post script
A little background is necessary especially where runway length and weights are involved. When the Shelco/Arup consortium developed the idea of high value low volume tourism with SHG as its development partner there were bound to be raised eyebrows. Who they?
Actually the idea had its merits, it was well-researched though costings were skimped and they had the civil engineering side of Boeing on board. [Yes they do other things besides build aircraft].
What Shelco badly misunderstood was how SHG would handle what could be taken as an intimation that the Castle was not up to its job or had fallen asleep at the wheel. The reaction of SHG was predictable to Castle watchers.
What Shelco proposed was twin runways, arranged in a Vee with 2200 metres facing into the prevailing wind and a cross runway of 1810 metres. The opposite direction of the longer runway was impossible because of terrain and cloud cover but on St Helena because of its geographical location and Southern latitude the wind only blows one way. [On Ascension it is even more one sided].
The point is that on 99% of occasions the long runway is available for take-off and the shorter landing runway is available 95% of the time for North-South operations. If the cross-wind so dictates then 5% of the time it will be South-North. From the runway length there flows how much depth of construction is necessary for the expected traffic. Over to Prof Overrun.
Picture in your mind 2200 metres for take-off and 1810 metres for landing. The significance of 1810 metres is that a 58676kg landing weight [eg A319-100] needs that much. The crucial factor was Runway End Safety Area or RESA. Ideally according ICAO this should be 240 metres at each end but the power to relax this recommendation lies in the hands of the Governor and is mediated through ASSI. Shelco repeatedly sought assurances that there was no objection to 160 metres of RESA at either end.
Now here come the twist. The Shelco proposal is predicated on not having to fill Dry Gut. If you insist on 240 metre RESAs then the project becomes unaffordable as far as Shelco is concerned and any partnership is off.
Here I can only conjecture; SHG wanted no part of a risk-sharing enterprise because a) it made them look foolish having a commercial upstart upsetting their colonial ways and b) with SHG it is my way or the highway.
So what happened?
The worst of all worlds – ASSI changed their minds or had their minds change for them, in came 240 metre RESAs and entailing colossal earthworks so huge that the cost scuppered all thoughts of the twin Vee runways. Shelco wanted no further part of the airport.
I wonder how SHG will spin this if the next round of consultants propose this for an idea. Remove 80 metres of gravel and substitute 80 metres of extra concrete, always handy for those wind-shear and float moments. After all Basil Read have already paid for the first 240 metres to be concrete out of their own pockets making it a displaced threshold, solid all the way. Yes SHG would look foolish and Basil Read would undoubtedly put in a claim. And then Shelco might be justified in saying so SHG put in all that unnecessary fill for Dry Gut and if you had followed our suggested alignment not only would you have two runways but they would have been longer with less environmental impact and much less cost to the public purse.
The airport was built so that Saints could come and go, people would not die for want of a passing ship. Relatives could visit the aged and infirm without having to tender one’s resignation. And high value low volume tourism could open the door for enterprise of all sorts.
Thank you for your concerns.