A Study of Factors Influencing Traffic Speeds
Author(s):
N.J. Rowan, C.J. Keese
Publication Date:
1961
Abstract:
This report was developed from a research project conducted by the TTI in cooperation with the Texas Highway Department. The over-all objectives of the research project were (1) to evaluate the effectiveness of speed limits established by present practices and (2) to develop new or more substantial criteria for the establishment of speed zones. This report covers the second phase of the research and deals specifically with an evaluation of factors influencing the drivers' selection of speed.|The first part of this report deals with a study of factors which influence traffic speeds in areas of transition from rural to urban conditions. In these areas the measurable factors can generally be categorized into three basic groups. These groups are: (1) roadway geometries, (2) characteristics of development, and (3) traffic conditions.|Two study techniques were used to measure speeds in transition areas: (1) Individual Vehicle Speed Study Method, and (2) Test Car Method .|The studies pointed up several roadway and development characteristics which influenced traffic speeds. The most significant were: (1) horizontal and vertical curves, (2) sight distance, (3) changes in roadway cross-section, (4) commercial development, and (5) appearance of residential development.|Several studies involving 12- and 24-hour speed observations were conducted to determine the influence of changing traffic conditions on traffic speeds. These studies showed that speeds were subject to only minor variations during the hours of normal traffic operation.|Other studies were concerned with the influence of radar enforcement operations on traffic speeds. These studies showed that enforcement operations caused appreciable speed reductions, but the influence did not extend beyond four miles on either side of the enforcement unit.
Report Number:
RP-17(04)
Electronic Link(s):
Document/Product
http://tti.tamu.edu/documents/RP-17-04.pdf
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