Showing papers in "Highway Research Record in 1970"

Design of experiments

Abstract: MAJOR FACTORS TO BE CONSIDERED IN THE DESIGN OF RESEARCH EXPERIMENTS ARE NOTED BRIEFLY. FOUR ARE CONSIDERED ESSENTIAL TO VALIDATE EXPERIMENTAL RESULTS: CAREFUL AND EXPLICIT PROBLEM DEFINITION, COST-EFFECTIVE REPLICATION, ANALYSIS OF "INFERENCE SPACE" (LIMITATIONS OF DATA, POPULATION, OR EXPERIMENTAL DESIGN THAT CONSTRAIN APPLICATION OF THE RESULTS WITHIN CERTAIN BOUNDS), AND UNDERSTANDING OF RESTRICTIONS ON RANDOMIZATION. METHODS OF HANDLING EXTRANEOUS VARIABLE AND THE USE OF HISTORICAL DATA ARE DISCUSSED, AND AN EXAMPLE IS GIVEN OF THE USE OF RANDOMIZATION RESTRICTION IN THE DESIGN OF A HEART VALVE EXPERIMENT.

Lateral load capacity of piles

Abstract: PILE FOUNDATIONS USUALLY FIND RESISTANCE TO LATERAL LOADS FROM (1) PASSIVE SOIL RESISTANCE ON THE FACE OF THE CAP, (2) SHEAR ON THE BASE OF THE CAP, AND (3) PASSIVE SOIL RESISTANCE AGAINST THE PILE SHAFTS. THE LATTER SOURCE IS USUALLY THE ONLY RELIABLE ONE. ANALYSIS OF THE PROBLEM YIELDS DEFLECTIONS, ROTATIONS, MOMENTS, SHEARS, AND SOIL REACTIONS AS REQUIRED FOR STRUCTURAL DESIGN. BEAM-ON-ELASTIC-FOUNDATION THEORY IS ADEQUATE FOR ANALYSIS OF THE PROBLEM. MOST PILES ARE RELATIVELY FLEXIBLE AND MAY BE ANALYZED AS THOUGH INFINITELY LONG. ONLY SHORT RIGID PILES ARE LIKELY TO REQUIRE CONSIDERATION OF THE LOWER BOUNDARY CONDITIONS IN ANALYSIS. NONDIMENSIONAL SOLUTIONS ARE AVAILABLE FOR BOTH CONSTANT AND LINEARLY INCREASING MODULUS-DEPTH RELATIONSHIPS; SOLUTIONS ARE ALSO AVAILABLE FOR A STEPPED VARIATION OF MODULS, K. SUFFICIENT EXPERIMENTAL DATA ARE NOW AVAILABLE TO ALLOW SELECTION OF THE APPROPRIATE VARIATION OF K WITH DEPTH. TYPICAL VALUES FOR K ARE AVAILABLE AND HAVE BEEN RELATED TO READILY OBSERVABLE SOIL CHARACTERISTICS. SIMPLE LATERAL LOAD TESTS ALSO ALLOW EXPERIMENTAL DETERMINATIONS OF THE MAGNITUDE OF K IF GREATER ACCURACY IS REQUIRED. /AUTHOR/

A heat transfer model for evaluating frost action and temperature-related effects in multilayered pavement systems

Abstract: A HEAT TRANSFER MODEL FOR EVALUATING FROST ACTION AND TEMPERATURE-RELATED EFFECTS WAS DEVELOPED FOR A MULTI-LAYERED PAVEMENT SYSTEM. THE MODEL WAS DERIVED FROM ONE-DIMENSIONAL, FORWARD-FINITE-DIFFERENCE, HEAT-TRANSFER THEORY AND PROGRAMMED FOR COMPUTER SOLUTION. IT WAS DESIGNED TO INCLUDE INPUT PARAMETERS AND CAN BE EXPANDED TO INCLUDE NEWLY DEVELOPED PARAMETERS. IT IS USED TO EVALUATE THE TEMPERATURE REGIME OF VARIED PAVEMENT SYSTEMS IN DIFFERENT GEOGRAPHICAL LOCATIONS. METEOROLOGICAL PARAMETERS SUCH AS SHORT-WAVE RADIATION, LONG-WAVE RADIATION, CONVECTION, AND AIR TEMPERATURE ARE THE BASIC EXTRINSIC FACTORS IN THE HEAT-TRANSFER MODEL. INTRINSIC FACTORS CONSIDERED ARE THE PHYSICAL PROPERTIES AND THERMAL PROPERTIES OF THE PAVEMENT MATERIALS THAT INCLUDE UNIT WEIGHT, MOISTURE CONTENT, MATERIAL CLASSIFICATION, THERMAL CONDUCTIVITY, HEAT CAPACITY, AND LATENT HEAT. THE MODEL WAS DEVELOPED SO THAT APPROPRIATE THERMAL PROPERTIES OF THE PAVEMENT MATERIALS ARE USED DEPENDING ON WHETHER THE UNFROZEN, FREEZING, OR FROZEN STATE EXISTS. PAVEMENT TEMPERATURES GENERATED BY THE MODEL WERE COMPARED WITH LABORATORY TEMPERATURE DATA AND TEMPERATURE DATA FROM THE AASHO ROAD TEST, AND THE MODEL GAVE VALID RESULTS. USE OF THE MODEL FOR EVALUATING FROST ACTION IN A PAVEMENT SYSTEM AT A SPECIFIED LOCATION WAS DEMONSTRATED FOR 30 YEARS OF PAST CLIMATIC RECORD. IT WAS SHOWN THAT NECESSARY QUANTITATIVE DATA FOR THE EVALUATING COULD BE OBTAINED. A CLEARER UNDERSTANDING OF THE QUALITATIVE FACTORS INVOLVED IN FROST ACTION RESEARCH WAS ALSO PROVIDED. /AUTHOR/

An empirical analysis of lane changing on multilane highways

Abstract: A MACROSCOPIC ANALYSIS IS DESCRIBED OF LANE-CHANGING BEHAVIOR ON MULTILANE HIGHWAYS. IT INCLUDES DESCRIPTIONS OF THE PATTERN AND FREQUENCY OF LANE-CHANGING MANEUVERS OBSERVED UNDER VARYING ROAD AND TRAFFIC CONDITIONS, THE DISTRIBUTION OF MANEUVER LENGTHS AND TIMES, AND THE ACCEPTANCE AND REJECTION OF GAPS BY LANE-CHANGING VEHICLES. DATA FOR THE STUDY WERE COLLECTED AT A SAMPLE OF 30 FREEWAY-LOCATIONS IN CHICAGO. /AUTHOR/

Pile load tests including quick-load test method, conventional methods, and interpretations

Abstract: THE GENERAL PRINCIPLES OF PILE LOAD TESTING ARE COVERED, INCLUDING OBJECTIVES OF PILE TESTING, IMPORTANCE OF PLANNING, VARIOUS TYPES AND METHODS OF TESTING, INSTRUMENTATION, DATA TO BE OBTAINED, AND INTERPRETATION AND USE OF THE TEST RESULTS. ALSO INCLUDED ARE SOME TYPICAL CASE HISTORIES TOGETHER WITH CORRELATIVE DATA BETWEEN STANDARD TEST METHODS AND THE CONSTANT RATE OF PENETRATION TEST METHOD. /AUTHOR/

The relationship of accidents to length of speed-change lanes and weaving areas on interstate highways

Abstract: THIS ANALYSIS WAS CONDUCTED ON DATA COLLECTED FOR THE INTERSTATE SYSTEM ACCIDENT RESEARCH, STUDY II. THIS STUDY, WHICH WAS INITIATED IN 1961, HAS AS ITS OBJECTIVE THE DETERMINATION OF THE RELATIONSHIP BETWEEN THE GEOMETRICS OF THE INTERSTATE HIGHWAY SYSTEM AND ITS ACCIDENT EXPERIENCE. THE ANALYSIS REPORTED HERE IS CONCERNED WITH THE RELATIONSHIP BETWEEN LENGTH OF WEAVING AREAS, ACCELERATION LANES, AND DECELERATION LANES AND THE ACCIDENT EXPERIENCE OF THESE TYPES OF UNITS. ALSO CONSIDERED IN THE ANALYSIS WAS THE NUMBER OF VEHICLES UTILIZING THESE UNITS AND THEIR RELATIONSHIP TO THE TOTAL NUMBER OF VEHICLES USING THE INTERSTATE. RESULTS OF THIS ANALYSIS INDICATE THAT INCREASING THE LENGTH OF WEAVING AREAS WILL REDUCE THE ACCIDENT RATE AND THAT INCREASING THE LENGTH OF ACCELERATION LANES WILL REDUCE ACCIDENT RATES IF THE PERCENTAGE OF MERGING VEHICLES IS GREATER THAN 6 PERCENT OF THE MAINLINE VOLUME. INCREASED LENGTH OF DECELERATION LANES WILL ALSO REDUCE ACCIDENT RATES BUT TO A LESSER DEGREE THAN THE COMPARABLE INCREASE OF LENGTH OF ACCELERATION LANES. A SMALLER DECREASE IN ACCIDENT RATE BECOMES APPARENT AFTER THE DIVERGING TRAFFIC EXCEEDS 6 PERCENT OF THE MAINLINE TRAFFIC. ONLY THOSE VARIABLES SPECIFIED IN THE REPORT WERE CONSIDERED, AND THEREFORE APPLICATION OF THE RESULTS MUST BE LIMITED ONLY TO THOSE VARIABLES. /AUTHOR/

Simulation of a computer-aided routing systems (cars)

Abstract: A SIMULATION MODEL THAT CONTAINS SUCH INPUTS AS NUMBER, CAPACITY, AND VELOCITY OF VEHICLES; TIME DISTRIBUTION OF DEMANDS; SPATIAL DISTRIBUTION OF ORIGINS, DESTINATIONS, AND INTERMEDIATE POINTS; AND OUTPUT OPTIONS HAS BEEN EXERCISED ON AN IBM 360/67 TO EVALUATE THE EFFECTIVENESS OF A REAL-TIME ROUTING ALGORITHM FOR A DEMAND-RESPONSE TAXI SERVICE NAMED CARS (COMPUTER-AIDED ROUTING SYSTEM) DEVELOPED AT M.I.T. THE ALGORITHM IS HERUISTIC BECAUSE OF THE INAPPLICABILITY OF EXISTING OPTIMIZATION TECHNIQUES. THE MODEL, WRITTEN IN FORTRAN AND COMPOSED OF 40 SUBPROGRAMS ABOUT 100,000 BYTES LONG, WAS DESIGNED TO EVALUATE VARIOUS HERUISTICS BASED ON TIME-VERSUS-COST TRADEOFFS. THE OPERATING VARIABLES AND INTERACTIVE CHARACTERISTICS OF THE MODEL ARE DESCRIBED AND ILLUSTRATED. FURTHER INVESTIGATION IS PLANNED TO SIMULATE THE SYSTEM INSTEAD OF MERELY THE ALGORITHM.

Relationship of rural highway geometry to accident rates in louisiana

Abstract: A STUDY WAS CONDUCTED TO: (1) DETERMINE WHICH GEOMETRIC VARIABLES CONTRIBUTE MOST TO ACCIDENTS, AND (2) PREDICT THE ACCIDENT POTENTIAL OF A CERTAIN SECTION OF LOUISIANA HIGHWAYS. THIS STUDY INVOLVED APPROXIMATELY 1,000 MILES OF RURAL HIGHWAYS DISTRIBUTED EVENLY THROUGHOUT LOUISIANA. THE ACCIDENT RECORDS INVESTIGATED COVER A 5-YEAR PERIOD FROM 1962 TO 1966. THE VARIABLES STUDIED, IN ORDER TO FIND THEIR RELATION TO ACCIDENTS, WERE PERCENTAGE OF TRUCKS, TRAFFIC RATIO, LANE WIDTH, SHOULDER WIDTH, PAVEMENT CROSS SLOPE, HORIZONTAL ALIGNMENT, VERTICAL ALIGNMENT, PERCENTAGE OF CONTINUOUS OBSTRUCTIONS, MARGINAL OBSTRUCTIONS PER MILE, AND TRAFFIC ACCESS POINTS PER MILE. THESE 10 VARIABLES, THEIR SQUARES, AND THEIR FIRST ORDER INTERACTIONS WERE USED IN A REGRESSION ANALYSIS TO CONSTRUCT MATHEMATICAL MODELS TO DETERMINE THE CONTRIBUTION OF THE VARIABLES TO TOTAL ACCIDENTS, ACCIDENTS ON WET ROADS, ACCIDENTS ON DRY ROADS, ACCIDENTS DURING THE DAY, ACCIDENTS DURING THE NIGHT, TOTAL INJURIES, AND TOTAL FATALITIES. ONE MATHEMATICAL MODEL SHOWS THAT A TOTAL OF APPROXIMATELY 46 PERCENT OF ALL ACCIDENTS ARE EXPLAINED BY THE 10 VARIABLES INCLUDED IN THIS STUDY. THE VARIABLES NOT INVESTIGATED-INVOLVING THE DRIVER, THE VEHICLE, AND OTHER GEOMETRICS-ACCOUNT FOR THE REMAINDER OF THE VARIATION IN TOTAL ACCIDENTS. BASED ON THEIR INTERACTION WITH TRAFFIC VOLUME, THE 2 GEOMETRIC VARIABLES HAVING THE MOST IMPORTANT EFFECT ON ACCIDENT RATES ARE PAVEMENT CROSS SLOPE AND TRAFFIC CONFLICTS. THE REMAINING GEOMETRIC VARIABLES STUDIED IN ORDER OF DECREASING EFFECT ON ACCIDENT RATES ARE LANE WIDTH, HORIZONTAL ALIGNMENT, AND SHOULDER WIDTH. /AUTHOR/

Pedestrian gap-acceptance

Abstract: RESEARCH WAS CONDUCTED TO INVESTIGATE THE GAP ACCEPTANCE OF PEDESTRIANS AT AN UNMARKED MIDBLOCK CROSSING. DATA WERE COLLECTED BY MEANS OF TIME-LAPSE PHOTOGRAPHY AND ANALYZED WITH THE AID OF A PHOTO-OPTICAL DATA ANALYZER. STATISTICAL TESTS, SUCH AS THE KOLMOGOROV-SMIRNOV TEST, THE CHI-SQUARE TEST, AND ANALYSIS OF VARIANCE, WERE UTILIZED TO INVESTIGATE THE RELATIONSHIP BETWEEN SIZE OF GAP ACCEPTED AND VARIOUS FACTORS SUCH AS TIME WAITED AT CURBSIDE, VOLUME OF TRAFFIC, NUMBER OF PERSONS WAITING AT CURBSIDE, SPEED OF APPROACHING VEHICLE, AND WALKING SPEED OF THE PEDESTRIAN. SOME CONCLUSIONS DRAWN FROM THE RESULTS OF THE TESTS ARE THAT FEMALE PEDESTRIANS WERE WILLING TO WAIT LONGER AT CURBSIDE FOR A SUITABLE GAP THAN WERE MALE PEDESTRIANS; MALE PEDESTRIANS ACCEPTED SHORTER GAPS THAN DID FEMALE PEDESTRIANS; THE MINIMUM ACCEPTABLE GAP IN A SINGLE STREAM OF TRAFFIC WAS 3 SEC OR 75 FT; SHORTER GAPS WERE ACCEPTED BY GROUPS OF PEDESTRIANS RATHER THAN BY INDIVIDUALS; AND INDIVIDUAL PEDESTRIANS CROSSED THE ROADWAY AT GREATER WALKING SPEEDS THAN DID GROUPS OF PEDESTRIANS. /AUTHOR/

The environmental influence of rain on freeway capacity

Abstract: RAINFALL INFORMATION IN HOUSTON, TEXAS, FOR THE PERIOD MARCH--DECEMBER 1968 WAS CORRELATED WITH TRAFFIC DATA RECORDS OF THE GULF FREEWAY SURVEILLANCE AND CONTROL CENTER TO DETERMINE THE EFFECT OF RAIN ON FREEWAY CAPACITY. CAPACITY WAS NOT DEFINED AS PEAK HOUR DEMAND BUT AS A FUNCTION OF PEAK HOUR OVERLOADING AT TWO DELECTED BOTTLENECKS: THE CAPACITY OF THE FREEWAY ASSOCIATED WITH THE PEAK HOUR SAMPLE WAS DEFINED AS THE MAXIMUM ORDINATE OF THE BEST-FIT FLOW-DENSITY CURVE. RAIN WAS FOUND TO REDUCE THE CAPACITY OF THE FREEWAY SECTION TO BETWEEN 81 AND 88 PERCENT OF ITS DRY WEATHER CAPACITY AT A CONFIDENCE LEVEL OF 95 PERCENT. /AUTHOR/

Design of tunnel support systems

Abstract: THIS PAPER DEALS WITH THE RESULTS OF A RECENT EVALUATION OF PROCEDURES FOR THE DESIGN OF TUNNEL LINER SYSTEMS; THE RELATIONSHIPS AMONG THE GEOLOGIC MATERIALS TO BE TUNNELED, CONSTRUCTION METHODS, AND SUPPORT SYSTEMS; PRACTICAL GUIDELINES FOR THE DESIGN OF TUNNEL SUPPORTS IN BOTH SOIL AND ROCK; AND PROBLEMS ASSOCIATED WITH IMPROVING EXISTING SUPPORT SYSTEMS FOR HIGH-SPEED TUNNELING. /AUTHOR/

Effectiveness of corrosion inhibitors and their influence on the physical properties of portland cement mortars

Abstract: THE RESULTS OF LABORATORY STUDIES USING SOME OF THE VARIOUS CHEMICAL CORROSIVE ADMIXTURES IN ORDER TO DETERMINE THEIR ACTION ON PHYSICAL PROPERTIES OF CEMENT MORTAR MIXES ARE PRESENTED. THE COMPRESSION AND SPLITTING TENSILE STRENGTH TESTS AS WELL AS THE WORKABILITY OF THESE MIXES WERE USED TO DETERMINE THE INFLUENCE OF THE CHEMICAL ADDITIVES ON THE CEMENT MORTAR MIXES. THE ABILITY OF THESE CHEMICAL ADMIXTURES TO PREVENT CORROSION IN REINFORCED CONCRETE WAS INVESTIGATED BY 2 METHODS: ANODIC POLARIZATION AND VISUAL TESTS. IN THESE TESTS, SMALL REINFORCING BARS WERE EMBEDDED IN CEMENT MORTAR AND EXAMINED AT A LATER DATE. CALCIUM CHLORIDE WAS ADDED IN VARYING AMOUNTS ALONG WITH RUST INHIBITORS TO OBSERVE THEIR EFFECT ON THE PHYSICAL AND CORROSIVE PROTECTION PROPERTIES. /AUTHOR/

The value of time for commuting motorists as a function of their income level and amount of time saved

Abstract: THE VALUE OF TRAVEL TIME SAVED FOR COMMUTING MOTORISTS IS ESTABLISHED AS A FUNCTION OF THE MOTORIST'S INCOME LEVEL AND AMOUNT OF TIME SAVED. THE RESULTS ARE BASED ON DATA PREVIOUSLY COLLECTED BY STANFORD RESEARCH INSTITUTE AND USED TO ESTIMATE A CONSTANT VALUE OF TIME PER MINUTE SAVED OF $2.82 PER PERSON PER HOUR. THE DATA WERE COLLECTED FOR COMMUTERS WITH A CHOICE BETWEEN A TOLL ROUTE AND FREE ROUTE. IT WAS FOUND THAT THE VALUE OF TIME IS HIGHER FOR MOTORISTS WITH HIGHER INCOMES, E.G., IN THE INCOME RANGE OF $4,000-$15,000 PER YEAR, THE VALUE OF TIME INCREASES AT THE RATE OF APPROXIMATELY $0.20 PER PERSON PER HOUR FOR EACH THOUSAND DOLLARS PER YEAR ($0.50 PER HOUR) INCREASE IN INCOME. FOR VERY SMALL AMOUNTS OF TIME SAVED, THE VALUE OF TIME PER MINUTE IS QUITE LOW. IT INCREASES WITH THE AMOUNT OF TIME SAVED AND THEN DECREASES AGAIN. AS AN EXAMPLE, THE EQUIVALENT HOURLY VALUES FOR A MOTORIST WITH A FAMILY INCOME OF $9,000 PER YEAR ARE AS FOLLOWS: THE FIRST MINUTE SAVED IS $0.79 PER PERSON PER HOUR, THE 14TH MINUTE SAVED IS $3.72 PER PERSON PER HOUR, AND THE 25TH MINUTE SAVED IS $1.26 PER PERSON PER HOUR. THE PAPER INCLUDES A TABLE THAT PROVIDES THE VALUE OF THE AMOUNT OF TIME SAVED AS A FUNCTION OF THE MOTORISTS' INCOME LEVEL AND THE AMOUNT OF TIME SAVED. THESE RESULTS ARE LIMITED TO COMMUTER TRIPS WITH TIME SAVINGS OF NOT MORE THAN 30 MINUTES PER ONE-WAY TRIP. THE VALUE OF TIME IS ESTIMATED FROM MOTORISTS' ROUTE CHOICES AS A FUNCTION OF THE MOTORISTS' CHARACTERISTICS AND THE CHARACTERISTICS OF THE ROUTES. A ROUTE CHOICE MODEL, BASED ON THE LOGIT FUNCTION, IS USED TO PREDICT THE MOTORISTS' ROUTE CHOICES BETWEEN THE ALTERNATIVE TOLL AND FREE ROADS. THE COEFFICIENTS OF THE DISCRIMINANT FUNCTION IN THIS MODEL ARE THEN STATISTICALLY ESTIMATED BY FINDING THEIR MAXIMUM LIKEIHOOD ESTIMATES. FROM THESE ESTIMATES THE INDIFFERENCE CURVE BETWEEN TOLL PER PERSON AND TRAVEL TIME SAVED IS DETERMINED, THE SLOPE OF WHICH YIELDS THE DESIRED VALUE OF TIME FUNCTION. /AUTHOR/

An elementary stochastic model of lane-changing on a multilane highway

Abstract: LANE-CHANGING ON A MULTILANE HIGHWAY MAY BE TREATED CONVENIENTLY AS A STOCHASTIC PHENOMENON. THIS PAPER DESCRIBES AN ELEMENTARY STOCHASTIC MODEL OF LANE-CHANGING BEHAVIOR, BASED ON ITS INTERPRETATION AS A HOMOGENEOUS MARKOV CHAIN. THE MODEL IS CALIBRATED USING DATA COLLECTED ON A SECTION OF 6-LANE FREEWAY IN CHICAGO. /AUTHOR/

Phenomenon and mechanism of frost heaving

Abstract: A MECHANISTIC EXPLANATION IS PRESENTED OF FROST ACTION IN SOILS, BASED ON THE HYPOTHESIS THAT LIQUID FILMS EXISTING BETWEEN PARTICLES AND AN ICE LENS ARE THE FOCAL CENTERS OF ENERGY FOR THE HEAVING (WORK) PROCESS HEAVING, UPON FREEZING, IS NOT A UNIQUE PROPERTY OF SOIL PARTICLES AND WATER; LENSING AND SEGREGATION OCCUR WITH OTHER POWDERED MATERIALS AND OTHER LIQUIDS AN EXPLANATION OF THE DEVELOPMENT OF "SUCTION" FORCES IN UNFROZEN LIQUID BELOW THE ICE LENS IS PRESENTED AND EXPERIMENTAL DATA ARE PROVIDED FOR TOW CASES-A CLOSED SYSTEM AND AN OPEN SYSTEM THE EFFECT OF HEAT EXTRACTION RATE AND FREEZING PENETRATION RATE OF HEAVING IS DISCUSSED EXPERIMENTAL LABORATORY DATA INDICATE TWO CIRTICAL RATES OF FREEZING: (1) MAXIMUM HEAVE RATE, AND (2) MINIMAL HEAVE RATE EQUAL TO VOLUME EXPANSION OF IN SITU (VOID) WATER HEAVE RATE AND WORK OF HEAVING AND THEIR DEPENDENCE ON FREE ENERGY GENERATION DURING FREEZING ARE DISCUSSED IN GENERAL TERMS TYPICAL EXPERIMENTAL DATA ARE PRESENTED ILLUSTRATING THE REDUCTION IN HEAVE RATE WITH INCREASE EXTERNAL (AND INTERNAL) RESISTANCE THE ROLE OF SOIL STRUCTURE IN FROST SUSCEPTIBILITY IS DISCUSSED CHANGES IN FROST HEAVING RATES CAN BE EFFECTED BY ADDITION OR REMOVAL OF EITHER, OR BOTH, THE COARSE AGGREGATE OR SOIL FINES SUGGESTIONS ARE OFFERED FOR APPROACHES TO SOIL MODIFICATION TO REDUCE HEAVING EASILY UNDERSTANDABLE MECHANISTIC DESCRIPTION OF THE FROST HEAVING PHENOMENON AND THE SIMULTANEOUS PRESENCE OF PRESSURE AND SUBPRESSURE IN THE SYSTEM IS PRESENTED AND THE IMPORTANT SOIL PARAMETERS INVOLVED IN FROST HEAVING ARE POINTED OUT /AUTHOR/

The bump at the end of the bridge

Abstract: THE GENERAL RELATIONSHIP IS SUMMARIZED BETWEEN THE APPEARANCE OF BRIDGE APPROACH SETTLEMENT AND VARIOUS CONDITIONS AT BRIDGE SITES. DATA OBTAINED FROM A SURVEY OF EXISTING BRIDGE APPROACHES CONDUCTED IN THE SUMMERS OF 1964 AND 1968 PROVIDED GENERAL INFORMATION AS TO THE PREVALENCE OF EMBANKMENT OR FOUNDATION PROBLEMS IN KENTUCKY. THE APPROACHES WERE CLASSIFIED ACCORDING TO ONE OF THE FOLLOWING SETTLEMENT CATEGORIES: (1) GROUP 1 SETTLEMENT, NO MAINTENANCE NECESSARY AND NO APPROACH FAULT NOTICABLE, (2) GROUP 2 SETTLEMENT, NO MAINTENANCE PERFORMED, HOWEVER, AN APPROACH FAULT WAS OBSERVED, AND (3) GROUP 3 SETTLEMENT, MAINTENANCE PERFORMED ON THE APPROACH. THE CRITERION USED TO DISTINQUISH BETWEEN GROUPS 1 AND 2 WAS WHETHER OR NOT A BUMP WAS EVIDENT WHEN AN AUTOMOBILE PASSED ONTO OR OFF THE BRIDGE DECK. ADDITIONAL INFORMATION WAS OBTAINED BY VISUALLY INSPECTING EACH APPROACH. THE AGES OF THE APPROACHES WERE NOTED. FROM THESE DATA, IT IS EVIDENT THAT PRESENT DESIGN AND CONSTRUCTION PROCEDURES ARE NOT SUFFICIENT TO GUARANTEE SMOOTH BRIDGE APPROACHES. A COMPARISON OF PORTLAND CEMENT CONCRETE AND BITUMINOUS CONCRETE APPROACHES SHOWS A MARKEDLY HIGHER PERCENTAGE OF BITUMINOUS CONCRETE APPROACHES WITH PATCHING THAN RIGID APPROACH PAVEMENTS WITH MUD JACKING IN 1964. HOWEVER IN 1968, THE DIFFERENCE IN PERCENTAGE OF MUD JACKED AND PATCHED APPROACHES, AS WELL AS SMOOTH APPROACHES, WAS ALMOST INSIGNIFICANT. APPARENTLY FOR A SHORT PERIOD OF TIME THE RIGIDITY OF PORTLAND CEMENT CONCRETE PAVEMENT REDUCED THE OCCURRENCE OF THE APPROACH FAULT BY BRIDGING THE PRESUMED DEPRESSMENT BEHIND THE ABUTMENT. A COMPARISON OF THE MOST COMMONLY USED TYPE OF ABUTMENTS WITH RESPECT TO THE 3 SETTLEMENT GROUPS REVEALED THAT THE OPEN-COLUMN (OPEN-END) TYPE WAS MORE COMMONLY ASSOCIATED WITH SETTLEMENT GROUP 3 THAN EITHER THE PILE-END-BENT (OPEN-END) TYPE OR STUB (CLOSED-END) TYPE IN 1964. HOWEVER, IN 1968, THERE WAS AN INCREASE IN PERCENTAGE OF FAULTED APPROACHES FOR ALL TYPES OF ABUTMENTS WITH THE PERCENTAGE FOR PILE-END-BENT INCREASING THE MOST. THERE WERE SMALL DIFFERENCES IN PERCENTAGES BETWEEN THE PILE-END-BENT AND OPEN-COLUMN ABUTMENT. THE PERFORMANCE OF BRIDGE APPROACHES WITH AND WITH-OUT SPECIAL GRANULAR BACKFILL WAS COMPARED. NO ADVANTAGE WAS SHOWN AND THE INFLUENCE OF DIFFERENT GEOLOGICAL AND SOIL CONDITIONS WAS ONLY SLIGHTLY NOTICEABLE.

The safety index: a method of evaluating and rating safety benefits

Abstract: EACH YEAR THE CALIFORNIA DIVISION OF HIGHWAYS PREPARES A PLANNING PROGRAM, WHICH SCHEDULES THE FUNDING OF MAJOR CONSTRUCTION PROJECTS FOR THE NEXT 8 TO 11 YEARS. IT SHOWS THE AMOUNTS AND THE FISCAL YEARS OF FUNDING FOR CONSTRUCTION AND RIGHT-OF-WAY ACQUISITION FOR 2,500 TO 3,000 PROJECTS COSTING MORE THAN $100,000 EACH. EVERY ATTEMPT IS MADE TO SCHEDULE THE MOST NEEDED PROJECTS FIRST. TO DETERMINE PRIORITIES OBJECTIVELY, IT IS DESIRABLE TO QUANTIFY THE BENEFITS OF EACH PROJECT (E.G., HOURS OF CONGESTION REDUCED, VEHICLE-HOURS OF DELAY REDUCED, NUMBER OF ACCIDENTS PREVENTED, AND NUMBER OF LIVES SAVED) AND RELATE THESE BENEFITS TO THE COST OF OBTAINING THEM. THE BENEFIT-COST RATIO, BASED ON THE DOLLAR SAVINGS ACCRUED TO THE ROAD USER BECAUSE OF REDUCED TRAVEL TIMES, DISTANCES, AND OPERATING COSTS IS USED. A FEW YEARS AGO, THE CALIFORNIA DIVISION OF HIGHWAYS DEVELOPED THE SAFETY INDEX TO EVALUATE SAFETY IMPROVEMENT PROJECTS. THE SAFETY INDEX REPRESENTS THE PERCENTAGE OF THE PROJECT'S CONSTRUCTION PLUS RIGHT-OF-WAY COSTS THAT IS RETURNED TO THE MOTORISTS AS SAVINGS IN THE COST OF PREVENTED ACCIDENTS. IN REALITY, IT IS A SAFETY BENEFIT-COST RATIO. THE DECIMAL POINT HAS BEEN MOVED TO THE RIGHT 2 PLACES, AND RATIO IS CALLED AN INDEX. IN THE 1969 PROGRAM, FOR THE FIRST TIME, THE USE OF THE SAFETY INDEX IS EXTENDED TO ALL MAJOR CONSTRUCTION PROJECTS. FOR EACH PROJECT AN ESTIMATE WAS MADE OF THE NUMBER OF ACCIDENTS THAT WILL BE PREVENTED BY THE PROPOSED IMPROVEMENT AND OF THE COST SAVINGS RESULTING FROM THE ACCIDENT REDUCTION. THE SAVINGS, EXPRESSED AS A PERCENTAGE OF THE COST OF PROVIDING THE IMPROVEMENT (CONSTRUCTION PLUS RIGHT-OF-WAY, IS THE PROJECT SAFETY INDEX. /AUTHOR/

Optimization of vertical alignment for highways through mathematical programming

Abstract: THE DESIGN OF THE VERTICAL ALIGNMENT PORTION OF A MODERN HIGHWAY IS AN ENGINEERING PROBLEM OF LARGE COMPUTATIONAL MAGNITUDE CHARACTERISTICALLY POSSESSING AN UNLIMITED NUMBER OF SOLUTIONS. THE FAMILIAR ALIGNMENT PROBLEM IS SUBJECTED TO FORMAL MATHEMATICAL DECISION THEORY. AN ALGORITHM IS DEVELOPED THAT IS CAPABLE OF GENERATING A SEQUENCE OF FEASIBLE DESIGN STATEMENTS AND THAT TERMINATES WITH AN OPTIMAL DESIGN. THE DESIGN ALGORITHM IS DEVELOPED FOR RAPID SOLUTION ON A DIGITAL COMPUTER TO PRODUCE A HIGHLY REFINED DESIGN STATEMENT. A LIST OF DESIGN CONSTRAINTS IS COMPILED AND MATHEMATICALLY DESCRIBED IN TERMS OF THE ALIGNMENT DESIGN VARIABLES. A GENERAL COST FUNCTION IS DERIVED IN TERMS OF THE DESIGN VARIABLES. THE DESIGN VARIABLES DEFINED IN THE SOLUTION PROCESS ARE THE CENTERLINE ELEVATIONS AND THE LOCATION OF THE CATCH POINTS AT EITHER SIDE OF THE ROADWAY. /AUTHOR/

Action space formation: a behavioral approach to predicting urban travel behavior

Abstract: A CONCEPTUAL FRAMEWORK FOR EXAMINING THE PROCESS OF ACTION SPACE (THE COLLECTION OF ALL URBAN LOCATIONS ABOUT WHICH THE INDIVIDUAL HAS INFORMATION AND THE SUBJECTIVE UTILITY OR PREFERENCE HE ASSOIATES WITH THESE LOCATIONS) FORMATION, A PROCESS IMPORTANT IN THE UNDERSTANDING OF URBAN TRAVEL BEHAVIOR IN URBAN AREAS, IS DELINEATED. URBAN TRAVEL BEHAVIOR IS CONSIDERED A DIRECT PRODUCT OF THE ACTION SPACE OF HOUSEHOLDS LIVING WITHIN URBAN AREAS. ACTION SPACE FORMATION IS CONSIDERED THE OUTCOME OF A TWO-STAGE PROCESS. THE FIRST CENTERS ON THE RELATIONSHIPS BETWEEN THE HOUSEHOLDERS' RESIDENTIAL LOCATION LENGTH OF RESIDENCE, SOCIOECONOMIC ATTRIBUTES, OBJECTIVE URBAN SPATIAL STRUCTURE (THE LOCATION OF A HOUSEHOLD RELATIVE TO THE ACTUAL LOCATIONS OF ALL POTENTIAL ACTIVITIES AND THEIR ASSOCIATED OBJECTIVE LEVELS OF ATTRACTIVENESS WITHIN AN URBAN AREA), AND TRAVEL PREFERENCES AND PERCEPTION OF THE URBAN ENVIRONMENT. THE SECOND STAGE TREATS THE INTERRELATIONS OF TRAVEL PREFERENCES, PERCEPTION OF THE URBAN ENVIRONMENT, AND THE ACTION SPACE FORMATION PROCESS. AN ANALYTICAL FRAMEWORK, DESIGNED TO TEST AND CALIBRATE THE CONCEPTUAL FRAMEWORK, IS PRESENTED. PRELIMINARY EMPIRICAL FINDINGS RELATED TO THE STRUCTURE OF AGGREGATIVE ACTION SPACES OF TWO QUITE DIFFERENT URBAN NEIGHBORHOODS ARE PRESENTED LINKAGES BETWEEN THE ACTION SPACE OF AN URBAN HOUSEHOLD AND ITS URBAN TRAVEL BEHAVIOR ARE DEFINED IN THE EMPIRICAL ANALYSES.

The new model of hardened portland cement paste

Abstract: FELDMAN AND SEREDA REJECT THE POWERS MODEL OF THE STRUCTURE OF HARDENED PORTLAND CEMENT PASTE ON THE GROUND THAT THE BET SURFACE AREA AND THE POROSITY OF D-DRIED PASTES AS MEASURED BY WATER VAPOR ADSORPTION IS WRONG BECAUSE FOUR-FIFTHS OF THE UPTAKE OF WATER IS INTERLAYER WATER AND NOT ADSORBED WATER. THEY PROPOSE THAT NITROGEN ADSORPTION MEASURES THE SURFACE APPROXIMATELY CORRECTLY AND, ON THE BASIS OF THESE IDEAS, PRESENT A NEW MODEL OF PASTE STRUC- TURE. THE PRESENT PAPER SHOWS THAT WATER VAPOR ADSORPTION MEASURES THE SURFACES AND POROSITIES OF DRIED PASTES CORRECTLY, WHEREAS NITROGEN MEASURES ONLY PART OF THE SURFACE AND POROSITY. D-DRIED PASTES HAVE NO INTERLAYER WATER NOR ADSORBED WATER. PORE STRUCTURE ANALYSIS SHOWS THAT NITROGEN CANNOT PENETRATE INTO MANY LARGE PORES. COMPLETELY HYDRATED D-DRIED PASTES OF THE SAME CEMENT HAVE THE SAME SURFACE AREA WHEN MEASURED BY WATER ADSORPTION REGARDLESS OF W/C, WHEREAS NITROGEN AREAS VARY BY A FACTOR OF ALMOST 3. THE DATA OF FELDMAN AND SEREDA SHOW THAT THEIR QUICK-DRYING PROCEDURE IS APPROXIMATELY EQUIVALENT TO P-DRYING. P-DRIED PASTES CONTAIN BOTH INTERLAYER WATER AND ADSORBED WATER. THE ENERGIES OF BINDING OF THESE 2 TYPES OF WATER STRONGLY OVERLAP; CONSEQUENTLY, THEY CANNOT BE SEPARATED BY TESTS OF REVERSIBILITY. FURTHERMORE, BECAUSE OF THE DIFFERNET DRYING PROCEDURE, NO CONCLUSION CAN BE DRAWN FROM THE EXPERIEMENTS OF FELDMAN AND SEREDA FOR D-DRIED PASTES. THE AUTHORS OF THE NEW MODEL CONTEND THAT NO EQUILIBRIUM IS REACHED IN THE SURFACE AREA MEASUREMENTS BY WATER ADSORPTION ON D-DRIED PASTES. IT IS SHOWN IN THE PRESENT PAPER THAT EQUILIBRIUM WAS REACHED IN THSES MEASUREMENTS BUT WAS NOT REACHED IN MOST OF THE EXPERIMENTS OF FELDMAN AND SEREDA. THEIR DESORPTION ISOTHERMS, AS WELL AS THE LOOPS, BY WHICH THEY ATTEMPT TO TEST REVERSIBILITY, REPRESENT NONEQUILIBRIUM CONDITIONS. THE MAIN CONCLUSION OF THE PAPER IS THAT THE AUTHORS KNOW OF NO PROPERLY INTERPRETED EVIDENCE TO DATE THAT CONTRADICTS THE POWERS MODEL. /AUTHOR/

Durability of concrete bridge decks - a review of cooperative studies

Abstract: THE RESULTS OF CONCRETE BRIDGE DECK DURABILITY STUDIES ARE SUMMARIZED. CONDITION SURVEYS WERE MADE OF OVER 1,000 RANDOMLY SELECTED DECKS IN CALIFORNIA, ILLINOIS, MICHIGAN, MINNESOTA, NEW JERSEY, OHIO, TEXAS, AND VIRGINIA TO ASSESS THE EXTENT OF DETERIORATION. DETAILED FIELD AND LABORATORY INVESTIGATIONS WERE MADE ON 68 DECKS IN KANSAS, MICHIGAN, CALIFORNIA, AND MISSOURI TO DETERMINE THE CAUSES OF DETERIORATION. ATTENTION IS GIVEN TO SCALING, CRACKING, AND SPALLING. SCALING IS NOT A PARTICULARLY SERIOUS PROBLEM AND HAS BEEN KEPT UNDER CONTROL-ALTHOUGH NOT ELIMINATED-WITH USE OF AIR-ENTRAINED CONCRETE. THE OBSERVED SCALING IS USUALLY ASSOCIATED WITH DEFICIENCIES IN THE ENTRAINED AIR VOID SYSTEMS AND WITH INADEQUATE DECK DRAINAGE. MANY FORMS OF CRACKING ARE OF SECONDARY IMPORTANCE BECAUSE THEY DO NOT LEAD TO MORE SERIOUS FORMS OF DECK DISTRESS. LONGITUDINAL CRACKING IS SOMETIMES FOUND ON THE THICKER SLAB-TYPE BRIDGES AND APPARENTLY RESULTS FROM SUBSIDENCE OF HIGH SLUMP CONCRETE AROUND THE REINFORCING BARS. TRANSVERSE CRACKING IS THE FORM MOST OFTEN ENCOUNTERED. SHRINKAGE AND THERMAL VOLUME CHANGES IN THE CONCRETE APPARENTLY ARE THE PRIMARY FACTORS PRODUCING THESE CRACKS. SURFACE SPALLING, A MAJOR PROBLEM IN SOME STATES, IS THE RESULT OF INTERNAL EXPANSIVE FORCES IN THE CONCRETE GENERATED BY THE CORROSION OF TOP REINFORCING BARS. CRACKS OVER BARS, SHALLOW CONCRETE COVER OVER BARS, AND PERMEABLE CONCRETE ALLOW THE DE-ICING CHEMICAL SOLUTIONS TO REACH THE BARS AND CAUSE THE CORROSION. RECOMMENDATIONS FOR IMPROVED DURABILITY INVOLVE THE USE OF HIGHER QUALITY CONCRETES, IMPROVED CONSTRUCTION PRACTICES, AND ATTENTION TO DESIGN DETAILS THAT HAVE AN INFLUENCE ON DURABILITY. ATTENTION IS ALSO INVITED TO 2- COURSE BONDED CONSTRUCTION (SUCH AS IS USED FOR INDUSTRIAL FLOOR CONSTRUCTION) AS AN ALTERNATIVE TO SINGLE COURSE BRIDGE DECK CONSTRUCTION. /AUTHOR/

Factors affecting the tensile strength of cement-treated materials

Abstract: RECENT THEORETICAL AND ANALYTICAL ADVANCES CONCERNED WITH PAVEMENT FAILURES DUE TO EXCESSIVE TENSILE STRESSES OR STRAINS OR BOTH WITHIN THE SOIL-PAVEMENT SYSTEM HAVE PLACED ADDED EMPHASIS ON THE INVESTIGATION OF TENSILE PROPERTIES OF HIGHWAY CONSTRUCTION MATERIALS. THIS STUDY EVALUATES THE FACTORS AND INTERACTIONS AFFECTING THE TENSILE CHARACTERISTICS OF CEMENT-TREATED MATERIALS. NINE FACTORS WERE INVESTIGATED: CEMENT CONTENT, MOLDING WATER CONTENT, AGGREGATE GRADATION, CURING TIME, CURING TEMPERATURE, TYPE OF AGGREGATE, TYPE OF CURING, TYPE OF COMPACTION, AND COMPACTIVE EFFORT. THE FIRST FIVE WERE INVESTIGATED AT 3 LEVELS AND THE LAST FOUR AT 2 LEVELS IN A STATISTICALLY DESIGNED FRACTIONAL FACTORIAL EXPERIMENT. THE PARAMETER CONSIDERED AS A PRIMARY INDICATOR OF THE TENSILE PROPERTIES OF CEMENT-TREATED MATERIALS WAS THE INDIRECT TENSILE STRENGTH. AN ANALYSIS OF VARIANCE WAS USED TO DETERMINE THE SIGNIFICANCE OF ALL MAIN FACTORS, 2-FACTOR INTERACTIONS, AND 3-FACTOR INTERACTIONS IN THE EXPERIMENT. THE HIGHLY SIGNIFICANT EFFECTS THAT ARE ALSO OF PRACTICAL SIGNIFICANCE TO THE ENGINEER ARE DISCUSSED, AND TABLES OF ALL ADDITIONAL FACTORS AND INTERACTIONS SIGNIFICANT AT ALPHA LEVELS OF 1 AND 5 PERCENT ARE SHOWN. A REGRESSION EQUATION THE PREDICTS VALUES OF INDIRECT TENSILE STRENGTH WITHIN THE FACTOR SPACE DEFINED BY THE EXPERIMENT IS PRESENTED. /AUTHOR/

Use of domestic waste glass as aggregate in bituminous concrete

Abstract: THE INCREASING AMOUNTS OF WASTE GLASS BEING GENERATED IN THE UNITED STATES ARE NECESSITATING THE DEVELOPMENT OF NEW METHODS FOR DISPOSAL OF THIS REFUSE COMPONENT. THE USE OF WASTE GLASS AS AN AGGREGATE IN BITUMINOUS CONCRETE WAS INVESTIGATED IN THIS STUDY. THE OBJECTIVES WERE TO DETERMINE WHETHER A MIXTURE USING GLASS AGGREGATE COULD BE DESIGNED THAT WOULD MEET MARSHALL TEST DESIGN CRITERIA, TO INVESTIGATE THE AMOUNT OF DEGRADATION OCCURRING IN THESE MIXTURES, AND TO DETERMINE THE WATER-RESISTANCE OF SUCH MIXTURES. WASTE GLASS WAS CRUSHED AND SCREENED INTO SEVERAL SIZE FRACTIONS, WHICH WERE THEN COMBINED TO GIVE A MAXIMUM DENSITY GRADATION. STANDARD MARSHALL DESIGN METHODS WERE USED TO DETERMINE STABILITY, FLOW, AND VOID PARAMETERS AT SEVERAL ASPHALT CONTENTS, AND TO DETERMINE AN OPTIMUM ASPHALT CONTENT SATISFYING MARSHALL DESIGN CRITERIA EXTRACTION TESTS WERE CONDUCTED ON SOME OF THE SPECIMENS TESTED, AND MECHANICAL ANALYSES OF THE RECOVERED AGGREGATE WERE USED TO ASSESS THE AMOUNT OF DEGRADATION OF THE AGGREGATE. STATIC STRIPPING TESTS WERE CONDUCTED ON SEVERAL COMBINATIONS OF GLASS AGGREGATES AND BITUMINOUS MSTERIALS. BITUMINOUS MIXTURES SATISFYING MARSHALL DESIGN CRITERIA CAN BE DESIGNED USING AGGREGATES COMPOSED ENTIRELY OF CRUSHED GLASS. SOME DEGRADATION OF THE GLASS AGGREGATE DOES OCCUR UNDER LABORATORY MIXING, COMPACTING, AND TESTING CONDITIONS, WITH GREATER DEGRADATION APPEARING TO BE ASSOCIATED WITH GRADATIONS DEVIATING FROM THOSE GIVING MAXIMUM DENSITY. SEVERE STRIPPING OCCURS WHEN THE GLASS-AGGREGATE BITUMINOUS CONCRETE WITH NO ANTISTRIPPING AGENT IS EXPOSED TO WATER. GLASS AGGREGATES COATED WITH ASPHALT CEMENTS CONTAINING ANTISTRIPPING AGENTS OR COATED WITH CATIONIC EMULSIONS DO NOT STRIP IN THE STATIC STRIPPING TEST. /AUTHOR/

Accident experience with parking lights as running lights

Abstract: AN ATTEMPT IS MADE TO TEST THE NEED FOR BETTER VISUAL DEFINITION OF THE AUTOMOTIVE VEHICLE THROUGH THE USE OF RUNNING LIGHTS DURING DAYLIGHT HOURS. IN LIEU OF THE ADDITION OF SPECIAL LIGHTING SYSTEMS, THE PARKING LIGHTS AND TAILLIGHTS OF SOME 200 MOTOR VEHICLES WERE MADE TO TURN ON AUTOMATICALLY ON IGNITION. AFTER 1 YEAR, OBSERVATION OF THESE VEHICLES, AND OF ABOUT 400 UNMODIFIED VEHICLES AS A CONTROL GROUP, GAVE RESULTS INDICATING THAT THE MODIFIED VEHICLES AS A GROUP HAD A BETTER ACCIDENT RATE (SOME 18 PERCENT BETTER OVERALL) AND A BETTER SEVERITY RATE (66 PER-CENT LOWER ON A NUMERICAL SCALE) THAN THE UNLIGHTED VEHICLES. SPECIFICALLY, THE REAR-END ACCIDENT RATE WAS REDUCED BY 45 PERCENT, WITH SIGNIFICANT REDUCTIONS OF OTHER ACCIDENT TYPES. VARIATION BY TYPE OF VEHICLE AND COLOR OF VEHICLE ARE ALSO DISCUSSED. /AUTHOR/

Effect of particle shape and surface texture on the fatigue behavior of asphaltic concrete

Abstract: A LABORATORY INVESTIGATION IS REPORTED ON THE EFFECTS OF PARTICLE SHAPE AND PARTICLE SURFACE TEXTURE ON THE FATIGUE BEHAVIOR OF AN ASPHALTIC SURFACE MIXTURE. THE INVESTIGATION WAS LIMITED TO ONE MIXTURE TESTED IN A CONSTANT-STRAIN MODE. THREE AGGREGATES WERE USED IN SEPARATE MIXTURES FOR THE PARTICLE SHAPE FATIGUE COMPARISONS: ROUND GRAVEL, LIMESTONE, AN INTERMEDIATE-SHAPED AGGREGATE THAT WAS NEITHER ROUND NOR SLABBY, AND SLABBY SLATE. TWO MIXTURES, ONE CONTAINING UNETCHED LIMESTONE AND THE OTHER ETCHED LIMESTONE, WERE COMPARED IN THE PARTICLE SURFACE TEXTURE-FATIGUE STUDY. BEAMS DIMENSIONED TO 2.5 BY 3 BY 4 IN. WERE COMPACTED FROM EACH MIXTURE AND TESTED IN THE LABORATORY. THE FATIGUE LIFE WAS DEFINED BY CRACKING OF THE BEAM SURFACE AND MONITORED BY THE RESULTANT CRACKING OF FOIL STRIPS GLUED TO THE BEAM. THE RESULTS OF THE CONSTANT-STRAIN MODE FATIGUE TESTS SHOW THAT THE MIXTURE CONTAINING THE SLABBY-SHAPED AGGREGATES HAD A SIGNIFICANTLY SHORTER FATIGUE LIFE THAN THE MIXTURE CONTAINING THE ROUNDED GRAVEL. THERE WAS NO SIGNIFICANT DIFFERENCE BETWEEN THE FATIGUE LIFE OF THE UNETCHED LIMESTONE MIXTURE AND THAT OF THE ETCHED LIMESTONE MIXTURE. THE DATA ON RUPTURE MODULUS VERSUS NUMBER OF CYCLES INDICATE THAT A LINEAR RELATIONSHIP ON A LOG-LOG PLOT EXISTED FOR ALL MIXTURES CONTAINING AGGREGATES WITH DIFFERENT SHAPES AND SURFACE TEXTURES. THE CURVES ARE ESSENTIALLY PARALLEL FOR ALL MIXTURES, AND THE UNETCHED AND ETCHED LIMESTOME CURVES ARE ESSENTIALLY IDENTICAL. /AUTHOR/

Dodotrans i: a decision-oriented computer language for analysis of multimode transportation systems

Abstract: THE MAJOR FEATURES ARE PRESENTED WITH AN EXAMPLE OF A COMPUTER LANGUAGE AND SET OF PROGRAMS THAT WERE DEVELOPED AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY. THE OBJECTIVES MOTIVATING THIS DEVELOPMENT, ONE SUBSTANTIVE AND ONE PROCEDURAL WERE: (1) THE SYSTEM SHOULD BE POLICY-SENSITIVE, THAT IS, ABLE TO PREDICT THE CONSEQUENCES OF A WIDE RANGE OF ALTERNATIVE POLICIES TOWARD MULTIMODAL TRANSPORTATION SYSTEMS IN A THEORETICALLY ACCEPTABLE MANNER AND (2) THE SYSTEM SHOULD SUPPORT AN ANALYSIS PROCESS IN WHICH THE ANALYST EXPLORES A WIDE RANGE OF ALTERNATIVES AND AMASSES LARGE QUANTITIES OF INFORMATION WHILE SEEKING TO DEVELOP HIS UNDERSTANDING OF THE POLICY ISSUES IN A PARTICULAR PROBLEM. THE DECISION-ORIENTED DATA ORGANIZER-TRANSPORTATION ANALYSIS SYSTEM (DODOTRANS), REFLECTS THIS PHILISOPHY. IT IS POLICY-SENSITIVE IN THAT IT ANALYZES MULTIMODAL TRANSPORTATION SYSTEMS; CAN TEST A WIDE RANGE OF OPTIONS; CAN PREDICT A WIDE RANGE OF IMPACTS; FINDS EQUILIBRIUM OF SUPPLY AND DEMAND IN THE NETWORK EXPLICITLY; AND CONTAINS SUPPLY, DEMAND, EQUILIBRIUM, RESOURCE REQUIREMENTS, DEMAND SHIFT, AND EVALUATION CAPABILITIES. THE EVOLUTIONARY NATURE OF DODOTRANS IS STRESSED. A MODEL IS DESCRIBED FOR DETERMINING A SUITABLE LEVEL OF HIGHWAY INVESTMENT IN A LARGE, PRIMARILY URBANIZED REGION AND THE ALLOCATION OF THIS INVESTMENT TO SUBAREAS WITHIN THE REGION BASED ON THE COMMON SET OF SOCIAL AND ECONOMIC CONSIDERATIONS. THE MODEL OFFERS THE FOLLOWING ADVANTAGES AS COMPARED TO EXISTING METHODS: (1) IT REQUIRES A MINIMAL AMOUNT OF TRAVEL INFORMATION, (2) THE OBJECTIVE FUNCTION MAY BE MODIFIED TO REFLECT THE VALUES OF THE REGION UNDER STUDY, (3) THE IMPORTANCE OF DIFFERENT OBJECTIVES ON THE FINAL PROPOSAL MAY BE TESTED, (4) THE OBJECTIVE FUNCTION PROVIDES A BASIS FOR MAKING TRADE-OFFS BETWEEN THE ALLOCATION OF RESOURCES TO HIGH-DENSITY AREAS WHERE COSTS AND BENEFITS ARE HIGH AND LOW-DENSITY AREAS WHERE COSTS AND BENEFITS ARE LOW, AND (5) A GENERAL LEVEL OF REQUIREMENTS, WHICH WILL SERVE AS A FRAMEWORK FOR DEVELOPMENT OF MORE SPECIFIC PROPOSALS, CAN BE ESTABLISHED EARLY IN THE PLANNING PROCESS. THE MODEL IS DESCRIBED IN DETAIL.

A utilitarian theory of travel mode choice

Abstract: INTENSIFIED STUDY OF PUBLIC TRANSIT SERVICE HAS PLACED DEMANDS ON THE TRANSPORTATION PLANNER FOR IMPROVED CHOICE OF TRAVEL MODE MODELING TECHNIQUES. AN UNDERLYING OF MODAL CHOICE IS NEEDED TO CORRECT INADEQUACIES IN OUR PRESENT APPROACH. A THEORY IS PROPOSED THAT IS BUILT ON THE SUPPOSITIONS THAT INDIVIDUAL CHOICE OF MODE IS UTILITARIAN, THAT COMMON MEASURES OF INDIVIDUAL TRIP UTILITY ARE SUBJECT TO CHANCE ERRORS DESCRIBABLE BY THE NORMAL DISTRIBUTION ERROR FUNCTION, AND THAT DEVIATIONS RESULT FROM PREDICTABLE INFLUENCES. A DIFFERENCE IN DISUTILITY MEASURE IS SET FORTH FOR COMPARISON OF TRAVEL UTILITY. THE MEASURE COMBINES TIME, CONVENIENCE, AND DOLLAR COST INTO A COMMON UNIT OF EQUIVALENT TIME. THE PROBABILITY OF FREE CHOICE OF A GIVEN MODE IS DESCRIBED MATHEMATICALLY AS A FUNCTION OF THE POSSIBLE DISUTILITY SAVINGS. THE FORMULATION IS POSTULATED TO BE THE NORMAL PROBABILITY DENSITY FUNCTION, PREDICTING 50 PERCENT PROBABILITY AT ZERO DISUTILITY DIFFERENCE. SUBMODAL-SPLIT STUDY RESULTS PERTAINING TO BOTH TRANSIT AND HIGHWAY ROUTE CHOICE ARE EXAMINED AND FOUND TO SUPPORT THE FREE MODAL CHOICE MATHEMATICAL DESCRIPTION. DEVIATIONS TO BE EXPECTED IN APPLYING THE THEORY TO CHOICE OF PRIME MODE ARE EXAMINED. IT IS ASSUMED THAT LONG TERM CAPTIVITY TO TRANSIT OR AUTO CAN BE EXPRESSED AS A CONSTANT PROBABILITY, AND THE RESULTANT CONSTRAINED FORMULATIONS ARE ILLUSTRATED. EFFECTS OF EXCESSIVE TRIP LENGTH AND DESIRABLE OPERATIONAL REFINEMENTS ARE DISCUSSED. IT IS CONCLUDED THAT THE PROPOSED THEORY IS READILY APPLICABLE TO MODALCHOICE FORECASTING AND MULTIMODE ANALYSIS AND MAY LEAD ALSO TO BROADER APPLICATIONS. /AUTHOR/ BROADER APPLICATIONS /AUTHOR/

A pavement overlay design system considering wheel loads, temperature changes, and performance

Abstract: A RECENT REVIEW OF CURRENT OVERLAY DESIGN PROCEDURES REVEALED THAT A FEW BONA FIDE PROCEDURES EXIST AND THAT EVEN THE BEST OF THEM, I.E., THOSE BASED ON DEFLECTION, HAVE LIMITATIONS AND INCONSISTENCIES. FURTHERMORE, THE REVIEW EMPHASIZED THE NEED FOR CONSIDERING VOLUME CHANGE STRESSES. THE PURPOSE OF THIS PAPER, THEREFORE, IS TO BRIEFLY DISCUSS A RECENTLY DEVELOPED OVERLAY DESIGN PROCEDURE, WHICH HAS BEEN APPLIED TO 11 MILES OF INTERSTATE HIGHWAY AND 2 AIRPORTS. A BRIEF DESCRIPTION OF THE OVERLAY DESIGN SYSTEM AND ITS APPLICATION IS PRESENTED HERE; A DETAILED DESCRIPTION IS AVAILABLE. THE GENERAL PAVEMENT SYSTEM IS DISCUSSED AND APPLIED TO DEVELOP AN OVERLAY SYSTEM THAT IS APPLIED TO THE DESIGN OF AN OVERLAY FOR CONTINUOUSLY REINFORCED CONCRETE PAVEMENT IN TEXAS. THIS DESIGN IS DISCUSSED IN TERMS OF WHEEL LOAD AND TEMPERATURE STRESSES. /AUTHOR/

Predetermining the polish resistance of limestone aggregates

Abstract: RESEARCH DATA SHOW THAT AGGREGATE TYPE IS A VITAL FACTOR IN PAVEMENT FRICTION AND LIMESTONE AGGREGATES TEND TO POLISH MORE READILY THAN OTHER AGGREGATES. SIGNIFICANT DIFFERENCES IN POLISH SUSCEPTIBILITY EXIST AMONG LIMESTONES AND THESE DIFFERENCES ARE RELATED PRIMARILY TO THE NON-CARBONATE OR ACID INSOLUBLE CONSTITUENTS IN THE ROCK. SINCE 1946, THE VIRGINIA HIGHWAY RESEARCH COUNCIL HAS ACCUMULATED A LARGE NUMBER OF PAVEMENT FRICTION MEASUREMENTS AND INFORMATION ON AGGREGATE CHARACTERISTICS. BASED ON THESE DATA, IT APPEARS THAT A SIMPLE RELATIONSHIP EXISTS BETWEEN THE TOTAL ACID INSOLUBLE CONTENT OF VIRGINIA LIMESTONES AND THEIR POLISH RESISTANCE AS EVALUATED BY STOPPING DISTANCE NUMBERS. FROM THIS RELATIONSHIP AND OBSERVATIONS ON TRAFFIC VOLUMES, TENTATIVE GUIDELINES FOR USING LIMESTONES IN PAVEMENT SURFACES ARE PROPOSED. THIS INVOLVES USING LIMESTONES WITH INCREASINGLY HIGHER INSOLUBLE FRACTIONS IN PAVEMENT SURFACES CARRYING PROGRESSIVELY GREATER TRAFFIC VOLUMES. IT IS THOUGHT THAT CERTAIN RELATIVELY IMPURE LIMESTONES MAY BE USED IN PAVEMENTS CARRYING UP TO 10,000 VEHICLES PER DAY. IF SELECTED LIMESTONES CAN BE USED IN PAVEMENT SURFACES, CONSIDERABLE ECONOMIES WILL RESULT, BECAUSE MANY STATES ARE EITHER EXCLUDING OR CONSIDERING EXCLUSION OF ALL LIMESTONES FROM PAVEMENT SURFACES. IT IS RECOMMENDED THAT OTHER STATES CARRY OUT SIMILAR STUDIES RELATING PAVEMENT FRICTION TO LIMESTONE AGGREGATE CHARACTERISTICS, PARTICULARLY THE INSOLUBLE CONTENT. THUS THE TENTATIVE GUIDELINES SUGGESTED HERE MAY BE REFINED AND FOUND USEFUL OUTSIDE VIRGINIA. /AUTHOR/

An analysis of driver preferences for alternative visual information displays

Abstract: SEVERAL TRAFFIC INFORMATION DESCRIPTORS HAVE BEEN EVALUATED AS TO HOW DESIRABLE THEY ARE TO DRIVERS RESIDING IN THE CHICAGO METROPOLITAN AREA THESE DESCRIPTORS ARE MESSAGES ABOUT THE CONDITIONS ON A FREEWAY AND ARE DISPLAYED BY ELECTRONIC SIGNS EVALUATED WERE 7 DESCRIPTORS AT THE LEVEL OF HEAVY CONGESTION, 6 AT THE LEVEL OF MODERATE CONGESTION, AND 6 AT THE LEVEL OF NO CONGESTION THE MESSAGES CONTAINED DESCRIPTIVE INFORMATION, QUANTITATIVE INFORMATION, AND NO INFORMATION FOR ALL LEVELS OF CONGESTION, TRAFFIC INFORMATION WAS PREFERRED TO NO INFORMATION ABOUT TRAFFIC CONDITIONS FOR THE LEVEL OF HEAVY CONGESTION, INFORMATION ABOUT AN ACCIDENT HAVING OCCURRED AND CAUSING HEAVY CONGESTION WAS THE DESCRIPTOR MOST PREFERRED BY RESPONDENTS IN THE TOTAL SAMPLE THE SPEED DESCRIPTOR RANKED SECOND (THE ACCIDENT DESCRIPTOR RANKED FIRST) FOR THE LEVEL OF HEAVY CONGESTION AND FIRST FOR THE OTHER TWO LEVELS OF CONGESTION THE TWO REMAINING DESCRIPTORS (EXCLUDING THE ACCIDENT DESCRIPTOR) WERE SCALED FAIRLY HIGH, BUT WERE LESS DESIRABLE THAN THE SPEED DESCRIPTOR THE TWO QUANTITATIVE DESCRIPTORS, DELAY AND TRAVEL TIME, HAD RELATIVELY LOW SCALE VALUES AND WERE SIMPLY NOT DESIRED BY THE RESPONDENTS /AUTHOR/