Methodologies for Estimating Advisory Curve Speeds on Oregon Highways

摘要

This report reviews an Oregon research effort to evaluate the identification and marking of advisory speeds on Oregon highways. In particular, this research effort focused on the implications of modified advisory speed thresholds and identification procedures following the most recent and the upcoming MUTCD and the Traffic Control Devices (TCD) Handbook recommendations. The primary objectives of this research effort were to help identify the basis for the current and proposed advisory speed posting procedures (with specific attention to the horizontal curve location on rural roads and passenger vehicle condition), to evaluate Oregon placement strategies at a variety of locations, and to identify potential criteria for establishing advisory speeds for these curved sections on Oregon highways. Included with this evaluation is an assessment of associated costs for implementation of a modified advisory speed policy in Oregon. Through the use of both manual and digital ball-bank devices, the report identifies compliance of current and future advisory speed thresholds for both State- and county-maintained roads, expected costs for upgrading State-maintained facilities, evaluation of alternative computational methods, and an assessment of the differences observed between the two different ball-bank devices.