11 Revision 33 October 2022
2.10 Length of MegaRail
The minimum length of MegaRail required to meet the length of need FOR
N2, H1 or H2 systems are shown on our drawing numbers MR-GA-042 &
MR-GA-043.
Where MegaRail is being erected between other VRS systems, for example
between two parapets, the minimum length can be to suit the need. EN
1317 states: the length of the safety barrier tested shall be sufficient to
demonstrate the full performance characteristic of any longer length. It does
not require a minimum length of installation.
2.11
Post Foundations
The type of post foundation used will be dictated by the ground conditions
on the site. As a general rule, soil type ground properly compacted will allow
the use of driven posts or driven foundations. The suitability of driven posts
or foundations must be established by following the SAFEROAD testing
procedure for MegaRail driven posts or foundations.
Where site conditions preclude the use of driven posts, the posts may be
surface mounted or set in concrete foundations.
When using surface mounted posts, the anchors must be proven by
applying the test loads set out in the SAFEROAD testing procedure for
surface mounted MegaRail posts. The contractor must also prove by
calculation that the foundation will resist the overturning moment and that
the posts will become plastic before any movement in the foundation occurs
at the initial type test angle as described in EN 1317.
For posts set in concrete foundations the same test criteria applies as for
driven posts. However, this does not ensure a survivable foundation. A
compliant foundation which will pass the soil test can move under impact
such that it may need to be replaced when the VRS is repaired.
We recommend that survivable foundations are designed and installed
wherever practical. We would suggest this is clarified with the scheme
designers.
3. Li
mitations on Use
MegaRail VRS must be installed in accordance with this manual, current
MegaRail drawings, BS EN 1317, series 400 MCHW, CD377, CD127, TD 9
and
Refer to CD377, MR-GA-42 & MR-GA-43 for minimum lengths.
Refer to section 5.8 for installation on curves
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