1. What is a Terminal?

A Terminal or “end treatment” is a vehicle restraint system placed at the point where a side
impact crash barrier commences. The terminal is designed to attenuate the violence of a head on or side impact crash.

2. What are the dangers to the occupants of a vehicle when it crashes into an obstacle ?

The occupants unrestrained body follows the trajectory of the vehicle and smashes into the sides of the passenger compartment most often resulting in fractures and possible irreparable damage to internal organs. The body may be restrained by a seat belt but the internal organs may suffer the acceleration / deceleration effects of a crash.
The head may suffer from whiplash or hit the side of the passenger compartment.
Car manufacturers endeavour to design their vehicle passenger compartment to cater for a crash speed of up to 50 km/h. but above this speed injuries can be expected to become far more serious.

3. What are the dangers to the occupants of a vehicle when it crashes into the point where a side impact crash barrier commences which has no terminal protection ?

If the barrier is solid concrete the vehicle and the occupants could be crushed .
If the barrier is made up of one or more steel beams the vehicle and the occupants could
be speared by the unprotected beams.

4. How dangerous are slope down terminals or hand / fan terminals ?

Slope down terminals where the end is buried into the represent a slight danger where the traffic speed is less than 50 km/h because there is unlikely to be enough energy for the vehicle to drive onto them.
But at higher speeds the vehicle has far more energy and can use this type of terminal as a take off ramp i.e. fly through the air and possibly rollover as it crashes to the ground.
The hand or fan terminals are very unlikely to provide any protection even at low speeds

5. How does a Terminal work?

An efficient terminal must absorb energy and dissipate much of the energy from the impacting vehicle before the vehicle arrives at a hard point.
Some non EU systems modify the terminal absorbing structure by forming Z or curling type structures out of the steel barrier sections which can be over a metre in size.
TESI however absorbs the energy from the impacting vehicle through the plastic deformation of the hollow sections in the steel strips. These strips make up the strong metal structure which incorporates a triple overlapping wave beam capable of telescoping up as it absorbs the energy.

6. Where do you put Terminals?

The point wherever a side impact crash barrier commences.
Terminals provide protection for traffic going in one direction only.
A redirective crash cushion should be used for central reservation situations i.e. where traffic flows each side of the barrier.

7. What is meant by "redirective"?

Where errant vehicles encounter a side impact with a terminal the design of the terminal should safely redirect the vehicle towards its original course without causing serious damage to the vehicle or its occupants.

8. How do you select the right Terminal?

The selected longitudinal side impact crash barrier may have its own specified approved terminal which may also include for a transition.
However the terminal may be an independent unit which has been approved for use with the several crash barriers.
Procurers need to check whether or not impacting crash forces are transferred to the adjoining longitudinal side impact crash barrier.
TESI is an independent terminal where impacting crash forces are not transferred to the adjoining longitudinal side impact crash barrier.

9. What test criteria should a Terminal meet?

All terminals, like any crash barrier, must meet the test requirements of the EU standard ENV 1317-4 which sets out specified performance classes which demonstrate how the impacting vehicle shall perform together with the measurement of forces likely to be encountered by the vehicle occupants The tests for redirective terminals include:

• TT 1.3.110, A direct head-on crash impact (0º), car mass 1500 kg speed 110 km/h
• TT2.1.100, An offset impact on front section (0º º L veh.), car mass 900 kg ,speed 100 km/h
• TT4.3.110, A side crash impact (15º,? length), car mass 1500 kg, speed 110 km/h

10. Why are tests carried out on cars of different weights?

The 1500 kg car is the heaviest vehicle use and the impact speed of 110 km/h provides the maximum test to check the structural adequacy and the capacity of the terminal to absorb the energy under the controlled test criteria. There is also provision in the standard controlled test procedures for a 1300 kg car.
The 900 kg car is the lightest vehicle used and the impact speed of 100 km/h provides the test for checking that acceleration levels for the vehicle occupants will remain within an acceptable safe ASI criteria.

11. What is ASI?

ASI shall be computed using measurements form instruments placed in the test crash vehicle. These instruments measure acceleration / deceleration levels in three directions forwards , sideways and upwards.
ASI, which measures impact severity and possible injury to occupants, is an established
index level where :

• Level 1 is considered to be quite safe
• Level 1.4 is considered still acceptable

Vehicle restraint systems including terminals with ASI levels above 1.4 are not currently permitted by the EU standard.

12. How does the TESI^® Terminal work?

TESI^® is a modular steel structure made up of steel supports and triple wave beam external panels which when impacted by the crash vehicle telescope up into the base. The panels have grooves where bolts connect them to their supports which at the time of the crash impact run along the grooves in a sliding action.
Energy absorption is constant and the length of the terminal is designed to meet the vehicle and traffic speed requirements
The structure includes a steel cable connected to the supports and anchor posts which are driven into the ground.
When a side crash impact occurs the cable re-acts and helps to redirect the vehicle without excessive acceleration. The cable also ensures that when a head on crash impact occurs no force is transferred to the adjoining longitudinal side impact barrier

13. How is TESI^® supplied?

The TESI^® Terminal may be supplied in a kit form where the parts are assembled on site or in an assembled form ready for erection.

14. How is the TESI^® Terminal installed and how long does it take?

Installation Instructions describe the procedures and equipment required. Installation will take account of the site specific Health & Safety plan including arrangements for traffic management.
A pre-formed hard surface, as per crash barrier is required to mount the terminal on.
The installation equipment needs to include :

• Post driver for the cable anchorage posts
• Lorry mounted crane
• Small tools –shovels, spanners ,sweeping brushes etc.
• Plus 3 trained personne

The time taken is usually two hours including the time to provide the bolt couplings to the
adjoining side impact barrier but excluding the time to put up and take down the traffic
management system or to form the hard surface.

15. What maintenance is required for the TESI^® Terminal?

Maintenance instructions describe the procedures and equipment required.
An annual inspection is recommended including the cleaning and protection measures to the critical parts of the terminal which could otherwise deteriorate because of weather and pollutants.

16. How is the TESI^® Terminal repaired after a crash and how long does it?

Repair instructions describe the procedures and equipment required which will take account of the site specific Health & Safety plan including arrangements for traffic management.
The work usually involves :

• Replacement of affected blades and components
• Check and replace / reposition, if necessary, anchorage posts
• Tighten sliding bolts
• Steel cable and supports are not usually damaged but ensure that cable tension is restored
• Plus 3 trained personnel

The time taken is usually about two hours but this excludes the time to put up and take down the traffic management system.