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.

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.

Speeds of Cars on Horizontal Curves

1998 ◽  
Vol 1612 (1) ◽  
pp. 42-47 ◽  
Author(s):  
Vojo Andjus ◽  
Mihailo Maletin
Keyword(s):  
Free Flow ◽  
Flow Conditions ◽  
Passenger Cars ◽  
Design Standards ◽  
Rural Roads ◽  
Horizontal Curves ◽  
Road Design ◽  
Realistic Approach ◽  
Actual Design ◽  
Design Speed

Revision of existing Yugoslav road-design standards, specifically in the area of road-design speed definition, required studying driver behavior in free-flow conditions in order to define drivers’ responses to the radii of horizontal curves. A specific approach with variable design speed for horizontal curves is discussed and is supported by speed measurements on roads. The pilot research was undertaken on several test sites on Yugoslav two-lane rural roads to collect reliable speed data related to characteristics of horizontal curves. Characteristics of test sites, experimental procedures, data collected, and results of data analyses are described. It is concluded that speeds of free-flow passenger cars show good correlation with radii and that actual design policy with a constant design speed underestimates speeds in radii less than 250 m. Thus, the variable design speed concept is a more realistic approach. Further research on more test sites is recommended.

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.

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.

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 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.

scholarly journals Speed Models for Motorcycle Riders for Two-lane Rural Roads

2021 ◽  
Vol 17 ◽  
pp. 595-603
Author(s):  
Panagiotis Lemonakis ◽  
George Botzoris ◽  
Athanasios Galanis ◽  
Nikolaos Eliou
Keyword(s):  
Prediction Models ◽  
Flow Speed ◽  
Operating Speed ◽  
Rural Roads ◽  
The Road ◽  
Horizontal Curves ◽  
Road Geometry ◽  
Speed Prediction ◽  
The Subject ◽  
On The Road

The development of operating speed models has been the subject of numerous research studies in the past. Most of them present models that aim to predict free-flow speed in conjunction with the road geometry at the curved road sections considering various geometric parameters e.g., radius, length, preceding tangent, deflection angle. The developed models seldomly take into account the operating speed profiles of motorcycle riders and hence no significant efforts have been put so far to associate the geometric characteristics of a road segment with the speed behavior of motorcycle riders. The dominance of 4-wheel vehicles on the road network led the researchers to focus explicitly on the development of speed prediction models for passenger cars, vans, pickups, and trucks. However, although the motorcycle fleet represents only a small proportion of the total traffic volume motorcycle riders are over-represented in traffic accidents especially those that occur on horizontal curves. Since operating speed has been thoroughly documented as the most significant precipitating factor of vehicular accidents, the study of motorcycle rider's speed behavior approaching horizontal curves is of paramount importance. The subject of the present paper is the development of speed prediction models for motorcycle riders traveling on two-lane rural roads. The model was the result of the execution of field measurements under naturalistic conditions with the use of an instrumented motorcycle conducted by experienced motorcycle riders under different lighting conditions. The implemented methodology to determine the most efficient model evaluates a series of road geometry parameters through a comprehensive literature review excluding those with an insignificant impact to the magnitude of the operating speeds in order to establish simple and handy models.

scholarly journals Quantifying the Effects of Visual Road Information on Drivers’ Speed Choices to Promote Self-Explaining Roads

2020 ◽  
Vol 17 (7) ◽  
pp. 2437
Author(s):  
Yuting Qin ◽  
Yuren Chen ◽  
Kunhui Lin
Keyword(s):  
Field Experiments ◽  
Prediction Models ◽  
Semantic Segmentation ◽  
Qualitative And Quantitative ◽  
Road Design ◽  
Driving Speed ◽  
Road Geometry ◽  
Controlling Variables ◽  
The Right ◽  
Road Characteristics

Roads should deliver appropriate information to drivers and thus induce safer driving behavior. This concept is also known as “self-explaining roads” (SERs). Previous studies have demonstrated that understanding how road characteristics affect drivers’ speed choices is the key to SERs. Thus, in order to reduce traffic casualties via engineering methods, this study aimed to establish a speed decision model based on visual road information and to propose an innovative method of SER design. It was assumed that driving speed is determined by road geometry and modified by the environment. Lane fitting and image semantic segmentation techniques were used to extract road features. Field experiments were conducted in Tibet, China, and 1375 typical road scenarios were picked out. By controlling variables, the driving speed stimulated by each piece of information was evaluated. Prediction models for geometry-determined speed and environment-modified speed were built using the random forest algorithm and convolutional neural network. Results showed that the curvature of the right boundary in “near scene” and “middle scene”, and the density of roadside greenery and residences play an important role in regulating driving speed. The findings of this research could provide qualitative and quantitative suggestions for the optimization of road design that would guide drivers to choose more reasonable driving speeds.

Analytical Model for Sight Distance Analysis on Three-Dimensional Highway Alignments

1996 ◽  
Vol 1523 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Yasser Hassan ◽  
Said M. Easa ◽  
A. O. Abd El Halim
Keyword(s):  
Three Dimensional ◽  
The Finite Element Method ◽  
Horizontal Curve ◽  
Design Standards ◽  
New Model ◽  
Distance Analysis ◽  
Horizontal Curves ◽  
Sight Distance ◽  
Proposed Model ◽  
Standards And Guidelines

Existing sight distance models are applicable only to two-dimensional (2-D) separate horizontal and vertical alignments or simple elements of these separate alignments (vertical curve, horizontal curve). A new model is presented for determining the available sight distance on 3-D combined horizontal and vertical alignments. The model is based on the curved parametric elements that have been used in the finite element method. The elements presented are rectangular (4-node, 6-node, and 8-node elements) and triangular. These elements are used to represent various features of the highway surface and sight obstructions, including tangents (grades), horizontal curves, vertical curves, traveled lanes, shoulders, side slopes, cross slopes, superelevation, lateral obstructions, and overpasses. The available sight distance is found analytically by examining the intersection between the sight line and the elements representing the highway surface and the sight obstructions. Application of the new model is illustrated using numerical examples, and the results show that existing 2-D models may underestimate or overestimate the available sight distance. The proposed model should be valuable in establishing design standards and guidelines for 3-D highway alignments and determining the effect of various highway features on sight distance.

Sign in / Sign up

Export Citation Format

Share Document