TECHNICAL ARTICLE

AS PUBLISHED IN The Journal January 2019 Volume 137 Part 1

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Atmospheric AUTHOR:

Alan Whiston railways: FPWI A look to the past to drive the future

This White Paper provides a technical This has left people wondering if there is This White Paper provides a technical overview of the development of another way? overview of the development of Atmospheric Atmospheric Railways from 1799 to Railways from 1799 to the current day and the current day and looks at both the The word on everyone’s lips when considering looks at both the Style and the Hyperloop Style and the Piston Style of this is simple; Hyperloop. This system was first Piston Style of systems, and, compares systems, and, compares advantages and discussed by Elon Musk, the tech entrepreneur advantages and disadvantages over existing disadvantages over existing High Speed in 2013 as the future of high speed ground High Speed systems. systems. transportation systems. Moving people or freight from A – B at high speed. This is the A TIMELINE OF ATMOSPHERIC INTRODUCTION future, or is it? RAILWAYS

Any proposal for the introduction of a new A 21st Century World requires a 21st century MEDHURST - 1799 innovative and futuristic transport system. transportation mode requires a complete analysis that should address among others the The need for a high speed, technologically George Medhurst was a mechanical engineer following questions - . advanced and fuel-efficient transportation see image 1 and inventor, who came up with the idea of system has intensified in recent decades, moving goods through tunnels pneumatically. It may surprise people that an Hyperloop as highways become more clogged with He first proposed to blow a railed vehicle style system (low tech by our standards, but road traffic and pollution levels increase. An through a tube like a large piston. In 1812 he revolutionary at the time) was first proposed alternative solution has been sought which had developed the idea further and discussed by George Medhurst in 1799, whereby goods would bring fast and efficient travel between the possibility of moving passengers in a would be delivered by being blown through cities, cities and airport hubs and inter-region. similar manner. He also looked at a separate cast iron pipes on carriages. He developed High speed railways have been the backbone idea where instead of the whole vehicle being the idea further to include passengers in 1812. in fast intercity travel since the early sixties the piston, a separate piston placed within a He proposed two alternative system; a fully when Japan’s Shinkansen started operation tube would propel the vehicle. He published enclosed carriage within a pipe which we with its own dedicated high speed line. several papers in relation to moving goods will call the “Hyperloop style” and a carriage Upgrades to existing lines have also brought and people using air pressure, and while he connected to a piston that is enclosed in a increases in speed with several lines in the patented designs for the pumps to power these smaller diameter tube between the running UK operating at 201km/h through the use of systems, he never patented the system itself. rails which we will call the “piston style”. electric rolling stock, diesel rolling stock or new Unfortunately his designs were never put into Unfortunately, Medhurst never patented his hybrid . Another consideration has been operation. Maglev. However, each of these systems have ideas, though he is considered the father of the their limitations. .

High speed railways require wheel/rail contact and a power supply, namely traction motors for electrically powered trains, diesel engines powering the wheels of a diesel , or both systems if a hybrid. The result of this is a relatively large mass for each vehicle to provide the propulsion system. For the maglev system, while there is no contact between the train and the guideway, for some systems wheels are required at low speed (less than 100km/h). However, all systems require magnets to provide the separation between train and guideway, which are also heavy. For both systems, power consumption is an issue, either fossil fuels for diesel and hybrid non-electrified running or electrical power generation from power stations using fossil fuel or renewable energy for the electrically powered systems. Image 1

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VALLANCE - 1824 SAMUDA AND CLEGG – 1840 E is the roller that opens the flap valve to allow passage of D, F is the roller behind piston that In 1824, John Valance took out a patent and The Samuda brothers were shipbuilders closes the flap valve re-sealing the pipe. See built a short section of 6’ diameter cast iron and engineers, Samuel Clegg was a gas image 3. tube with rails cast inside. The vehicle was engineer. They Invented a pipe completely enclosed within the tube and bear system in 1838 and developed a small-scale DALKEY ATMOSPHERIC RAILWAY – 1843 skin was used to seal the space between the model in Southwark at their ironworks after vehicle and the tube. Speed was reduced reading about Medhurst’s system in 1835. An extension to the Dublin to Kingstown (now by opening doors at the front and rear of the In 1840 they leased a half mile of unopened Dun Laoghaire) railway was proposed to vehicle, it worked but was never adopted railway in Wormwood Scrubs. It used a 9-inch Dalkey, an additional 2 miles, which needed commercially. diameter pipe with a 16hp steam engine to climb an average gradient of 1 in 115, with pump for the vacuum which drew the train up a ¼ mile stretch of 1 in 57, deemed too steep PINKUS – 1835 a 1 in 115 gradient on a single line at speeds for the steam locomotives of the time. The up to 30mph. The train then returned to the Treasurer of the company had visited In 1835, Henry Pinkus patented a system start using gravity. The trial continued for 2 and witnessed the Samuda and Clegg system consisting of a 9 sq. ft square section pipe years. In 1841, Joseph Samuda released a and suggested this would be ideal for the with a partial vacuum, later changed to a small paper entitled “A Treatise on the adaption extension. bore full vacuum pipe, which used a rope to of Atmospheric pressure to the purposes seal the slot where the piston connected to the of Locomotion on Railways”, this gave a In 1843 the extension was opened, which vehicle, rollers lifted the rope clear of the pipe detailed breakdown of the critical parts of an consisted of a 15-inch diameter pipe, with a for the piston connection, then rollers behind atmospheric railway and how they would work. single pumping station at Dalkey. Speeds of re-sealed the pipe. This system had problems In 1844, patents were taken out by the Samuda 30mph were obtained up the gradient, with the due to the rope stretching and breaking the brothers. train returning using gravity. By 1844, 35 train seal, which resulted in Henry not being able to movements a day were taking place carrying attract investors. Though it failed, it became A is the piston tube, B is the valve, C is the 4500 passengers a week. The line operated the prototype for later systems which enjoyed beam holding piston and (W) counter weight, D for 10 years and was the first commercially partial success. is the rod connecting the piston to the vehicle, operating atmospheric railway which attracted inspection from a lot of eminent engineers of the time. See image 4.

LONDON AND CROYDON RAILWAY (L&CR) – 1844

A new line was required from New Cross to Forest Hill due to three separate railways sharing the same two track railway, but having different stopping patterns causing congestion. As this section was on a gradient of 1 in 100 it was decided that an atmospheric railway would be ideal after the Dalkey railway had been visited. It opened on 1st May 1844, with an additional section from Forest Hill to Croydon opening in January 1846.

Through 1846, several problems started to develop; the static pump station crankshafts started to fail, requiring replacement. The leather flaps sealing the system used tallow, made from animal fat, which attracted rats who ate the leather causing loss of vacuum. The flaps were also affected by extremes of weather, due to the system used on the L&CR not having the steel flap covers used on the Dalkey Atmospheric railway which protected the leather flaps from snow, rain and heat. The L&CR merged with the London and Brighton Railway and a decision was made on 4th May 1847 to convert the line back to a steam locomotive powered system.

PARIS TO ST. GERMAIN – 1847

The line from Paris to Pecq was started in 1835 and completed in 1837. However, the section from Pecq to St Germain was deemed to be too steep for steam locomotives requiring a gradient of 1 in 28, the minister of transport had heard of the Dalkey Railway and persuaded the Pereire brothers to adopt the atmospheric railway principle to be able to finish the final 1.5km of the line. The extension was opened Image 2: Timeline of atmospheric railways on the 15th April 1847 and utilised a central

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Image 3: Design for an atmospheric railway vehicle

1. Service headway is limited to 75% of theoretical headway as defined by the UIC, this provides a factor of safety for reaction and transmission times. Automatic train control would reduce headways by 25% and are shown in brackets.

2. Headway shown is based on plain line headway, where there are no junctions to negotiate or intermediate stations, these would increase headway by approx. 200%

3. Assumed that Hyperloop would be automatic train control for such high speeds, therefore no manual control headway shown.

4. Several lines in development with proposed running speeds of 360km/h, max current operational speed of 320km/h. Image 4: Adverse cant and its filtered counterpart 5. 505km/h is the proposed speed of the Chuo Shinkansen when fully operational, currently takes passengers over the test track at 505km/h.

6. Flightrail have not stipulated a top operational speed for their proposals, stating that it is proposed to run at more than 200mph (320km/h), therefore it is assumed that it would run at same speeds as proposed high speed lines.

7. Original Hyperloop proposal was to run at up to Mach 0.99, which equates to 1234km/h at sea level. There are 2 main companies proposing Hyperloop systems, Virgin Hyperloop one which states speeds of 1080km/h, and Hyperloop HTT which states speeds of 1200km/h.

Table 1: Comparison of performance

Image 5: Route of London Pneumatic Despatch Railway

Image 9: Comparison of speeds. Los Angeles to San Francisco

Image 6: London Pneumatic Despatch Railway

Image 7: Crystal Palace Image 10: Comparison of journey times. Los Angeles to San Francisco. Atmospheric Railway

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vacuum pipe of 25 inch diameter, slotted at the Eversholt Street to Holborn and Holborn to the city of Canoas, which is 4.7km long and with a top and closed with 2 leather flaps. The train GPO sorting office near St Paul. This consisted proposal to extend it further to 18km. could traverse the rising 1 in 28 gradient at a of twin tunnels 4.3km long. Carriages on this speed of 22mph and returned back to Pecq section were recorded as travelling at up to FLIGHT RAIL CORP – 2011 under gravity. In 1860, steam locomotives 60mph. See image 5 for the route. had become more powerful and took over the Flight Rail Corp have taken the idea of an running along the whole length of the line. The second stage used a larger diameter atmospheric railway and brought it into the tunnel of 1.5m, and traction (push/suck 21st Century, a 1/6th scale model of a high SOUTH DEVON RAILWAY – 1847 system) was provided by a 21 foot diameter speed atmospheric Railway claiming to be able fan powered by Cornish engines, these were to achieve speeds of 200mph has been built. The (GWR) reached updated constantly, as 2 carriages would The model consists of an elevated trackway, Exeter in 1844. It was proposed to extend be hauling 12 tonnes of mail etc. at 30mph. 639m long, with grades of 2%, 6% & 10%. The the line to Plymouth, but the issue was the People queued for the chance to ride on the atmospheric tube is fully sealed, the piston steep gradients. The South Devon Railway system and while it worked well as a novelty, it connecting to the rail vehicle via magnets was created and it was proposed to use an failed at what it was built for, the quick delivery ensuring no leakage from the piston pipe. The Atmospheric system, after I Brunel had of mail, due to the location of the stations in wheel / rail interface more closely resembles witnessed the Dalkey Atmospheric railway basements. By the time the heavy mail sacks that of a rollercoaster, with the wheels inclined in operation, and wanted to use the Samuda were loaded and unloaded, and carried up to at 45 degrees and wheels above and below the Brothers system. On the 13th September the main sorting offices, all the time saved from head of the rail to stop derailment. The system 1847, the line started operating using the travelling from A – B underground had been also has the benefit of requiring no diesel or Atmospheric system. Unfortunately Brunel had lost. In October 1874, the last train ran, and it electric on-board traction therefore reducing undercalculated the size of the pipes, which quickly fell into obscurity. See image 6. the mass of the vehicle and subsequent axle required them to be scrapped and replaced by loads. The only electrical system requirements larger ones. He also specified under powered CRYSTAL PALACE ATMOSPHERIC RAILWAY will be for the onboard systems such as steam engines for the pumping stations. They – 1864 braking, communication, on-board signalling therefore needed to work harder and the interface, lighting, air-con and door power consumption of coal increased considerably Designed by Thomas Webster Ramell, who systems. It is envisaged that axle loading making the system more expensive than using also helped to build the London Pneumatic would be no more than 15 tonnes fully loaded. steam locomotives. In the winter of 1847 – 48, Despatch Railway. problems started with the leather flap valves, Atmospheric Railway was built as a test site HYPERLOOP - 2013 Brunel had omitted the iron flap covers that from the Sydenham to Penge entrances of the protected the flaps from weather, which caused park covering a length of 550m. The single Hyperloop is an open access concept and the flaps to freeze, breaking the vacuum seal. coach had a collar of bristles that provided a proposed transportation system for passenger A similar problem occurred in the summer partial airtight seal to the tunnel wall and a fan and/or freight. It was initially proposed to use where the heat caused the leather flaps to was used to blow the train down the length a cushion of air to levitate (much like a game crack. Samuda was contracted to maintain the of the tunnel. For the reverse direction, the of Air Hockey) and a linear induction motor for system, but, considering the cost of replacing fan was reversed to suck the vehicle back. It thrust to carry vehicles/pods through partial- the valves was in the region of £32,000, (a operated between August and October 1864, vacuum tubes to offer high speed inter-city huge sum of money in today’s terms), he and was used as a test site for a future line transport, the example given being Los declined to do so stating that the omission of between Waterloo and Whitehall, which was Angeles and San Francisco, though the route the metal flap valve protector was the cause never built. See image 7. shown is actually from San Fernando (which of failure. At a meeting of the shareholders on is approx. 45km North of Union Station in Los 6th January 1849, a vote was taken, and it was , Angeles) to San Francisco. The main goal of decided to scrap the atmospheric running of – 1870 the concept is to reduce air resistance and the railway. friction to achieve very high speeds (near- built a 95m long subway sonic speeds over 680 mph; 1,100 km/h) and LONDON PNEUMATIC DESPATCH RAILWAY tunnel under as a demonstration for moderate energy consumption. As the system – 1861 a larger pneumatic subway system. It consisted has developed, the majority of companies of a 2.4m diameter tunnel. The system worked have dropped the air cushion concept for an Thomas Webster Rammell and Josiah Latimer in a similar fashion to the Crystal Palace Inductrack Passive EDS Maglev. Currently Clark were asked to design an underground Atmospheric railway, it lasted 3 years before it Hyperloop test tracks are short, therefore no railway system to move letters, parcels and was closed down. testing has taken place at more than 324km/h the occasional person for the General Post (201mph. As test tracks get longer, these Office, due to congestion on the streets of AEROMOVEL CORPORATION – 1970 speeds should increase. London. They started designing a system in 1855 and by 1859 were ready to test a system. Though the system was designed in 1970, the The major difference between Inductrack The London Pneumatic Despatch Railway first operational line opened in 1989 in Jakarta, Maglev and Hyperloop, is that Hyperloop was created, headed up by the 3rd Duke of Indonesia, in a theme park, with a loop of is a Maglev surrounded by a low pressure Buckingham, Thomas Brassey and Mr W 3.22km, and 6 stations. Lightweight trains tube, reducing air resistance and reducing H Smith. A 411m long test site was created run on an elevated concrete U section beam the amount of propulsion coils required. An alongside the Thames at Battersea Pier with rails; the U section being the tube for the existing Inductrack EDS Maglev currently consisting of a 0.8m tall pipe, and 2 carriages. atmospheric system, sealed with a rubber flap. operates in Japan and is called the Chuo Parcels and people were fired along the pipe Square plates within the U section act as a Shinkansen which in trials has operated at up at up to 30mph. Trials were a success and piston and electric pumps are located along to 605km/h (376mph) along the Yamanashi test it was decided to build a system for use by the route to either blow air into the section or track which is over 48km long. This is a full- the GPO. The first section was built in 1863, suck air out causing the train to move. It utilises sized train (approx. 3.5m wide) rather than a which makes it the second oldest underground normal train brakes to slow the vehicle and small diameter vehicle like the Hyperloop which railway in the world after the Paddington to power for the onboard systems is provided is less than half that size. The initial design Farringdon line. The first section ran between by a 50v charge running through the rails. A for tubes proposed to carry the passenger platform 1 of Euston Station to the GPO sorting further system was opened at Porto Alegre pods were relatively small diameter, nominally office in Eversholt Street and consisted of a Airport in Brazil in 2013, 1km long, connecting 2.23m, with pods in the region of 1.35m wide single tunnel 480m long. A second section the metro station to terminal 1. And in 2017 and 1.1m high, therefore passengers would sit was built between 1863 and 1866 between another system was opened in the Brazilian side by side in a 1+1 configuration, and would

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not be able to move about the cabin, due to COMPARISON OF The “Piston System” is predominantly existing acceleration and deceleration values of up PERFORMANCE technology modified and updated for the to 1g (though supporting information showed 21st Century for high speed mass transit, the acceleration values of 0.5g). Passengers would “Hyperloop System” is all new cutting edge Each system has strengths and weaknesses. have to be restrained by seatbelts, (it is worth technology for low volume and high speed One of the most important requirements will be noting that the Chuo Shinkansen Maglev has a travel. the vehicle performance; modern high speed current max. acceleration of 0.2g). A separate rail and Maglev details have been added in to proposal for a vehicle/passenger system talks provide baseline samples of performance. CONCLUSION about tubes with a diameter of 3.3m and pods capable of snuggly fitting a medium sized SUV. MODERN HIGH SPEED RAIL There are obvious benefits for both systems, As the system has developed, Virgin Hyperloop a piston based system is a development of one has proposed much bigger vehicles, nearly Modern High Speed rail’s performance is existing rail and high speed rail technology twice the size of those previously discussed. restricted by power requirements, route utilising a different propulsion system to reduce alignment, rail/ wheel adhesion. Modern high energy consumption, and improve traction that The system is suitable for long straight speed trains have a power output of between will enable the railway to follow the existing routes, as lateral acceleration at this speed 12 – 16Mw to enable them to reach speeds of terrain more closely, whilst achieving speeds traversing a curve would be a problem. As an between 300 – 360km/h (186 – 224mph) of up to 360km/h and carrying up to 800 example, for high speed railways, at 400km/h, passengers. minimum horizontal curve radius is approx. EDS MAGLEV 8000m, for Hyperloop at 1100km/h this would The Hyperloop system appears to have moved need a minimum radius of approx. 70km. While no EDS Maglevs are currently in service, away from the original “5th Mode of Transport” The white paper on Hyperloop produced by the Chuo Shinkansen runs on a 48km long concept originally proposed by Elon Musk, to Elon Musk, states that for 1100km/h they are test track at Yamanashi in Japan. It regularly a development of existing experimental EDS proposing horizontal radii of 23.5km, therefore runs at 505km/h (314mph) carrying the public Maglev technology, scaled down in size and passengers would experience nearly 3 times in trials. The power requirements to run at length, and enclosed in a low-pressure tube the lateral g acceleration as experienced in a this speed are in the region of 5 times that to reduce power consumption and increase high speed train. Vertical changes in bearing of a standard Shinkansen high speed train, speeds by up to 200% to achieve up to will also require large vertical curves, in the between 50 – 80Mw. 1100km/h whilst carrying 28 people. region of 44km to remove the g effect on passengers stomachs when cresting a hill or FLIGHTRAIL Neither system is radical, and I believe that if reaching the bottom of a sag curve. This will Maglev and High Speed Rail is brought into the either require tunnelling or extremely high The Flightrail Vectorr atmospheric system equation, then there is space for all 4 specific pylons to carry the tubes over the obstacle at has an external power source powering fixed forms of transport, though there are still certain acceptable gradients. lineside equipment at approx. 80km centres. obstacles to overcome which are listed below. Power consumption for the vehicle is very It is worth noting that the original proposal for low as it is only required to power on-board The current issue is power consumption Hyperloop did not show it reaching downtown systems such as lighting, signalling and control and cost; for Maglev, this is huge and until Los Angeles, but stopping approx. 45km north systems and ir-conditioning. Low voltage could this can be reduced Maglev is more likely of Union Station at San Fernando. It would be provided through the rails and picked up by to be a novelty showcasing technology, require a change of transport mode to reach the wheels. rather than a viable high speed transport Downtown LA, drastically increasing journey network. Construction costs of the new Chuo times. HYPERLOOP Shinkansen in Japan are currently estimated at £210million/mile, though other Maglev systems The main technologies used in Hyperloop are: The original Hyperloop proposal was for an have been constructed for £52million/mile. external powered lineside system, powering • Partial-vacuum tubes to reduce discreet linear accelerators placed at approx. Hyperloop, whilst reducing the amount of environmental pressure and air resistance 130km distances, with on board removable power required to overcome air resistance, on pods. battery pods to power the air compressor, and additional power is required for both the • Passive magnetic levitation (Inductrack) on board systems. As the system has been Maglev elements of the system and also for air to reduce friction of the vehicles. developed, the Hyperloop vehicles need to be evacuation of the propulsion tube. This reduces • Linear induction motor (LIM) as a powered in much the same way as the EDS some of the benefits of Hyperloop. Elon Musk propulsion and braking system. Maglev using the inductrack system. This stated that the system could be wholly powered • Vehicles/pods to transport passengers requires superconductors located in the vehicle by solar panels on the tubes, but this has and/or freight. as the coils in the tube will be passive, though been brought into question, especially now with the propulsion coils spread further apart the vehicles and tubes have become larger LINES IN OPERATION due to the reduced air pressure in the tubes and therefore require more power. Again reducing drag, additional lineside power though power consumption per passenger is going Two test tracks have been built to test the is required to reduce the air pressure in the to be prohibitive, until the cost of cooling the technology: tubes. Though no values have been published super conductive magnets is reduced. Initial It is believed that power consumption will construction costs were stated as being in the • SpaceX’s test facility in California probably sit nearer that of a modern high speed region of £19million/mile, costs were kept down (1.25km) rail system than that for an EDS Maglev, due by not running the system into the city centre • Hyperloop One’s “DevLoop,” in Nevada to its reduced size and the need to power the and keeping the tubes and vehicles small. (500m)) superconducting magnets in the vehicle. Current proposals show vehicles and tubes nearly twice the size, therefore it assumed CURRENT DEVELOPMENT AND costs would be nearer £30million/mile.

FUTURE CHALLENGES High speed rail is starting to reach the limits of speed, due to the exponential increase The “piston system” v’s the “hyperloop”system: in power required to push the trains faster Both systems have their Pro’s and con’s, these and overcoming air resistance. For the last have been considered and listed in table 2. French TGV speed record, the overhead

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power systems had to be boosted from 25kv The piston system for speeds up to 360km/h would dramatically increase construction and to 32kv to achieve a speed of 574.8km/h on over moderate distances (>700km) and high operational costs and remove one of the major a specially upgraded and shortened train in passenger numbers (>1000 passengers) benefits of Hyperloop. An Hyperloop system 2007. Currently, maximum service speeds provides all the benefit of full size train travel between Los Angeles and New York, being a for new lines are proposed for 360km/h. It is with improved performance and reduced minimum of 4000km would require an increase unlikely that in the future trains will run at more energy costs. in speed and an increase in vehicle size for that 450km/h in service due to high power passenger comfort, as new quieter supersonic requirements. The costs for construction are The Maglev for speeds up to 600km/h over passenger planes are currently in development the benchmark for comparison of the other long distances (>1200km) and moderate which would be able to compete on journey systems and are currently about £18.5million/ passenger numbers (>700 passengers), time and have an improved passenger mile. provides all the benefits of full size train experience, I do not believe that Hyperloop travel with improved comfort once costs have would be a viable alternative to medium Flight rail has the benefit of only requiring reduced.The Hyperloop system is for very high distance airline travel. fixed power supplies at discreet locations speeds of up to 1100km/h for long distances along its length to power the static vacuum (>1800km) and low passenger numbers (>28 REFERENCES pumps, as minimal on-board power is required. passengers). Again, this system becomes This reduces overall power consumption as more viable once costs have reduced for the Wikipedia the system still uses a rail / wheel interface, Maglev elements of the system. With current Flightrail therefore no additional power is required for proposals I do not believe Hyperloop could be The New Statesman – The London Pneumatic magnetic levitation. No traction is required from used for journeys taking more than an hour Dispatch Railway the vehicle and therefore there are no issues and a half as passengers cannot move around with adhesion between the wheel and rail as all the cabin and there would be no possibility of propulsion is provided through the tube on the using rest room facilities apart from at station magnetically attached piston. Flightrail have terminals. For longer journeys, a larger system not released any potential construction costs, would be required where passengers could but it is assumed that these would be in the move around the cabin, like a standard train region of £15million/mile. or airliner. Moving to a larger vehicle size

“PISTON SYSTEM” “HYPERLOOP SYSTEM”

ELEMENT PROS CONS PROS CONS

SPEED Suitable for high speed, up to 400km/h (250mph) Air resistance will become a problem at very high Suitable for very high speed, up to 1200km/h System has little benefit over conventional for moderate to long distances speed e.g. 500km/h (310mph) and above (745mph) due to low air resistance in a partial systems at low to moderate high speed e.g. Example time from San Francisco to Los Angeles vacuum tube. And over long distances. <500km/h (310mph), or over short distances. (618km) with no stops = 1hr 46mins, London – Example time from San Francisco to Los Angeles Example London – Didcot (85.5km) = 6mins, Didcot (85.5km) = 17mins, London – Swindon with (San Fernando 575km) with no stops = 38mins London – Swindon with 1 additional Stop (125km) 1 additional Stop (125km) = 26mins = 12mins Original proposal does not show Hyperloop reach- ing Downtown LA, therefore a change of mode of Transport is required which will significantly increase the journey time city centre to city centre from the stated 38 mins to nearer 1hr 36 (currently trains take 46 mins from San Fernando – LA, a 12 min connection time has been provided in the timing)

FUEL Highly fuel efficient due to piston being in a Air resistance on vehicle becomes an issue at Highly fuel efficient due to partial vacuum reducing Requires large air pumps to remove air from EFFICIENCY partial vacuum and light weight of vehicle with very high speed air resistance, partial vacuum can be powered running tubes, though once pressure reduced, no onboard propulsion system. Fixed propulsion by fixed power supply utilising renewable or would require minimum power to maintain. Vehicle system can use renewable energy (wind, solar fossil fuels needs to be powered to provide the levitation. etc), as well as existing fossil fuels

COMPLEXITY Only new technology required is in the propulsion Requires a mixture of some existing and a lot of system piston tube and magnetic connector, new technology, elements of Maglev for levitation all other systems and technology are currently (existing), all other systems new and untried. available

COST Comparable construction costs as new high speed Hyperloop are quoting a price of approx. £19mil- Large capital cost due to fully enclosed tube lines, potential for existing lines to be converted or lion/mile requiring high precision construction or tunnelling/ mixed piston stock and existing stock viaduct in locations of large vertical level differ- ences, “new technology” and limiting geometry for very high speed to get into city centres. Original cost of £19million/mile was based on small diameter tubes and vehicles, current proposals are nearly twice the size therefore cost would increase by approx. 60%.

CAPACITY Same as an existing high speed train, capacity of Requires individual pods, limited to approx. 20 – between 400 – 1000 per train possible, potential 30 people per pod, would be potential for 12 pods for up to 30 trains/hr (between 12,000 – 30,000 an hour (between 240 – 360 passengers/hr) to passengers/hr) for non-stopping services keep a safe distance between pods of 37.8km

FLEXIBILITY With a system like the one proposed by flight rail, A level of complexity to allow trains to switch Good for A-B direct services between main Would be complex to allow diverging routes where magnets are used to connect the vehicle tracks, would require a piston switch which centres of population with limited stops without changing vehicles, which would reduce to the piston, a piston switch has been developed requires connectivity to the rail switches to ensure the effectiveness of very high speed travel. Only which allows for continuous running through correct operation. useful over large distances, as the pod would junctions require approx. 20km (12.5 miles) to accelerate and decelerate to/from 1100km/h (683mph)

SAFETY Can utilise either “normal” train wheel/rail Fully enclosed system removing the risk of vehicle Partial vacuum system will require additional interface, with the addition of the connection to collision with outside influences, due to the safety procedures and systems in case of vehicle the piston providing an added safety factor, or low-pressure system, stations would need to be break-down/tube rupture, will require emergency an option with the Flightrail system, is more like sealed from the tube with access doors at platform on board air supply, and pressure equalising a rollercoaster where wheels are angled at 45 level that only open when the vehicle is present equipment and regular escape hatches along degrees and have upper and lower wheels holding increasing safety for passengers and normalising tunnel, assume system will be a 3 tunnel/tube the vehicles to the rail providing added safety. air pressure system, 2 running tubes and a maintenance Easy to detrain passengers in an emergency, due & evacuation tube or dedicated access road to no pressure differential between vehicle and along side outside atmosphere. Table 2: Pros and cons of ‘Piston’ system and ‘Hyperloop’ system

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