Thanks for your replies OverRun. They are very helpful and I really appreciate you taking the time to respond to my questions.
Typically, how many layers would be needed to build up an extra 200mm of asphalt?
When strengthening a runway in this manner, does the surface ever get reclassified from being rigid to being flexible and, if so, what thickness of asphalt does there need to be for the surface to be considered to be flexible? Or will it always be considered to be a rigid surface if there is concrete under the asphalt?
A few years ago, runway 06/24 at EDI was resurfaced and I seem to recall they tried to do that in a seven hour window each night with the runway closed from 11pm to 6am. During these works, I think the runway was strengthened very slightly from 72/R/C/W/T to 74/R/C/W/T. I’m surprised BAA didn’t take the opportunity to upgrade the PCN by more than that, given all the press announcements they have made in recent years about trying to attract additional long-haul flights. If 200mm of asphalt would take the runway from PCN 74 to 108 then an increase from 72 to 74 sounds like a negligible increase to the thickness (perhaps 12mm?). Are there technical reasons why BAA couldn’t have strengthened it more at that time and, if so, how are these reasons likely to affect any future strengthening?
As regards the length of runway 06/24 at Edinburgh, it seems to be adequate for many long-haul operations, although longer would be better. If necessary, it can be extended at both ends using starter strips according to the BAA Masterplan. It would still have a displaced threshold at both ends (on 24 for noise/PSZ reasons I suspect and on 06 because of the adjacent railway embankment) but the LDA should be fine for most aircraft. The Masterplan also reserves land for a second parallel runway to the north of the River Almond which would be a similar length to the proposed extension to the existing 06/24.
At the moment;
Runway 06 has TORA of 2,556m, TODA of 2,616m, ASDA of 2,616m and LDA of 2,344m.
Runway 24 has TORA of 2,553m, TODA of 3,002m, ASDA of 2,614m and LDA of 2,347m. (447 m of clearway declared within TODA)
The maps in the Masterplan indicate that the starter strips they have in mind would result in a total surface length of perhaps 3,300m (I’ve manually scaled the extensions versus the existing runway length on the Masterplan maps) which I think might give approximately;
Runway 06 TORA of 2,800m, TODA of 2,800m, ASDA of 3,300m (but no over-run as there is likely to be jet-blast deflectors and then there is a railway embankment at the stop end), LDA 2,600m.
Runway 24 TORA of 3,300m, TODA of 3,300m, ASDA of 3,300m, LDA 2,800m
Edit: On reflection, perhaps these distances will be less due to obsticle clearance and/or other considerations.
To extend the runway beyond that would require relocating the railway line at the east end of the runway. It wouldn’t be economic to extend it the other way as it would involve re-routing the M9 motorway and clearing a lot of properties. The possible runway extensions mentioned above should be reasonably adequate for the type of long-haul routes / aircraft that EDI might attract and the main restriction for long-haul is likely to remain the PCNs unless they are strengthened.
Even without extending the runway, the length is okay for a fair number of different types of aircraft to operate the long-haul routes that EDI might attract. By “long-haul” I mean transatlantic, Middle East or further afield.
I looked at the detailed performance characteristics for the A332 on the Airbus web site and even without a runway extension this aircraft should have a range from 06/24 on a standard day of about 4,200nm at MZFW, about 5,000nm with 237 pax (typical 3-class) plus 20,000lbs of cargo and about 6,000nm with no cargo (assuming that a suitable stand can be provided). That should be fine for a good range of destinations.
A B744 has a reasonable payload/range from EDI too as does a B763 and A333. The biggest problem for EDI is the B777 series, and especially the B773ER. This pretty much rules Emirates out of EDI in the immediate future and perhaps explains why they chose GLA and NCL rather than EDI. The PCNs at these airports allow a B773ER to lift about an extra 60,000lbs or more compared to EDI, assuming ACN=PCN. This represents a lot of payload/range.
The main constraint to additional long-haul flights from EDI at the moment is not the runway length or even the PCNs of the runway and main aprons. It is the weak PCNs between taxiway alpha and the SE apron, because this is the only apron at EDI currently capable of taking any aircraft larger than a non-wingletted B763. It seems very strange that BAA would invest in three large stands on the SE apron and then not upgrade the relatively short taxiways to be sufficient strength to use the stands for long-haul operations.
In summer 2010, Japan Airlines flew charters into EDI using B744s. Having arrived with a full load of passengers, they departed empty on a short hop (for a B744) to Frankfurt. I analysed the detailed airfield performance and payload/range charts for the B744 on the Boeing website, and as far as I can tell, it should be able to depart EDI for Japan with a full load of pax. Range with 412 pax and no cargo from EDI, given the existing PCNs of the aprons and runways, is about 6,400nm for a B744ER and about 5,750nm for a standard B744; EDI-NRT is 5,010nm.
The only reason I can think that they didn't do that is because the low PCNs of the links to the stands on the SE apron prevented a high ACN departure. The ACN of a B744 operating at that weight would have been about double the PCN of the taxiways leading to the stand.
I hope that one of the first things the new owners will do will be to strengthen these taxiways to something more suitable. It’s only a few hundred metres of taxiway so the costs should not be excessive.
Since this thread started, BAA have produced a revised Masterplan for the Edinburgh Airport which substantially reduces the previous growth forecasts and pushes back the date for a second runway by 20 years. Here is a brief summary from the AirportWatch web site (source:
AirportWatch | Edinburgh Airport Master Plan released – barely changed from the draft )
The airport Master Plan is for the next 30 years, up till 2040. They anticipate passenger numbers will grow from 9 million per annum now, to 12.3 million (central forecast) by 2020. (The central forecast in the 2006 Master Plan was 17.6 million by 2020). They anticipate 20.5 million passengers per year by 2040 (the central forecast in the 2006 Master Plan was 23 million by 2030). They expect 141,300aircraft movements per year by 2020 and 200,600 per year by 2040. Cargo and mail might grow to 56,300 tonnes by 2020 and 81,900 tonnes per year by 2040. They do not anticipate “needing” a 2nd runway until 2040, but have plans to set aside land before 2040 for such a runway.
The 2006 Masterplan also anticipated procuring a large chunk of land to the SW of the existing terminal, currently occupied by the Royal Highland Agricultural Society of Scotland (RHASS) as their showground, and add further aprons and a terminal there. That plan has also been indefinitely delayed, not least because of the huge amount of money the RHASS were demanding to cover the cost of relocation.
It’s hard to know which forecast to believe; the 2006 Masterplan seemed to be very optimistic but the 2011 Masterplan seems very pessimistic. I can’t help suspecting skulduggery on the part of BAA in one or both of these Masterplans.
The ACN for the Vulcan is surprisingly low, but I was forgetting about the sixteen wheel main undercarriage (eight per leg). As you say, it spreads the weight much better than modern undercarriages. Given the runway length at EDI at that time (12/30 is about 5,900ft), the MTOW and therefore the ACN would have been limited by the runway length. Presumably if they ever needed to operate from EDI they would have taken off with a partial fuel load and topped up from a Victor or Valiant once airborne.