Arizona Department Of Transportation Research Articles

Network-Level Safety Metrics for Overall Traffic Safety Assessment: A Case Study

Driving safety analysis has recently experienced unprecedented improvements thanks to technological advances in precise positioning sensors, artificial intelligence (AI)-based safety features, autonomous driving systems, connected vehicles, high-throughput computing, and edge computing servers. Particularly, deep learning (DL) methods empowered volume video processing to extract safety-related features from massive videos captured by roadside units (RSU). Safety metrics are commonly used measures to investigate crashes and near-conflict events. However, these metrics provide limited insight into the overall network-level traffic management. On the other hand, some safety assessment efforts are devoted to processing crash reports and identifying spatial and temporal patterns of crashes that correlate with road geometry, traffic volume, and weather conditions. This approach relies merely on crash reports and ignores the rich information of traffic videos that can help identify the role of safety violations in crashes. To bridge these two perspectives, we define a new set of network-level safety metrics (NSM) to assess the overall safety profile of traffic flow by processing imagery taken by RSU cameras. Our analysis suggests that NSMs show significant statistical associations with crash rates. This approach is different than simply generalizing the results of individual crash analyses, since all vehicles contribute to calculating NSMs, not only the ones involved in crash incidents. This perspective considers the traffic flow as a complex dynamic system where actions of some nodes can propagate through the network and influence the crash risk for other nodes. The analysis is carried out using six video cameras in the state of Arizona along with a 5-year crash report obtained from the Arizona Department of Transportation (ADOT). The results confirm that NSMs modulate the baseline crash probability. Therefore, online monitoring of NSMs can be used by traffic management teams and AI-based traffic monitoring systems for risk analysis and traffic control.

Results of the 10-Year Arizona Quiet Pavement Pilot Program

In April 2003, the Arizona Department of Transportation (ADOT) initiated a Quiet Pavement Pilot Program in cooperation with the Federal Highway Administration (FHWA). Under this program, many freeway segments in the Phoenix metropolitan area with Portland Cement Concrete pavement surfaces received 25.4-mm thick asphalt rubber friction course overlays to reduce highway-related traffic noise. This pilot program represented the first time that pavement type was allowed as a noise mitigation strategy on federally funded projects. As part of this program, ADOT developed a 10-year research program with FHWA to evaluate the long-term acoustic performance of this noise mitigation approach. The final measurements were completed in 2015. The program was done with three types of measurements: Type 1 examined tire/pavement noise at the source at 115 milepost locations; Type 2 examined noise in residential neighborhoods near the freeways; and Type 3 evaluated noise using direct measures of traffic noise adjacent to the freeways. Sound absorption measurements were also made at specific sites at various times throughout the project. Type 1 measurements documented an average initial reduction of 8.7 dBA and an average increase of 0.5 dB/year. The Type 2 measurements revealed an average initial reduction of 5.2 dBA, whereas the Type 3 measurements showed an average initial reduction of 9.1 dBA and an average increase of 0.5 dB/year. The measured reductions were also compared with ADOT and FHWA noise abatement criteria.

Forensic approach to predict film thickness of reacted and activated rubber (RARX) modified asphalt mixtures

The major objective of this study was to arrive at an optimum threshold asphalt binder film thickness, and develop predictive equation that includes materials and mixture properties, which could be used in all future forensic assessment of asphalt mixtures. Also, 18 field asphalt mixtures constructed as test sections were investigated for their field performance and correlated with . Furthermore, the performance criteria set by Arizona department of transportation (ADOT) in the USA to assess the field mixtures were related to established in this study. An optimum of 12 µ was selected as the threshold magnitude for asphalt mixtures that incorporates activated crumb rubber modified products, termed RARX. It was found that with increase in the overall cumulative surface area (SA) of the mix matrix, the required binder content also increased, in turn decreasing . predictive equation encompassing materials properties and associated volumetrics was established as a best-fit nonlinear regression model that had excellent statistical measures: R 2 = 99.8%; Se/Sy = 0.0447. It is noteworthy that the predictive model was established using the robust concept that introduced utilisation of SA of the whole mixture matrix, including, those that of SA of aggregate fractions not estimated by current models. Based on the methodical approach followed in this study to calculate , it is recommended that more amount of RARX be tried in other mixtures to enhance pavement performance. The current study involved only 18 field asphalt mixtures, amongst which six were without RARX. So, it is suggested that additional field sections be placed and monitored for their performance keeping in mind the volumetrics and specifically, , which can potentially be a quality control parametric assessor for field performance forensic evaluation, and that which becomes an integral characteristic in perpetual pavement design philosophy.

Analysis of Factors Affecting Injury Severity in Traffic Crashes on Arizona Tribal Lands

Reducing fatal and serious injuries sustained in traffic crashes on tribal lands is a priority of federal, state, and local agencies in the United States. In the state of Arizona, the proportion of fatal and severe injury crashes on several areas of tribal land are 4.0% higher compared with statewide statistics. There is a need to investigate why higher proportions of fatal and severe injuries are occurring on tribal lands to plan effective countermeasures aimed at improving traffic safety in these areas. This study presents an analysis of factors affecting injury severity in crashes occurring within five tribal reservations in the state of Arizona. Crash data were obtained from the Arizona Department of Transportation, and the analysis included data for 9,597 persons involved in traffic crashes on these tribal lands for the years 2010–2016. An ordered logit model with random parameters was estimated using this data to identify factors significantly associated with severe injury outcomes in the event of a crash on tribal lands. Several person-, vehicle-, roadway-, and environmental-related variables were found to impact injury severity. For instance, alcohol and safety device usage were significantly associated with severity outcomes. The results of this study have the potential to aid transportation agencies effectively plan strategies to reduce traffic crash injuries and fatalities on tribal lands, and potential countermeasures considering the 4Es of traffic safety (engineering, education, enforcement, and emergency medical services) are discussed.

A Tale of Two Pavements: Forensic Investigation of an Unbonded Concrete Overlay and a Concrete Pavement Reconstruction on I-40 near Flagstaff, Arizona

In 1990, the Arizona Department of Transportation (ADOT) constructed a Specific Pavement Studies (SPS)-6 experiment on eastbound Interstate 40 (I-40) east of Flagstaff, AZ, as part of the Long-Term Pavement Performance Program. The SPS-6 experiment was designed to evaluate treatment and rehabilitation options for an existing concrete pavement. Nineteen sections were constructed, one of which was a 10 in. thick unbonded concrete overlay (UBCOL). Additionally, ADOT planned to construct an 11 in. unbonded portland cement concrete (PCC) overlay on the adjacent I-40 westbound to investigate benefits of additional concrete thickness. The eastbound unbonded PCC overlay has significantly outperformed all other pavement sections and remains in good condition after 27 years of service. However, the westbound PCC section is severely distressed and in need of immediate rehabilitation. An investigation was conducted to evaluate why two similar unbonded PCC overlays performed with vastly different results. It was found that the westbound “unbonded PCC overlay” was not an overlay after all, but instead a 12 to 13 in.thick jointed plain concrete pavement (JPCP). The high level of distress in the westbound JPCP is likely related to the presence of a weak subgrade that infiltrated the aggregate base. Additionally, during coring, water filled the core holes suggesting that the subgrade in the westbound direction was saturated. Further, petrographic analysis indicated deicing chemicals contributed to corrosion of the dowel bars and deterioration of the concrete joints. This investigation demonstrates some advantages for using unbonded overlays as rehabilitation alternatives for existing concrete pavements.

Laboratory evaluation of foaming-based and chemical-based warm mix asphalt

A recent joint study by Arizona State University and the Arizona Department of Transportation (ADOT) was conducted to evaluate certain warm mix asphalt (WMA) properties in the laboratory. WMA material was taken from an actual ADOT project that involved two WMA sections. The first section used a foamed-based WMA admixture, and the second section used a chemical-based WMA admixture. The rest of the project included control hot asphalt mixture. The experimental plan included three main objectives. The first objective was to explore the concept of re-heating WMA by conducting the dynamic modulus |E*| at 21.1 °C (70 °F) and compare plant to laboratory prepared mixtures using specimens from the foaming-based mixture. The second objective was to evaluate the effect of WMA on the compaction energy. The third objective was to assess the moisture damage using the Hamburg wheel-track test and AASHTO T-283 tensile strength ratio (TSR) test. The |E*| results tested at 21.1 °C for both laboratory prepared and plant foaming-based mixtures showed similar |E*| values. The statistical analysis indicated that there is no statistical significance of the dynamic moduli between the two mixtures at two compaction temperatures 132 °C (270 °F) and 154 °C (310 °F). This indicated that there is no effect of re-heating on the plant produced WMA mixture. The compaction energy results supported the conclusion from the re-heating study. The moisture sensitivity evaluation based on the TSR results indicated low resistance to moisture damage; while the Hamburg testing results indicated very good performance.

Evaluation of Multiple Stress Creep and Recovery (MSCR) Data for Arizona

In the recently released AASHTO M332 asphalt binder specification, the Multiple Stress Creep and Recovery (MSCR) test replaces the current modulus and phase angle based method used for high temperature characterization. In anticipation of possible future adoption of this standard, the Arizona Department of Transportation (ADOT) has cataloged Multiple Stress Creep and Recovery (MSCR) test results on more than 375 different asphalt binder samples dating back to 2008. In this paper, this database is reviewed to evaluate potential implications of the adoption of a revised grading procedure based on the outcomes from the MSCR test. The database is graded in both the current and the M332 system to compare temporal changes in asphalt binder under both systems. The standard is then evaluated for its ability to detect polymer modified asphalt binder supplied in Arizona, and for the interaction between grade and temperature. It is found that under the M332 system the number of required grades for the state of Arizona would increase from the current number of eight to a total of fourteen. Future work includes the reduction of the total number of grades through engineering judgment and knowledge of asphalt binder selection based on local Arizona conditions. Under this review, Arizona asphalt binder suppliers may not necessarily have to add additional storage capacity to their facilities to accommodate a transition to the M332 standard.

Waste Water Force Main Pipe Construction Alternatives to Protect Existing Foundations in the City of Chandler: Case Study

To provide additional wastewater capacity and redundancy in South Chandler, Arizona, a new 28” High Density Polyethylene (HDPE) force main was installed from the upsized Kyrene Lift Station three miles east to tie into an existing 66” transmission sewer line. The force main was installed under the State Route Loop 202 (SR 202L) freeway through existing 48” steel casings constructed ten years prior. Additionally, the force main was constructed through a narrow Arizona Department of Transportation (ADOT) corridor, which required clearance from existing utilities, including overhead 69kV power poles. Two locations required innovative solutions to both access the existing sleeves and cross the transmission power pole foundations: 1) crossing of the 69kV power pole required detailed slope stability analysis and location specific trench backfilling; and 2) access to the existing 48” was within 15 feet of an existing ADOT sound wall. Various alternatives for access were analyzed in this paper including temporary shoring, sheet pile installation, and full wall replacement and reconstructing on drilled shafts. Based on the objectives above, the existing power pole does not have sufficient embedment for maximum design loads but is stable with reduced load factors and lower operation wind forces. Also, for construction issue with the existing ADOT sound wall, the temporary shoring and sheet piles used due to the geotechnical conditions and construction costs.

Analytical evaluation of maximum cover limits for thermoplastic pipes used in highway construction

The objective of this analytical study was to evaluate the maximum burial depths (cover) allowed for highway construction using thermoplastic pipes. Most state highway agencies have used thermoplastic pipes extensively for side drain applications over the past several decades. Recently, with the advent of thermoplastic pipe products up to 1.5 m (60 in.) in diameter, states have also begun allowing limited use of thermoplastic pipes under roadways (cross drain applications). However, there has been little rigorous analytical research into the maximum cover limitations needed for thermoplastic pipes in highway construction, and full-scale testing that simulates actual field conditions is costly and difficult. Furthermore, the maximum cover limits specified by the 38 state departments of transportation who responded to a 2006 survey given by the Arizona Department of Transportation vary greatly and are typically more conservative than those recommended by industry guidelines. These many disparities and challenges indicate a need for additional research. This study provides a rigorous analytical basis for burial depth limits of thermoplastic pipes in highway construction and illustrates reasons for disparities in maximum fill height recommendations and standards.

Implementation of Asphalt-Rubber Mixes into the Mechanistic Empirical Pavement Design Guide

ABSTRACT The Mechanistic-Empirical Pavement Design Guide (MEPDG) developed by the National Cooperative Highway Research Program (NCHRP) utilizes material properties to predict distresses in pavement structures. This new MEPDG is in the process of replacing the traditional pavement design based on the AASHTO 1993 Design Guide. The Arizona Department of Transportation (ADOT) uses Asphalt- Rubber (AR) mixes state-wide. These mixes include both gap and open gradation designs. However, the national calibration process that was undertaken for the MEPDG did not include asphalt-rubber mixes. Because of their unique characteristics, this paper addresses steps and efforts undertaken in a recent study to implement these AR mixes into the MEPDG. There were several issues and limitations identified pertaining to the implementation of AR mixes in the MEPDG. Short and long term recommendations were provided. An important outcome includes a modified Dynamic Modulus predictive equation for AR mixes that is expected to be used in a future implementation of AR mixes in MEPDG.

Impact of Traffic Data on the Pavement Distress Predictions using the Mechanistic Empirical Pavement Design Guide

ABSTRACT This study examines the adequacy of using conventional traffic data and national default values in the absence of weigh-in-motion (WIM) data for pavement design. A comparative study was conducted on 14 unique sections in Arizona (AZ), where WIM data are available through the Long Term Pavement Performance (LTPP) program. The study consists of two parts: 1) comparisons of input traffic data and 2) comparisons of pavement distresses predicted by the Mechanistic Empirical Pavement Design Guide (MEPDG). The traffic related input parameters include average design-lane truck volumes, Vehicle Classification Percentages (VCP), Monthly Adjustment Factors (MAF), axle load distribution factors and the number of axles per truck. The truck volumes and VCPs are available through the Arizona Department of Transportation (ADOT) while only national average values are available for the other traffic inputs in the absence of WIM data. The comparisons of the input variables showed that the truck volumes for a design lane estimated from the ADOT database and default MAFs differed significantly from those in the LTPP database. The national default axle load distribution factors differed somewhat from the site-specific values. The differences in input data were reflected in the pavement distress values that were predicted by MEPDG. The outputs of the design guide reveal large prediction errors, particularly for longitudinal cracking, exceeding 40 percent in absolute percent error on average. The large difference in design-lane truck volume was the major source of the large prediction errors. The national default factors also generated moderate prediction errors, and the performance improved slightly with the use of the AZ average factors. Finally, the differences in MAF had little impact on predictions of pavement distress.

Impact of Traffic Data on the Pavement Distress Predictions using the Mechanistic Empirical Pavement Design Guide

ABSTRACT This study examines the adequacy of using conventional traffic data and national default values in the absence of weigh-in-motion (WIM) data for pavement design. A comparative study was conducted on 14 unique sections in Arizona (AZ), where WIM data are available through the Long Term Pavement Performance (LTPP) program. The study consists of two parts: 1) comparisons of input traffic data and 2) comparisons of pavement distresses predicted by the Mechanistic Empirical Pavement Design Guide (MEPDG). The traffic related input parameters include average design-lane truck volumes, Vehicle Classification Percentages (VCP), Monthly Adjustment Factors (MAF), axle load distribution factors and the number of axles per truck. The truck volumes and VCPs are available through the Arizona Department of Transportation (ADOT) while only national average values are available for the other traffic inputs in the absence of WIM data. The comparisons of the input variables showed that the truck volumes for a design lane estimated from the ADOT database and default MAFs differed significantly from those in the LTPP database. The national default axle load distribution factors differed somewhat from the site-specific values. The differences in input data were reflected in the pavement distress values that were predicted by MEPDG. The outputs of the design guide reveal large prediction errors, particularly for longitudinal cracking, exceeding 40 percent in absolute percent error on average. The large difference in design-lane truck volume was the major source of the large prediction errors. The national default factors also generated moderate prediction errors, and the performance improved slightly with the use of the AZ average factors. Finally, the differences in MAF had little impact on predictions of pavement distress.

Implementation of Asphalt-Rubber Mixes into the Mechanistic Empirical Pavement Design Guide

ABSTRACT The Mechanistic-Empirical Pavement Design Guide (MEPDG) developed by the National Cooperative Highway Research Program (NCHRP) utilizes material properties to predict distresses in pavement structures. This new MEPDG is in the process of replacing the traditional pavement design based on the AASHTO 1993 Design Guide. The Arizona Department of Transportation (ADOT) uses Asphalt- Rubber (AR) mixes state-wide. These mixes include both gap and open gradation designs. However, the national calibration process that was undertaken for the MEPDG did not include asphalt-rubber mixes. Because of their unique characteristics, this paper addresses steps and efforts undertaken in a recent study to implement these AR mixes into the MEPDG. There were several issues and limitations identified pertaining to the implementation of AR mixes in the MEPDG. Short and long term recommendations were provided. An important outcome includes a modified Dynamic Modulus predictive equation for AR mixes that is expected to be used in a future implementation of AR mixes in MEPDG.

Necessary Assessment of Use of State Pavement Management System Data in Mechanistic–Empirical Pavement Design Guide Calibration Process

Calibration and validation of the Mechanistic–Empirical Pavement Design Guide (MEPDG) for state department of transportation (DOT) networks requires detailed information for a variety of pavement inputs. The biggest database resource that most states possess is their pavement management system (PMS). It is understandable for any DOT to maximize the use of this resource to the greatest extent possible. However, before any state uses PMS data in MEPDG calibration, it is important that a careful comparison be made of the equality of the measurements, data, and so forth in the PMS database with national Long-Term Pavement Performance (LTPP) values. The purpose of this paper is to review possible differences between several key data found in a state PMS database and the LTPP database. Arizona Department of Transportation (ADOT) PMS data are used for this purpose. The specific variables examined in this paper deal with distress type (rutting, cracking, and roughness) and nondestructive deflection testing (NDT) backcalculated moduli to predict in situ pavement layer properties. It was concluded that significant differences did exist between the ADOT PMS values and LTPP measurements. Differences were found between ADOT's NDT measurements and LTPP data in rut measurements, asphalt cracking, international roughness index, and all layer backcalculated moduli. Consequently, ADOT may incur significant expense to calibrate the MEPDG to Arizona conditions. The paper discusses several possible reasons for differences between the PMS data of a specific agency and those in the LTPP database.

Supplementing Signalized Intersection Infrastructure to Provide Automated Performance Measures with Existing Video Detection Equipment

The objective of this work was to retrofit a signalized intersection with the goal of developing event-based performance measures while leveraging existing infrastructure to its fullest extent. A TS1 intersection managed by the Arizona Department of Transportation in Flagstaff was chosen as the test location. In addition to video from the existing cameras, video detector interface cards were installed in the cabinet to provide contact closure outputs of vehicle flow rates. These outputs were then conveyed to an onboard event-based data logger within the traffic controller via TS2 communications. Performance measures were generated [volume-to-capacity (v/c) ratio and cumulative counts] from the video-generated data and compared with manually counted data over a 24-h analysis period. The v/c values generated by the video data were shown to be statistically different from those calculated with the manual count data; however, on all but one phase, the difference was not operationally significant. Analysis of cumulative count data showed operationally significant differences. A cost analysis determined that the price of equipping a similar intersection for this type of vehicle count capability is about $16,000 if the equipment specified for this project is used and if it is installed during the construction of the intersection. It is recommended that jurisdictions interested in developing this type of flow information consider equipping future intersections in a similar manner and that future work be completed in the evaluation of the use of video detection units for flow rate collection at signalized intersections.

Irrigation facility relocations along the Arizona state route 85 corridor

In 1999 the Arizona Department of Transportation (ADOT) began improvements along the State Route 85 (SR85) corridor between Gila Bend and Interstate 10 (I-10). At the time SR85 was a two-lane highway that carried a large volume of truck traffic between Interstate 8 near Gila Bend and Phoenix. The SR85 roadway improvements project is broken into phases. The first phase includes the construction of frontage roads and using these roads as a divided highway. Once the divided highway is completed, the final freeway cross section will be constructed between the frontage roads. The project impacted existing irrigation facilities for three irrigation districts located between the Gila River and I-10; the Arlington Canal Company, Buckeye Water Conservation and Drainage District (BWCDD) and Roosevelt Irrigation District (RID). The roadway improvements impact three main canals, turnouts from the main canal, main canal check structures, delivery structures, laterals, groundwater wells and tailwater collection systems. Three miles of irrigation facilities relocations were completed in various phases between 1999 and 2009. Total construction cost as of May 2009 is about $9.4 million. ADOT is currently working on 30% design plans for the main line between the Gila River and Broadway Road. The irrigation districts are coordinating with ADOT regarding the impacts to the irrigation facilities. In this paper we present the institutional and functional constraints to infrastructure modernization in an urbanizing area with historic irrigated agriculture. This process was complicated by the need to continue to operate the irrigation delivery facilities on an almost year-round basis.

Comparison of Asphalt Rubber and Conventional Mixture Properties

In 1999 the Arizona Department of Transportation (ADOT) started outlining and developing a long-range pavement research program. This research program was established in cooperation with Arizona State University (ASU) and had the ultimate goal of implementing the Mechanistic–Empirical Pavement Design Guide (MEPDG) for Arizona. Since ADOT uses asphalt rubber (AR) mixes for new and rehabilitation pavement designs, an integral part of the MEPDG calibration effort must include AR mixtures, which were not included in the MEPDG's development. The objective of this study was to perform a comparison between AR properties and those of the conventional dense graded asphalt mixtures typically used for MEPDG development, calibration, and validation. Another important task was to evaluate how these mixes could be implemented into the MEPDG in the short term and to make recommendations on how to use them in future designs. A total of 23 AR mixtures were available for analysis from a joint ADOT-ASU database. The database contains several engineering properties of AR mixes and binders. These data were used to compare properties, select MEPDG input parameters, generate design analysis for permanent deformation and fatigue cracking, run case studies to predict performance, and compare results with field performance data. Several issues were identified pertaining to the implementation of AR mixes in the MEPDG, and recommendations were provided.

Quieter Hot-Mix Asphalt Pavements in Washington State

Historically, traffic noise has been reduced through the construction of noise walls and berms, which can be costly (US$2 to $3 million per kilometer in Washington State). Open-graded friction courses (OGFCs) have been found to reduce tire–pavement-related noise. However, OGFC pavement surface lives of less than 10 years, and as short as 4 years, have occurred in Washington State. The primary reason for early failure is surface wear caused by studded tires. In 2006, the Washington State Department of Transportation (WSDOT) placed the first of three test sections (the second test section was placed in 2007 and the third will be placed in 2009) to evaluate noise reduction qualities and pavement performance with the Arizona Department of Transportation (Arizona DOT) asphalt rubber–asphalt concrete friction course, Arizona DOT asphalt concrete friction course modified with styrene–butadiene–styrene, and a standard WSDOT 12.5-mm dense-graded hot-mix asphalt. This paper focuses on pavement surface life and quantifies the reduction and sustainability of tire–pavement-related noise for the project placed in 2006. Initial findings suggest that the OGFC noise reduction benefits quickly diminish as a result of increased surface wear caused by studded tires.

Performance in the Project Trailer

It is a well-established fact that construction is a complex process that involves technical and personal skills and requires many entities to work together to achieve a successful result. For that reason, formal partnering on construction projects in recent years throughout the United States has become a popular approach to total quality management. Although most owners and contractors agree that partnering is a benefit to project performance, sometimes project participants go through the motions without really committing to the process. The Arizona Department of Transportation has developed a sophisticated partnering evaluation system that can measure the performance of its project teams relative to their ability to work together. The result is an accurate assessment tool that can be used by all members of the project team to determine at any time during the project if a performance problem is brewing and that thereby allows the team leadership to react and take corrective action.

Enhancement of Arizona Pavement Management System for Construction and Maintenance Activities

The Arizona Department of Transportation (ADOT) has used Markovian chain–based pavement management systems (PMS) to support its pavement design, construction, and preservation activities for three decades. These systems provide a strong tool for pavement network optimization. However, the probabilistic nature of the Markovian chain model means that the systems lack the flexibility to consider the distinct conditions associated with individual pavement projects or sections. Recently, a new PMS has been developed and implemented to replace the previous PMS through a research project funded by ADOT. The new system was designed to expand the use of PMS tools to support pavement design, construction, and maintenance operations. Various relevant data, including data on inventory, traffic, pavement structural history, maintenance, and performance, have been integrated into one centralized database to support the system's functions. The system has also incorporated ADOT's overlay design procedure based on the falling weight deflectometer–based; the procedure is much desired by the pavement designers. The system provides a great deal of flexibility in allowing individual pavement sections under different conditions to be treated differently in performance prediction analysis and project prioritization. The system's functional module for statewide needs and budget analysis provides detailed and deterministic information about the selected projects such as project limits, optimal treatments, and resulting performance. However, the new system requires users to set up many parameters for the analyses; this demands a great deal of engineering experience and judgment.