Combining the Resources of the Existing State-Wide Roadway Databases and Interactive Highway Safety Design Model (IHSDM) to Improve the Safety of Two-Lane Rural Highways

2008 ◽  
Author(s):  
Mitsuru Saito ◽  
Kaitlin Chuo ◽  
Thomas G. Jin
Keyword(s):  
Highway Safety ◽  
Design Model ◽  
Rural Highways ◽  
Safety Design

Speed-Profile Model for Two-Lane Rural Highways

2000 ◽  
Vol 1737 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Kay Fitzpatrick ◽  
Jon M. Collins
Keyword(s):  
Highway Safety ◽  
Geometric Features ◽  
Speed Profile ◽  
Model Design ◽  
Rural Highways ◽  
Profile Model ◽  
Safety Design ◽  
Acceleration And Deceleration ◽  
Speed Prediction ◽  
Design Consistency

Design consistency refers to highway geometry’s conformance with driver expectancy. Generally, drivers make fewer errors at geometric features that conform with their expectations. A proposed method for evaluating design consistency is to predict the speed along an alignment by using a speed-profile model. A speed-profile model was developed by using the following: speed prediction equations that calculate the expected speed at horizontal, vertical, or combination curves; assumed desired speed for the roadway; TWOPAS equations that determine the performance-limited speeds at every point; acceleration and deceleration rates; and several documented assumptions. The speed-profile model can be used to evaluate the design consistency of a facility or to generate a speed profile along an alignment. In conclusion, the speed-profile model developed appears to provide a suitable basis for the Interactive Highway Safety Design Model design consistency module.

Improved speed-profile model for two-lane rural highways

2003 ◽  
Vol 30 (6) ◽  
pp. 1055-1065 ◽  
Author(s):  
Said M Easa
Keyword(s):  
Highway Safety ◽  
Extended Model ◽  
Speed Profile ◽  
Rural Highways ◽  
Profile Model ◽  
Horizontal Curves ◽  
Sight Distance ◽  
Safety Design ◽  
Speed Change ◽  
Design Consistency

The speed-profile model has been suggested as a valuable tool for evaluating geometric design consistency for two-lane rural highways with isolated and combined horizontal and vertical alignments. The model determines the operating speeds on the speed-change (SC) segment, which is the distance between speed-limiting curves. The speed-limiting curves are the horizontal curves and the limited sight-distance crest vertical curves on horizontal tangents, where the sight distance required by the design guides is not satisfied. The model assumes that deceleration begins where required, which implies that the next curve is visible when deceleration starts. This paper presents an extension to the speed-profile model to incorporate the effect of sight obstruction on operating speeds and deceleration rates. The SC segment may include nonlimited sight–distance crest vertical and sag vertical curves. These curves may present sight obstruction. A procedure to determine whether the sight line is obstructed is developed. If it does, simple formulas are applied for revising the operating-speed profile. The extended model is suitable for inclusion in the design consistency module of the interactive highway safety design model.Key words: speed profile, model, two-lane highways, alignments, design consistency.

Computational Techniques Used in the Driver Performance Model of the Interactive Highway Safety Design Model

2001 ◽  
Vol 1779 (1) ◽  
pp. 17-25 ◽  
Author(s):  
William H. Levison ◽  
Ozgur Simsek ◽  
Alvah C. Bittner ◽  
Steven J. Hunn
Keyword(s):  
Computer Aided Design ◽  
Driving Simulator ◽  
Research Area ◽  
Highway Safety ◽  
Performance Model ◽  
Design Model ◽  
Computational Techniques ◽  
Design Environment ◽  
Driver Performance ◽  
Safety Design

The Interactive Highway Safety Design Model (IHSDM) is a high-priority research area for FHWA. IHSDM is a software system for evaluating the safety of alternative highway designs in a computer-aided design environment. The initial phase of this research program is to develop IHSDM for use in the design of two-lane rural highways. IHSDM includes a driver-vehicle module that simulates the moment-to-moment actions of a single driver-vehicle unit. Reviewed are the computational approaches that have guided the implementation of the driver performance model (DPM) that along with a vehicle model and other components constitute the driver-vehicle module. Five major computational functions of DPM are reviewed: perception, speed decision, path decision, speed control, and path control. Comparison of model results with data from a driving simulator demonstrates the ability of DPM to account for the horizontal curve deflection angle on the speed profile.

Empirical Investigation of Interactive Highway Safety Design Model Accident Prediction Algorithm: Rural Intersections

2003 ◽  
Vol 1840 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Craig Lyon ◽  
Jutaek Oh ◽  
Bhagwant Persaud ◽  
Simon Washington ◽  
Joe Bared
Keyword(s):  
Research Effort ◽  
Methodological Approach ◽  
The United States ◽  
Highway Safety ◽  
Design Model ◽  
Prediction Algorithm ◽  
Parameter Estimates ◽  
Wide Range ◽  
Safety Design ◽  
The Impact

One major gap in transportation system safety management is the ability to assess the safety ramifications of design changes for both new road projects and modifications to existing roads. To fulfill this need, FHWA and its many partners are developing a safety forecasting tool, the Interactive Highway Safety Design Model (IHSDM). The tool will be used by roadway design engineers, safety analysts, and planners throughout the United States. As such, the statistical models embedded in IHSDM will need to be able to forecast safety impacts under a wide range of roadway configurations and environmental conditions for a wide range of driver populations and will need to be able to capture elements of driving risk across states. One of the IHSDM algorithms developed by FHWA and its contractors is for forecasting accidents on rural road segments and rural intersections. The methodological approach is to use predictive models for specific base conditions, with traffic volume information as the sole explanatory variable for crashes, and then to apply regional or state calibration factors and accident modification factors (AMFs) to estimate the impact on accidents of geometric characteristics that differ from the base model conditions. In the majority of past approaches, AMFs are derived from parameter estimates associated with the explanatory variables. A recent study for FHWA used a multistate database to examine in detail the use of the algorithm with the base model-AMF approach and explored alternative base model forms as well as the use of full models that included nontraffic-related variables and other approaches to estimate AMFs. That research effort is reported. The results support the IHSDM methodology.

Interactive Highway Safety Design Model: Issues Related to Driver Modeling

1998 ◽  
Vol 1631 (1) ◽  
pp. 20-27 ◽  
Author(s):  
William H. Levison
Keyword(s):  
Decision Processes ◽  
Highway Safety ◽  
Design Model ◽  
Accident Analysis ◽  
Policy Review ◽  
Federal Highway ◽  
Safety Design ◽  
Design Consistency ◽  
And Control ◽  
Geometric Designs

The Federal Highway Administration has undertaken a multiyear project to develop the Interactive Highway Safety Design Model (IHSDM), which is a set of software tools to analyze candidate highway geometric designs from a safety standpoint. The IHSDM is envisioned to contain five analysis tools or “modules”: (1) policy review, (2) design consistency, (3) accident analysis, (4) traffic analysis, and (5) driver/vehicle analysis. The structure of the driver/vehicle module is reviewed, with emphasis on the driver component. Modeling issues regarding decision and control are discussed. Major issues include (1) perceptual and decision processes in planning speed and path profiles during curve approach and curve negotiation, and (2) nonlinear versus linear aspects of control.

scholarly journals ESTIMACIÓN DEL NIVEL DE SERVICIO DE UN CARRIL LENTO

2016 ◽  
Author(s):  
Víctor Gabriel Valencia Alaix ◽  
Alfredo García García
Keyword(s):  
Travel Speed ◽  
Highway Safety ◽  
Design Model ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Percent Time ◽  
Safety Design ◽  
Percent Time Spent Following

La operación vehicular en una carretera convencional depende de la atención adecuada de los adelantamientos de los vehículos lentos por parte de los más rápidos; una alternativa es mediante la provisión de carriles auxiliares a lo largo de la vía antes de pasar a una carretera multicarril.El objetivo es calibrar el modelo de simulación TWOPAS y aplicarlo en una carretera convencional española para estimar y comparar el nivel de servicio estimado en ella y en un carril lento con el resultado del procedimiento del Highway Capacity Manual - HCM.Se observó la operación vehicular en una carretera convencional de España mediante el registro a través de cámaras de control dispuestas a lo largo de la carretera, y en el carril lento, de manera que sirvió para calibrar el modelo de microsimulación TWOPAS considerando parámetros operacionales del parque automotor y aplicándolo para estimar el nivel de servicio.Se aplicó el procedimiento del HCM para estimar el nivel de servicio en segmentos de carretera con carril lento para comparar sus resultados con los obtenidos en la simulación.El modelo de simulación usado fue el TWOPAS, inserto en el Traffic Analisys Module (TAM) del Interactive Highway Safety Design Model (IHSDM), cuyos resultados en términos de Percent Time Spent Following (PTSF), Average Travel Speed (ATS) y otros permite la evaluación operacional.Los resultados y conclusiones permiten valorar la utilidad del modelo, la correspondencia de la realidad operacional en carretera y la norma española y la conveniencia operacional del carril lento estudiado.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4220

Estimating Safety by the Empirical Bayes Method: A Tutorial

2002 ◽  
Vol 1784 (1) ◽  
pp. 126-131 ◽  
Author(s):  
Ezra Hauer ◽  
Douglas W. Harwood ◽  
Forrest M. Council ◽  
Michael S. Griffith
Keyword(s):  
Professional Practice ◽  
Empirical Bayes ◽  
Highway Safety ◽  
Design Model ◽  
Bayes Method ◽  
Safety Improvement ◽  
Safety Design ◽  
Empirical Bayes Method ◽  
History Of ◽  
Safety Estimation

The empirical Bayes (EB) method addresses two problems of safety estimation: it increases the precision of estimates beyond what is possible when one is limited to the use of a 2- to 3-year accident history, and it corrects for the regression-to-mean bias. The increase in precision is important when the usual estimate is too imprecise to be useful. The elimination of the regression-to-mean bias is important whenever the accident history of the entity is in some way connected with the reason why its safety is estimated. The theory of the EB method is well developed. It is now used in the Interactive Highway Safety Design Model and will be used in the Comprehensive Highway Safety Improvement Model. The time has come for the EB method to be the standard and staple of professional practice. The study’s goal is to facilitate the transition from theory into practice.

Research on highway accident prediction based on interactive highway safety design model

2021 ◽  
Author(s):  
Shi-lun Zheng ◽  
Yun-wei Meng ◽  
Hong-qi Cai ◽  
Jian-qun Luo ◽  
Shi-quan Sun
Keyword(s):  
Highway Safety ◽  
Design Model ◽  
Accident Prediction ◽  
Safety Design

scholarly journals Uso del módulo de predicción de accidentes (CPM) del IHSDM para evaluación de seguridad en segmentos de carreteras de dos carriles

Respuestas ◽  
2013 ◽  
Vol 18 (2) ◽  
pp. 87-95 ◽  
Author(s):  
Yasmín Andrea Pérez-Rojas
Keyword(s):  
Highway Safety ◽  
Design Model ◽  
Seguridad Vial ◽  
Federal Highway ◽  
Safety Design

El presente documento plantea una alternativa para la evaluación de la seguridad en carreteras rurales de dos carriles en Colombia, dada la ausencia de este tipo de prácticas en la ingeniería de vías Colombianas. Por lo anterior, se aborda a profundidad el Módulo de Predicción de Accidentes (CPM CrashPrediction Module) del programa IHSDM (Interactive Highway Safety Design Model) de FHWA (Federal Highway Administration, agencia del departamento de transporte de Estados Unidos), adoptado ampliamente en otros países para evaluar la seguridad vial. De este modo, se presenta la descripción de las principales características del módulo CPM para el pronóstico de accidentes en segmentos de carreteras sin considerar los ocurridos o relacionados a las intersecciones, los algoritmos del modelo de predicción, la información que se requiere para el uso del módulo y la propuesta metodológica para lograr que Colombia consolide una base de datos suficiente para el uso y aplicación del módulo. Por último, se analizan los resultados obtenidos por el módulo CPM.Palabras clave: CPM, IHSDM, Modelo Predictivo de accidentes viales, seguridad vial.

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