Design Speed, Operating Speed, and Posted Speed Survey

1996 ◽  
Vol 1523 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Kay Fitzpatrick ◽  
Brian Shamburger ◽  
Dan Fambro
Keyword(s):  
Functional Class ◽  
Warning Signs ◽  
Speed Limit ◽  
Operating Speed ◽  
Worst Case ◽  
Highway Design ◽  
Horizontal Curves ◽  
Design Speed ◽  
Transportation Departments ◽  
The City

At some locations, the posted speed limit, based on 85th percentile operating speed, exceeds the roadway's design speed. This situation is a result of the fact that criteria used in highway design incorporate a significant factor of safety, that is, roadways are designed for near worst-case conditions. When this situation occurs, however, liability concerns can arise although drivers can safely exceed the design speed. A mail-out survey for state, city, and county transportation departments was conducted to document concerns and difficulties the engineering profession is experiencing with the relationships among design speed, operating speed, and posted speed. The factors most frequently considered when selecting design speed are anticipated operating speed and/or posted speed; however, these were not the most common factors selected by respondents. Urban versus rural and functional class were selected more often by the state respondents, whereas cross section was selected more often by the city/county respondents. Most respondents indicated that a ball bank indicator is used to set advisory speeds on horizontal curves. Many respondents expressed the desire to have a new procedure for selecting advisory speeds. Several agencies acknowledged that they have or have had sites with an operating speed greater than the design speed. The most frequent action taken was to install advance warning signs. Few respondents stated that they reduce the posted speed limit to match the design speed. Although few lawsuits involving the posted speed/design speed issue have occurred, liability concerns still exist. Several respondents provided comments that indicated their concern with current definitions and procedures.

scholarly journals Evaluation of Horizontal Curve Radius Effect on Driving Speed in Two Lane Rural Road. Pilot Study

2020 ◽  
Vol 15 (4) ◽  
pp. 252-270
Author(s):  
Mindaugas Šeporaitis ◽  
Viktoras Vorobjovas ◽  
Audrius Vaitkus
Keyword(s):  
Pilot Study ◽  
Prediction Models ◽  
Speed Limit ◽  
Operating Speed ◽  
Horizontal Curve ◽  
Design Standards ◽  
Horizontal Curves ◽  
Road Design ◽  
Driving Speed ◽  
Design Speed

This paper presents a case study of driving speed at horizontal curves in the regional road. The literature review of operating speed at horizontal curves in regional roads expresses the difference between design speed and driving speed. Driving speed was measured in ten horizontal curves on regional road No. 2610. Collected data was compared to the design speed, various design standards, and Operating Speed Prediction Models for traffic in low-volume roads. Based on result analysis, was proposed initial adjusted minimum radius of the horizontal curve based on operating speed. It is justified that proposed corrections based on operating speed ensure a credible speed limit effect on road safety. The performed experiment showed different tendencies comparing measured driving speed with permitted and design speeds. It was determined that dependent on specific curved section drivers tend to exceed posted speed limit from 17% to 98% of cases, and from 41% to 100% − the design speed in the horizontal curve. This research led to identifying the limitations of experimental research methodology. These limitations are related to experimental Site selection with different combinations of alignment elements, traffic, and accident data. A pilot study showed significant results and gave essential insights into the full-scale research plan. The results are expected to benefit both other researchers and the organisations responsible for the development and implementation of normative technical documents for road design.

scholarly journals KELIO TRASOS HORIZONTALIŲJŲ KREIVIŲ ĮTAKA TRANSPORTO SRAUTO GREIČIUI / INFLUENCE OF ROAD ALIGNMENT HORIZONTAL CURVE ON TRANSPORT FLOW OPERATING SPEED

2019 ◽  
Vol 11 (0) ◽  
pp. 1-7
Author(s):  
Mindaugas Šeporaitis ◽  
Viktoras Vorobjovas
Keyword(s):  
Road Network ◽  
Operating Speed ◽  
Horizontal Curve ◽  
The Road ◽  
Horizontal Curves ◽  
Legal Documents ◽  
Transport Flow ◽  
Design Speed ◽  
Side Friction ◽  
Curve Selection

Geometric parameters of road alignment are fundamental elements defining permissible speed and vice versa. Unlike permissible speed, determined operating speed in upgrade projects has a significant impact on the safe movement of transport on the roads. The article reviews the composition of the regional road network in Lithuania, the design speed, the permitted speed, the practical problems of applying the geometry parameters of the road alignment according to the legal documents valid in Lithuania, methods of horizontal curve selection in Lithuania and other countries are analysed in more detail. Comparative initial calculations of horizontal curves were performed using different side friction coefficients. Review summary of analysis conducted and statements are prepared for discussion.

Assessment of horizontal curves of an existing road using reliability concepts

2005 ◽  
Vol 32 (6) ◽  
pp. 1030-1038 ◽  
Author(s):  
Tomás Echaveguren ◽  
Marcelo Bustos ◽  
Hernán de Solminihac
Keyword(s):  
High Impact ◽  
Point Of View ◽  
Maximum Speed ◽  
Operating Speed ◽  
Skid Resistance ◽  
Operational Conditions ◽  
Horizontal Curves ◽  
Margin Of Safety ◽  
Design Speed ◽  
Curve Radius

Horizontal curves on road are commonly analyzed under design speed point of view, where it is assumed that the maximum speed of a vehicle in a curve is the design speed. The empirical evidence has demonstrated that when the design speed is low, the operating speed tends to be higher. This happens because of an available remaining lateral (or transverse) friction for speeds over design speed. This condition is determined by a speed limit, obtained from the demand and supply equilibrium of friction of a pavement. The difference between operating and design speeds is usually considered as the margin of safety of a horizontal curve on a road. In this study, a methodology to determine the margin of safety of an existing curve is proposed. The methodology is based on the reliability theory by which reliability of operational conditions can be analyzed by using a reliability index as a margin of safety. A case study for light vehicles is evaluated to determine high impact variables over reliability, such as, macrotexture, skid resistance, curve radius, and superelevation. The results obtained in this study demonstrated that curve radius, skid resistance, and macrotexture are variables with high impact over failure probability. In constrast, superelevation has little effect on the failure probability.Key words: reliability, horizontal curves, operating speed, skid resistance, pavement texture.

A model for estimating advisory speeds for horizontal curves in two-lane rural roads

2013 ◽  
Vol 40 (12) ◽  
pp. 1234-1243 ◽  
Author(s):  
Tomás Echaveguren ◽  
Sergio Vargas-Tejeda
Keyword(s):  
Field Data ◽  
Lateral Acceleration ◽  
Operating Speed ◽  
Bank Angle ◽  
Rural Roads ◽  
Horizontal Curves ◽  
Driving Speed ◽  
The Difference ◽  
Advisory Speed ◽  
Design Speed

Horizontal curves are designed using a design speed, which is the speed used to determine the geometric features of highways. In sharp curves, drivers sometimes exceed the design speed. Depending of the difference between design speed and operating speed, drivers can face risky situations, which can be mitigated using signs informing drivers of advisory speeds. Advisory speeds at the horizontal curves are normally estimated as a function of the lateral acceleration for a maximum driving speed, at which comfort is low. This paper proposes an analytical model to estimate advisory speeds based on ball-bank readings and consistency concepts. Field data were obtained using a digital ball-bank indicator, an accelerometer, and a GPS logger. Readings were obtained on 24 test sections at speeds between 40 and 110 km/h. The model proposed yields an advisory speed value and a limit ball-bank angle that require consistent behavior of drivers.

scholarly journals An application of direct method and ball-bank indicator method to determine advisory speeds for horizontal curves in Vietnam

2020 ◽  
Vol 14 (1) ◽  
pp. 136-145
Author(s):  
Do Duy Dinh ◽  
Le Tien Dung
Keyword(s):  
Traffic Safety ◽  
Direct Method ◽  
Speed Limit ◽  
Operating Speed ◽  
Horizontal Curve ◽  
Indicator Method ◽  
Horizontal Curves ◽  
Road Signs ◽  
The World ◽  
Advisory Speed

Advisory speed signs on horizontal curves have been widely used in many countries over the world to improve traffic safety; however these road signs have not been applied in Vietnam. This paper aims to use the direct method and ball-bank indicator one to determine advisory speeds for 10 horizontal curves all with speed limit of 60 km/h on National Highway No. 4A in Lang Son province. The results showed that, advisory speeds were determined by the ball-bank indicator method ranging from 40 to 45 km/h for curves with radius of 70 m or less and from 50 to 55 km/h for curves with radius varying from 75 m to 120 m. As compared to the ball bank indicator method, advisory speeds determined by the direct method were 0 – 5 km/h higher if using 85th percentile speeds of cars, but 5 – 10 km/h lower if using average speeds of trucks. Keywords: advisory speed limit; operating speed; horizontal curve; ball-bank indicator; traffic safety.

Safety at Curves and Road Geometry Standards in Some European Countries

1996 ◽  
Vol 1523 (1) ◽  
pp. 99-106 ◽  
Author(s):  
Thierry Brenac
Keyword(s):  
Urban Areas ◽  
National Standards ◽  
European Countries ◽  
Design Standards ◽  
The Road ◽  
Horizontal Curves ◽  
Road Design ◽  
Road Geometry ◽  
Design Speed ◽  
Curve Geometry

This paper deals with safety at horizontal curves on two-lane roads outside urban areas and the way the road design standards of different European countries account for this safety aspect. After a review of some research results, the main aspects of curve geometry and the curve's place in the horizontal alignment are analyzed. The main conclusions are that the traditional design speed approach is insufficient and that formal complementary rules in road design standards, especially to improve compatibility between successive elements of the alignment, must be introduced. If such complementary rules already exist in some national standards, they are neither frequent nor homogeneous throughout the different countries, and it seems that they are not based on sufficiently developed knowledge.

Evaluation of the 30km/h speed limit trial in the City of Yarra, Melbourne, Australia

2021 ◽  
pp. 1-11
Author(s):  
B. Lawrence ◽  
B. Fildes ◽  
L. Thompson ◽  
J. Cook ◽  
S. Newstead
Keyword(s):  
Speed Limit ◽  
The City

scholarly journals A Proposed Framework for Identification of Indicators to Model High-Frequency Cities

2021 ◽  
Vol 10 (5) ◽  
pp. 317
Author(s):  
Ahmad M. Senousi ◽  
Junwei Zhang ◽  
Wenzhong Shi ◽  
Xintao Liu
Keyword(s):  
Urban Studies ◽  
Traffic Congestion ◽  
High Frequency ◽  
Urban Policy ◽  
Low Frequency ◽  
Highway Design ◽  
City Life ◽  
Cultural Affiliation ◽  
Internal Mobility ◽  
The City

A city is a complex system that never sleeps; it constantly changes, and its internal mobility (people, vehicles, goods, information, etc.) continues to accelerate and intensify. These changes and mobility vary in terms of the attributes of the city, such as space, time and cultural affiliation, which characterise to some extent how the city functions. Traditional urban studies have successfully modelled the ‘low-frequency city’ and have provided solutions such as urban planning and highway design for long-term urban development. Nevertheless, the existing urban studies and theories are insufficient to model the dynamics of a city’s intense mobility and rapid changes, so they cannot tackle short-term urban problems such as traffic congestion, real-time transport scheduling and resource management. The advent of information and communication technology and big data presents opportunities to model cities with unprecedented resolution. Since 2018, a paradigm shift from modelling the ‘low-frequency city’ to the so-called ‘high-frequency city’ has been introduced, but hardly any research investigated methods to estimate a city’s frequency. This work aims to propose a framework for the identification and analysis of indicators to model and better understand the concept of a high-frequency city in a systematic manner. The methodology for this work was based on a content analysis-based review, taking into account specific criteria to ensure the selection of indicator sets that are consistent with the concept of the frequency of cities. Twenty-two indicators in five groups were selected as indicators for a high-frequency city, and a framework was proposed to assess frequency at both the intra-city and inter-city levels. This work would serve as a pilot study to further illuminate the ways that urban policy and operations can be adjusted to improve the quality of city life in the context of a smart city.

Sign in / Sign up

Export Citation Format

Share Document