1,721,048 research outputs found
Prediction method of real discount rate to improve accuracy of life-cycle cost analysis
No full textThis study proposes a method to predict the real discount rate i for use in life-cycle cost analysis (LCCA) of buildings because i is compounded to adjust future value to present value. The method combines a multivariate time series and stochastic variability analysis. The value predicted using this method achieved higher prediction accuracy than when the past average value of i was used. The average value of past data has been generally applied to i in previous studies and actual work. Especially, the accuracy was improved when old data that differ greatly from recent data were excluded, and the stochastic variability analysis improved the prediction accuracy when the variability of the past data was large. The proposed method was applied to a case project to select exterior glass on the basis of LCCA. Initial investment over 10 years predicted by the presented Method was about 5% higher than the average value of past data. The proposed method can contribute to accurate decision-making because the cost that corresponds to 5% of initial investment increases as the initial investment increases. The method may also be useful to estimate other factors such as electric and gas charges for LCCA. (C) 2016 Elsevier B.V. All rights reserved.1151Nsciescopu
State-of-practice Technologies on Accelerated Urban Highway Rehabilitation: I-15 California.
No full textThis case study paper presents an innovative fast-track approach applied to a heavily trafficked urban freeway reconstruction project in Southern California. Badly deteriorated truck lanes in both directions along a 4.5-km stretch of I-15 were rebuilt from the gravel base up. The operations, estimated to take 10 months using traditional nighttime closures, were completed in two 9-day continuous closures with round-the-clock (about 210 h for each direction) operations. This "Rapid Rehab" project adopted state-of-practice technologies to accelerate construction, mitigate traffic disruptions, and propagate project information. As a result, traffic demand through the construction work zone was reduced by 20% and the maximum peak-hour delay was reduced by 50%. The estimated benefits of accelerated reconstruction on this project included a 28% reduction in agency cost and 29% time value savings to road users, compared to the traditional approach of using repeated nighttime closures. Web surveys showed dramatic changes in public perception of the Rapid Rehab approach from initial reluctance and objection to positive support.X111112sciescopu
Automated work zone information system an urban freeway rehabilitation - California implementation
No full textIn October 2004, about 9 lane km of deteriorated truck lanes on Interstate 15 at Devore in Southern California was rebuilt during 18 days with extended one roadbed full-closures with the counterflow traffic system and 24-h construction operations. The project implemented the automated work zone information system (AWIS) to reduce peak hour delay during construction by changing road user's travel patterns and diverting traffic to detour routes. This paper describes the design, performance, and validation of AWIS with monitored traffic data before and during construction used. The AWIS was installed to provide road users with real-time travel information so that they could avoid traffic delays in the construction work zone (CWZ) corridor. Travel times through the CWZ were estimated from speed data and enhanced in two ways: (a) portable and permanent changeable message signs on site and (b) off-site (project website) implementation with travel time messages, traffic snapshots, and video streaming. AWIS travel time was estimated at 90% of actual travel times as measured by probe vehicles. The peak hour traffic demand through the CWZ was reduced by up to 18%, with significant volume increases to detour freeways. The AWIS operation contributed to a decrease in the maximum delay for weekday peak hours (from expected 90 min to measured 50 min on average during construction). The outcome of this study will help transportation agencies and practitioners efficiently design and operate AWIS for highway rehabilitation under high traffic volume.open112sciescopu
Fast-Track Construction for Concrete Pavement Rehabilitation: California Urban Highway Network
No full textThis case study presents an innovative fast-track reconstruction approach applied to a heavily trafficked Long-Life (30-plus years) Pavement Rehabilitation Strategies (LLPRS) project on 1-15 in Devore in Southern California. A 4.5-km stretch of badly damaged concrete truck lanes was rebuilt over two 215-h (approximately 9-day) periods with one-roadbed full closures with counterflow traffic and around-the-clock (24 h per day/ 7 days per week) construction operations. The same project would have taken 10 months to complete with traditional nighttime closures. State-of-practice technologies were adopted on this Rapid Rehab project to accelerate construction, mitigate traffic disruptions, and propagate project information. From the initial planning and design stages, engineers used CA4PRS (Construction Analysis for Pavement Rehabilitation Strategies) software incorporated with traffic simulation models to develop an optimal and economical rehabilitation scenario. Post-construction data validated the preconstruction analysis and simulation estimates of productivity and traffic delays. Because of the implementation of an Automated Work Zone Information System and proactive public outreach, a 20% reduction in traffic demand through the construction work zone was achieved and thereby reduced the maximum peak hour delay to a "tolerable" level. Surveys on the project website showed dramatic changes in public perception of the Rapid Rehab extended closures approach from initial reluctance and objection to positive support. Advantages of using this method of fast-track accelerated highway reconstruction included less traffic disruption for the traveling public, longer (more than 30 years) pavement life expectancy, improved safety for motorists and workers, and reduced agency cost compared with the traditional approach using repeated nighttime closures.open111sciescopu
Computer simulation model: Construction Analysis for Pavement Rehabilitation Strategies.
No full textMost state highways in the United States were built during the 1960s and 1970s with an infrastructure investment of more than $1 trillion. They now exceed their 20 year design lives and are seriously deteriorated. The consequences are high maintenance and road user costs because of degraded road surfaces and construction work zone delays. Efficient planning of highway rehabilitation closures is critical. This paper presents a simulation model, Construction Analysis for Pavement Rehabilitation Strategies (CA4PRS), which estimates the maximum amount of highway rehabilitation/reconstruction during various closure timeframes. The model balances project constraints Such as scheduling interfaces, pavement materials and design, contractor logistics and resources, and traffic operations. It has been successfully used on several urban freeway rehabilitation projects with high traffic volume, including projects on I-10 and I-710. The CA4PRS helps agencies and contractors plan highway rehabilitation strategies by taking into account long-life pavement performance, construction productivity. traffic delay, and total cost.X113139sciescopu
Planning urban highway reconstruction with traffic demand affected by construction schedule
No full textThis paper introduces an integrated approach to the development of construction and traffic management plans for the reconstruction of high-volume urban freeways. The Devote project, which rebuilds a 4.2 km stretch of the deteriorated concrete pavement (truck lanes) on Interstate-15 (I-15) in San Bernardino County in southern California, is used as a case study. Alternative closure timing, closure duration, and number of closed lanes were compared to identify the best rehabilitation strategy for the Devore reconstruction project. The perspectives of construction schedule, traffic inconvenience (road user cost and maximum delay), and agency costs were considered. The analysis concluded that full closure of one roadbed with counter-flow traffic during repeated three or four continuous weekdays, utilizing round-the-clock reconstruction operations, was the best strategy for both the public and the sponsoring agency. A delay in the start of construction from Spring to Fall 2004 is expected to cause a 5% seasonal traffic increase, which will result in a $4.5 million increase in road user cost and a 20% increase in maximum queue delay per closure.X117sciescopu
Productivity Aspects of Urban Freeway Rehabilitation with Accelerated Construction.
No full textOver the last 5 years the California Department of Transportation (Caltrans) has completed three experimental long-life urban freeway rehabilitation projects by utilizing a fast-track (accelerated) construction approach of around-the-clock operations under extended closure. This paper presents the fast-track rehabilitation approaches and the as-built production rates of major rehabilitation operations monitored at the three experimental projects. The monitoring results show that the contractor's production rates varied considerably depending upon the construction logistics, material delivery and hauling methods, lane-closure tactics, and/or pavement designs being implemented. A higher production rate and a noticeable "learning-curve effect" were observed when full-width rehabilitation was compared with partial-width rehabilitation, when continuous lane reconstruction was compared with random slab replacements, and when full roadbed closures were compared with partial lane closures. Findings in this study suggest that Caltrans should evaluate project-specific conditions and constraints, which might restrict use of a preferred rehabilitation scheme, by taking production rate variances into account when establishing schedule baselines of construction staging plans and incentive/disincentive contracts for urban freeway rehabilitation projects.X1163sciescopu
Accelerated Pavement Rehabilitation and Reconstruction with Long-life Asphalt Concrete on High-trafficked Urban Highway.
No full textRehabilitation of urban highways is a critical issue confronting the California Department of Transportation because the state has a significant inventory of overaged, heavily trafficked urban highways showing extensive signs of distress. This paper presents the innovative pavement rehabilitation technologies and techniques that the agency applied in the first asphalt concrete (AC) project for its Long-Life Pavement Rehabilitation Strategies (LLPRS) program. A 4.4-km stretch of deteriorated concrete pavement on 1-710 in Long Beach was rehabilitated successfully with 230 mm of AC overlay or 325 mm of full-depth AC replacement during eight 55-h weekend closures. The pilot project proved that the accelerated (fast-track) rehabilitation with 55-h weekend closures is a viable option that can drastically shorten the overall construction time and lessen the negative effects of construction in an urban area. The project also proved that AC pavement designed to provide a design life of 30-plus years can be constructed in a series of weekend closures even on the most heavily loaded truck route in the state. The construction-monitoring study indicated that contractor productivities were noticeably improved (through the learning effect) as weekend closures were repeated. In addition, the pay factor clause in the contract effectively encouraged the contractor's awareness of quality. The traffic measurements study showed that traffic operated at free-flow speeds throughout the surrounding highways and arterial roads during the construction weekends. It is expected that the construction and traffic management techniques adopted in this project will be used in LLPRS projects on California urban highways with high-traffic volumes.open111sciescopu
Knowledge-based Scheduling Analysis Software for Highway Rehabilitation and Reconstruction Projects.
No full textMost of California's highway infrastructure was built between 1955 and 1970. These pavements had 20-year design lives, and many now require frequent maintenance. In 1998, the California Department of Transportation (Caltrans) launched the Long-Life Pavement Rehabilitation Strategies (LLPRS) program to rebuild approximately 2,800 lane kilometers of high-traffic-volume urban freeway in the 78,000-lane kilometer state highway network over a 10-year period. Priorities identified for the successful implementation of LLPRS projects are the selection of construction schedules and the development of traffic management plans that minimize road user and agency costs. This paper presents a construction simulation program called CA4PRS (Construction Analysis for Pavement Rehabilitation Strategies). The program was developed as a scheduling and production analysis tool for LLPRS projects for use during the planning and design stages. CA4PRS estimates the optimized distance and duration of highway rehabilitation projects. It takes into account the constraints of scheduling interfaces, pavement design, lane closure tactics, and contractor logistics. As a knowledge-based computer system on a Microsoft Access database, it uses Monte Carlo simulation, critical path method analysis, and linear scheduling. CA4PRS is designed to help highway agencies and paving contractors make construction schedule decisions that balance rehabilitation productivity, traffic inconvenience, and agency cost. Application of the CA4PRS model to urban freeway rehabilitation projects in California, including the I-10 Pomona, I-710 Long Beach, and I-15 Devore projects, has demonstrated its value in saving millions of dollars for both Caltrans and road users.open111sciescopu
Minimizing Total Cost for Urban Freeway Reconstruction with Integrated Construction/Traffic Analysis.
No full textThis paper introduces an innovative approach to development of construction and traffic management plans for the I-15 Devore project, a fast-track urban freeway reconstruction project with high traffic volume in Southern California. The goal of this approach is to determine the most economical reconstruction closure scenario by integrating construction schedule, traffic delay, and agency cost. Construction Analysis for Pavement Rehabilitation Strategies (CA4PRS) software was used for scheduling analysis. The demand-capacity model based on the Highway Capacity Manual, and macroscopic and microscopic traffic simulation models were utilized for traffic delay analysis. Based on these analyses, the California Department of Transportation decided to implement eight 72 h weekday closures with round-the-clock operations for this reconstruction project. This was found to be more beneficial for both the agency and the traveling public than the alternative of: (1) 55 h weekend, (2) 10 h nighttime, or (3) one-time continuous closures. Our analysis concludes that the 72 h closure scenario has 77% less total closure time, 34% lower road user cost, and 38% lower agency cost when compared with the traditional nighttime closures.X1169sciescopu
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