Sustainable bridge construction through innovative advances

Sustainability is now recognised as a key issue that must be addressed in the design, construction and lifelong maintenance of civil engineering structures. This paper briefly discusses the generic aspects of sustainability, but the main focus is its application to bridges. Motorway bridges built in the 1960s and 1970s had design lives of 120 years; many, however, were showing signs of deterioration after only 20–40 years. This led to much (ongoing) debate on the issue of initial versus full life-cycle costing. In order to address the highly complex issue of the sustainability of bridges, this paper considers the following specific areas that impinge on this important subject: the impact on sustainability of different forms of bridge construction and maintenance/repair/replacement strategies; the utilisation of innovative in situ testing equipment for assessing the long-term durability of concrete; the development of innovative structural designs for bridges that inherently have greatly extended lives at minimal, if any, additional cost.

Can publicly available webcameras and mechanical Turks be used to evaluate physical activity policy and built environment change?

Introduction: Fewer than 50% of adults and 40% of youth meet US CDC guidelines for physical activity (PA) with the built environment (BE) a culprit for limited PA. A challenge in evaluating policy and BE change is the forethought to capture a priori PA behaviors and the ability to eliminate bias in post-change environments. The present objective was to analyze existing public data feeds to quantify effectiveness of BE interventions. The Archive of Many Outdoor Scenes (AMOS) has collected 135 million images of outdoor environments from 12,000 webcams since 2006. Many of these environments have experienced BE change. Methods: One example of BE change is the addition of protected bike lanes and a bike share program in Washington, DC.Weselected an AMOS webcam that captured this change. AMOS captures a photograph from eachwebcamevery half hour.AMOScaptured the 120 webcam photographs between 0700 and 1900 during the first work week of June 2009 and the 120 photographs from the same week in 2010. We used the Amazon Mechanical Turk (MTurk) website to crowd-source the image annotation. MTurk workers were paid US$0.01 to mark each pedestrian, cyclist and vehicle in a photograph. Each image was coded 5 unique times (n=1200). The data, counts of transportation mode, was downloaded to SPSS for analysis. Results: The number of cyclists per scene increased four-fold between 2009 and 2010 (F=36.72, p=0.002). There was no significant increase in pedestrians between the two years, however there was a significant increase in number of vehicles per scene (F=16.81, p