Highway Research Board bulletin最新文献

{"title":"RE-EVALUATION OF KENTUCKY FLEXIBLE PAVEMENT DESIGN CRITERION","authors":"W. B. Drake, J. H. Havens","doi":"10.13023/KTC.RR.1959.135","DOIUrl":"https://doi.org/10.13023/KTC.RR.1959.135","url":null,"abstract":"PRIOR TO 1948, THE CRITERION IN KENTUCKY FOR DESIGNING THE THICKNESS OF BITUMINOUS PAVEMENTS WAS BASED UPON A MODIFIED LABORATORY CBR AND THE 1942 CURVES DEVELOPED BY THE CALIFORNIA DEPARTMENT OF HIGHWAYS. IN 1948, THE MATERIALS RESEARCH LABORATORY REPORTED: AN INVESTIGATION OF FIELD AND LABORATORY METHODS FOR EVALUATING SUBGRADE SUPPORT IN THE DESIGN OF HIGHWAY FLEXIBLE PAVEMENT. INCLUDED IN THAT REPORT AS A RECOMMENDED METHOD OF THICKNESS DESIGN FOR USE IN KENTUCKY WAS A SET OF CURVES BASED UPON AN EMPIRICAL RELATIONSHIP BETWEEN MINIMUM LABORATORY CBR AND OBSERVED PAVEMENT PERFORMANCE. THESE FIVE CURVES ACCOUNTED FOR TRAFFIC GROUPS UP TO 10,000,000 EWL'S. SINCE THAT TIME SIX ADDITIONAL CURVES HAVE BEEN INCLUDED IN THE DESIGN CHARTS FOR EWL GROUPS UP TO 320,000,000. THESE ADDITIONAL CURVES WERE DETERMINED BY EXTRAPOLATION OF THE RESULTS FROM THE 1948 STUDY. EARLY IN 1957, AN EVALUATION OF THE DESIGN METHOD WAS UNDERTAKEN. THE BASIS FOR THIS RE-EVALUATION WAS A STATISTICAL COMPARISON OF ACTUAL PAVEMENT PERFORMANCES WITH THE DESIGNED LIFE AS ANTICIPATED OR PREDICTED BY THE DESIGN CURVES CURRENTLY IN USE. ON THIS BASIS, PROJECTS WERE SELECTED, DESIGN RECORDS ASSEMBLED, PERFORMANCES SURVEYED, AND THE DATA ANALYZED. SELECTED PAVEMENTS WHICH HAD BEEN DESIGNED BY THE METHOD DEVELOPED IN THE 1948 STUDY WERE CHECKED FOR PERFORMANCE BY VISUAL SURVEY, BY ROUGHNESS MEASUREMENTS, BY MEASUREMENTS OF RUTTING, BY MEASUREMENTS OF LOADED-DEFLECTION WITH THE BENKELMAN BEAM, AND BY OPENING PAVEMENTS FOR OBSERVATION AND SAMPLING. FLEXIBLE BASE TYPES STUDIED INCLUDED WATERBOUND MACADAM, BITUMINOUS CONCRETE, GRANULAR DENSE-GRADED AGGREGATE AND COMBINATIONS. LABORATORY EVALUATION ON BASIS OF BEARING TESTS WERE MADE. SOME CONCLUSIONS WERE: (1) THE VISUAL SURVEY ESTABLISHED A RANGE OF PERFORMANCE, (2) ROAD ROUGHNESS MEASUREMENTS WERE RELATED TO CBR BUT NO ATTEMPT WAS MADE TO DRAW DESIGN CURVES FROM THIS DATA SINCE IT COULD BE GREATLY AFFECTED BY FACTORS NOT RELATED TO STRUCTURAL DESIGN, (3) PAVEMENTS OPENED FOR INSPECTION REVEALED PERMANENT DEFORMATION IN THE UPPER LAYERS OF THE SYSTEM AS WELL AS INTRUSIONS OF SUBGRADE IN WATERBOUND BASE COURSES, AND (4) AN ALTERNATE METHOD OF DESIGN BASED ON LIMITING DEFLECTION UNDER LOAD WAS DEVELOPED FROM THE BENKELMAN BEAM MEASUREMENTS. CURVES DRAWN FROM THIS DATA INDICATE A NEED FOR A SLIGHTLY GREATER THICKNESS THAN PROVIDED BY THE 1948 CURVES. /AUTHOR/","PeriodicalId":12918,"journal":{"name":"Highway Research Board bulletin","volume":"58 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1959-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74554771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LABORATORY RESEARCH ON PAVEMENTS CONTINUOUSLY REINFORCED WITH WELDED WIRE FABRIC","authors":"M. J. Gutzwiller, J. L. Waling","doi":"10.5703/1288284313564","DOIUrl":"https://doi.org/10.5703/1288284313564","url":null,"abstract":"Since February 1955, research has been conducted at Purdue University on reinforced concrete pavements using welded wire fabric as the principal reinforcement. This research has been carried on in the Structural Engineering Laboratory of the School of Civil Engineering. The final techniques as used in the laboratory are presented. The specimens chosen were 28 feet long by 3 feet wide by 8 inches thick. The reinforcement consisted of either 6 x 12, 0/3; 6 x 12, OOOOO/O; or 4 x 12, OOOOO/O welded wire fabric. The specimens were cast in a portable form in which the amount of steel, the location of the steel, and the depth of slab could be varied. Each of the specimens was fabricated with preformed weakened planes in order that the slab would crack at definite locations in the test region. This permitted the measurement of strains in the fabric reinforcement at these predetermined cracks. The slabs were tested on an elastic subgrade having a modulus of approximately 160 pci. The subgrade was of such material that its modulus could be varied within reasonable limits. The slab specimens were loaded with vertical static loads to simulate traffic loads and horizontal loads to simulate stresses induced by temperature changes. Electric SR-4 strain gages were placed at various locations on the fabric to determine the stresses in the fabric. Vertical deflections of the slab were obtained by use of Federal dial indicators, and crack widths or surface strains in the concrete were obtained by use of a Whittemore strain gage.","PeriodicalId":12918,"journal":{"name":"Highway Research Board bulletin","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1959-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73694005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CRACK FORMATION IN CONTINUOUSLY-REINFORCED PAVEMENTS","authors":"M. J. Gutzwiller, J. L. Waling","doi":"10.5703/1288284314390","DOIUrl":"https://doi.org/10.5703/1288284314390","url":null,"abstract":"RESULTS OF A SERIES OF LABORATORY EXPERIMENTS ON SIMULATED CONTINUOUSLY REINFORCED CONCRETE SLABS ARE GIVEN, WITH THOSE RESULTS PERTAINING TO THE FORMATION OF CRACKS BEING EMPHASIZED. THE FINDINGS OF THESE LABORATORY EXPERIMENTS ARE CORRELATED WITH THE FIELD OBSERVATIONS REPORTED IN THE LITERATURE. SOME OF THE MORE IMPORTANT CONCLUSIONS REACHED AS A RESULT OF THIS RESEARCH, SUBJECT TO THE LIMITATIONS IMPOSED BY THE RANGE OF VARIABLES STUDIED, ARE AS FOLLOWS: (1) THE EFFECTS OF CONCRETE SHRINKAGE, TEMPERATURE CHANGES, AND WHEEL LOADS ON CRACK FORMATION IN CONTINUOUSLY REINFORCED PAVEMENTS CAN BE ADEQUATELY SIMULATED IN THE LABORATORY WITHOUT PRODUCING ACTUAL TEMPERATURE CHANGES IN AN INFINITELY LONG PAVEMENT SLAB. (2) THE FORMATION OF COMPLETE CRACK PATTERN IN A CONTINUOUSLY REINFORCED PAVEMENT IS THE RESULT OF A SUPERPOSITION OF THE EFFECTS OF CONCRETE SHRINKAGE, TEMPERATURE CHANGES AND LIVE (WHEEL) LOADS. (3) CRACK SPACING IN A CONTINUOUSLY REINFORCED PAVEMENT WITH SOME AGE AND USE VARIES INVERSELY WITH THE PERCENTAGE OF LONGITUDINAL STEEL REINFORCEMENT, IF THE STEEL IS PLACED AT MID-DEPTH, WITH A MINIMUM AVERAGE CRACK SPACING OF ABOUT 2 FT IN A SLAB HAVING 0.768 PERCENT LONGITUDINAL STEEL. (4) IT IS GENERALLY AGREED THAT A CONTINUOUSLY REINFORCED PAVEMENT SLAB MUST BE REINFORCED WITH LONGITUDINAL STEEL IN SUFFICIENT AMOUNT TO MAINTAIN ALL TRANSVERSE CRACKS IN A TIGHTLY CLOSED CONDITION. FOR MID-DEPTH REINFORCEMENT THIS CONDITION IS MET WHEN INCREASING LONGITUDINAL FORCES CAUSED BY TEMPERATURE DROPS, IN COMBINATION WITH LIVE LOADS, TEND TO CAUSE ADDITIONAL CRACKS RATHER THAN TO OPEN EXISTING CRACKS FOREVER WIDER. (5) THE SUGGESTED DESIGN CRITERION IS SATISFIED FOR AN 8-IN. PAVEMENT RESTING ON A SUBGRADE HAVING A MODULUS OF 160 PCI, BY 0.45 PERCENT LONGITUDINAL REINFORCEMENT EITHER IN THE FORM OF DEFORMED BARS OR WELDED WIRE FABRIC REINFORCEMENT PLACED AT MID-DEPTH IN THE SLAB. /AUTHOR/","PeriodicalId":12918,"journal":{"name":"Highway Research Board bulletin","volume":"17 1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1959-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80175360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Rate of Strain on the Strength of Compacted Soil","authors":"D. Hampton, E. J. Yoder","doi":"10.5703/1288284314383","DOIUrl":"https://doi.org/10.5703/1288284314383","url":null,"abstract":"THE RESULTS OF A LABORATORY INVESTIGATION ARE REPORTED OF THE EFFECTS OF RATE OF STRAIN ON THE STRENGTH OF REMOLDED SOIL. TWO SOILS WERE SELECTED FOR PURPOSES OF THIS STUDY: (1) A CLAY DERIVED FROM LIMESTONE AND PEDOLOGICALLY CLASSIFIED AS FREDERICK, AND (2) A GLACIAL SILTY CLAY, PEDOLOGICALLY CLASSIFIED AS CROSBY, B HORIZON. THESE SOILS WERE SELECTED PRIMARILY ON THE BASIS OF THEIR DIFFERENCE IN PLASTICITY. RATE OF STRAIN WAS CONSIDERED THE MOST IMPORTANT VARIABLE AND IT WAS STUDIED FROM 0.55 IN./MIN. TO 1,780 IN./MIN. THE FACTORS OF MOISTURE CONTENT AND DRY DENSITY WERE ALSO OF PRIME IMPORTANCE. CONSEQUENTLY, THREE COMPACTIVE EFFORTS WERE USED AND SPECIMENS WERE MOLDED AND TESTED ON BOTH SIDES OF THE OPTIMUM MOISTURE CONTENT OF EACH COMPACTIVE EFFORT. THE UNCONFINED COMPRESSIVE STRENGTH TEST WAS USED AS A STRENGTH CRITERION AND THE EFFECT OF THE AFOREMENTIONED VARIABLES UPON THE ULTIMATE STRENGTH AND MODULUS OF DEFORMATION OF THE SAMPLES, AS DETERMINED BY THIS TEST, ARE REPORTED. /AUTHOR/","PeriodicalId":12918,"journal":{"name":"Highway Research Board bulletin","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1958-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89641850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A study of the polishing characteristics of limestone and sandstone aggregates in regard to pavement slipperiness","authors":"W. Stutzenberger, J. H. Havens","doi":"10.13023/KTC.RR.1958.124","DOIUrl":"https://doi.org/10.13023/KTC.RR.1958.124","url":null,"abstract":"THE COEFFICIENT OF FRICTION ON DRY HIGHWAY SURFACES REGARDLESS OF STONE COMPOSITION AND TEXTURE HAS IN MOST CASES BEEN AT LEAST 0.4 OR ABOVE. HOWEVER, SOME OF THESE SAME SURFACES WHEN LUBRICATED BY A SMALL AMOUNT OF WATER HAVE GIVEN TEST RESULTS DANGEROUSLY LOWER. SOME INTERESTING THEORETICAL ASPECTS OF THIS SITUATION ARE PRESENTED HERE ALONG WITH RESULTS FROM A LABORATORY STUDY OF THE FUNDAMENTAL FACTORS AFFECTING TRACTIVE FRICTION. A MACHINE IS DESCRIBED FOR MEASURING THE COEFFICIENT OF FRICTION BETWEEN THE PLANE SURFACES OF 4 IN. DIAMETER STONE SPECIMENS AND A RUBBER ANNULUS OF SLIGHTLY SMALLER DIAMETER. MEASUREMENTS WERE MADE BOTH WET AND DRY ON FINELY POLISHED SURFACES AND ON SURFACES GROUND WITH 80 AND 150 GRIT CARBORUNDUM. TESTS WERE CONDUCTED UNDER VARYING LOADS AND SPEEDS. A 60 DEGREE REFLECTOMETER WAS USED TO EVALUATE TEXTURE AND ROUGHNESS OF THE PLANE SURFACES. REFLECTIVITY (GLOSS) VALUES CORRELATED SIGNIFICANTLY WITH WET FRICTION VALUES IN THE HIGHLY POLISHED RANGES. TESTS WERE CONDUCTED ON REPRESENTATIVE SAMPLES OF FOUR LIMESTONES AND TWO SANDSTONES. COEFFICIENT OF FRICTION VALUES OF 0.01 AND ABOVE WERE MEASURED ON FINELY POLISHED WET LIMESTONE SURFACES. SANDSTONES SUBJECTED TO THE SAME POLISHING ACTION AVERAGED ABOUT 0.22 WHEN WET. IN ANOTHER SERIES OF TESTING, THE SPECIMENS WERE ABRADED WITH A COARSE CARBORUNDUM GRIT, AND THE WET FRICTION VALUES WERE CONSISTENTLY BETWEEN 0.6 AND 0.7 FOR BOTH LIMESTONES AND SANDSTONES. FOR FURTHER COMPARISON A PIECE OF PLATE GLASS WAS ABRADED WITH THIS SAME MATERIAL, AND IT TOO MEASURED WITHIN THE ABOVE LIMITS. DRY FRICTION VALUES REMAINED FAIRLY CONSTANT REGARDLESS OF TYPE OF STONE OR TEXTURE. TEST RESULTS REVEAL THE TENDENCY FOR FINE GRAINED PARTICLES BOUND IN A MATRIX OF SIMILAR HARDNESS TO POLISH MORE READILY AND TO A GREATER EXTENT THAN HARD PARTICLES SUCH AS QUARTZ BOUND IN A SOFT MATRIX. LIMESTONES, BEING TYPICAL OF THE FORMER CONDITION, POLISHED EASIER THAN SANDSTONES. /AUTHOR/","PeriodicalId":12918,"journal":{"name":"Highway Research Board bulletin","volume":"74 1","pages":"58-81"},"PeriodicalIF":0.0,"publicationDate":"1958-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86155820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CORRELATION BETWEEN CONCRETE DURABILITY AND AIR-VOID CHARACTERISTICS","authors":"F. K. Fears","doi":"10.5703/1288284313536","DOIUrl":"https://doi.org/10.5703/1288284313536","url":null,"abstract":"THE THEORY OF THE ACTION OF ENTRAINED AIR IN PRODUCING FROST-RESISTANT CONCRETE DEMONSTRATES THE IMPORTANCE OF THE SIZE AND DISTRIBUTION OF THE AIR VOIDS IN THE PORTLAND CEMENT PASTE. THE CHARACTERISTICS INVESTIGATED WERE (1) AIR CONTENT, (2) NUMBER OF VOIDS INTERSECTED PER UNIT LENGTH OF TRAVERSE, (3) SPECIFIC SURFACE OF THE AIR VOIDS, (4) NUMBER OF HYPOTHETICAL SPHERES OF EQUAL RADIUS HAVING THE SAME VOLUME OF AIR PER UNIT VOLUME OF CONCRETE AND THE SAME SPECIFIC SURFACE AS THE ACTUAL SYSTEM OF RANDOM SIZED VOIDS AND (5) SPACING FACTOR. STATISTICAL METHODS WERE APPLIED TO THE STUDY OF THE VARIABILITY OF THE AIR CONTENT AND NUMBER OF VOIDS PER INCH WITHIN A CONCRETE BEAM. THE ANALYSIS SHOWED THAT THE MEASUREMENT OF THESE CHARACTERISTICS FOR A PARTICULAR BEAM MAY BE CONSIDERED AS ONE LONG TRAVERSE WITHOUT REGARD TO THE POSITION OR LENGTH OF THE INDIVIDUAL TRAVERSES. THIRTY-EIGHT BEAMS FROM 19 MIXES WERE USED TO STUDY THE CORRELATION BETWEEN EACH OF THE FIVE AIR-VOID CHARACTERISTICS AND DURABILITY. A DURABILITY FACTOR WAS USED TO EXPRESS THE RESISTANCE OF EACH BEAM TO DETERIORATION IN A LABORATORY FREEZE-THAW TEST. THE FIVE AIR-VOID CHARACTERISTICS RANKED IN ORDER OF THEIR CORRELATION WITH DURABILITY ARE (1) SPACING FACTOR, (2) SPECIFIC SURFACE, (3) NUMBER OF VOIDS PER INCH, (4) HYPOTHETICAL NUMBER OF VOIDS PER CUBIC INCH AND (5) TOTAL AIR CONTENT. THE SPACING FACTOR AND THE SPECIFIC SURFACE WERE FOUND TO BE OF ALMOST EQUAL IMPORTANCE IN PRODUCING DURABLE CONCRETE. HENCE, EITHER OF THESE TWO CHARACTERISTICS MAY BE USED AS A CRITERION FOR DETERMINING THE AIR REQUIREMENTS FOR FROST-RESISTANT CONCRETE. /AUTHOR/","PeriodicalId":12918,"journal":{"name":"Highway Research Board bulletin","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1957-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86787021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Driver obedience to stop and slow signs","authors":"W. Jackman","doi":"10.5703/1288284313503","DOIUrl":"https://doi.org/10.5703/1288284313503","url":null,"abstract":"THE PURPOSE OF THIS STUDY WAS TO DETERMINE THE EFFECTIVENESS OF STANDARD MANUFACTURED STOP AND SLOW SIGNS. FOUR OF THE STOP SIGNS USED WERE OF THE NEW TYPE (RED AND WHITE, REFLECTORIZED), THE REMAINING STOP SIGN AND THE SLOW SIGN WERE OF THE OLD TYPE (YELLOW AND BLACK ENAMEL, NON-REFLECTORIZED). IN ADDITION TO THE SLOW SIGN ITSELF, THE SLOW SIGN STUDY UTILIZED A RADAR METER AND A PNEUMATIC TUBE SPEED METER. THE STUDY SHOWED THAT NO COMBINATION OF STOP SIGN TYPE OR POSITION WAS MORE EFFECTIVE THAN ANY OTHER UNDER THE GIVEN CONDITIONS. HOWEVER, AN ATTEMPT WAS MADE TO WEIGH THE INFORMATION GATHERED AND ASSIGN DEFINITE OBEDIENCE FACTORS TO THE SIGN TYPE-POSITION COMBINATIONS STUDIED. THE STUDY ALSO SHOWED THAT A SLOW SIGN PLACED AT A LOCATION WHICH OBVIOUSLY DOES NOT WARRANT IT, IS DEFINITELY INEFFECTIVE. THIS SEEMS TO INDICATE THAT THE AVERAGE DRIVER IS INFLUENCED BY THE APPARENT FACTORS INVOLVED RATHER THAN BY THE SLOW SIGN ITSELF. /AUTHOR/","PeriodicalId":12918,"journal":{"name":"Highway Research Board bulletin","volume":"33 1","pages":"9-17"},"PeriodicalIF":0.0,"publicationDate":"1957-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88279663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AIMING FOR BETTER HEADLIGHTING","authors":"V. J. Roper","doi":"10.4271/570343","DOIUrl":"https://doi.org/10.4271/570343","url":null,"abstract":"Dynamic tests were conducted of the night driving situation using observer-drivers. Test methods are described although it is concluded that a dynamic test of this kind is still not fully representative of a typical driving situation. Part of the variance is that observer-drivers knowingly engaged in a test, and therefore they were paying more attention than would the normal driver. The importance of proper headlight aiming is emphasized. Two recent improvements have recently been made by manufacturers: Improved sealed beam lamps installed on 1956 cars, and the dual-unit system. A considerable increase in seeing distance can be accomplished by having headlights aimed exactly right. All sealed beam headlights are now manufactured with three aiming pads on the front surface of the lens. The front surfaces of these pads are correctly aligned with respect to the aim of the beam. This permits the use of simple, inexpensive mechanical aimers to seat on the front surfaces of these pads and to align the lamps correctly without the need for a darkened area.","PeriodicalId":12918,"journal":{"name":"Highway Research Board bulletin","volume":"1 1","pages":"49-52"},"PeriodicalIF":0.0,"publicationDate":"1957-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90777571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of Skid Testing in Indiana","authors":"H. Michael, D. L. Grunau","doi":"10.5703/1288284314343","DOIUrl":"https://doi.org/10.5703/1288284314343","url":null,"abstract":"Many studies have been made in recent years with various types of skid equipment to evaluate skidding characteristics of pavement surfaces. This paper briefly summarizes the equipment used and the results found in these studies and presents a detailed description of a semi-automatic braking device used on a conventional automobile in Indiana. The device is electrically operated and when activated applies the brakes and initiates measurement of stopping distance simultaneously. The speed at which the brakes were activated is also recorded. The method used eliminates much of the human variable from the measurement of stopping distance and makes it possible for the good reproduction of stopping distance. The skid testing program in Indiana is also outlined and preliminary results are presented. A number of experimental surfaces were tested along with four major surface types used in Indiana. These four were rock asphalt, Portland cement concrete, bituminous concrete, and other bituminous surfaces. A total of 233 different roads were tested, each road being tested at three locations with two skids being performed at each location. The skidding properties of the various roads were compared in terms of mean skid distances at 30 mph. Variability of the skid distances was determined along with the means. The tests showed that rock asphalt had the best skidding properties of all the surfaces tested with respect to both average distance and variability. Its mean skid distance changed little between the wet and dry condition. Portland cement surfaces provided relatively good skid characteristics but were subject to some polishing by traffic during the first few years of their life. The bituminous concrete surfaces tested had poorer skid characteristics than any other major type considered. The bituminous surfaces tested, other than rock asphalt and bituminous concrete, had a relatively low mean but were extremely variable. This variability was almost invariably associated with bleeding. Those roads with no bleeding yielded a mean 18 feet less than those that displayed some bleeding. The bituminous roads constructed with limestone aggregate had a lower mean than those containing gravel, although the limestone in some cases polished extensively under prolonged heavy traffic.","PeriodicalId":12918,"journal":{"name":"Highway Research Board bulletin","volume":"2 1","pages":"60-78"},"PeriodicalIF":0.0,"publicationDate":"1956-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89190667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"HUMAN FACTORS IN HIGHWAY-TRANSPORT SAFETY","authors":"R. Mcfarland","doi":"10.4271/560064","DOIUrl":"https://doi.org/10.4271/560064","url":null,"abstract":"ACCIDENTS ARE ANALYZED FROM THE STANDPOINT OF HUMAN FACTORS AND ACCIDENT PRONENESS. MANY VARIABLES ARE RECOGNIZED THAT CONTRIBUTE TO MOTOR TRANSPORT ACCIDENTS. IMPROVEMENT CAN BE ACCOMPLISHED THROUGH INCREASED VIGILANCE AND RESEARCH WITH REGARD TO THE DESIGN OF EQUIPMENT, THE SELECTION AND TRAINING OF PERSONNEL AND SAFE OPERATING PRACTICES. IT IS CONCLUDED THAT THE PREVENTION OF ACCIDENTS REQUIRES TEAMWORK OF (1) RESEARCH SPECIALISTS, (2) OPERATORS WHO ARE CONCERNED WITH ROUTINE SCHEDULING AND MAINTENANCE OF EQUIPMENT, AND (3) THE MANAGEMENT GROUPS INTERESTED IN MAKING AN OPERATING PROFIT.","PeriodicalId":12918,"journal":{"name":"Highway Research Board bulletin","volume":"28 1","pages":"36-43"},"PeriodicalIF":0.0,"publicationDate":"1956-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78845052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}