MODELS THAT PREDICT THE OPERATING SPEED IN TERMS OF HIGHWAY GEOMETRY ASSUME THAT DRIVERS ARE HOMOGENOUS INDIVIDUALS. HOWEVER, ROAD USERS BUILD THE WAY THEY DRIVE BASED ON THEIR BEHAVIOR AND SKILLS, THEREBY CONFIGURING THE SO-CALLED DRIVING STYLE. THE STATE-OF-THE-ART LITERATURE DEFINES AT LEAST EIGHT DRIVING STYLES THAT AFFECT THE OPERATING SPEED OF DRIVERS. THE OPERATING SPEED-GEOMETRY MODELS DO NOT CONSIDER THIS ASPECT. THE PURPOSE OF THIS PAPER IS STUDY THE EFFECT OF DRIVING STYLES ON THE OPERATING SPEED IN CREST VERTICAL CURVES OF TWO-WAY ROADWAYS. THEREFORE, 16 DRIVERS WERE SELECTED AND CLASSIFIED ACCORDING TO THEIR DRIVING STYLE, BASED ON THE MULTIDIMENSIONAL DRIVING STYLE INVENTORY (MDSI). SUBSEQUENTLY, THE CIRCULATION SPEED OF EACH DRIVER WAS TESTED ON 40 CREST VERTICAL CURVES THROUGH A GPS LOGGER OF 10 HZ INSTALLED IN EACH VEHICLE. NEW OPERATING SPEED-VERTICAL GEOMETRY MODELS WERE DEVELOPED AND CLASSIFIED BY DRIVING STYLES. IT WAS CONCLUDED THAT MODELS THAT DO NOT CONSIDER DRIVING STYLES CONCEAL THE SENSITIVITY OF THE OPERATING SPEED TO THE VERTICAL GEOMETRY OF HIGHWAYS. ADDITIONALLY, AMONG THE DIFFERENT DRIVING STYLES THERE IS AN OPERATING SPEED DIFFERENCE OF UP TO 8 KM/H. THEREFORE, INCLUDING THE DRIVING STYLE VARIABLE IN OPERATING SPEED MODELS OF TWO-WAY ROADWAYS IS A RELEVANT FACTOR.

PREVIOUS STUDIES HAVE SHOWN THAT THERE ARE INCONSISTENCIES BETWEEN THE ASSESSMENTS OF SIGNAL TIMING PLANS BASED ON THE RESULTS OF OPTIMIZATION TOOLS THAT USE MACROSCOPIC SIMULATION MODELS AND THE ASSESSMENTS OF THE SAME PLANS BASED ON MICROSCOPIC SIMULATION MODELS. THE STUDIES SHOW THAT THE SIGNAL TIMING PLANS, IDENTIFIED TO BE OPTIMAL BY THE OPTIMIZATION TOOLS, ARE DETERMINED TO BE NOT OPTIMAL AND SOMETIMES DO NOT PERFORM WELL ACCORDING TO MICROSCOPIC SIMULATION ASSESSMENTS. HOWEVER, NO ATTEMPTS HAVE BEEN MADE IN PREVIOUS STUDIES TO DETERMINE THE REASONS BEHIND THESE INCONSISTENCIES. THIS PAPER INVESTIGATES WHETHER ADJUSTING THE PARAMETERS OF THE MACROSCOPIC SIMULATION MODELS TO CORRESPOND TO THE CALIBRATED MICROSCOPIC SIMULATION MODEL PARAMETERS CAN REDUCE THE ABOVE MENTIONED INCONSISTENCIES. THE RESULTS SHOW THAT ADJUSTING THE VALUES OF PLATOON DISPERSION PARAMETERS, CODED CRUISE SPEEDS, AND SATURATION FLOW RATES IN THE MACROSCOPIC SIMULATION MODELS CAN HAVE SIGNIFICANT IMPACTS ON THE PERFORMANCE OF THE SIGNAL TIMING PLANS AS ASSESSED BY MICROSCOPIC SIMULATION.

HISTORICALLY, THE CONSTRUCTION INDUSTRY HAS PRESENTED HIGH ACCIDENT RATES, AND IN ORDER TO GET A DEEPER UNDERSTANDING AND MAKING RIGHT DECISIONS, IT IS INTERESTING TO CONSIDER THE RISKS FROM A WORKER?S POINT OF VIEW. THIS RESEARCH DDRESSES THE PERCEPTION OF RISKS BY CONSTRUCTION WORKERS FROM A PSYCHOMETRIC PARADIGM AND CONSIDERING SOME OCIODEMOGRAPHIC VARIABLES. THE STUDY CONSIDERED A SAMPLE CONSISTED OF A GROUP OF WORKERS WHO BELONG TO THE CHILEAN CONSTRUCTION INDUSTRY, PARTICULARLY FROM THE BUILDING CONSTRUCTION SECTOR. RELEVANT RISKS ASSOCIATED WITH A HIGH ACCIDENT RATE WERE IDENTIFIED THROUGH AN EXTENSIVE LITERATURE REVIEW. IN ADDITION, THE RELATIVE RISK RELATED TO PHYSICAL OVEREXERTION AND THAT RELATED TO THE EXPOSURE TO PHYSICAL AND CHEMICAL AGENTS ARE CONSIDERED. BASED ON A PSYCHOMETRIC APPROACH FOR THE EVALUATION OF QUALITATIVE ATTRIBUTES, A MEASUREMENT INSTRUMENT WAS APPLIED; RESULTS WERE THEN STATISTICALLY ANALYZED. ADDITIONALLY, THE INCIDENCE OF SOCIODEMOGRAPHIC VARIABLES WAS EVALUATED: AGE, PROFESSION, EXPERIENCE AND EDUCATIONAL LEVEL IN RELATION TO THE PERCEIVED RISK LEVEL. STATISTICALLY SIGNIFICANT DIFFERENCES OF THE PERCEIVED RISK ASSOCIATED TO NOISE EXPOSURE, DEPENDING ON THE AGE OF THE WORKERS WERE OBTAINED. ON THE OTHER HAND, IT WAS DETERMINED THAT WORKERS WITH THE MOST EXPERIENCE CONSIDER THAT THOSE JOBS THAT INVOLVE UNCOMFORTABLE OR FORCED POSTURES CONSTITUTE A RELEVANT PHYSICAL RISK. MEANWHILE, JOBS SUCH AS: REBAR WORKERS, BRICKLAYERS AND CONCRETE WORKERS, PERCEIVE THE GRAVITY AND IMMEDIACY OF THE EFFECT ASSOCIATED TO RISK SIGNIFICANTLY MORE IN ACTIVITIES THAT INVOLVE REPETITIVE MOVEMENTS.

THE INFLUENCE OF THE FRECUENCY CONTENT OF SEISMIC EXCITATIONS ON THE BEHAVIOR OF AN OPTIMAL TUNED MASS DAMPER (TMD) IS STUDIED IN THE CONTEXT OF A SYSTEM WITH EXPLICIT CONSIDERATION OF SOIL-STRUCTURE INTERACTION. A STOCHASTIC ANALYSIS IS MADE IN THE TIME DOMAIN FOR TWO RANDOM PROCESSES, ONE CONSIDERING A BROAD BANDWIDTH PROCESS (BBP) AND OTHER CONSIDERING A NARROW BANDWIDTH PROCESS (NBP). A STRUCTURE BUILT OVER THREE DIFFERENT TYPES OF SOIL (SOFT, MEDIUM AND HARD) IS CONSIDERED. FOR THE OPTIMIZATION OF THE TMD, THE MINIMIZATION OF THE RATIO BETWEEN THE STANDARD DEVIATION OF THE DISPLACEMENT OF THE MAIN STRUCTURE WITH TMD WITH RESPECT TO A STRUCTURE WITHOUT TMD, IS USED AS THE TARGET FUNCTION. IT IS FOUND THAT FOR SEISMIC EXCITATIONS WITH HIGH FRECUENCY CONTENT, THE RATIO OF THE TMD FREQUENCIES COMPARED TO THE FIXED BASE FREQUENCY OF THE STRUCTURE APPROACHES TO 1 AS THE SOIL BECOMES MORE RIGID. IT IS ALSO OBSERVED THAT THE TMD BECOME TUNED WITH THE FLEXIBLE BASE FREQUENCY FOR ALL SOIL TYPES, PRODUCING PERFECT TUNING FOR SMALL MASS RATIOS AND DETUNING GRADUALLY FOR HIGHER MASS RATIOS. ON THE OTHER HAND, THE TMD OPTIMAL DAMPING RATIO INCREASES AS THE TMD MASS RATIO IS HIGHER, INDEPENDENTLY OF THE SOIL TYPE. THE TMD IS MORE EFFICIENT FOR HIGHER VALUES OF THE TMD MASS RATIOS, ESPECIALLY ON SOFT SOIL.

SUPERVISION DURING THE EXECUTION PHASE OF A CONSTRUCTION PROJECT IS ESSENTIAL TO ENSURE SUCCESSFUL PROJECT COMPLETION. IN MOST INSTANCES, THIS TASK IS COMPLETED BY QUALIFIED TECHNICAL AUTHORITIES, ALSO KNOWN AS OWNER?S REPRESENTATIVES (ORS). THIS RESEARCH PRESENTS A MODEL TO ANALYZE THE ROLE OF THE OR DURING THE EXECUTION PHASE OF CONSTRUCTION PROJECTS USING A MULTIVARIABLE?PARTIAL LEAST SQUARES (PLS)?ANALYSIS. THIS ANALYSIS WAS USED TO DETERMINE THE INTERRELATION OF OR ACTIVITIES THAT PERTAIN TO PROJECT SUCCESS. A PLS MODEL WAS DESIGNED TO ASSESS THE SIGNIFICANT FACTORS THAT INFLUENCE THE EFFECTIVENESS OF OR OPERATIONS USING THE DATA GATHERED THROUGH SURVEYS DISTRIBUTED TO MANAGERS OF CONSULTING FIRMS THAT PROVIDE OR SERVICES IN CHILE. THE PLS MODEL RESULTS INDICATED THAT THE MOST IMPORTANT ACTIVITIES FULFILLED BY THE ORS ARE QUALITY CONTROL, COST CONTROL, SCHEDULE TRACKING (TIME), OWNER/CONTRACTOR RELATIONS, AND PRODUCTIVITY VERIFICATION. ALTHOUGH THE FIRST THREE ARE GENERALLY ACCEPTED TO BE THE FUNDAMENTAL ELEMENTS OF A SUCCESSFUL PROJECT, FINDINGS PRESENTED HERE PROVIDE ADDITIONAL INSIGHT, QUANTITATIVE ASSESSMENT OF ALL THESE FACTORS, THEIR INTERRELATIONS, AND THE STRENGTH OF THESE RELATIONSHIPS. THIS ARTICLE IS CONCLUDED WITH PRACTICAL IMPLICATIONS OF THE FINDINGS THAT WOULD ENABLE MORE EFFICIENT CONSTRUCTION PROJECT MANAGEMENT.

SEVERAL METRICS OF RELIABILITY HAVE BEEN RECOMMENDED FOR USE. THESE METRICS MAY NEED TO BE CALCULATED AT RELATIVELY FINE LEVELS OF AGGREGATION OF TRAVEL TIME DATA WHEN USED FOR ADVANCED MANAGEMENT STRATEGIES AND TRANSPORTATION SYSTEM MODELING AND ANALYSIS. THIS STUDY INVESTIGATES THE VARIATION OF TRAVEL TIME DISTRIBUTIONS BY TIME OF DAY AT FINE TEMPORAL AGGREGATION LEVELS, THE SENSITIVITY OF VARIOUS RELIABILITY METRICS TO THESE VARIATIONS, THE EFFECT OF THE AGGREGATION LEVEL CHOICES ON THE CALCULATED METRICS, AND THE AMOUNT OF DATA REQUIRED TO ESTIMATE STABLE VALUES OF THE RELIABILITY METRICS. THE INVESTIGATION IS MADE FOR A FACILITY THAT HAS GENERAL PURPOSE LANES AND HIGH-OCCUPANCY-TOLL LANES. THE RESULTS SHOW THAT THE PARAMETERS OF TRAVEL TIME DISTRIBUTIONS VARY DURING THE PEAK PERIOD, REFLECTING THE EFFECTS OF TRAFFIC CONGESTION, TRAFFIC FLOW DYNAMICS, AND HOW MUCH NONRECURRENT FACTORS, SUCH AS INCIDENTS, CONTRIBUTE TO THE UNRELIABILITY OF TRAVEL TIME ON THE INVESTIGATED FACILITY. TRENDS OF VARIATIONS ARE OBSERVED WHEN RELIABILITY METRICS ARE USED TO ASSESS RELIABILITY AS THE CONGESTION LEVEL CHANGES DURING THE PEAK PERIOD. THE RESULTS ALSO SHOW THAT EXAMINING COMBINATIONS OF TIME-VARIANT STATIC DISTRIBUTION PARAMETERS AND RELIABILITY METRICS OF THE GENERAL PURPOSE AND HIGH-OCCUPANCY-TOLL LANES CAN PROVIDE VALUABLE INFORMATION THAT CANNOT BE OBTAINED WHEN THE ANALYSIS IS PERFORMED AT HIGHER AGGREGATION LEVELS. THE STUDY RESULTS SUGGEST USING AT LEAST ONE YEAR OF DATA TO OBTAIN STABLE VALUES OF RELIABILITY METRICS.