materials in concrete resulted in improved strength, reduction of air voids and permeability, and enhancement of resistance to corrosive chloride salts.

Priority Programming For Highway Reconstruction, Charles V. Zegeer, Rolands L. Rizenbergs

Kentucky Transportation Center Research Report

An adequacy-rating procedure was developed for use in priority programming for highway reconstruction. The procedure makes use of 15 roadway and traffic elements to rate highway sections in urban and rural areas based on 100 points. Condition elements (35 points) include a subjective rating of highway foundation, pavement surface, drainage, and maintenance economy. Safety elements (35 points) are stopping sight distance, highway alignment, skid resistance, accident experience, and traffic control devices. Service elements (30 points) include shoulder width, passing opportunity, rideability, surface width, volume/capacity ratio, and average speed.

Some of the advantages of the new procedure include computerized analysis of …

Seatbelt Usage In Kentucky [Nov. 1978], Kenneth R. Agent, Michael Barclay, Robert C. Deen

Kentucky Transportation Center Research Report

In this report, the effectiveness and usage of seatbelts in Kentucky and factors affecting usage are examined and identified. Data were obtained from three sources: field observations, accident reports, and a questionnaire.

Kentucky drivers and passengers were found to have lower seatbelt usage rates (slightly under 10 percent) than drivers and passengers in other states. The accident data showed that the chances of being killed or severely injured is greatly reduced by wearing a seatbelt. Seatbelts reduced the chance of being killed by a factor of six and the chance of being severely injured by a factor of two. Several …

Design System For Asphaltic Concrete Overlays, Herbert F. Southgate, Gary W. Sharpe, Robert C. Deen

Kentucky Transportation Center Research Report

A method of designing asphaltic concrete overlays has been developed from (1) Kentucky's theoretical design curves, (2) an estimate of future traffic and the associated fatigue (five procedures are presented according to types of information available), (3) strength of subgrade on subject project (laboratory CBR tests or results of dynamic in-place tests such as the Road Rater), and (4) present condition of the existing pavement (from dynamic in-place tests, roughness measurements, or present serviceability index). Deterioration has been expressed as reduced or effective thicknesses of new-quality materials producing the same measured dynamic deflections. The total thickness required for the future …

Analysis Of Weekday, Weekend, And Holiday Accident Frequencies, Jerry G. Pigman, Rolands L. Rizenbergs, Donald R. Herd

Kentucky Transportation Center Research Report

On rural roads, the largest number of accidents have occurred on Saturdays, Fridays, and Sundays, respectively. Tuesdays generally had the lowest number of accidents. The highest accident rates for two-lane roads were on Sundays and Saturdays, and the rates for expressways (interstates and toll roads) were the highest on Sundays. Accident rates on weekends were substantially higher than on weekdays. Rates of fatal and all accidents were lower during holiday periods than during weekends not involving holidays. Holiday periods had fewer accidents per day than weekends but had more accidents per day than weekdays. Traffic during holidays, however, was significantly …

Statewide Survey Of Skid Resistances Of Pavements [Nov. 1978], Rolands L. Rizenbergs, James L. Burchett

Kentucky Transportation Center Research Report

In 1969, a research-type, skid-test trailer was acquired, U.S. routes were surveyed in 1970 and 1971, and the interstate and toll-road systems were surveyed in 1971. The data were used for research purposes and have been reported. The interstate and toll-road systems were surveyed again for research purposes in 1974. Since October 1974, surveys have been performed under highway safety project grants (interaccounted to 108, subsection OSKID). Primary and principal secondary roads, involving 4,613 miles (7,427 km), were surveyed in 1975. A second skid tester, a survey-type, was acquired in April 1976; and survey-testing of major, rural collector roads continued …

Pavement Evaluation Using Dynamic Deflections, Gary W. Sharpe, Herbert F. Southgate, Robert C. Deen

Kentucky Transportation Center Research Report

Dynamic test deflections have been duplicated by elastic theory using the Chevron N-layered computer program. Dynamic surface deflections obtained using the Road Rater have been used in conjunction with elastic theory to analyze pavement behavior. A procedure has been developed to use field measured Road Rater deflections to estimate the elastic moduli of the foundation material and to determine the equivalent thicknesses of new material which approximate the behavior of the structure. The estimated moduli and (or) equivalent thicknesses may be used as inputs to design overlay thicknesses. An analysis of the deflections of the first three sensors of the …

Warrants For Left-Turn Signal Phasing, Kenneth R. Agent, Robert C. Deen

Kentucky Transportation Center Research Report

Warrants for the installation of left-turn phasing were developed. A review of literature was conducted along with a survey of the policies of other states. Field data of delays and conflicts were taken before and after installation of exclusive left-turn signalization. Left-turn delay studies were conducted at intersections with varying volume conditions. Analysis of the effect on accidents of adding a left-turn phase was made. The relationship between left-turn accidents and conflicts was investigated. Other types of analyses concerning gap acceptance, capacity, and benefit-cost ratios were also performed.

It was found that exclusive left-turn phasing significantly reduced left-turn accidents and …

A Rational Thickness Design System For Asphaltic Concrete Overlays, Herbert F. Southgate, Gary W. Sharpe, Robert C. Deen

Kentucky Transportation Center Research Report

A method of designing asphaltic concrete overlays has been developed making use of (1) Kentucky's proposed design curves, (2) an estimate of future traffic and the associated fatigue (five procedures are presented according to types of information available), (3) strength of subgrade on subject project (laboratory CBR tests or results of dynamic in-place tests such as the Road Rater), and (4) present condition of the existing pavement (from dynamic in-place tests, roughness measurements, or present serviceability index). Deterioration was expressed as reduced thicknesses of new-quality materials producing the same measured dynamic deflections. The total thickness for the predicted traffic minus …

Simulation Of Travel Patterns For Small Urban Areas, Jerry G. Pigman, Robert C. Deen

Kentucky Transportation Center Research Report

The objective of this study was to develop models which would simulate internal-external trips and external-external (through) trips. Regression analysis and cross-classification of data were tested in an attempt to predict the number of internal-external trips and the percentage of through trips. Regression analysis was used in the development of a through-trip distribution model. Grouping data for analysis created some problems; however, trial-and-error evaluation enabled selection of variables which produced reasonable results. Variables found to be most significant in the development of internal-external models were population and employment. For through-trip models, variables used were population, functional classification, AADT at the …

Green-Extension Systems At High-Speed Intersections [Sept. 1978], Charles V. Zegeer, Robert C. Deen

Kentucky Transportation Center Research Report

The purpose of this study was to determine the effectiveness of green-extension systems (GES) for reducing the dilemma-zone problem associated with the amber phase of traffic signals at high-speed intersections. Reactions of 2,100 drivers were noted during the amber phase at nine intersections, and the dilemma-zone distances with respect to the stop bar were determined.

Before-and-after studies made at three green-extension sites showed a 54-percent reduction in total accidents and a 75-percent reduction in rear-end accidents after GES installation. Accident severity was unaffected.

Conflict, volume, delay, and speed data were taken before and after GES installation at two sites. A …

Evaluation Of Paint Stripe Beads, Jerry G. Pigman, Kenneth R. Agent

Kentucky Transportation Center Research Report

This report presents another phase of a study on evaluation of paint stripes and glass beads. The results from the previous phases of this study indicated that large-scale, experimental evaluation of a 1.65 refractive-index bead and a large-gradation, 1.52 refractive-index bead was warranted. Poor embedment of beads, however, precluded the evaluation because the quick-drying paint used did not allow beads to be properly embedded. After progressive thinning of the paint with solvent, adequate bead embedment was obtained. Drying time, of course, was longer.

Attempts were made to obtain good embedment without extending the drying time. This included testing of a …

Pavement Evaluation Using Road Rater Deflections, Gary W. Sharpe, Herbert F. Southgate, Robert C. Deen

Kentucky Transportation Center Research Report

Dynamic test deflections have been duplicated by elastic theory using the Chevron N-layered computer program. Dynamic surface deflections obtained using the Road Rater have been used in conjunction with elastic theory to analyze pavement behavior. A procedure has been developed to use field measured Road Rater deflections to estimate the elastic moduli of the foundation material and to determine the equivalent thicknesses of new material which approximate the behavior of the structure. The estimated moduli and (or) equivalent thicknesses may be used as inputs to design overlay thicknesses. An analysis of the deflections of the first three sensors of the …

Determination Of Rutting In Asphaltic Concrete Pavements: Field Instrumentation And Laboratory Characterizations, David L. Allen

Kentucky Transportation Center Research Report

This report describes a number of gages developed to measure the location and magnitude of ruts. These were installed in a newly constructed asphaltic concrete pavement. They measure lateral deflections and transient and permanent vertical deflections. Some preliminary vertical deflections are reported. An investigation of materials is also reported. The asphalt concrete base, dense-graded aggregate base, and subgrade material were characterized by (1) shear strength (triaxial tests), (2) rheologic behavior (creep tests), (3) permanent deformation characteristics (repeated-load and creep tests), (4) Young's modulus (resonant column tests), and (5) resilient properties (repeated-load tests). Empirical functions were formulated to describe the permanent …

Characteristics Of Bicycle-Related, Motor Vehicle Accidents In Kentucky, Kenneth R. Agent, Charles V. Zegeer

Kentucky Transportation Center Research Report

The purpose of this study was to determine the characteristics associated with bicycle-related, motor vehicle accidents. Bicycle-related, motor vehicle accidents in Kentucky were analyzed.

A sample of injury-producing bicycle accidents was also analyzed. It was found that cyclists 10 to 14 years of age were involved in the largest number of motor vehicle related accidents. Males were involved in four times as many accidents as females. Most accidents occurred in urban areas, mostly on residential streets. The majority of accidents resulted from errors by the cyclists. The most common type was the right-angle accident, but the leading types varied with …

Seasonal Variations In The Skid Resistance Of Pavements In Kentucky, James L. Burchett

Kentucky Transportation Center Research Report

Frequent measurements of skid resistance were made on 20 pavements in common use in Kentucky. Tests were conducted from November 1969 through 1973. Principal analysis involved relating changes in skid resistance to day of the year and relating skid resistance to temperature at the time of test, to average antecedent temperatures, and to average rainfall.

Seasonal variations exhibited an annual, sinusoidal cycle. The changes in sand-asphalt and bituminous concrete under higher volumes of traffic were about 12 skid numbers. The changes in portland cement concrete and bituminous concrete under lower volumes of traffic were about 5 skid numbers. The lowest …

Acoustic Emission And Fatigue Characteristics Of Typical Bridge Steels, Theodore Hopwood Ii, James H. Havens

Kentucky Transportation Center Research Report

Acoustic emission monitoring was used during tensile tests of low-carbon structural steels to determine the physical characteristics of the acoustic emission phenomena. Results indicate that acoustic emissions are caused by micro-plastic deformation processes (i.e., dislocation motion).

A series of axial-fatigue tests was performed on several types of structural steels, some of which had extensive service in bridges. There was no apparent relation between specimen load histories and subsequent performance in fatigue tests. Tensile tests of specimens subjected to extensive fatigue testing, at stresses below the yield strength of the material, revealed no major difference in mechanical properties or acoustic emission …

Green-Extension Systems At High-Speed Intersections [Apr. 1978], Charles V. Zegeer, Robert C. Deen

Kentucky Transportation Center Research Report

The purpose of this study was to determine the effectiveness of green-extension systems (GES) for reducing the dilemma-zone problem associated with the amber phase of traffic signals at high-speed intersections. Reactions of 2,100 drivers were noted during the amber phase at nine Intersections, and the dilemma-zone distances with respect to the stop bar were determined.

Development Of Procedures For Preparation Of The Interstate Safety Improvement Program, Jerry G. Pigman, Kenneth R. Agent, Charles V. Zegeer

Kentucky Transportation Center Research Report

This report summarizes background information and presents the development of procedures for preparing and updating the lnterstate Safety Improvement Program. There are two major sections: (1) development of procedures for identifying safety needs and (2) development of procedures for prioritizing safety needs. Related to the identification of needs are eleven subsections which are based on historical data, inventories of existing facilities, and analysis of current data. Several accident surveillance procedures were used to identify sites, sections, and elements of the roadway which warrant improvements. Procedures for prioritizing safety needs are based on summaries of data from two reports by the …

Simulation Of External-Internal And Through Trips For Small Urban Areas, Jerry G. Pigman

Kentucky Transportation Center Research Report

The objective of this study was to develop models which would simulate internal-external trips and external-external (through) trips. Regression analysis and cross-classification of data were tested in an attempt to predict the number of internal-external trips and the percentage of through trips. Regression analysis was used in the development of a through-trip distribution model. Grouping data for analysis created some problems; however, trial-and-error evaluation enabled selection of variables which produced reasonable results. Variables found to be most significant in the development of internal-external models were population and employment. For through-trip models, variables used were population, functional classification, AADT at the …

Heating Bridge Decks By Electrical Resistance, James H. Havens, Wm. Vernon Azevedo, Assaf S. Rahal, Robert C. Deen

Kentucky Transportation Center Research Report

The 9th-Street interchange was designed and constructed with an automated electrical heating system for snow and ice removal. This report describes the heating system, its construction, and initial operation. The heating system was capable of keeping the interchange free of ice and snow accumulation. The average daily slab temperature fell below 0°C (32°F) on only one occasion. The average cost of electrical power for heating the interchange was $1,075 per day.

Analysis Of Time-Independent Consolidation Data, E. Gregory Mcnulty, Tommy C. Hopkins, C. Thomas Gorman

Kentucky Transportation Center Research Report

The one-dimensional laboratory consolidation test developed by Terzaghi permits deformation and drainage only in the vertical direction. The stress-strain characteristics of data obtained from this test are normally studied using a semilogarithmic graphical representation, that is, vertical strain or void ratio is plotted as a function of the logarithm of effective stress. Such a representation permits an analysis of the stress history and compressibility characteristics of soils. Knowledge of these material characteristics is of great practical value in the prediction of settlement associated with loading where the effects of lateral consolidation may be neglected.

Development Of A Traffic Conflict Procedure For Kentucky, Charles V. Zegeer

Kentucky Transportation Center Research Report

The objective of this report was to develop a procedure for the collection and use of traffic conflict data. Data were collected at five intersections to determine characteristics of conflicts. Observer reliability was found to be excellent. Traffic volumes accounted for only about 30 percent of the variation in numbers of conflicts. At one intersection, repeatability of conflict numbers, rates, and types was found to be very good. A total of 6,535 conflicts and 2,957 benign weaves were observed at the test sites.

Based on the data, recommendations were made for collecting data during three peak hours at each site. …

Heating The 9th Street Interchange: Construction And Initial Operation, Wm. Vernon Azevedo, Assaf S. Rahal, James H. Havens

Kentucky Transportation Center Research Report

The 9th-Street interchange was designed and constructed with an automated, electrical heating system for snow and fee removal. This report describes the heating system, its construction, and initial operation. The heating system was capable of keeping the interchange free of ice and snow accumulation. The average daily slab temperature fell below 32°F (0°C) on only one occasion. The average cost of electrical power for heating the interchange was $905 per day.

Characteristics Of Kentucky Drivers, Kenneth R. Agent

Kentucky Transportation Center Research Report

The characteristics of the driver population in Kentucky were examined and related to their driving record. Also, the characteristics of high-risk drivers were determined and compared to the driver population. Accident records and responses to a questionnaire distributed to a random sample of the driver population and to high-risk drivers were the data source for the study.

Frequency of accidents was found to be much higher among males than it was among females and was highest among teenage drivers. However, females had a higher accident rate. Teenage drivers had the highest accident rate. The rate decreased for middle-aged drivers and …