- Posted 3 years ago

METRO In-tunnel Overheating: Problem defined… Solution proposed…

Authors: Calvin R Barrows, BSc (Hons), CEng, MICE & Sylvia J Telatycka, BA (Hons) 1.  Big Picture Findings Metro Railways, which are mixed underground/overground networks like London’s Tube, gain more heat on the surface in the summer – the source of which, rationally, can only be attributed to the sun [1] . Such mixed underground/overground networks are “open systems”, and subject to the Laws of Thermodynamics [2] . These points are absolutely fundamental to understanding all that follows and are easily verifiable. 2.  The Macro Evidence [3] Underground-only trains/networks (c.f. Glasgow, Prague and Warsaw Metros) DO NOT overheat due to operational heat, nor due to the sun, as they remain below ground. (However, it should be noted that underground only lines in a generally mixed over/underground network do NOT share the same benefits because of the Laws of Thermodynamics – but see further below!) Overground-only trains/networks (c.f. urban and intercity networks) are clearly affected by ambient surface temperatures, requiring heating in colder seasons and air conditioning [AC] when the weather becomes hotter. Such networks are not affected by operational heat loads because these are readily disbursed to atmosphere, including the heat generated and disbursed outwards by controlling summer temperatures in the saloons.  A summer cooling solution (e.g. AC) is required for passenger comfort but the failure of AC in this context potentially exposes passengers and staff to very serious health, safety and welfare risks, as past incidents have graphically shown [4] . As identified under 1., mixed underground/overground networks DO NOT share any of the above advantages because of the Laws of Thermodynamics! Overheating is seasonal: LU’s own data confirm this [5] [6] . Even Metro train carriages require heating in winter. Passengers confirm these symptoms through their seasonal choice of clothing. “Operational” heat sources, (which LU/TfL are now describing as “base load”), like braking, traction, auxiliary systems (station and tunnel), etc are year-round sources of heat load, so cannot be implicated in a seasonal problem [7] . In the earliest days of networks like London’s Tube overheating was not a problem.  It was only later, when such networks were extended overground and on into the suburbs (defined above as “mixed underground/overground networks”), that over time the increasing underground heat load was flagged up as a concern that would become a danger if not addressed.  On the London Tube in a stalled train event below ground during the hotter months, with saloon temperatures reaching 40°C+, forced ventilation (by piston effect) is absent causing passengers and staff to be exposed to unacceptable risks [8] . The effects and consequences of solar irradiation from the sun on the surface was already recognised and addressed back in the mid-1970s by Parsons Brinckerhoff [PB], in their seminal subway design handbooks and associated software [9] [10] .  [For easy reading the reference made here is to Volume 1 in its Second Edition, since in the First Edition copy that we located, published in 1975, the print is very faint and hard to read.  However, we have verified that in the relevant pages quoted, there is no difference in the actual text between the First and Second Editions.] Despite becoming the go-to resource for tunnel design, nevertheless over the last 40+ years successive rail engineers have failed to explore these heat transfer mechanisms.  By 1993 the New York Subway had air-conditioned 99% of its cars but in 2021 they still suffer from summer overheating below ground – evidencing that AC in a mixed underground/overground network environment is hardly the way forward [11] . Progress resolving this problem has been negligible and today’s generation of engineers, including LU as network operators of London’s Tube, other consultants, academics, and even PB themselves, are still narrowly focussed on “operational” heat load and especially the “brakes”.  Astonishingly, however, they have overlooked any significant operational contribution from traction, and no one seems to agree on which and to what extent all these sources are culpable [12] .  Unfortunately, through unrelenting repetition, these (erroneous) views have become widely accepted, stifling any creative, investigative efforts or constructive debate by others.  Undoubtedly, this is not a successful way to resolve such a seemingly challenging problem. 3.  Understanding the Cyclical Heat Transfer Mechanisms The sun irradiates everything exposed to it on the surface [13] , comprising: - The entire external fabric of the train, including the undercarriage; plus The entire rail track and ballast, which in turn…. Re-irradiates and convects to the undercarriage of the entire train. This summer heat from the overheated trains is dissipated into the tunnel via thermodynamic action [14] . The more specific discussions about this process and potential impact were elaborated on by PB in consultation and collaboration with the US rail industry leaders [15] [16] [17] [18] in their afore-mentioned design handbooks.  New York Subway and other US rail networks were experiencing similar problems to those of London’s Tube and when many networks in the USA were surveyed, the Southeastern Pennsylvania Transportation Authority [SEPTA] reported very explicitly that the cars on the Market Street Line were absorbing solar heat whilst above ground and bringing this heat into the subway [19] .  However, this key finding appears to have been “lost” over time and, whilst all the LU/TfL’s cooling team, their consultants and academic advisers appear to have subconsciously recognised the seasonal nature of the problem and most of the press reports have also alluded to it, no one seems to have asked the questions: “why should this be?” and “what is the mechanism that is causing it?”  Seasonal symptoms can only result from seasonal causes! 4.  The Metro Overheating Consequences The cumulative consequences of increasing tunnel heat load as summarised below is illustrated by reference to a useful infographic (Appendix H below) that clarifies the consequential outcome of solar irradiation in mixed underground/overground networks [20] . The carriages heated by the sun leave the surface sections and enter the underground tunnel section of the network. Like storage radiators they re-irradiate and convect their heat into the tunnel environment. As each individual train service begins its run along the overground and underground sections of the network and then back to its starting point, the heat load of the carriages increases cumulatively throughout the day with each new loop. As the hotter summer months progress, the heat load within the underground part of the network, carried in from the surface, also increases day on day throughout the season – until external ambient temperatures start to moderate in the autumn. 5.  The Remedial Proposals [21] There is still a prevailing and mistaken assumption in the industry that AC is a viable solution for London’s Tube.  However, AC is NOT an option in mixed underground/overground networks since its hot discharge cannot be satisfactorily vented to free air, so that this heated air is added to the overall, in-tunnel heat load [22] . Viable remedial solutions could include the following:- Solar-reflective paint, which these days can reflect up to 98% of solar irradiation (carriages, undercarriages, and non-wearing surfaces of the rails) [23] . Solar-reflective glass, which these days can already restrict about 70% of the sun’s heat passing through the train windows into the saloons [24] . Solar barriers on the undercarriage. This could be a specially designed, robust reflective paint for surfaces where oxidation of the metal may be an issue, or the chosen base material could have low oxidation properties.  “Therma-Light” manufactured by Blocksil may be an option.  It is an aerogel product in an acrylic solution.  Because aerogels disperse heat quickly, the heat cannot penetrate the surface, so keeping everything at a constant temperature.  For example, if you have a surface temperature of 170°C, with the application of 2mm of the aerogel product the reverse side will stay at a constant 39°C.  Blocksil have confirmed that reduced surface temperatures deliver pro-rata benefits [25] . Reduction of absorbed heat in the track environment could be achieved by green planting (e.g. sedum) as a protective screen for traditional ballast and sleepers [26] . It has become clear that the only effective, straightforward solutions are those that mitigate the ever-increasing heat load absorbed by the trains on the surface, and which at present is carried into the tunnel sections of the network.  These various EXISTING technologies could be readily “retro” applied and should certainly be specified at the point of manufacture going forward. 6.  Environmental / Climate Change Benefits of Remedial Proposals Network Rail’s Chief Track and Lineside Engineer, John Edgley, reporting to the House of Commons Adaptation [to Climate Change] Sub-Committee, which was examining how climate extremes affect public transport, noted service breakdown events were expected to increase four to five times by the 2050s with a predicted eight-fold increase in related costs by the 2080s [27] .  TfL’s Policy Manager for Environment, Sam Longman, also expressed the concerns in relation to London Underground, around the effect of excessive heat on equipment causing failures and delays to services, which could lead to people being trapped in tunnels, and their consequential overheating [28] . The public have been conditioned by LU/TfL and the industry’s erroneous PR regarding the causes of in-tunnel heat load and so there is increased public demand for AC, but no one troubles to explain publicly that AC will exacerbate the in-tunnel, heat load problem, not to mention it would negatively affect climate change [29] .  Despite LU/TfL’s statements to Parliament regarding AC in para 109 [30] , AC has now been mooted by LU for new rolling stock on some lines – in complete contradiction to their previous stance and that of others regarding the negative outcomes for heat load in the tunnelled sections of the network [31] . LU/TfL continue seeking to resolve the relatively small problem of reducing operational heat, including significant investment in the futile, flawed Bunhill heat recovery project, which cannot deliver the advertised solution, since in wintertime when heat is needed, there is no surplus heat in the tube tunnels available to be exported commercially to provide the heating for above ground spaces [32] [33] . It is an absurdity that LU/TfL are totally resistant to climate being implicated in the historic and present tunnel overheating problem, whilst at the same time being cognisant of the longer-term climate change consequences – at least to the extent it could affect their short-term bottom line.  In the present time, they continue to address the symptoms that will give negligible positive results and significant detrimental climate change implications, instead of addressing the major cause and seeking to implement the readily available, one-time, preventative solutions. We have mentioned some specific solutions for London’s Tube – solar-reflective paint [34] , perhaps combined with flexible “peel and stick” solar panels [35] on train roofs.  Since Cooling the Tube’s inception, our fellow Europeans have not been idle, building a railway tunnel topped and walled with solar panels, both delivering power to run trains, whilst also providing protective overground shading for trains [36] . There are myriad innovative and climate-friendly options available, which would not only mitigate the Tube’s “immediate” heat load problem but can also deliver major long-term economic benefits.  It should not be so difficult to engage in fruitful (truly open-minded) dialogue to answer these questions accurately:- WHAT the prime cause of elevated in-tunnel heat load? WHETHER it is indeed “base load” increase, or WHETHER (OR NOT) the action of the sun on the surface part of the line could be the principal cause of this challenge [37] [38] ). This work should NOT be about professional egos and fear of “losing face”, nor indeed about blame or scapegoating.  Such concerns are reprehensible.  It is more about the importance of “black box thinking” – collaboration, a willingness to seek an understanding of what causal evidence the symptoms are revealing, and to define the problem properly, to constantly RE-EVALUATE as necessary, which in turn will uncover potentially sound and innovative solutions. Regardless of who originally said it, the following point is very valid and sadly is certainly applicable in this context of “Cooling the Tube” . "Insanity is doing the same thing over and over again and expecting different results" [39] . Appendix A LU-average-monthly evening peak temperatures by line (Jan 2013 to Dec 2020) A graphical representation of LU-average-monthly evening peak temperatures by line (Jan 2013 to Dec 2020) Appendix B Why will Air Conditioning not work in the Deep Tube? The answer to this question is one that we have arrived at over time, developing the theory through several short papers, examining different elements of the high heat load in metro networks like London’s Tube to identify the root cause(s). We believe the hitherto, generally accepted proposition within London Underground [LU]/Transport for London [TfL] of air conditioning in the underground being unviable is still the case.  LU’s expressed intention to bring air conditioning into use for the new Deep Tube lines is an act of desperation and ignores everything that could help them resolve this seemingly intractable heat load issue – including the laws of physics. Thinking all this through brought to light for us several questions:- What is the problem? (Ever increasing tunnel heat load); When does it occur? (Seasonally in the hot weather); Where does it arise? (On the surface prior to entering the underground sections); Why (aka how) does it occur? (Thermodynamics)! Our first paper Cooling the Tube still on ice [40] covered most of these questions but subsequent papers went on to develop these themes, especially in the light of seeming wilful blindness on the part of LU/TfL and their various consultants and academic advisers. Regarding the first question, LU/TfL have focused on analysing the heat IN the tunnels, brakes, passengers/stations, mechanical losses, tunnel systems, drive losses, etc etc.  These are OPERATIONAL heat sources, that are produced YEAR-ROUND – LU’s “engineers” are now describing as “base load”.  All this has led them down a blind alley.  See Pie Chart and associated text referred to in the link in Endnote 1. The second question of when? is explained by LU’s own data gathering [41] , which unequivocally confirms that the problem is SEASONAL – the tube gets progressively hotter as the outside temperature warms up.  It does not overheat in winter, as can also be seen by passengers’ winter clothing and the fact that train saloons are heated. This connects to the third question of where it arises?  London’s Tube is a mixed over overground and underground NETWORK, unlike (e.g.) Glasgow’s, Warsaw’s and Prague’s, which are entirely UNDERGROUND and do not overheat.  This leads to the inevitable conclusion that the heat from the SUN must have something to do with this overheating – see infographic and associated text referred to in the link in Endnote 1.  It is instructive to note from David Attenborough’s “Perfect Planet” series, episode 2 where at minute 38, Attenborough reminds us: “The solar energy that strikes our planet in just an hour contains more power than that used by all of humanity in an entire year! ” [42] On the fourth question of how? – if every part of the surface of the track, and every part of the train saloons is being irradiated by the sun, including the undercarriage which is re-irradiated by the track bed, then when a train enters the underground section of the network, that heat load is re-radiated into the tunnels, attempting to reach equilibrium.  This is where the Laws of Thermodynamics come in – see again the infographic and associated text referred to in Endnote 1 and in more detail in our paper: A Reflective Perspective: The Whys and Wherefores of Metro Overheating [43] pp2-3.  The overheating cycle is cumulatively repeated by every train for every “round trip” journey throughout the day and so the tunnel heat load increases….. So, why does installing AC on the metro train not work for combined over/underground Metro Networks? Once one has got one’s head around the thermodynamics of mixed networks like London’s, it is not too great a leap to understand why the use of air conditioning in this context will not only fail to achieve its objective, but it will also simply add to the overall tunnel heat load. As with all air conditioning systems the principle remains the same, whereby the heat is removed from one area and replaced with chilled dry air, and the hot air is expelled, normally to the outside atmosphere via an outside unit.  In the outside air conditioning unit, the ambient air is drawn over the condenser that can best described as a ‘radiator’ as seen on motor vehicles but instead of water running through the system it contains a refrigerant gas. On its journey around the AC system, it has three main stages:- The evaporator contains the sub-cooled refrigerant and air blows through its fins to release the chilled dry air into the saloon; The condenser contains the high temperature gas and air is blown through the heat exchanger matrix collecting the expelled saloon heat as it passes through; and The hot exhaust air is then expelled outside. For AC to work, there must be a difference between the incoming and outgoing air in the outside AC unit (aka a ΔT – Delta T).  If the air that is blown through is too hot because of the severely overheated tunnels, then the heat cannot be dispersed, because ΔT is near or at zero. As one of our scientist colleagues said, the simple explanation is that AC simply adds two additional heat sources to the already overheated tunnel: The extracted heat from the saloon and Heat from the energy required to run the AC. As far back as 2016, LU’s George McInulty from the Cooling Project Team confirmed in RAIL Magazine [44] (about halfway through the article) the unworkability of AC in this context. Moreover, the New York Subway have had air-conditioned trains for the last 30 years, but they still suffer from summer overheating below ground [45] . Appendix C Heat Loads…? and so what happened to traction energy? CONCLUSION: So, on that theoretical basis, it takes two to three times the energy to accelerate the train from 0-40mph than it does to decelerate the train from 40-0mph, but in terms of total energy, we must add in the energy to maintain the train at 40mph.  The precise figures might be debatable and need formal calculation – but the concept is not! DISCUSSION: The starting assumption is that it takes the same amount of energy to accelerate a resistanceless / frictionless train from 0-40mph as it does to decelerate a train from 40-0mph as the mass remains constant! The London South Bank University [LSBU] claimed in their report “Underground railway environment in the UK Part 2: Investigation of heat load” [46] that braking energy contributes 60% of the heat load in the London Underground [LU] Network! The above concept diagram demonstrates that traction energy must contribute a significantly greater heat load than braking energy.  Despite this predictable and blatantly obvious conclusion, traction has never figured in the thinking of Transport for London’s [TfL’s] cooling team, their consultants and academic advisers! We believe this exercise has uncovered a monumental weakness in their argument – you cannot have more than 100% heat load!  On further examination, using the LSBU's 60% braking energy contribution, which did not consider any other heat sources, the above concept diagram indicates that the total heat load from brakes and traction might be 240% using a comparative 3:1 ratio.  Even using the “measured” comparative ratio of 2:1 it might be 180%. This contrasts with later figures released by TfL, published in "Rail Engineering" [47] , which give a somewhat different picture.  TfL’s claim is that only 38% of the heat is caused by braking energy, so with a 3:1 comparative ratio, it then produces 152% of the heat load.  At a comparative ratio of 2:1 it is 114%.  If these TfL statistics were to include the other heat sources, which were part of the same information release, the heat load including traction increases to176%. We believe that this is further evidence of the flawed data and irrational propositions that TfL, its consultants, and advisors have endlessly peddled!   Appendix I Harnessing heat from the Tube 11 May 2020. Available at: https://www.newcivilengineer.com/innovative-thinking/harnessing-heat-from-the-tube-11-05-2020/ Comments 27 August – 7 September 2020.   Calvin Ronald Barrows 27 Aug, 2020 at 1:28 pm (This is the full text of my letter, which is published in the September 2020 issue. Unfortunately due to insufficient space the omissions very much watered down my reasoning as to why the Bunhill 2 System/Concept is flawed!  This was then included in the e-article as a comment, which raised subsequent reactions!) Harnessing “HOT AIR” from the Tube. I was intrigued to read your article “Harnessing heat from the Tube”. I happened on the root cause of LU’s overheating several years ago and went on to develop a hypothesis that clearly fits the evidence as to the seasonal nature of the problem. LU’s official temperature monitoring indicates that the Northern Line below ground temperatures vary from about 20°C in the winter to about 28°C in the summer; similarly, it indicates on the Jubilee Line the temperature ranges generally from about 18°C to 26 °C between winter and summer. However, it should be noted that these seasonal data for tunnel temperatures clearly proves it cannot be the brakes nor indeed any other operational heat causing the overheating in the tunnels, as these happen year-round. Moreover, if operational heat does NOT cause overheating in underground-only networks like the Warsaw’s metro system, then why would it cause overheating in mixed networks like LU’s? As a logical extension of these observations, extracting heat from the tunnels in winter seems to me to be a fool’s errand. So, it is necessary to examine the myth that the Tube is always hot! In the first instance, it begs the question at which locations these LU temperatures were taken, since they do not fit with my experiences of travelling underground in winter. Whilst discussing the myth with an engineering colleague, he relayed his experience of a station where a vent shaft was close to the platform tunnel. It was snowing outside, and he could see the snow fluttering down onto the rails and track bed – and it was settling, not melting immediately! Interesting also is that Rachel Holdsworth of the Londonist prepared a video cum article entitled  ( “How Warm is a Tube Train in Winter?” ). This monitoring was undertaken on the Jubilee Line, in the direction of Stanmore to Stratford. In February 2016 she recorded temperatures on the surface of 6-9°C and in the tunnel 9-13°C. So, there was not that much waste heat at that time of year when Bunhill 2 would most need it! With the heat pumps commissioned to provide District Heat to the London Borough of Islington at 70°C and with the benefit of waste heat from the tunnels in winter likely to be only 3-4°C above ambient, it would appear that these heat pumps are going to have to top up most of the required District Heat – circa 55-60°C. This being the case, I wonder:- What was the extra-over investment cost of the infrastructure and associated plant required to raise the slightly warmer than ambient air up the vent shaft; and What is the likely return on investment for the extra-over costs, compared to a conventional Air to Water Heat Pump using ambient air? Moreover, the necessary requirement to incorporate two gas-fired Combined Heat and Power [CHP] engines (smaller than those used in Bunhill 1) both to provide heat and to supply electricity to the heat pumps when electricity from the power grid is most expensive, raises further questions about the environmental effectiveness of this scheme. So, it seems to me that, because of a perverse, ongoing lack of understanding of the temperatures underground in London’s Tube Network, there is a fundamental flaw in the Bunhill 2 concept since:- In a report by the University of Cambridge, Engineering Department (UCED) for TFL/LU “Thermal Modelling and Parametric Analysis of Underground Rail Systems” their plotted graphs of platform and tunnel temperatures both demonstrate an almost linear relationship when set against overground ambient temperature; and At the time the system requires the most waste heat, it has the least; yet when there is little or no demand for heat, there is masses available. Regarding its summer operation, a heat pump works by extracting heat from where it is not needed and transferring it to where it is needed. So, the method of passing air over the cooled heat pump coil then blowing it into the tunnel is far less effective than Air Conditioning. Ventilation does not equal cooling, though it will be slightly better than blowing in ambient air at 30°C. So, using a fan will always give the impression of cooling because of the “wind chill factor”, however, it will have a limited range and when it is turned off the temperature will immediately climb. Moreover, the passage of trains causes a wave effect, which will alternately push and suck the air within the vent shaft. In summary, the whole engineering approach has slavishly followed TfL’s flawed historic interpretation of the evidence, rather than analysing and confirming the prevailing, below ground conditions. As a result, with very little of the district heat produced in winter being derived from tunnel waste heat, most of the heat is going to be produced by a combination of heat pumps and gas-fired CHP engines – not the environmentally-friendly project it has been assumed or made out to be. I believe this Project will eventually be seen as a vanity project rather than an environmentally and financially viable source of heat – especially when extracting what little available heat there is in the underground network in the winter season will:- leave the travelling public colder, and the train saloons requiring more heating than might have otherwise been the case….. In my opinion, Bunhill 2 is unlikely to provide the environmentally-friendly district heating project it was intended to and is likely to be yet one more of a number of multi-million-pound projects carried out by the Cooling the Tube team that has completely failed to improve the well-being of passengers in the summer heat! Andrew Simkin 01 Sep, 2020 at 8:53 am The industry doesn’t make capital investment decisions such as this based on subjective beliefs and casual observations. Watching snow falling on lines and how commuters ‘feel’ isn’t particularly useful data. The industry undertakes detailed scientific measurements and surveys and uses modelling developed from scientifically based reasoning and the laws of physics. Heat pumps are not a new invention, and their application is well understood. Referring to the results of surveys and science as myths is akin to Trumps ‘fake news’ mantra which gets used when he doesn’t like an alternative view to his own. Commuters come in all different shapes and sizes and wear a huge variety of clothing. Some arrive at the tube heart racing from a brisk walk, others are still asleep! My vote is with scientific data and the laws of physics. Calvin Ronald Barrows 06 Sep, 2020 at 9:22 pm @ Andrew. Thank you for responding to my comment above on the Bunhill 2 article. You may not have known that I have been involved directly and indirectly with these issues for some length of time, so I am not coming to my conclusions without a considerable amount of research and discussion with other engineers and specialists, both within and outside the rail industry, because the challenge facing TfL/LU and other similar networks around the world needs more than those specialising in rail engineering to resolve it. With that in mind, you may find it helpful first to read my most recent papers on this topic, which will lay out for you how I arrived at my ultimate conclusions over time .  I do not question the technology of the heat pump; I use one to heat my own home, so I am very familiar with their workings and capabilities and the use of them to heat these homes is not in question. However, although the initial data provided to the Bunhill 2 Project suggest that the heat in the tunnels in winter is around 18-20°C and could therefore be used as a free source of heat for these particular homes, this is dubious at best, since there is a wealth of empirical evidence to confirm that tunnel temperatures are indeed seasonal, so I maintain winter temperatures are much lower than this. Moreover, whilst I did not comment above on the physical variety of commuters and their clothing, the difference in what they wear in summer versus winter as shown in this link confirms (albeit subjectively!) the existence of this seasonal temperature variation acting on the saloons, trains and the tunnel itself and demonstrates the hard reality of how in winter there is little practical or financial benefit in extracting this negligible “waste” heat in the tunnels to heat Bunhill 2 homes. You have taken issue with what you refer to as [my] subjective beliefs and [another’s] casual observations, reminding us all that “the industry does not make capital investment decisions such as this based on subjective beliefs and casual observations”. Of course, it doesn’t. However, all the modelling, science-based reasoning, and laws of physics and thermodynamics in the world cannot help to provide the necessary understanding of the problem, if the problem itself is not properly defined at the outset and the right questions are not raised. For example, when the New York Subway said the cause of overheating was the brakes, TfL/LU did not assess that claim scientifically, and so allowed themselves to be led up the wrong track. Even the below ground monitoring TfL/LU have done confirms that tunnel overheating is seasonal. However, since the primary problem is neither a “tunnel problem”, as this defies the laws of thermodynamics, nor a year-round “operational heat” one, chasing solutions along these lines will go nowhere in dealing with the overheating. It is necessary to identify the CAUSE of the overheating and consider ways to treat it at source, such as can be seen here . On the back of my papers and discussion with the Research and Development arm of The Rail Safety and Standards Board (RSSB), they believe investigating my theories on train, track and tunnel overheating could well merit further research, which would likely be funded by the Department for Transport, and they are currently undertaking an initial knowledge search of the industry’s extensive databases to that end. It is worth remembering that part of scientific research is about observation and logic, which then needs to be empirically tested in order to substantiate it before moving on to the next step in the process. I have never claimed to have the last word on this topic. Through my publications I have sought to encourage the industry (and TfL/LU in particular) to engage in open-minded exchanges of views with me and other engineers and specialists around the world, urging them to undertake programmes of monitoring to test such hypotheses as mine and to identify solutions. Regrettably, the evidence shows that every project CTP have ever done, except one, has been unintentionally based on opinion and subjective beliefs, and not a true interpretation of the evidence. The one success is the partial use of solar barriers on the Central Line! Unfortunately, the appointment of the new Managing Director for London Underground, who has embraced my theories with enthusiasm, came too late for Bunhill 2. In conclusion, the Cooling the Tube Project has been in existence since 2005 and lamentably after 15 years they are no nearer a solution now than they were then. Rather than my albeit rudimentary research as a regular passenger being compared with Trumpian “fake news”, I am sure the readers of NCE would find it far more useful if you could provide links to your own research or information resources, where you have identified key points that we can all benefit from.   ENDNOTES [1] Barrows, C. R. 24 Jan 2019. Cooling the Tube still on ice . [Online]. Available from: https://www.tunneltalk.com/Discussion-Forum-Jan2019-Considering-the-issue-of-metro-system-climate-control.php [Accessed 19 October 2021].  Based on Barrows, C R. 2018. Cooling the Tube –  on Ice till 2030? [2] Barrows, C. R & Telatycka, S. J. 3 August 2020. A Reflective Perspective: The Whys and Wherefores of Metro Overheating . Available from: https://news.railbusinessdaily.com/a-reflective-perspective-the-whys-and-wherefores-of-metro-overheating/ [Accessed 19 October 2021]. [3] Ibid. [4] Near disaster on sweltering Tube 23 January 2003. BBC News [Online]. Available at: http://news.bbc.co.uk/1/hi/england/2686441.stm [Accessed 19 Oct 2021], and   Cool the Tube and win £100k 16 July 2003. BBC News [Online]. Available at: http://news.bbc.co.uk/1/hi/magazine/3069037.stm [Accessed 19 Oct 2021], and    Commuters led off stalled train 16 June 2006. BBC News [Online]. Available at: http://news.bbc.co.uk/1/hi/england/london/5086396.stm [Accessed 19 Oct 2021]. [5] London Underground Average Monthly Temperatures 2019 [Updated 2021]. [Online]. Available from: https://data.london.gov.uk/dataset/london-underground-average-monthly-temperatures then open CSV file. [Accessed 19 October 2021]. [Appendix A]. [6] Barrows, C R. 2019. A graphical representation of LU-average-monthly-evening peak temperatures (Jan 13 to Dec 20). Based on data from: London Underground Average Monthly Temperatures. 2019 [Updated 2021]. [Online}. Available from: https://data.london.gov.uk/dataset/london-underground-average-monthly-temperatures (then open CSV file). [Accessed 19 October 2021]. [Appendix A].   [7] Ibid. [8] Op. cit. 2. [9] Parsons, Brinckerhoff, Quade & Douglas, Inc. March 1976. Subway Environmental Design Handbook, Volume I: Principles and Applications, Second Edition , reproduced by U.S. Dept of Commerce, National Technical Information Service. Available at: https://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDetail/PB254788.xhtml [Accessed 19 October 2021]. [10] Parsons, Brinckerhoff, Quade & Douglas, Inc. October 1975. Subway Environmental Design Handbook, Volume II: Subway Environment Simulation Computer Program (SES) , reproduced by U.S. Dept of Commerce, National Technical Information Service. Available at: https://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDetail/PB254789.xhtml [Accessed 19 October 2021]. [11] Barrows, C. R. & Telatycka, S. J. April 2021. Why will AC not work in the Deep Tube . [Appendix B]. [12] Barrows, C. R. & Telatycka, S. J. April 2021. Heat Loads…? and so what happened to traction energy? [Appendix C]. [13] A Perfect Planet. Series 1: Episode 2 ‘The Sun’ Minute 38 . 3 January 2021. Available on BBC iPlayer at: https://www.bbc.co.uk/iplayer/episode/p08xc2x7/a-perfect-planet-series-1-2-the-sun [Accessed 19 October 2021]. [14] Op. cit. 2. [15] Op. cit. 9, pp 2-8, 4-56, 4-65, 4-66, 4-67, 4-68 and C-15 original text page references but e-pp 68, 268, 277-280, 363. [Appendix D]. [16] Op. cit. 10, pp 5-1 and 14-110 original text page references but e-pp 130, 1206. [Appendix E]. [17] Op. cit. 9, p C-15 original text page reference but e-p 363. [Appendix F]. [18] Op. cit. 9, pp xvi – xviii.  (e-pp26-28). [Appendix G]. [19] Op. cit. 17, p C-15 original text page reference but e-p 363. [20] Barrows, C. R. & Telatycka, S. J. May 2021 Cumulative Daily Heat Transfer Cycle of Multiple Round Trip Train Journeys on a Mixed Under-Overground Network in Summer . [Appendix H]. [21] Op. cit. 2. [22] Op. cit. 11 [23] Whitest ever paint reflects 98% of sunlight 16 April 2021. BBC News [Online]. Available at: https://www.bbc.co.uk/news/science-environment-56749105 . [Accessed 19/10/2021]. [24] Bouvard, O., Burnier, L., Oelhafen, P. et al. 2018. Solar heat gains through train windows: a non-negligible contribution to the energy balance . Available at:   https://www.researchgate.net/profile/Olivia-Bouvard/publication/323592680_Solar_heat_gains_through_train_windows_a_non-negligible_contribution_to_the_energy_balance/links/5dd65ec5a6fdcc2b1fa96c1e/Solar-heat-gains-through-train-windows-a-non-negligible-contribution-to-the-energy-balance.pdf . [Accessed 19/10/2021]. [25] Thermally Efficient Coatings. No date. Available at: https://blocksil.co.uk/solutions/thermally-efficient-coatings/ [Accessed 22 October 2021]. [26] Green Tracks . 2021. Available at: https://www.sempergreen.com/en/solutions/green-ground-covering/green-tracks [Accessed 21 October 2021]. [27] Productivity during heatwaves 26 July 2018. Parliamentary Business [Online] Paragraph 106. Available at: https://publications.parliament.uk/pa/cm201719/cmselect/cmenvaud/826/82607.htm [Accessed 20 October 2021]. [28] Productivity during heatwaves 26 July 2018. Parliamentary Business [Online] Paragraph 107 & 109. Available at: https://publications.parliament.uk/pa/cm201719/cmselect/cmenvaud/826/82607.htm [Accessed 20 October 2021]. [29] Productivity during heatwaves 26 July 2018. Parliamentary Business [Online] Paragraph 109. Available at: https://publications.parliament.uk/pa/cm201719/cmselect/cmenvaud/826/82607.htm [Accessed 20 October 2021]. [30] Ibid. [31] Op. cit. 5 [32] Productivity during heatwaves 26 July 2018. Parliamentary Business [Online] Paragraph 111. Available at: https://publications.parliament.uk/pa/cm201719/cmselect/cmenvaud/826/82607.htm [Accessed 20 October 2021]. [33] Harnessing heat from the Tube 2020. Available at:  https://www.newcivilengineer.com/innovative-thinking/harnessing-heat-from-the-tube-11-05-2020/ [Accessed 22 October 2021]. [See Appendix I for reproduction of comments 27 August – 7 September 2020 with accessible links] [34] Op. cit. 24. [35] FLEXTRON Flexible Solar Module 2020.  Available at: https://www.specifiedby.com/bipvco/flextron-flexible-solar-module [Accessed 19 October 2021]. [36] 16,000 solar panels 4 train tunnel from Paris 2 Amsterdam No date. Available at: https://www.dailymotion.com/video/xj4psq [Accessed 20 October 2021] [37] Op. cit. 1. [38] Op. cit. 2 [39] Did Einstein really define insanity as 'doing the same thing over and over again and expecting different results? 2018. Available at: https://www.quora.com/Did-Einstein-really-define-insanity-as-doing-the-same-thing-over-and-over-again-and-expecting-different-results [Accessed 19 October 2021]. [40] Op. cit. 1. [41] Op. cit. 5. [42] Op. cit. 13. [43] Op. cit 2. [44] Paul Stephen. 3 February 2016. Cooling the Tube . Available from: https://www.railmagazine.com/infrastructure/stations/cooling-the-tube [Accessed 27 October 2021] [45] A Brief History of Air-Conditioning on the New York Subway 15 August 2012. Bloomberg CityLab [Online]. Available at: https://www.bloomberg.com/news/articles/2012-08-15/a-brief-history-of-air-conditioning-on-the-new-york-subway . [Accessed 27 October 2021]. [46] F. Ampofo, G. Maidment, and J. Missenden 2004. Underground railway environment in the UK part 2: Investigation of heat load . Applied Thermal Engineering 24 pp 633-645. Available for purchase at https://www.sciencedirect.com/science/article/abs/pii/S1359431103003375 for $37.95 [Accessed 19/10/2021]. [47] Brian Tinham November/December 2007. Cooling the Tube in Plant Engineer pp8-11. Website no longer available. Republished November 2018. Available from: http://www.operationsengineer.org.uk/article-images/23757/cooling.pdf [Accessed 19/10/2021].   BIBLIOGRAPHY Ampofo F., Maidment G., & Missenden J. 2004 Underground railway environment in the UK part 2: Investigation of heat load ’ Applied Thermal Engineering 24. Available for purchase at https://www.sciencedirect.com/science/article/abs/pii/S1359431103003375 Bouvard, O., Burnier, L., Oelhafen, P. et al. 2018. Solar heat gains through train windows: a non-negligible contribution to the energy balance. Available at: https://www.researchgate.net/profile/Olivia-Bouvard/publication/323592680_Solar_heat_gains_through_train_windows_a_non-negligible_contribution_to_the_energy_balance/links/5dd65ec5a6fdcc2b1fa96c1e/Solar-heat-gains-through-train-windows-a-non-negligible-contribution-to-the-energy-balance.pdf Barrows, C. R. 24 Jan 2019. Cooling the Tube still on ice . [Online]. Available from: https://www.tunneltalk.com/Discussion-Forum-Jan2019-Considering-the-issue-of-metro-system-climate-control.php . Based on Barrows, C R. 2018. Cooling the Tube –  on Ice till 2030? Barrows, C R. 2019. A graphical representation of LU-average-monthly-evening peak temperatures (Jan 13 to Dec 20). Based on data from: London Underground Average Monthly Temperatures. 2019 [Updated 2021]. [Online}. Available from: https://data.london.gov.uk/dataset/london-underground-average-monthly-temperatures (then open CSV file). [Accessed 19 October 2021]. [Appendix A] Barrows, C. R & Telatycka, S. J. 3 August 2020. A Reflective Perspective: The Whys and Wherefores of Metro Overheating . Available at: https://news.railbusinessdaily.com/a-reflective-perspective-the-whys-and-wherefores-of-metro-overheating/ . Barrows, C. R. & Telatycka, S. J. April 2021. Why will AC not work in the Deep Tube . [Appendix B]. Barrows, C. R. & Telatycka, S. J. April 2021. Heat Loads…? and so what happened to traction energy? [Appendix C]. Barrows, C. R. & Telatycka, S. J. May 2021 Cumulative Daily Heat Transfer Cycle of Multiple Round Trip Train Journeys on a Mixed Under-Overground Network in Summer . [Appendix I]. BBC iPlayer 3 January 2021. A Perfect Planet - Series 1: 2. The Sun. Available at: https://www.bbc.co.uk/iplayer/episode/p08xc2x7/a-perfect-planet-series-1-2-the-sun . BBC News [Online] 23 January 2003. Near disaster on sweltering Tube . Available at: http://news.bbc.co.uk/1/hi/england/2686441.stm . BBC News [Online] 16 July 2003 Cool the Tube and win £100k . Available at: http://news.bbc.co.uk/1/hi/magazine/3069037.stm . BBC News [Online] 16 June 2006. Commuters led off stalled train . http://news.bbc.co.uk/1/hi/england/london/5086396.stm . BBC News [Online] 16 April 2021. Whitest ever paint reflects 98% of sunlight . Available at: https://www.bbc.co.uk/news/science-environment-56749105 . BiPVco 2020. FLEXTRON Flexible Solar Module . Available at: https://www.specifiedby.com/bipvco/flextron-flexible-solar-module . Blocksil Thermally Efficient Coatings. No date. Available at: https://blocksil.co.uk/solutions/thermally-efficient-coatings/ . Bloomberg CityLab [Online] 15 August 2012. A Brief History of Air-Conditioning on the New York Subway . Available at: https://www.bloomberg.com/news/articles/2012-08-15/a-brief-history-of-air-conditioning-on-the-new-york-subway . Data.london.gov.uk 2019 [updated 2021]. London Underground Average Monthly Temperatures . Available from: https://data.london.gov.uk/dataset/london-underground-average-monthly-temperatures then open CSV file. Dailymotion.com 16,000 solar panels 4 train tunnel from Paris 2 Amsterdam No date. Available at: https://www.dailymotion.com/video/xj4psq . Green Tracks. 2021. Available at: https://www.sempergreen.com/en/solutions/green-ground-covering/green-tracks . New Civil Engineer 11 May 2020 Harnessing heat from the Tube. Available at: https://www.newcivilengineer.com/innovative-thinking/harnessing-heat-from-the-tube-11-05-2020/ . Parliamentary Business 26 July 2018 Productivity during heatwaves. Available at: https://publications.parliament.uk/pa/cm201719/cmselect/cmenvaud/826/82607.htm . Parsons, Brinckerhoff, Quade & Douglas, Inc., March 1976 Subway Environmental Design Handbook, Volume I: Principles and Applications , Second Edition New York reproduced by U.S. Dept of Commers, National Technical Information Service. Available at: https://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDetail/PB254788.xhtml . Parsons, Brinckerhoff, Quade & Douglas, Inc., October 1975 Subway Environmental Design Handbook, Volume II: Subway Environment Simulation Computer Program (SES) , New York, reproduced by U.S. Dept of Commers, National Technical Information Service. Available at: https://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDetail/PB254789.xhtml . 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