Infrastructure & Transportation Archives - Page 14 of 20

Efficiency Index for Fiber-Reinforced Concrete Lining at Ultimate Limit State

Fantilli, Alessandro P.; Nemati, Kamran M.; Chiaia, Bernardino. (2016). Efficiency Index for Fiber-Reinforced Concrete Lining at Ultimate Limit State. Sustainable And Resilient Infrastructure, 1(1-2), 84 – 91.

View Publication

Abstract

The fiber contribution to the ultimate limit state capacity of precast and cast-in situ tunnel linings is analytically investigated. By means of a numerical model, capable of computing the interaction curves of reinforced concrete cross sections subjected to combined compressive and bending actions, the mechanical performances of plain and fiber-reinforced concrete are compared. As a result, a new index is introduced to quantify the effectiveness of fiber addition. The higher the efficiency index, the higher the amount of steel reinforcing bar that can be removed from a plain concrete cross section. The application to real concrete linings, where shear resistance is ensured without shear reinforcement, shows that a large volume of rebar can be saved by the presence of steel fibers. This gives significant advantages in terms of durability and rapidity of tunnel construction.

Keywords

Fiber-reinforced Concrete; Efficiency Index; Ultimate Limit State; Cast-in Situ Concrete Lining; Precast Tunnel Segments

Light Rail Leads to More Walking Around Station Areas

Huang, Ruizhu; Moudon, Anne V.; Zhou, Chuan; Stewart, Orion T.; Saelens, Brian E. (2017). Light Rail Leads to More Walking Around Station Areas. Journal Of Transport & Health, 6, 201 – 208.

View Publication

Abstract

Areas around Light Rail Transit (LRT) stations offer ideal conditions for Transit-Oriented Development (TOD). Relatively dense, mixed-use neighborhoods can have positive impacts on mobility, health, and perceptions of neighborhood safety among nearby residents, primarily through walking activity for both transit and other purposes. To examine how station areas may attract new activity, this study analyzed changes in walking around station areas among people living close to an LRT station before and after the opening of a new transit system. This study examined walking behavior among the subset of 214 participants living within one mile of one of 13 LRT stations from among a sample of residents living close or further away from a new LRT line in Seattle. They completed a survey and a travel log and wore an accelerometer and a GPS for 7 days both before (2008) and after the opening of the Seattle area LRT (2010). Walking bouts were derived using a previously developed algorithm. The main outcome was the individual-level change in the proportion of daily walking within one quarter Euclidean mile of an LRT station. Overall walking decreased from before to after the LRT opening while station area walking did not change significantly, indicating a shift in walking activity to the station areas after the introduction of LRT. Increases in the proportion of station area walking were negatively related to participants' distance between home and the nearest LRT station, peaking at .0.75 mile. Male gender, college education, normal weight status, less access to cars, and frequent LRT use were also significantly associated with greater positive changes in the proportion of station area walking. The shift in walking to station areas after the completion of light rail provides evidence that the local proximate population is attracted to station areas, which may potentially benefit both transit use and TOD area economic activity. The residential catchment area for the shift in LRT area walking was < 0.75 mile of the LRT stations. (C) 2017 Elsevier Ltd All rights reserved.

Keywords

Body-mass Index; Physical-activity; Built Environment; Travel Behavior; Transit; Stop; Transit Oriented Development (tod); Behavior Change; Global Positioning Systems; Geographic Information Systems

Estimating Traffic Volume for Local Streets with Imbalanced Data

Chen, Peng; Hu, Songhua; Shen, Qing; Lin, Hangfei; Xie, Chi. (2019). Estimating Traffic Volume for Local Streets with Imbalanced Data. Transportation Research Record, 2673(3), 598 – 610.

View Publication

Abstract

Annual average daily traffic (AADT) is an important measurement used in traffic engineering. Local streets are major components of a road network. However, automatic traffic recorders (ATRs) used to collect AADT are often limited to arterial roads, and such information is, therefore, often unavailable for local streets. Estimating AADT on local streets becomes a necessity as local street traffic continues to grow and the capacity of arterial roads becomes insufficient. A challenge is that an under-represented sample of local street AADT may result in biased estimation. A synthetic minority oversampling technique (SMOTE) is applied to oversample local streets to correct the imbalanced sampling among different road types. A generalized linear mixed model (GLMM) is employed to estimate AADT incorporating various independent variables, including factors of roadway design, socio-demographics, and land use. The model is examined with an AADT dataset from Seattle, WA. Results show that: (1) SMOTE helps to correct imbalanced sampling proportions and improve model performance significantly; (2) the number of lanes and the number of crosswalks are both positively associated with AADT; (3) road segments located in areas with a higher population density or more mixed land use have a higher AADT; (4) distance to the nearest arterial road is negatively correlated with AADT; and (5) AADT creates spatial spillover effects on neighboring road segments. The combination of SMOTE and GLMM improves the estimation accuracy on AADT, which contributes to better data for transportation planning and traffic monitoring, and to cost saving on data collection.

Keywords

Average; Prediction; Network; County

Moving Toward Physical Activity Targets by Walking to Transit: National Household Transportation Survey, 2001-2017

Le, Vi T.; Dannenberg, Andrew L. (2020). Moving Toward Physical Activity Targets by Walking to Transit: National Household Transportation Survey, 2001-2017. American Journal Of Preventive Medicine, 59(3), E115 – E123.

View Publication

Abstract

Introduction: Public transportation systems can help people engage in physical activity. This study assesses sociodemographic correlates and trends in the daily time spent walking to and from transit in the U.S. from 2001 to 2017. Methods: This cross-sectional study used data from the 2001, 2009, and 2017 National Household Transportation Survey. Data were analyzed in 2019 to assess the daily level of physical activity attained solely by walking to and from transit. Regression models were used to examine predictors of daily transit-associated walking. Results: Compared with the full National Household Transportation Survey sample, transit users who walked to and from transit tended to be younger, from households earning <$25,000 per year, in areas with rail infrastructure, and did not have a household-owned car. Transit walkers spent a median of 20 minutes per day (95% CI=18.5, 21.5) walking to and from transit in 2017, compared with a median of 19 minutes (95% CI=17.5, 20.5) in 2001. Among transit walkers, daily transitassociated physical activity was 27% higher for those residing in areas with rail infrastructure (adjusted coefficient=1.27, 95% CI=1.11, 1.46) and 34% higher for those from households earning $99,999 per year (adjusted coefficient=1.34, 95% CI=1.15, 1.56). Conclusions: As documented in a growing literature, most public transit trips include at least some walking; thus, efforts to encourage transit use are favorable to public health. Continued monitoring by transportation surveys is important as new forms of mobility and changing demographics may impact future transit use and associated physical activity. (C) 2020 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

Keywords

Physical Activity; Household Surveys; Public Transit; Cross-sectional Method; Public Health; Walking; Exercise; Research Funding; Transportation; Replacing Sedentary Time; Public-transit; Travel; Mortality; Adults; Health; Work

A Global Horizon Scan of the Future Impacts of Robotics and Autonomous Systems on Urban Ecosystems

Goddard, Mark A.; Davies, Zoe G.; Guenat, Solene; Ferguson, Mark J.; Fisher, Jessica C.; Akanni, Adeniran; Ahjokoski, Teija; Anderson, Pippin M. L.; Angeoletto, Fabio; Antoniou, Constantinos; Bates, Adam J.; Barkwith, Andrew; Berland, Adam; Bouch, Christopher J.; Rega-brodsky, Christine C.; Byrne, Loren B.; Cameron, David; Canavan, Rory; Chapman, Tim; Connop, Stuart; Crossland, Steve; Dade, Marie C.; Dawson, David A.; Dobbs, Cynnamon; Downs, Colleen T.; Ellis, Erle C.; Escobedo, Francisco J.; Gobster, Paul; Gulsrud, Natalie Marie; Guneralp, Burak; Hahs, Amy K.; Hale, James D.; Hassall, Christopher; Hedblom, Marcus; Hochuli, Dieter F.; Inkinen, Tommi; Ioja, Ioan-cristian; Kendal, Dave; Knowland, Tom; Kowarik, Ingo; Langdale, Simon J.; Lerman, Susannah B.; Macgregor-fors, Ian; Manning, Peter; Massini, Peter; Mclean, Stacey; Mkwambisi, David D.; Ossola, Alessandro; Luque, Gabriel Perez; Perez-urrestarazu, Luis; Perini, Katia; Perry, Gad; Pett, Tristan J.; Plummer, Kate E.; Radji, Raoufou A.; Roll, Uri; Potts, Simon G.; Rumble, Heather; Sadler, Jon P.; De Saille, Stevienna; Sautter, Sebastian; Scott, Catherine E.; Shwartz, Assaf; Smith, Tracy; Snep, Robbert P. H.; Soulsbury, Carl D.; Stanley, Margaret C.; Van De Voorde, Tim; Venn, Stephen J.; Warren, Philip H.; Washbourne, Carla-leanne; Whitling, Mark; Williams, Nicholas S. G.; Yang, Jun; Yeshitela, Kumelachew; Yocom, Ken P.; Dallimer, Martin. (2021). A Global Horizon Scan of the Future Impacts of Robotics and Autonomous Systems on Urban Ecosystems. Nature Ecology & Evolution, 5(2), 219.

View Publication

Abstract

The future challenges and potential opportunities of robotics and autonomous systems in urban ecosystems, and how they may impact biodiversity, are explored and prioritized via a global horizon scan of 170 experts. Technology is transforming societies worldwide. A major innovation is the emergence of robotics and autonomous systems (RAS), which have the potential to revolutionize cities for both people and nature. Nonetheless, the opportunities and challenges associated with RAS for urban ecosystems have yet to be considered systematically. Here, we report the findings of an online horizon scan involving 170 expert participants from 35 countries. We conclude that RAS are likely to transform land use, transport systems and human-nature interactions. The prioritized opportunities were primarily centred on the deployment of RAS for the monitoring and management of biodiversity and ecosystems. Fewer challenges were prioritized. Those that were emphasized concerns surrounding waste from unrecovered RAS, and the quality and interpretation of RAS-collected data. Although the future impacts of RAS for urban ecosystems are difficult to predict, examining potentially important developments early is essential if we are to avoid detrimental consequences but fully realize the benefits.

Keywords

Smart City; Green Infrastructure; Automated Vehicles; Water-quality; Land-use; Cities; Opportunities; Biodiversity; Challenges; Services; Robotics; Horizon; Ecosystems; Land Use; Ecosystem Management; Transportation Systems; Strategic Management; Urban Areas

Intermodal Transfer Between Bicycles and Rail Transit in Shanghai, China

Pan, Haixiao; Shen, Qing; Xue, Song. (2010). Intermodal Transfer Between Bicycles and Rail Transit in Shanghai, China. Transportation Research Record, 2144, 181 – 188.

View Publication

Abstract

Large cities in China are building rail transit systems as part of a key strategy to address their pressing urban transportation problems. Because the high construction cost of subways and light rail limits the network density of rail transit, urban transport planners must seek effective intermodal connections between rail and other modes. This research examines the challenges and opportunities for improving the bicycle rail connection by using Shanghai as a case study. On the basis of two questionnaire surveys of rail transit riders, the research analyzes the existing mode shares of rail station access and egress trips, the underlying mechanisms for choosing among alternative modes, and the comparative advantages of the bicycle for trips that have certain distance and location characteristics. Empirical results suggest that the potential for travel improvement for rail transit riders lies primarily in the collection and distribution phases. Results point to several promising approaches to improving the bicycle rail connection and utilizing the bicycle more fully as an efficient supplement mode for the rapidly expanding urban rail transportation in China. In addition, the work can be a useful reference for cities in other countries in which rail transit development is accompanied by the continued importance of bicycles in residents' travel.

Threats to Municipal Information Systems Posed by Aging Infrastructure

Armbruster, Ginger; Endicott-Popovsky, Barbara; Whittington, Jan. (2013). Threats to Municipal Information Systems Posed by Aging Infrastructure. International Journal Of Critical Infrastructure Protection, 6(3-4), 123 – 131.

View Publication

Abstract

State and local governments across the United States are leveraging the Internet and associated technologies to dramatically change the way they offer public services. While they are motivated to capture efficiencies, the public entities increasingly rely on information systems that are dependent on energy and related civil structures. This reliance is incongruous with the widespread awareness of aging infrastructure - decaying for lack of investment - in cities across the United States. Important questions that come up in this environment of persistent expansion of the use of digital assets are the following: What threat does aging infrastructure pose to governmental reliance on computing infrastructures? How are local governments responding to this threat? Are the solutions posed appropriate to the problem, or do they pose new and different threats? This paper uses a case involving the disruption of a local government data center due to the failure of an electrical bus to illustrate how the threats of aging infrastructure grow, quietly and steadily, into emergencies, on par with the catastrophic events encountered in the context of critical infrastructure protection. The decisions precipitating the disruption are routine, borne of circumstances shared by agencies that are pressed to maintain services with scarce resources. Patterns of capital investment and management explain the emergence of crises in routine operations. If, as in the case described in this paper, deferred maintenance motivates public agents to explore private cloud services, then governments may solve several problems, but may also be exposed to new risks as they enter into arrangements from which they are unable to exit. (C) 2013 Elsevier B.V. All rights reserved.

Keywords

Aging Infrastructure; Municipal Data Center; Capital Improvement; Interdependence

Multistate Evaluation of Safe Routes to School Programs

Stewart, Orion; Moudon, Anne Vernez; Claybrooke, Charlotte. (2014). Multistate Evaluation of Safe Routes to School Programs. American Journal Of Health Promotion, 28, S89 – S96.

View Publication

Abstract

Purpose. State Safe Routes to School (SRTS) programs provide competitive grants to local projects that support safe walking, bicycling, and other modes of active school travel (AST). This study assessed changes in rates of AST after implementation of SRTS projects at multiple sites across four states. Design. One-group pretest and posttest. Setting. Florida, Mississippi, Washington, and Wisconsin. Subjects. Convenience sample of 48 completed SRTS projects and 53 schools affected by a completed SRTS project. Intervention. State-funded SRTS project. Measures. AST was measured as the percentage of students walking, bicycling, or using any AST mode. SRTS project characteristics were measured at the project, school, and school neighborhood levels. Analysis. Paired-samples t-tests were used to assess changes in AST. Bivariate analysis was used to identify SRTS project characteristics associated with increases in AST. Data were analyzed separately at the project (n = 48) and school (n = 53) levels. Results. Statistically significant increases in AST were observed across projects in all four states. All AST modes increased from 12.9% to 17.6%; walking from 9.8% to 14.2%; and bicycling from 2.5% to 3.0%. Increases in rates of bicycling were negatively correlated with baseline rates of bicycling. Conclusion. State-funded SRTS projects are achieving one of the primary program goals of increasing rates of AST. They may be particularly effective at introducing bicycling to communities where it is rare. The evaluation framework introduced in this study can be used to continue tracking the effect of state SRTS programs as more projects are completed.

Keywords

Transportation Of School Children; Physical Activity Measurement; Health Promotion; Cycling; Walking; School Children -- United States; Bicycling; Children; Commuting; Health Focus: Fitness/physical Activity; Manuscript Format: Research; Outcome Measure: Behavioral; Prevention Research; Research Purpose: Program Evaluation; Schools; Setting: School; Strategy: Skill Building/behavior Change, Built Environment; Study Design: Quasi-experimental; Target Population Age: Youth; Target Population Circumstances: Geographic Location; Physical-activity; Mental-health; Travel; Association; Validity; Mode; Bus

Cross Sectional Association between Spatially Measured Walking Bouts and Neighborhood Walkability

Hwang, Liang-dar; Hurvitz, Philip M.; Duncan, Glen E. (2016). Cross Sectional Association between Spatially Measured Walking Bouts and Neighborhood Walkability. International Journal Of Environmental Research And Public Health, 13(4).

View Publication

Abstract

Walking is the most popular choice of aerobic physical activity to improve health among U.S. adults. Physical characteristics of the home neighborhood can facilitate or hinder walking. The purpose of this study was to quantify neighborhood walking, using objective methods and to examine the association between counts of walking bouts in the home neighborhood and neighborhood walkability. This was a cross-sectional study of 106 adults who wore accelerometers and GPS devices for two weeks. Walking was quantified within 1, 2, and 3 km Euclidean (straight-line) and network buffers around the geocoded home location. Walkability was estimated using a commercially available index. Walking bout counts increased with buffer size and were associated with walkability, regardless of buffer type or size (p < 0.001). Quantification of walking bouts within (and outside) of pre-defined neighborhood buffers of different sizes and types allowed for the specification of walking locations to better describe and elucidate walking behaviors. These data support the concept that neighborhood characteristics can influence walking among adults.

Keywords

Physical-activity; Accelerometer Data; United-states; Urban Form; Land-use; Validation; Health; Transportation; Environments; Intensity; Geographic Information Systems; Residence Characteristics; Twins; Walking

GPS-Based Exposure to Greenness and Walkability and Accelerometry-Based Physical Activity

James, Peter; Hart, Jaime E.; Hipp, J. Aaron; Mitchell, Jonathan A.; Kerr, Jacqueline; Hurvitz, Philip M.; Glanz, Karen; Laden, Francine. (2017). GPS-Based Exposure to Greenness and Walkability and Accelerometry-Based Physical Activity. Cancer Epidemiology Biomarkers & Prevention, 26(4), 525 – 532.

View Publication

Abstract

Background: Physical inactivity is a risk factor for cancer that may be influenced by environmental factors. Indeed, dense and well-connected built environments and environments with natural vegetation may create opportunities for higher routine physical activity. However, studies have focused primarily on residential environments to define exposure and self-reported methods to estimate physical activity. This study explores the momentary association between minute-level global positioning systems (GPS)-based greenness exposure and time-matched objectively measured physical activity. Methods: Adult women were recruited from sites across the United States. Participants wore a GPS device and accelerometer on the hip for 7 days to assess location and physical activity at minutelevel epochs. GPS records were linked to 250mresolution satellitebased vegetation data and Census Block Group-level U.S. Environmental Protection Agency (EPA) Smart Location Database walkability data. Minute-level generalized additive mixed models were conducted to test for associations between GPS measures and accelerometer count data, accounting for repeated measures within participant and allowing for deviations fromlinearity using splines. Results: Among 360 adult women (mean age of 55.3 +/- 10.2 years), we observed positive nonlinear relationships between physical activity and both greenness and walkability. In exploratory analyses, the relationships between environmental factors and physical activity were strongest among those who were white, had higher incomes, and who were middle-aged. Conclusions: Our results indicate that higher levels of physical activity occurred in areas with higher greenness and higher walkability. Impact: Findings suggest that planning and design policies should focus on these environments to optimize opportunities for physical activity. (C) 2017 AACR.

Keywords

Built Environments; Health Research; Breast-cancer; Obesity; Neighborhood; Validation; Validity; Walking; Risk; Energetics