1. The Tacoma Narrows Bridge. In class we discussed a mathematical model that might expalin the collapse of the Broughton Bridge as a column of soldiers marched across it. It does not explain the collapse of the Tacoma Narrows Bridge, however, as that was caused by torsional, or twisting, oscillations. Consider a roadway of width 2L hanging between two suspended cables, as pictured below. (This...

BACKGROUND Sudden cardiac death (SCD) is a major source of mortality and is the first manifestation of heart disease for the majority of cases. Thus, there is a definite need to identify risk factors for SCD that can be modified at the population level. Exposure to traffic, measured by residential roadway proximity, has been shown to be associated with an increased risk of cardiovascular diseas...

Pricing of roadways opens doors for infrastructure financing, and congestion pricing seeks to address inefficiencies in roadway operations. This paper emphasizes the revenue-generation opportunities and welfare impacts of flat-tolling schemes, standard congestion pricing, and credit-based congestion pricing policies. While most roadway investment decisions focus on travel time savings for exist...

BACKGROUND Living near major roadways has been linked with increased risk of cardiovascular events and worse prognosis. Residential proximity to major roadways may also be associated with increased risk of hypertension, but few studies have evaluated this hypothesis. METHODS AND RESULTS We examined the cross-sectional association between residential proximity to major roadways and prevalent h...

While rural freeways generally have lower crash rates, interactions between driver behavior, traffic and geometric characteristics, and adverse weather conditions may increase the crash risk along some freeway sections. This paper examines the safety effects of roadway geometrics on crash occurrence along a freeway section that features mountainous terrain and adverse weather. Starting from pre...

The CPA's Chemical Mass Balance Receptor Model (CMB7) was used for analysis of nonmethane hydrocarbon source-receptor relationships in the Raleigh, North Carolina Metropolitan Statistical Area (MSA). Three hour integrated ambient samples collected 15 km southeast of downtown Raleigh from 5-8 AM weekdays during August, 1993 were analyzed for speeiated hydrocarbons and used as inputs in the model...

This paper predicts and compares the carbon monoxide (CO) concentration levels along Sembulan Road for years 2004 and 2014 using CAL3QHC air dispersion model at two major locations, i.e., at Sembulan Roundabout and Sutera Harbour Intersection, Kota Kinabalu, Sabah, Malaysia. The CO concentration “hot-spots” were also identified at Sutera Harbour Intersection, and the highest maximum 1-hr averag...

Finding a least-cost-path in a raster data format is a useful function in geographical information systems. However, existing algorithms are often inadequate for practical roadway planning. This paper improves conventional algorithms by including the considerations of spatial distances, anisotropic costs and the presence of bridges and tunnels in the paths. This new algorithm is implemented in ...

Abstract: A stochastic-computational scheme is presented for generating as-is graph structure spanning complex local geographics. In this schematics, GPS tracks uploaded by a multitude of probe vehicles are exploited to expand a network of feasible roadway patterns. By associating the GPS tracks with a multitude of Brownian motions conditioned by landmark allocation, the graph structure is succ...

In recent years, there has been an abundance of research that has used Poisson models and its variants (negative binomial and zero-inflated models) to improve our understanding of the factors that affect accident frequencies on roadway segments. This study explores the application of an alternate method, tobit regression, by viewing vehicle accident rates directly (instead of frequencies) as a ...