Chapter 7: Traverses

Question 1

What is a traverse?

Answer 1

A barrier intended primarily to intercept the high velocity fragments from an explosive event on one side and prevent the initiation of explosives stored on the other.

Question 2

What may be used as a traverse?

Answer 2

Natural ground features
Artificial earth mounds
Reinforced concrete and masonry walls
A combination of these types

Question 3

Is it essential for a traverse to survive an explosion?

Answer 3

No - a traverse may be completely destroyed in an explosion, but its design must be such that it will stop or sufficiently slow down high velocity fragments before it collapses.

Question 4

What is the primary function of a traverse?

Answer 4

The prevention of initiation of explosives by high velocity fragments.

Question 5

What are the secondary functions of a traverse ?

Answer 5

a) To protect personnel from high velocity missiles
b) To intercept fragments
c) To shield an ES from blast and flame

Question 6

Where should a traverse be located in relation to the PES/ES it protects?

Answer 6

As close as possible to either the PES or ES. Ideally the traverse toe or face should be positioned 1m from the stack of explosives, or wall of any building it protects.

Question 7

Why might a traverse be positioned a greater distance from the PES/ES it protects?

Answer 7

The requirements of access for stock and/or building maintenance
For HD 1.1, where a traverse may be undermined by the potential crater, or the NEQ exceeds 75,000 kg HD 1.1, the traverse should be moved outwards to avoid undermining.

Question 8

What is an alternative to moving the traverse further away from the PES/ES it protects?

Answer 8

The thickness of the traverse can be increased in proportion to the quantity of explosives so that at least 2/3 of its base is excluded from the crater.

Question 9

What are the four types of traverse?

Answer 9

1-Receptor Traverse
2-Interceptor Traverse
3-Container Traverse
4-Screening Traverse

Question 10

What is the function of a Receptor Traverse?

Answer 10

Protects the explosives within the ES it surrounds from direct attack by low angle high velocity fragments and debris projected from an explosion in an adjacent PES.

Question 11

When should a Receptor Traverse be used for ES?

Answer 11

Where the explosive quantities are too large for an interceptor Traverse at the PES to be effective.

Question 12

Where should a Receptor Traverse be sited?

Answer 12

As close as possible to the ES it is protecting.

Question 13

What is the function of an Interceptor Traverse?

Answer 13

It is designed to protect explosives at the ES from direct attack by low angle, high velocity fragments.

Question 14

Where should an Interceptor Traverse be sited?

Answer 14

Close to the ES.

Question 15

What is the essential requirement for an Interceptor Traverse?

Answer 15

The Traverse can be undermined by the crater and destroyed by the blast loading, but it must remain in position long enough to intercept and retard fragments before it collapses.

Question 16

What is the function of a Container Traverse?

Answer 16

To contain the high velocity fragments projected from an explosion within.

Question 17

What does a Container Traverse protect?

Answer 17

It protects personnel and ES in the vicinity from the effects of an internal explosion, and therefore must remain substantially intact after an explosion.

Question 18

Why may a Container Traverse only be used around certain Process Building and small stacks of explosives?

Answer 18

Because it must remain substantially intact after an explosion, which is practical only for small quantities of explosives less than 1000kg.

Question 19

What is the function of a Screening Traverse?

Answer 19

It acts as a screen between the PES and ES to intercept fragmentation at a higher angle than is normal for a traverse.

Question 20

Where should a Screening Traverse be sited?

Answer 20

It may be situated at the ES, but is more effective if situated at the PES.

Question 21

If located at a PES, what other requirements must the Screening Traverse meet?

Answer 21

It must be high enough to intercept all fragments projected at 40 degrees or less.
It must remain substantially intact after an explosion.

Question 22

Where is the 40 degree line measured from?

Answer 22

The centre of the top of the explosives stack if the roof is lightweight.

From the centre of the roof if it is not lightweight construction.

Question 23

Why is proper traverse geometry essential?

Answer 23

To reduce the risk of high velocity fragments or debris escaping above or around the ends of the traverse.

Question 24

What should the minimum width of a traverse be at the level of the maximum height of the explosives?

Answer 24

2.4m

Question 25

What is the length of a traverse subject to?

Answer 25

An overriding minimum extension of 1m at each end of the traverse on all traversed sides of the PES.

Question 26

If a traverse does not completely surround the PES it protects, how far is it to extend?

Answer 26

Sufficiently beyond the sides of the PES to eliminate any potential lines of sight to other PES/ES, without any reduction in overall height.

Question 27

What gradient should a traverse slope be constructed to?

Answer 27

No steeper than 1:2, or 26 degrees from the horizontal so as to ensure the stability of the materials.

Question 28

What material must a traverse not contain and why?

Answer 28

Rubble from demolished building or any other similar material due to the enhanced risk of projection hazard.

Question 29

What preventative measures should be in place in a traverse?

Answer 29

To prevent the burrowing or rabbits or similar creatures.

Question 30

For temporary expediency ie on Ops, What materials may be used for an improvised traverse?

Answer 30

Hesco-Bastion walls
Titan water tank barriers
Splinter Protection Units/Pendine blocks
Unmortared autoclaved aerated concrete block
Stocks of non-explosive components
Explosives of HD 1.4 in certain circumstances (see Chapter 11).

Question 31

A traverse built with a vertical side facing a launch platform may be used to minimise the hazards from directional weapons provided:

Answer 31

a) the IE has approved the type and method of construction
b) it is positioned at right angles to the most probable line of fire
c) the length of the barrier encompasses an arc of 5 degrees either side of the probable line of fire
d) the height of the barrier exceeds the height of the probable line of fire or point of impact by 1m.

Question 32

What are the 6 constructional designs of traverses?

1 of 3

Answer 32

Type I
Double slope earth mound.

Type II
Single slope vertical face earth mound (or partial vertical face mound).

Question 33

What are the 6 constructional designs of traverses?

2 of 3

Answer 33

Type III
Steep double slope earth mound or ‘Chilver’ type.

Type IV
‘Bunker’ building or ‘combined’ traverse. This includes fully buried buildings not more than 600mm below ground level.

Question 34

What are the 6 constructional designs of traverses?

3 of 3

Answer 34

Type V
Wall traverses constructed of brick, reinforced concrete and composite construction.
Type VI
Natural features of site e.g. hillocks. These are to be the same as a Type I at a minimum size.

Question 35

Which traverse constructional designs are most common and why?

Answer 35

Types I, II and III as they can function in all 4 protective roles (Interceptor, Receptor, Container and Screening)

Question 36

In order of preference, what materials should a traverse be constructed from?

Answer 36

Well graded sand
Well graded gravelly or clayey or silty sand
Inorganic fill