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Certain curves have been widely used in highway design engineering. The most common and important of these curves is the Bloss curve and it is important to investigate the existence of new Bloss curves for computer-aided geometric design (CAGD). In this paper, we consider certain curves that are very well known in CAGD and check the suitability of such curves in highway design engineering. © 2022, Institute of Mathematics. All rights reserved.

The aim of this study is to analyze the influence of horizontal geometric design and vehicle operation on fuel consumption and gas emissions produced by passenger cars. Continuous speed data were collected along 15 two-lane rural road sections. Different horizontal alignment indexes and operational variables were obtained. Fuel consumption and gas emissions were estimated by applying the VT-Micro model. The results showed that Curvature Change Rate and average speed have a significant impact on average fuel consumption and gas emissions. Finally, different regression models were calibrated based on these variables to estimate fuel consumption [l/100 km] and emissions [gr/km]. These results could be the basis to incorporate environmental sustainability principles into road design guidelines, since currently they do not take into account the environmental impact related to highway geometric design.

Easa, S., & Dabbour, E. (2005). Establishing design guidelines for compound horizontal curves on three-dimensional alignments. Canadian Journal of Civil Engineering, 32(4), 615-626., In current design guides, the minimum radii of compound horizontal curves are based on the design require- ments of simple horizontal curves for each arc on flat terrain. Such a design ignores the effects of compound curvature and vertical alignment. This paper uses computer simulation software to establish the minimum radius requirements for compound curves, considering these effects. The actual lateral acceleration experienced by a vehicle negotiating a two- dimensional (2-D) simple curve is recorded as a base scenario to facilitate the analysis of a compound curve on a flat terrain or combined with vertical alignment (three-dimensional (3-D) compound curves). The vertical alignments exam- ined include upgrades, downgrades, crest curves, and sag curves. Mathematical models for minimum radius require- ments were developed for flat and 3-D compound curves. Three types of design vehicles were used. The results show that an increase in the minimum radius ranging from 5% to 26% is required to compensate for the effects of both compound curvature and vertical alignment