I am commenting as an American underrun victim/survivor and international truck safety activist. I am a truck underride survivor so will be commenting on Vision Zero and Safe System, TUBS (Truck Underrun Barriers), and truck or trailer mounted attenuators. I am also interested in safe and forgiving roadsides and the types of roadways and speeds involved in rear underrun truck crashes as these are all inter-related. There is strong support of these Vision Zero or Safe System holistic approaches to highway safety, you cannot separate the roadway and road hardware and rules from underrun guard design and effective use. We must move the formulation of roadway safety systems from political frameworks to roadway and vehicle engineering science collaborations. It is long overdue for the U.S. and Europe to also join the modern age and incorporate truck underride guard testing into the MASH testing system.
“In a Safe System, if a road user travels in accordance with all traffic laws and on a safe road in a safe vehicle, but finds through no fault of their own they become involved in a crash, the crash should not result in death or serious injury. Similarly, if a driver does make an error then a Safe System should react to minimize the consequences of the error. In a Safe System, the regulatory system should strongly discourage socially unacceptable road use behavior. Thus all road user training and behavior management, vehicle development and regulation, and road design and traffic management systems should be considered as a holistic inter-related system and governed according to this paradigm.
The Safe System comprises four major interconnected elements: safe use, safe roads and roadsides, safe vehicles and safe speeds.” We believe Vision Zero based systems will be the norm around the world and are already taking hold in the U.S., better late than never. We believe this integrated holistic approach improves safety outcomes and moves us to an forever improving system of road related on vehicle crash testing such as used in the MASH system in the U.S. where we can integrate NCAP type testing of underrun barriers. Testing of on-vehicle rear underrun guards at IIHS showed that failed tests accelerate improvement of safety technology, those that passed tests will not be improved as the need for improvement is not shown to the public. Real crash tests at speeds beyond safety equipment’s easily achievable capability provide ongoing public pressure for improvement such as NCAP testing has shown for cars.
The FHWA Office of Safety considers that a 100 km/h (62.2 mph) crash test is representative of worst case run-off-road crashes. If we test at real world crash speeds we will get underride protection that performs at these speeds, crash attenuators tested at 100 km/h (62.2 mph) perform beyond these speeds. Real crash tests give visual results to a non-technical public that 50 years of technical rules could not give public knowledge of real performance and thus also failed to give the public the knowledge necessary to push for safety improvements. We must relate real world crash speeds and types of roadways to our testing equation, if we fail to relate roadway types and crash speeds we end up testing for success of hardware rather than to meet real world needs. Low-speed crash tests do not test for real world needs.
We are concerned that political considerations are having an impact on test speeds and road users protected for side impacts. The cost difference is minimal for side protection strong enough for real world crashes with cars, side swipe lane changes and jack-knife crashes are too common. Most children die in cars. We have seen in the U.S. even bike only guard manufacturers agree that 48 km/h (30 mph) would be easily achievable and these guards already exist, we would recommend a minimum strength requirement for side guards of 50 kN rather than a bike only 1 kN or 2 kN. We believe in crash compatibility of all vehicles and road user types. We believe extending guards from the truck or trailer rear planes will become the norm due to energy-saving boat tails on trailers so extending underrun guards to increase available stroke distance to absorb crash energy at higher speeds will make practical and economic sense.
Moving guards away from the truck body plane by 500 mm or more increases effective crash speed to our recommended 100km/h for high-speed crash tests. The added stroke distance is an easy solution for higher speed guards and high-speed public testing would encourage quick designs and working solutions. Major truck and trailer manufacturers have used this extended guard equation in their future guard designs for 20 plus years.
“The size of an energy-absorbing truck front structure directly correlates to the survivable closing speed between car and truck in head-on collisions (e.g. 75 km/h (46 mph) survivable closing-speed requires a 400 mm long energy-absorbing structure, 90 km/h (56 mph), requires 800 mm (2.6 feet)).” From Volvo Report
Chalmers Car-to-Truck Frontal Crash Compatibility
Increasing the length of the HC (Honeycomb shaped front nose underrun guard) increases the critical impact speed
To 95 km/h (59 mph) with a 300 mm – length HC structure (+27%)
To 102 km/h (63 mph) with a 600 mm – length HC structure (+36%)
To 107 km/h (67 mph) with a 900 mm – length HC structure (+43%)
Vehicle types and mass, real world crash speeds and roadway types, and crash testing for failure rather than easy success will equal rapid improvements for safety. Increasing roadside hardware energy absorption and providing wide forgiving roadsides all improve safety as an holistic inter-related system. Crash types such as parked roadside crashes require multiple improvements. NCAP type testing will provide visual safety information to an usually technically poorly informed public, sales pressure will speed technical improvements. Australia has lead for twenty years or more in the world underrun guard regulation efforts. Instituting underrun guards into MASH type testing regime will speed world adoption of these improved crash testing systems and save lives around the world.