This proposal was reopened in Transportation 2016


MINI ELEVATED GREEN TRAINS powered by renewable energy - urban mobility for all - a comprehensive solution to public transit.




 - Fully Green Mass Transit

 - Urban mobility on a comprehensive scale 

We are proposing a design we believe to be the most efficient as a mass transit model through Mini Elevated Green Trains - in the past referred to as cTrains, Caterpillar Trains because of their appearance; however we believe that gTrains is more appropriate for their renewable energy efficiency 

The premise of our work is to find a solution to mass transit by addressing the elements that have failed to provide urban mobility in a comprehensive way that is non-polluting, comfortable, accessible, and provides coverage in all areas of human activity. A mass transit model that is fast, cheap and accessible everywhere within 0.5 km. The question we are asking is what would it take to have every major street in a city serviced by elevated trains.

A comprehensive solution for mass transit would need to meet the following  following essential requirements:

1.     Accessibility from within an acceptable walking distance.

2.     Frequency at a reasonable wait times.

3.     Speed at acceptable levels

4.     Comfort and privacy.

5.     Cost level acceptable to passenger and public expenditures.

6.     Emissions and noise free mass transit.

The cTrain can meet the above requirements which will be detailed further in the next sections.

The cTrain cheaper and more effective than other overhead transports because of the light weight and also the supporting structure design which make it least visually invasive on the urban landscape. The cTrain is supported by arches instead of  pillars and travels both above and bellow the  middle section of supporting arches. 

The arches are based on both sides of any  sidewalk that allows for a regular concrete light pole. By traveling always in the middle section of the supporting arch the cTrain is kept as far as possible from the built environment.




Is this proposal for a practice or a project?


What actions do you propose?

Mass transit has seen little improvement since the days of r the first buses subways and streetcars.


Overview of mass transit options

The paper will propose a design model that is believed to optimally meet the above goals which will be referred to as the six essentials features for comprehensive mass transit. Mass transit can be looked at from the perspective of three levels:

-        below ground level

-        at ground level and

-        above ground level 

Looking at mass transit in terms the three levels, underground transport is extremely expensive and takes years to build. Even in cities with high a density of stations the subway model presents shortcomings such as last-mile issues which is why taxis are in high demand in cities such as New York. Given the high, and most often prohibitive costs of building subways as a way to provide mass transit for all, it is reasonable to assume that underground transit is not likely to provide a comprehensive solution.

At ground level the barriers to a comprehensive solution are insurmountable given the limitations of available land. Moving large numbers of commuters at ground level, especially in dense areas facing traffic does not seem to be an option in meeting the six essential features needed for comprehensive mass transit.

Given that neither underground ground-level mass transit are likely to provide a comprehensive solution the only reasonable option left is above ground transit which will be referred to as elevated transport. 

Elevated Transport in the Past and Present

The main advantages of elevated transport are the fact that it is free from traffic limitations and is less expensive than underground transit. The disadvantages are the limitations of available space to be built in dense areas and the visual blight on the urban landscape, including darkening of the streets by the supporting structures for the tracks. Other disadvantages that resulted in their dismantling were the high level of noise and issues of hygiene. 


As a way to reduce visual blight the monorail presents a better alternative for elevated trains and even though it was introduced in the 1960’s it never became a widespread mode of transport. The images below show the Seattle monorail which was built in 1962 and the Mumbai monorail built in 2014. While monorails are bring significant improvements to the problems faced by elevated trains (less visual blight and noise) they are limited to areas that have sufficiently wide open space.

Personal Rapid Transit

Further progress in elevated transport has been made by using smaller vehicles on specially built guideways often referred to as Private Rapid Transit (PRT). The technology was introduced in the 70’s but never became a mode of transport to service urban environments and has been limited to areas such as airports and campuses. 

More advanced PRT models are being proposed and developed in the last few years such as at London Heathrow airport. Notably the title of an article reporting its implementation captures the history:  Fifty years on, it may be time for personal rapid transit  (RICHARD GILBERT, The Globe and Mail, Aug. 03, 2011). While this is a step forward this PRT model is limited to areas that have sufficiently open space, as are the other models, but to a lesser degree. 

One of the most advanced models to date in elevated mass transit is likely the SkyTran concept currently in testing stages of development. With its minimal height and width the SkyTran  brings progress in reducing visual blight on the urban landscape. However the hanging pods present challenges related to stability while the magnetically levitating technology is challenging and significantly more expensive than the model we are proposing. Given the need for large number of pods continuously moving over the streets the issue of visual blight continues to present a challenge. 

Proposed Elevated Mini cTrain (caterpillar train)

We propose a simpler model, a new mode of public transport, called the cTrain, to address the deficiencies of the existing public transport modes. To a large extent, it will ameliorate the problems related to last-mile access, comfort, cost and availability of public transport. In comparison with the SkyTran the cTrain model can be built on simpler technologies and at a significantly lower costs. In fact - with the exception of the software and electronics for automation - the cTrain can be built on technology as old as the advent of the electric motor.

The cTrain name comes from semblance of the cTrain to a caterpillar. 

Design principles

The cTrain concept is an automated mass transit mode of elevated light weight trains with seating room only. The cTrain is designed to minimize the visual impact on the urban landscape via the following features:

Minimal height of trains (via sitting room only)   +  Minimal width  m helps bring minimal weight and minimally visible supporting structures as well as Minimal thickness of tracks                                                     - travel both above and below the tracks

further reduces visual impact & allows the cTrain to be positioned furthest away from either side of the built environment.

At about 10 to12 seats placed in sequence (with two passengers per row), the cTrain has a low height and width for each vehicle to help minimize weight as well as visual impact on the urban landscape. The low weight of the trains also simplifies the size and cost of supporting structures as well as their visual impact. The trains are designed to move above as well as below the rails.

Compared to monorails or elevated trains the cTrain is about half the height and half the width which makes it far less visually invasive on the urban landscape.

The cTrain rails are held by arched supporting structures planted on the sidewalks designed to be no more visually invasive than an average concrete pole. Most of the weight of a cTrain is supported by the arches rather than the rails.  The thickness of the rails is a function of the distance between the supporting arches. Having at least one supporting arch at any time allows for relatively thin rails. The suggested design is for vertically oval rails at dimensions of (3x4 inches) though R&D will be needed to optimize the frequency of the arches and the thickness of the rails.

Advancements in material science may allow for parts of the supporting structures to be built from transparent or semi-transparent materials to further reduce visual impact.


The suggested number of seats are 10 in tandem in an average urban environment. Each row is a private space for a single but with sufficient space for travel with a significant other. This feature is valuable especially in the West where there is a great premium on privacy. This allows for a comparable level of comfort to cars.



The concave design of the wheels allows for secure and stable rolling on the tracks. Additionally, each wheel will have at least one safety wheel running horizontally along grooves within the rails positioned to protect against derailment. The interior of the wheels has rubber covering. The rubber contact area of the wheels with the rails, combined with optimal shock absorbing systems will minimize audible noise which is expected to be less than the noise from an electric car on the street.  

Minimal energy use per passenger

The suggested design is for small electric motors on each axel – distributed at approximately one motor per passenger (in tandem); however the optimal number, size and placement of the electric motors subject to R&D, including considerations for placing the motors within the wheels versus on the axels. Electric cables may run along the rails – similar to trolley cables to power the motors. Each train will have batteries as a backup in case of power loss and also to mitigate the strain on the grid when accelerating as well as when regenerating power through braking. 

NOTE: with the latest advancements in battery technology there are advantages to be considered in using batteries only, rather than having electric cables which can be costly to build and maintain.

Safety of supporting structures 

In case of an accident the supporting arches have sufficient concrete at the base withstand impact from a truck.


Quick and Easy Entry and Exit

In order to reduce the entry and exit time, the floor of the train is elevated above the platform of station. Given the height of the train floor above the station floor (shown by arrow) there is a reduction in the standing up and sitting down time and effort required for each passenger.

The differential in height of vehicle platform versus ground level makes for easy access, similar to seating into, and getting out from, an SUV or a golf cart.  The image below is from test videos showing that for an older person it takes less than 3 seconds to exit or enter the vehicle. Given this preliminary test, with a maximum of 3 seconds required for entry and 3 seconds for exit, a stop is not expected to exceed 6 seconds, thus an average of 8 to 10 seconds stop time per station may be a reasonable assumption.


Wheelchair Access

Each cTrain will have access for a wheel chair in a dedicated area where the floor of the train is at level with the platform. Seat folds vertically to make space for wheelchair when needed.

All stations are designed with an elevator for wheelchair access. 


Easy and Efficient Access to Available Seats

Given that all passengers have to be seated in a cTrain, there is a system to ensure smooth circulation for access to available seats without crowding and competing for seats. While entering a seat each passenger selects destination stop. This, combined with infrared or other technology that detects empty seats, provides passengers at upcoming stops with green light indicating where to stand for an open seat in the next cTrain. Passengers wait in a line similar to the customers in a bank waiting for the next teller light. 


Each cTrain has at least one section where two seats are facing each other to allow up to 4 people to sit together - couple with a child go to the area of designated for four seats and the green light indicating upcoming open seats. 



The capacity per train need not be high as the CTrain is designed to be built over every major street and avenue which will eliminate clustering. The image below shows a station an intersection at of two avenues with two lanes in each direction. Station is larger at intersections to accommodate passengers from both cTrain directions, otherwise a station is smaller if not at an intersection. The goal is to the cTrain service over every main street or avenue in a city so as to have sufficient coverage to have access from anywhere within a few blocks - in other words to have the equivalent of a "subway" stop at every major intersection.


Image below: design mechanism -  switch from travel above to below the tracks and vice-versa


Image below: "Vertical Depot" - based on principles in design mechanism for switching between travel on lower and upper tracks shown above.


Design for smooth crossing at intersections with minimal ware.




Crossing for the upper wheels (on the lower tracks) uses an auxiliary/transitional trackCLICK IMAGE TO EXPAND

Stations can have variable capacity for intersecting lines. The modular design makes it easy to expand capacity.


Who will take these actions?

Given the interest we received so far the likely avenue will be for local governments to commission a test route for the cTrain.  We have had interest from a number of authorities asking to have the cTrain as part of their transit system and especially to provide coverage in underserved areas.


Government of India organized a nation-wide event, Rail Vikas Shivir on Nov. 2016, to generate new ideas and innovations for the Railways sector in India. The cTrain proposal was received favorably.

Officials in the Indian government, both at federal and state levels, are currently developing proposals for the implementation of the cTrain.


We are currently developing a proposal working with a state government and a university in the US for R&D of a fully working model in a large city.


Our goal is to develop an optimal design that can be easily replicated anywhere in the world, with modular elements that can be assembled quickly and cheaply, as well as optimal design and positioning of the batteries, electric motors and other factors. 


We advocate for a global standard/convention for urban mobility (regardless if it is our design or if a better one will be proposed) that includes access to clean and affordable transportation as a human right to fight both poverty as well as climate change.


In order to arrive to the most efficient model we are engaging business and academia in the following areas:

Civil engineering and Material Science - minimizing the visibility of the tracks and supporting structures; use of transparent materials to further reduce visual impact on the urban landscape

Architecture - optimal design of the stations to blend with the urban environment

Mechanical - switch mechanism and process of cTrain traveling above the tracks to below the tracks

Electrical - Optimization of size, placement etc of electric motors; as well as of batteries to serve both as backups and minimizing the strain on the grid

Computer Science - developing algorithms for decisions of self driving trains for speed, number of trains to leave or return to depot, etc.

This project may be of historical relevance, in the sense that it can produce the blueprint for a mass transit model to be run entirely on renewable energy while providing coverage anywhere within a few blocks from residential places or businesses - a possible model as a global standard in the way cars and roads are manufactured an implemented worldwide.

We are in the process of beginning development in both India and the US. The following article reports interest from officials in India. 

The Indian Express

(NOTE: the article mistakenly listed E. Jacob as a PhD from MIT which is not correct and the author was notified)

Where will these actions be taken?

With a proof of concept in place  private companies will be commissioned by local governments to build "sample" routes and later the city and state gov. can create a charter company with a mandate to provide access in all areas at say maximum 0.5 mile distance from any building. The standard would be akin to standards requiring access to water, electricity etc. 

Any large city in the world is a good candidate for the cTrain. Though the desperation being greater in China and India for clean and efficient mass transit makes them primary candidates. Airports also make for ideal candidates as the cTrain can be built to go through terminals moving large numbers of passengers to their connections and to and from the city.

Adopting the cTrain model on a complete scale - i.e. to replace all existing modes of mass transit - provides a long list of benefits.

Replacing existing bus and train depots with the "vertical depots" represented by the blue structure in the figure below opens the land, (taken by the current depot represented by the yellow line) for commercial or residential development. Vertical Depot placement (blue structure) versus current mode of ground level depot (area marked by yellow line); example in Boston area (Brookline, Cleveland Circle Station, Massachusetts) 

In addition, specify the country or countries where these actions will be taken.

United States

Country 2


Country 3

No country selected

Country 4

No country selected

Country 5

No country selected


What impact will these actions have on greenhouse gas emissions and/or adapting to climate change?

The cTrain model is designed to be powered entirely by renewable energy.

For a city that provides cTrain service over its major avenues and roads, including connections from the suburbs into downtown, it is reasonable to conclude that it will reduce the rush hour traffic by at least at least 50% of.

Commuters will prefer the cTrain for being faster, cheaper and more comfortable than the car. NOTE: we are proposing the same level of comfort and privacy as the car.  


Reducing over 50% of commuter traffic brings drastic reductions in emissions. Additionally the smoother flow of truck traffic will further reduce emissions as a result of reduced stalling along metro area highways.  

Undesirable effect on the ecosystem and climate change

The cTrain model can have an impact resembling the effect of the first trains and later cars that created suburbs and caused urban sprawl. Many of the people we interviewed said that "if I have access to that kind of transportation I wouldn't mind leaving out of the city."  This reaction, while positive, carries a burden:  increasing urban sprawl. In order to minimize the urban sprawl effect policy makers need to create effective incentives for minimize expansion into green areas and make it attractive to build within existing suburbs (more apartment buildings). 

On the positive side the cTrain, if applied with appropriate policies, can help reduce urban sprawl by making many areas more attractive than without having mass transit. At some point in the future it may even help concentrate greater number of people in an area, while providing a higher quality of life. This aspect can help rewilding the planet  or at lease reduce the pace of human impact. 

The image below shows the impact of human expansion into green areas. Scientists are warning of "A looming mass extinction caused by humans  - The Anthropocene, or Age of Man, will be marked by a rapid decline in biodiversity as animals   ---

Finding ways to stop urban sprawl is is essential to reducing CO2

What are other key benefits?

A comprehensive solution for mass transit - complete coverage at a lower cost than all public transit modes to date

1.     Accessibility from within an acceptable walking distance.

2.     Frequency at a reasonable wait times.

3.     Speed at acceptable levels

4.     Comfort and privacy.

5.     Cost level acceptable to passenger.

6.     Emissions and noise free mass transit.

Further/exponential benefits:

Improved worker productivity –less stress, less time wasted in traffic less financial strain from car costs etc.

Greater, equity and employment– improved service to and from underserved areas would help both employers and workers and reduce poverty.

Improved health – lower pollution, fewer accidents, less aggravation from traffic

Improved freight transportation efficiency - fewer cars on the roads during rush hours

Lower public roads expenditures - on road repairs and and mass transit

Climate Change Mitigation

Higher revenues to local and state governments - from capitalizing one newly available land and buildings

More enjoyable cities - wider sidewalks. In cities such as New York the sidewalks of some of it's major avenues can be widened as car and cab traffic would be reduced, allowing for placement of benches and trees.



The cTrain model can meet demand entirely for any city more cheaply and effectively than subways. 

Given the expected flooding of coastal cities elevated mass transit is vital for preparedness. 

New York has spent billions restoring its subway system after flooding from Hurricane Sandy. The same billions can replace the subway system with an elevated mode such as the cTrain which would also be much cheaper to operate. 

NEW YORK TIMES: Could New York City Subways Survive Another Hurricane?

CNN: Hurricane Sandy cripples NYC subways




What are the proposal’s projected costs?


The greatest challenge is in minimizing the visual impact of the cTrains on the urban landscape. The ultimate design before implementation should ideally have extensive Civil engineering and Material Science research to minimize the visibility of the tracks and supporting structures; use of transparent materials to further reduce visual impact on the urban landscape. There is a degree of resistance to overhead transit - based more on the perceptions related to old models of elevated transport. The cTrain would be much smaller, and would have extensive use of transparent materials, when compared to the "L" or monorails. 


At the present time we can only extrapolate the costs. Assuming that a supporting structure (typically an arch holding the tracks) will be needed at every 20 meters it would come to 50 arches per kilometer.

The cost of installing a concrete light pole in one example is $3,500 (includes construction by an electrical contractor along with the City's design, inspection and processing).

We will assume from this that the cost of each supporting structure would at $10,000 x 50 per kilometer = $500k/km


Tracks resemble oval pipes and measure 4 inches vertically by 3 inches horizontally. Cost of tracks $500 per 20 meters at 50 per km = $500k/km

The cost of the stations - placed at every km estimated at $500,000 per km including the cost of elevators (the cost of a wheelchair accessible elevator in public transport is about $80k).

The electronic controls for automatic drivers including all the software and hardware estimated at $100,000/km including command and control centers for monitoring.

Each cTrain runs on electric motors and requires fewer parts and less material than an average car. Therefore we assume that it should not cost more than $50,000 per cTrain and we account for two cTrains (two directions) per kilometer.

NOTE: extrapolated numbers are based on post R&D costs and assuming construction of the cTrain over thousands of miles to benefit from economies of scale.

While the above numbers seem minuscule relative to typical costs of traditional mass transit (including monorails) there is a strong argument for the extrapolated numbers shown above. In other words concrete poles to support the arches are not any different than similar concrete poles used today. The elevators for wheelchair access at each station are not any different than similar elevators etc. 

The interesting lesson from the cTrain  is that even if the cost is many times greater than what is estimated above, the model still provides an effective solution for comprehensive mass transit.


2 years - full scale working prototype

5-15 years - a number of cities adopt the cTrain model as a comprehensive solution to mass transit and a tool against poverty and climate change. Having replaced all subways and trains cities benefit from sale/rental of land and subway stations.While running the entire system at less than a tenth of the cost needed for the old mass transit modes the coverage is extended to all areas where there is a road where people need access.

15-50 years - by the end of the period the Ctrain (or other form of elevated mass transit) is part of a global convention as a human right and as an obligation to combat global warming.

About the author(s)

Emil Jacob, owner and founder of Jacob Innovations LLC, design firm in Cambridge, MA.The cTrain is a comprehensive project and thesis in his Masters in DESIGN FOR HUMAN HEALTH at the Boston Architectural College.
He had his B.A.  in Economics from the University of Toronto and has worked extensively in IT as a Business Systems Analyst.


Below is a list of my 7 submissions creating synergies that curb climate change.

** 2 is based on **1 

*4 is based on *3  

Shifting Attitudes and Behaviors
**1. Global Civic Center & Capital - the road to a sustainable planet   --- CURRENT PROPOSAL

**2. CoLab City - a blueprint for resilient, green cities

*3. Mini Elevated GreenTrains - complete transit solution - powered by green energy               

*4. Mini Elevated GREEN TRAINS - preparing for flooded subways in coastal cities  

5. Universal Ceiling Fan- Heating, Cooling, Superior Ambiance Without Fossil Fuels

Energy Supply
6. Vertical Axis Windmill Tower for densely populated areas

7. Transforming low income housing areas: SUSTAINABLE, INCLUSIVE, PROFITABLE


A converging summary of the seven submissions



Dr Ashwani Kumar has a PhD from Singapore-MIT alliance, 
specializing in future urban transport. He is an adviser and 
collaborator on the project and started working on the cTrain 
concept during his PhD program at MIT in Cambridge, MA.

Presently, he is a senior civil servant with the government of India, where he heads the ticketing system and web applications on Indian Railways as a general manager with the Centre for Railway Information Systems (CRIS).

Apart from publishing in academic journals, he writes frequently in ‘Indian express’ and ‘Economic and Political Weekly’ on a variety of urban and transport related issues in India. He has presented papers and spoken extensively all across the world in various conferences.

Related Proposals

Other elevated mass transit models have failed to provide a comprehensive solution because of greater visual blight than the cTrain, or requiring more space to be implemented.

The most advanced model in elevated mass transit is the SkyTran:

The SkyTran requires complex maglev technologies which would be limited to capabilities available only to highly specialized companies. 

In comparison with the SkyTran the cTrain model can be built on simpler technologies and at a significantly lower costs. In fact - with the exception of the software and electronics for automation - the cTrain can be built on technology as old as the advent of the electric motor.

Following our win in the CoLab Transportation category, 2016 we received a favorable review from the:  THE AMERICAN SOCIETY OF CIVIL ENGINEERS   -- MASS TRANSIT INVENTION GOES ABOVE AND BEYOND




Last mile issues are one of the main reasons for mass transit failures researched by Dr. Ashwani Kumar.

Dr. Ashwani Kumar, PhD in Transportation from MIT will be presenting the cTrain at 14th World Conference on Transport Research - 10-15 July 2016 | Shanghai, China.

Articles and papers at: 



Capacity of the cTrain model

The capacity per train need not be high as the C-Train is designed to be built over every major street and avenue which will eliminate clustering. It appears that the optimal design is for each train to have 10-12 seats in sequence accommodating 1 passenger per seat (however each seat has enough space to accommodate parent with child or a couple traveling together).

The C-Train would have a frequency of 10 passengers every 10 seconds i.e. 3600 people per hour per direction. Providing this model on all the areas intensively (with many lines entering the city Centre) will not only obviate the need for buses, trains and subways in a city but can also wean away many commuters from cars.


Elevated mass transit holds the solution for a comprehensive cure to the ills stemming from the shortcomings of mass transit since the early days of the first streetcars and buses. The cTrain model contains a number of features that eliminate or sufficiently reduce the impediments that have to date stopped elevated transit from providing a comprehensive solution to public transport.




Evans, Gary W., and Richard E. Wener. "Crowding and personal space invasion on the train: Please don’t make me sit in the middle." Journal of Environmental Psychology 27, no. 1 (2007): 90-94.

Wener, Richard E., Gary W. Evans, Donald Phillips, and Natasha Nadler. "Running for the 7: 45: The effects of public transit improvements on commuter stress." Transportation 30, no. 2 (2003): 203-220

Boston Globe Article



The Indian EXPRESS

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Proposal summary
Mini Elevated GreenTrains - complete transit solution - powered by green energy
Team proposal: Only members listed on the proposal's Contributors tab will be able to edit this proposal. Members can request to join the proposal team on the Contributors tab. The proposal owner can open this proposal for anyone to edit using the Admin tab.
By:  Emil Jacob
Contest: Transportation 2016
What initiatives, policies and technologies can significantly reduce greenhouse gas emissions from the transportation sector?