Breakaway Posts

by:

Michael S. Stenko
President, Transpo Industries

Breakaway or frangible posts should be used on all posts located close to the road. The use of these breakaway or frangible devices will make the posts less rigid thereby safer when impacted by an errant motorist.

Full scale crash testing, required by the new proposed NCHRP 350 update in the United States, has shown that some multiple post sign panel designs currently in use are not capable of resisting the forces exerted when one of the support posts is impacted. The result is the inability of the impacted post fuse/hinge plates to activate, which could cause the failure of all of the remaining frangible bases. It is critical for safety that a multiple post sign should remain standing and be supported by the posts not impacted. The post fuse/hinge plates are critical components in the resultant change in velocity of the vehicle and passengers.

Research is needed to study the structural characteristics of ground mounted sign panels that are currently installed on multiple posts, This research should include a survey of sign panel designs currently in use and subsequent modeling of each design. Simulation crash testing should be performed with both the small car and pickup truck. Simulation should be verified by full scale crash testing. The final report would result in minimum sign panel design criterion for use on multiple post ground mounted signs with either breakaway posts or base assemblies with fuse/hinge plates.

How do we get this research funded and started?

Mike Stenko has over 25 years in the industry and has been with Transpo for over 16 years. He is a member of TRB, ACI, ASCE, Chairman of ACI Comm. on Polymers Concrete. Sub-Comm. Chair of AASHTO/AGC/ARTBA Taskforce 13 Subcommittee on highway signs and luminaries.

The Importance of Updated Standards for Roads

by: Mario Ledierman
M.J. Ledierman & Associates

There many topics to add to the road safety activities of the IRF but one of the most important issues from my point of view, and considering the experience I have on the road network in most of the Latin American countries, is the lack of standards to use for the geometric design of a highway or in many cases to avoid minimum standards related with road traffic safety.

That issue is not only a problem in most of the Latin American countries. It is also a problem in the USA and many countries of the "first world".

There are AASTHO´s standards regarding the width of shoulders (depending on the number of lanes in each direction), etc. So why don’t the geometric design engineers follow those standards?

There are many cases in which the problem of widening a road in terms of lanes would sacrifice the width of the shoulders. I believe it is more important to have a road with right and left shoulders keeping the width in each case depending on the number of lanes in each direction.

I have seen same problem in toll roads (access to the city of Buenos Aires) and in a freeway from La Guardia Airport to the City of N.Y.

What is more important – a wider road or a safer road?

As an example: two young boys were killed in a traffic accident on one of the toll roads in Argentina a few months ago. Their car experienced some mechanical failures and they had to stop the car on the left lane of the highway because there was no shoulder. Before the driver could alert the following drivers, a car crashed into the back of the stopped vehicle.

Who is responsible? The highway department that authorized the design? The professional engineer who did the design? The concessionaire, who without caring about safety, built the road without a left shoulder? Or the economical reasons to increase the amount of tolls and to keep the road at an acceptable traffic level?

Same thing applies to many roads in the USA and around the world.

Are we going to accept such things?