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- ItemComparing objective measures of environmental supports for pedestrian travel in adults(Springer Nature, 2009-11-19) Shay, Elizabeth; Rodriguez, Daniel A; Cho, Gihyoug; Clifton, Kelly J; Evenson, Kelly REvidence is growing that the built environment has the potential to influence walking--both positively and negatively. However, uncertainty remains on the best approaches to representing the pedestrian environment in order to discern associations between walking and the environment. Research into the relationship between environment and walking is complex; challenges include choice of measures (objective and subjective), quality and availability of data, and methods for managing quantitative data through aggregation and weighting. In particular, little research has examined how to aggregate built environment data to best represent the neighborhood environments expected to influence residents' behavior. This study examined associations between walking and local pedestrian supports (as measured with an environmental audit), comparing the results of models using three different methods to aggregate and weight pedestrian features. Using data collected in 2005-2006 for a sample of 251 adult residents of Montgomery County, MD, we examined associations between pedestrian facilities and walking behaviors (pedestrian trips and average daily steps). Adjusted negative binomial and ordinary least-squares regression models were used to compare three different data aggregation techniques (raw averages, length weighting, distance weighting) for measures of pedestrian facilities that included presence, condition, width and connectivity of sidewalks, and presence of crossing aids and crosswalks. Participants averaged 8.9 walk trips during the week; daily step counts averaged 7042. The three aggregation techniques revealed different associations between walk trips and the various pedestrian facilities. Crossing aids and good sidewalk conditions were associated with walk trips more than were other pedestrian facilities, while sidewalk facilities and features showed associations with steps not observed for crossing aids and crosswalks. Among three methods of aggregation examined, the method that accounted for distance from participant's home to the pedestrian facility (distance weighting) is promising; at the same time, it requires the most time and effort to calculate. This finding is consistent with the behavioral assumption that travelers may respond to environmental features closer to their residence more strongly than to more distant environmental qualities.
- ItemSmart Growth in Maryland: Looking Forward and Looking Back(2007) Frece, John; Knaap, GerritSpring of 2007 will mark the 10th anniversary of the passage of Maryland’s Smart Growth and Neighborhood Conservation Initiative; an effort designed to discourage sprawl development, foster more compact communities, protect the best remaining farms and open space in the state, and save taxpayers from the growing cost of providing services and infrastructure to serve far-flung development. Almost before its various provisions took effect in 1997 and 1998, the Maryland initiative generated interest and acclaim across the country. It received numerous awards and became the principal legacy of the program’s primary architect, former Governor Parris N. Glen- dening. Governors in other states, such as New Jersey, Colorado and Massachusetts, instituted their own “smart growth” proposals, often modeled after portions of the Maryland program. Even the popularity and wide usage of the now omnipresent phrase “smart growth” can be attributed in large part to the Maryland program. But, what has been the effect of Maryland’s Smart Growth pro- gram? Looking at it some ten years later, has it worked? Did it accomplish what it was designed to do? What have been the strengths and weaknesses of the Maryland approach, and how can lessons from the Maryland experience be used to offer a new set of policymakers in Maryland, as well as elsewhere in the nation, practical suggestions on how to make smart growth smarter?
- ItemThe Puzzle of Local Double Taxation: Why Do Private Community Associations Exist?(The Independent Review, 2009) Nelson, RobertPrivate community associations have spread quickly in many parts of the United States, even though their members must pay both association dues and local taxes for similar services. Not only do private community associations offer several advantages over traditional governance structures, but local governments often encourage developers to establish them.
- ItemGradual Rasterization: Redefining the Spatial Resolution in Transport Modeling(2014) Moeckel, Rolf; Donnelly, RickFinding the appropriate spatial resolution in modeling is a serious challenge at the beginning of every modeling project. The paper presents a methodology to adjust the spatial geography to the resolution of a network. Based on the quadtree algorithm, raster cells are generated that are dynamic in size. Smaller raster cells are used in urban areas and larger raster cells are used in low-density, rural areas. Trip tables of a travel demand model for the State of Georgia are disaggregated to this new zone system of raster cells, and assignment results validate significantly better than when using the original zone system.
- ItemComparing Driver and Capacity Characteristics at Intersections With and Without Red Light Cameras(2011) Weldegiorgis, Yohannes; Mishra, Sabyasachee; Jha, Manoj K.The primary purpose of installing Red Light Cameras (RLCs) is to improve intersection safety by discouraging motorists to cross the intersection when the signal for approaching vehicles turns red. Due to the fear of being fined when crossing an RLC equipped intersection at the onset of the red signal, many approaching vehicles may have a tendency of stopping during the yellow phase. This tendency may impact intersection capacity, which can be significant in congested transportation networks during rush hours, especially when several intersections are equipped with RLCs along a sequence of traffic signals, resulting in a disruption of traffic progression. In order to examine the driver and capacity characteristics at intersections with RLCs and compare them with those without RLCs we develop a binary probit choice model to understand driver's stop and go behavior at the onset of yellow intervals, also known as dilemma zone. Further, in order to capture the impact to intersection capacity at intersections with RLCs we develop a probabilistic computational procedure using data from ten intersection pairs (with and without RLCs) in the Baltimore area. The results indicate that, in general, RLCs reduce the intersection capacity since driver's travel behavior is influenced by the presence of the cameras. Other contributory factors for the so-called capacity reduction, such as driver population (e.g., familiar vs. unfamiliar drivers) and traffic-mix (e.g., trucks vs. passenger cars) characteristics have been left for future works.