Slip base trap
Every year numerous of fatal accidents occur on roads around the world when cars crash into traffic masts. Nearly all of these involve heavy and hard traditional traffic masts, with or without slip bases.
There are many reasons why this type of construction poses a sizeable risk.
Hard against hard
In addition to the evidence gathered from all the accidents, a number of crash tests have revealed the kinds of damage that heavy masts can cause. The reason is that heavy and massive steel masts are incapable of absorbing the kinetic energy (energy of motion) created in the instant of crash. The violent forces that are released collapse the car frame, endangering the lives of the driver and passengers.
Masts made of fibreglass and composite materials can cause many of the same injuries.
When slip bases fail to work
But will a slip base, a 30-year-old invention, prevent such injuries? In theory, yes, but a slip base does not make a massive traffic mast any more pliable. And this solution is dependent upon several factors to function.
Point of impact: If a vehicle hits too high, experience shows that the slip base or shearing joint fails to release. The same problem arises if the mast is struck from the side at a right angle to the direction it was meant for, or if the mast is placed behind a guardrail (see photos).
Bolting: Another problem occurs if the bolts are tightened too hard or if the wrong bolts are used. Then the design is not much help. This is a human-error factor that makes the installation extremely vulnerable. Who is stuck with the responsibility if this leads to a serious accident?
Rust: In time the upper and lower sides of a slip base can rust together as a single piece of material that fails to function according to intentions.
Secondary accidents
But the danger isn’t over even if the slip base separates. In a collision, a heavy steel mast can fly like a lethal projectile – possibly into oncoming traffic, where it is a severe threat to everyone in the vicinity of a collision.
The solution
A mounting number of countries have understood the problem posed by
heavy masts that are 100% dependent upon a slip base to avert a threat
against drivers and passengers. These countries make demands regarding
documentation and proper dimensions of traffic installations. In
addition they impose stringent restrictions on the use of slip bases.
All
installations at the roadside and within the road’s safety zone should
not only be approved, but also be pliable and light obstacles to crash
into in an accident. This is how Soft thinking should be applied.