The safety value of guardrails and crash cushions: A meta-analysis of evidence from evaluation studies

doi:10.1016/0001-4575(95)00003-I

Accident Analysis & Prevention

Volume 27, Issue 4, August 1995, Pages 523-549

https://doi.org/10.1016/0001-4575(95)00003-I Get rights and content

Abstract

Evidence from 32 studies that have evaluated the safety effects of median barriers, guardrails along the edge of the road, and crash cushions (impact attenuators) is summarized by means of a metaanalysis. Two hundred and thirty-two (232) estimates of safety effects are included in the meta-analysis. The presence of publication bias is tested by means of the funnel graph method. For most subsets of the data, no evidence of publication bias is found. Weighted mean estimates of safety effects are computed by means of the logodds method. Median barriers are found to increase accident rate, but reduce accident severity. Guardrails and crash cushions are found to reduce both accident rate and accident severity. The effects of guardrails and crash cushions on accident rate have been less extensively studied than the effects on accident severity. Current estimates of the effects on accident rate are highly uncertain because of methodological shortcomings of available studies. The effects of guardrails on accident severity are found to be quite robust with respect to study design and the number of confounding variables controlled in each study. In general, random variation in the number of accidents is the most important source of variation in study results.

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Describir la magnitud y las características de las colisiones y de los conductores/as implicados/as en colisiones frontales en carretera convencional, e identificar los factores asociados a la probabilidad de colisión frontal respecto a otro tipo de colisiones, en España, en 2007-2012.
Estudio de diseño transversal utilizando el Registro de víctimas y accidentes. Las variables dependientes fueron la colisión frontal con víctimas (sí/no) y ser un conductor implicado en colisión frontal (sí/no). Se estudiaron los factores asociados a colisión o a ser un conductor implicado en colisión frontal respecto a los otros tipos de colisión, mediante un modelo multivariado de regresión de Poisson robusta, estimando razones de proporción (RP) y sus intervalos de confianza del 95% (IC95%).
Ocurrieron 9192 colisiones frontales en carretera convencional, con 15.412 hombres y 3862 mujeres involucrados/as. Hubo una mayor probabilidad de colisión frontal respecto a otro tipo de colisión en carreteras con 7 m o más de calzada, en curvas, estrechamiento de calzada o cambios de rasante, con superficie húmeda o nevada, y durante el crepúsculo. Conducir en dirección contraria y realizar un adelantamiento indebido se asocian a colisión frontal en conductores/as. La existencia de mediana (RP = 0,57; IC95%: 0,48-0,68) o de arcén de menos de 1,5 m (PR = 0,81; IC95%: 0,77-0,86) o de 1,5 m a 2,45 m (PR = 0,90; IC95%: 0,84-0,96) se asocian a menor probabilidad de colisión frontal.
Este estudio ha permitido caracterizar las colisiones y los conductores/as implicados en colisiones frontales en carretera convencional. La menor probabilidad de colisión frontal cuando existen medianas hace recomendable su implementación como medida efectiva para disminuir este tipo de colisiones.

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PaperThe safety value of guardrails and crash cushions: A meta-analysis of evidence from evaluation studies

Abstract

Accident Analysis and Prevention

Accident Analysis & Prevention

Uheldsmønsteret på almindelige 4-sporede veje

Median barriers: One year's experience and further controlled fullscale tests

Effect of median barriers on driver behavior

Highway Research Board Bulletin

Median accident study—Long Island, New York

Highway Research Board Bulletin

Effect of parkway medians on driver behavior—Westchester County parkways

Highway Research Board Bulletin

Performance of highway traffic barriers

Metaanalyse av effektmålinger av trafikksikkerhetstiltak

Statistical methods for rates and proportions

Study of box-beam median barrier accidents

Objective criteria for guardrail installation

Highway Research Record

A review of roadside objects in relation to road safety

How effective are crash cushions in reducing deaths and injuries? Public Roads March

Guardrail installation and improvement priorities

Transportation Research Record 868

Statistical methods for metaanalysis

Crash cushion improvement priority and performance evaluation

Transportaton Research Record 1065

Methods of meta-analysis

A comparative performance study of longitudinal roadside barriers and end treatments

Paper
The safety value of guardrails and crash cushions: A meta-analysis of evidence from evaluation studies