The Environmentally Friendly Linkage System (Chinese: 環保連接系統), abbreviated to EFLS and commonly called the Kai Tak Monorail, is a government-proposed monorail system in the Kai Tak Development area, Hong Kong with 12 stations. The system's construction was estimated to start in 2018 for completion in 2023. The new links are expected to account for 15 percent of public transportation in the Kowloon East Development. The system is expected to cost $12 billion Hong Kong dollars.
Throughout the 1990s, a number of master plans were drawn up to prepare for the eventual reuse of the Kai Tak airport land. The South East Kowloon Development Statement (1993) and the Feasibility Study for South East Kowloon Development (1998) both proposed that the site be served by two conventional Mass Transit Railway lines running underground. A 2001 study deleted the line serving the former runway area, replacing it with a proposed "trolley bus or light rail". In light of the Protection of the Harbour Ordinance and overwhelming public opinion against further reclamation of Victoria Harbour, the plan for Kai Tak was further cut back. But this basic premise of a light railway linking the Sha Tin to Central Link station to the runway hinterland lives on in the monorail proposal.
In 2007, the Kai Tak Outline Zoning Plans with railway connection system was approved by the Executive Council.
The EFLS project was headed by the Development Bureau with public consultation carried out by the Civil Engineering and Development Department.
The Civil Engineering and Development Department appointed consultants to review the flexibility of the EFLS.
According to the 2011-2012 Policy Address, Kowloon East would become the city's second Central Business District.
Hong Kong Tramways Limited proposed building a modern tramway, instead of a monorail, on the grounds of lower construction cost, more affordable fares, lower operating cost, improved flexibility for future extensions, less visual impact, no noise pollution, and socio-economic benefits. Norman Y. S. Heung, project manager from the Civil Engineering and Development Department, responded that it would not be acceptable for a tramway to share ground space with cars. Emmanuel Vivant, general manager of Hong Kong Tramways, responded that "in a city that rightly prides itself on putting priority on public transport, and where only 10 per cent of trips are done by private car, it should not be impossible to allocate space to tram lanes that can each carry eight times as many people as a road lane" and that "promoting usage of emission-free modern tramways rather than polluting private cars, would be a perfectly sensible policy decision. Where necessary, the modern tramway can simply share space with other road users".
The need for heavy construction of any kind has been challenged by the Hong Kong Cycling Alliance, on the basis that the 13-kilometre cycling network already planned for the area provides viable and more flexible connectivity, at much lower environmental impact.
The South China Morning Post claimed that a "green bus network" would only cost up to HK$400 million, and could still make a profit.
The cost of construction at 2010 prices is $12 billion Hong Kong dollars. The patronage is expected to hit 200,000 by 2031, according to the government. In 2012 officials estimated that building a monorail would yield a return of one per cent, versus four per cent for a conventional railway. The Post reported that the system would break even only if the government bears the capital and asset replacement costs.
The MTR walk‐in catchment coverage has usually a 500-metre radius or less than 8-minute walking time. After considering estimated passenger and fire safety issues, the Civil Engineering and Development Department takes the MTR walk-in catchment coverage as an indicator for the selection of the EFLS station site.
At this time, the government plans to use two-car monorail trains with capacities of about 250 passengers. The stations would be designed to allow for future expansion to three-car trains.