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...

[1] The deposition and attachment mechanism of settling snow crystals during snowfall dictates the very initial structure of ice within a natural snowpack. In this letter we apply ballistic deposition as a simple model to study the structural evolution of the growing surface of a snowpack during its formation. The roughness of the snow surface is predicted from the behaviour of the time depende...

The mesoscale numerical weather prediction model MM5, the 5 generation Pennsylvania State University/NCAR Mesoscale Model, uses a global land-use map to set the physical parameters on the surface characteristics to model the soil-atmosphere processes. These parameters are albedo, emissivity, thermal inertia, roughness length and soil moisture. A new estimation of soil parameters is done for the...

Three synchronized pulsed Doppler wind lidars were deployed from May 2016 to June 2016 on the shores of a wide Norwegian fjord called Bjørnafjord to study the wind characteristics at the proposed location of a planned bridge. The purpose was to investigate the potential of using lidars to gather information on turbulence characteristics in the middle of a wide fjord. The study includes the anal...

The existence of a critical roughness height for outer layer similarity between smooth and rough wall turbulent boundary layers is investigated. Results are presented for boundary layer measurements on flat plates covered with sandgrain and woven mesh with the ratio of the boundary layer thickness to roughness height /k varying from 16 to 110 at Re =7.3 103–13 103. In all cases tested, the laye...