Seguranca Rodoviaria

RESUME

In this work is exposed the development process of a road restraint system, and how the use of Concrete allows to produce High Performance Systems designed to protect us – the road users.

Key words: Security, containment, severity, energy.

1. INTRODUCTION

The roads concepcion, in order to improve security, as to predict the installation in certain areas and specific locations, of road security barriers in order to contain or reroute with safety moving vehicles for benefit of is occupants and other road users [1].

Since the 1st of January / 2011, in Portugal, as became mandatory the fulfillment of the document “EN 1317 – 5:2007 + A1:2008 Road restraint systems – Part 5: Product requirements and evaluation of conformity for vehicle restraint systems” [2].

This reference norm, defines the testing methods e CE marking for all the vehicle restraint systems installed afterwards on every road of this country (new construction, replacement, temporary, permanent, steel, concrete, In situ, pre-casted…). This obligation, as a delay in some cases of almost a decade in comparison with other countries more developed from EU (Austria, Germany, Denmark, France, Holand, among others…).

This legislation as also changed the vision from some authorities, like I.N.I.R* (Instituto Nacional de Infra-Estruturas Rodoviárias) that have elaborated the document:

*National Institute of Road Infra-Structures

- “Sistemas de Retenção Rodoviários. Manual de Aplicação” – Road Restraint Systems. Application Manual

The refered document stipulates the metology to apply in the selection of the road restraint systems to fullfill the needs required to all the projects. Aims to inform and guide every responsible managers: Project, contractor, supervisiors in order to accomplish the norm obligation.

Controlo da qualidade e desenvolvimento do produto, Betafiel S.A. [e-mail]

2. THE USE OF CONCRETE FOR BARRIERS PRODUCTION

The Concrete, as one of the most complete and versatile construction materials in the world wide, allows us to apply it in a large wide range of solutions. In this specific application, road security, and with the “EN 1317-5” as reference, DELTA BLOC® developed a precasted solution of great performance in concrete, company which is represented in Portugal by BETAFIEL S.A.(fig. 1). The use of concrete in this tested containment systems, already applied all over the Europe and World, reduces drastically the accidents consequences, as well as human and material adversitys.

It´s comproved that the main factor for an accident is most of the times caused by wrong human behaviour on roads. But still, if you add it the adverse weather conditions (fog, rain, snow, ice, wind) and also some road problems sometimes cause by lack of maintenance or bad construction, vehicles with mechanic problems that circulate on roads or even overload of traffic on infra-structures not prepared for such fluxes. Such issues make safety and prevention every day a nuclear factor in order to minimize accident problems.

Nevertheless existing several tipes and models of concrete elements used as containment barriers for road safety, the DELTA BLOC® system is diferentiated by is great performance and adaptability and one of the most complete existing systems. An innovative “New Jersey” profile was developed, with high capacity of containment and low risks of injury for the vehicle occupants (ASI(3.3)) due to is energy dissipation of impacts.

Fig. 1 –DELTA BLOC® technology

These barriers, which are always tested, are fundamental to minimize the accidents consequences, both for the passengers and vehicles, as well as for third partes envolved.

In accordance with EN 1317, in case of an accident, the road barrier as to contain and reroute the vehicle without breaktrought of its elements and without separation of any portion that can hurt or be a problem for the rest of the traffic, car passengers, workers of construction or working areas. No intrusions or deformations in the vehicle are allowed by any barrier part that can result severe injurys [3].

2.1 System advantages and features

The accreditation of a road restraint system requires a large range of performance tests (board 2). The use of concrete in its production provides several advantages when compared for example with steel barriers (fig. 2). High hardiness and strenght of concrete reinforced with a special developed tension bar connected with a patented coupling really easy to hook that provides a controlled elastic behaviour of each element and high traction for all the elements connected. In the flexible systems this also allows the deflection of the barrier and great energy absorption. In rigid and semi-rigid DB barriers, the energy absorption is ensured by other construction technologies. The “soft and heavy body” of the barrier provides also protection to motorcycles, and doesn´t contain any cutting element, sharp edges or corners that can damage or cause serious injury when there is contact with the barrier. Thought to install with simplicity and velocity so that all the works can be executed with the lowest cost possible. In case of need, by damage or other reason is also possible to remove or replace any element easily from the system in a very simple and fast operation.

Figura 2 – Metalic barrier colapsed after impact.

Although the undeniable role of concrete in a good performance of the barrier there are still counteless examples where the concrete is used incorrectely. Containment systems that doesn´t bear the vehicle when it crashes, breaking througth the barrier and invanding the reverse lane (Fig.3) and others, like non tested / non certified In situ barriers, where, whilst sometimes it maintains integrity but the Aceleration Severity Index to the vehicle occupants is sometimes fatal. These are two examples of proibitive situations for the demands required that road restraint systems have to fullfil.

Fig. 3 –A1 accident (Vila Franca de Xira) 2 de June/2011

2.2 Concrete performance

In order to ensure durability of the structure