Abstract
The relationships between design speed, operating speed, and posted speed limits are important considerations in the geometric design of highways and streets. Highway designers establish geometric design criteria by using a designated design speed. The ultimate objective is compatibility between design speed, operating speed, and posted speed limit-or speed harmony. The design speed concept is intended to result in operating speeds that are consistent with the intended function of the highway or street and are therefore favorable with respect to safety and mobility. Because AASHTO's A Policy on Geometric Design of Highway Streets recommends using design values greater than the minimum for a designated design speed and because drivers choose to operate their vehicles according to perceived physical and operational limitations present along a roadway, higher than minimum design values may result in operational inconsistencies-or speed discord. Speed discord is a condition in which the design speed is lower than the posted speed limit, lower than various operating speed measures, or both. Highway designers may not necessarily perceive such a relationship as problematic, but the public and enforcement personnel may express compliance or safety concerns for highway segments that experience speed discord. This paper provides key definitions of speed concepts used in the geometric design process and presents several case studies that demonstrate the concepts of speed harmony and speed discord.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3-11 |
| Number of pages | 9 |
| Journal | Transportation Research Record |
| Issue number | 2120 |
| DOIs | |
| State | Published - Dec 1 2009 |
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All Science Journal Classification (ASJC) codes
- Civil and Structural Engineering
- Mechanical Engineering
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Understanding speed concepts : Key definitions and case study examples. / Donnell, Eric Todd; Himes, Scott C.; Mahoney, Kevin M.; Porter, Richard J.
In: Transportation Research Record, No. 2120, 01.12.2009, p. 3-11.Research output: Contribution to journal › Article
TY - JOUR
T1 - Understanding speed concepts
T2 - Key definitions and case study examples
AU - Donnell, Eric Todd
AU - Himes, Scott C.
AU - Mahoney, Kevin M.
AU - Porter, Richard J.
PY - 2009/12/1
Y1 - 2009/12/1
N2 - The relationships between design speed, operating speed, and posted speed limits are important considerations in the geometric design of highways and streets. Highway designers establish geometric design criteria by using a designated design speed. The ultimate objective is compatibility between design speed, operating speed, and posted speed limit-or speed harmony. The design speed concept is intended to result in operating speeds that are consistent with the intended function of the highway or street and are therefore favorable with respect to safety and mobility. Because AASHTO's A Policy on Geometric Design of Highway Streets recommends using design values greater than the minimum for a designated design speed and because drivers choose to operate their vehicles according to perceived physical and operational limitations present along a roadway, higher than minimum design values may result in operational inconsistencies-or speed discord. Speed discord is a condition in which the design speed is lower than the posted speed limit, lower than various operating speed measures, or both. Highway designers may not necessarily perceive such a relationship as problematic, but the public and enforcement personnel may express compliance or safety concerns for highway segments that experience speed discord. This paper provides key definitions of speed concepts used in the geometric design process and presents several case studies that demonstrate the concepts of speed harmony and speed discord.
AB - The relationships between design speed, operating speed, and posted speed limits are important considerations in the geometric design of highways and streets. Highway designers establish geometric design criteria by using a designated design speed. The ultimate objective is compatibility between design speed, operating speed, and posted speed limit-or speed harmony. The design speed concept is intended to result in operating speeds that are consistent with the intended function of the highway or street and are therefore favorable with respect to safety and mobility. Because AASHTO's A Policy on Geometric Design of Highway Streets recommends using design values greater than the minimum for a designated design speed and because drivers choose to operate their vehicles according to perceived physical and operational limitations present along a roadway, higher than minimum design values may result in operational inconsistencies-or speed discord. Speed discord is a condition in which the design speed is lower than the posted speed limit, lower than various operating speed measures, or both. Highway designers may not necessarily perceive such a relationship as problematic, but the public and enforcement personnel may express compliance or safety concerns for highway segments that experience speed discord. This paper provides key definitions of speed concepts used in the geometric design process and presents several case studies that demonstrate the concepts of speed harmony and speed discord.
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U2 - 10.3141/2120-01
DO - 10.3141/2120-01
M3 - Article
AN - SCOPUS:76149119455
SP - 3
EP - 11
JO - Transportation Research Record
JF - Transportation Research Record
SN - 0361-1981
IS - 2120
ER -