MANY cities around the world are facing a conundrum. With populations increasing and demand for public transport services intensifying, they are struggling to build new infrastructure fast enough to keep up.
The problem is particularly pertinent in the developing world where for many years governments have lacked the means to develop adequate infrastructure.
Jakarta is the epitome of this. With an estimated population of 10.2 million in the city, and 28.2 million across the metropolitan area, which has grown from 8.2 million in 1970, its limited and ageing commuter rail network is unable to serve the city's needs. The streets are consequently jammed with traffic, which makes getting around extremely difficult, and with the metropolitan population expected to increase to 35 million by 2020, these problems will only deepen.
Lagos, Addis Ababa, Hanoi, Delhi, Lahore, Baghdad, Kuala Lumpur, and Johannesburg suffer from similar problems and were all rated as having below average public transport offerings in the International Public Transport Association (UITP) and consultant Arthur D Little's Future of Urban Mobility 2.0 study issued in 2014.
Jakarta is attempting to address its issues by constructing a new metro line and airport rail link. However, these projects have been fraught with delays and will not go far enough to provide a viable alternative to the car. It's a similar story in Lagos where a plan to introduce a limited commuter service has stalled.
The expense and complexity of building new infrastructure in areas with high population density are the major challenges to delivering the high-capacity public transport networks these cities so badly need. However, Mercury Rail, and Anglo-Australian alliance, believes it has come up with an answer to this problem with a new concept for an affordable and sustainable elevated rail infrastructure system.
Mr Ian Saul, director of engineering solutions, at Mercury Rail, says the company recognised that elevated railways utilise huge structures which are over-designed for rail applications, take up too much space, and are expensive. As a result he says the team at Mercury decided to come up with an alternative concept which incorporates sustainable elements, is low-cost, increases safety for construction workers and passengers, and delivers socio-economic benefits.
Saul says Mercury's solution, the Low Cost Sustainable Transport System (LCSTS), is a modular design consisting of four main components, which are easily-transportable, straightforward to assemble, require less space than conventional elevated systems, and are flexible to the requirements of any project, whether it is standard or narrow gauge, single or double track.
The double-track standard-gauge viaduct requires a 4m-wide area (2.5m for single track), which can be a footpath or road central reservation, to install 2x550mm-diameter piles (2x400mm for narrow gauge). The piles are supported by a precast block positioned within a 3m² excavation area which is connected to the piles using embedded steel dowels with steel bracing installed around the four columns 1m below the surface. On top of the columns, two split cradles are installed which include a specialist rail housing unit, which consists of a hard-wearing polymer to prevent degradation and has a lifespan of 25 years, and a vibration mitigation layer, which is encased in steel to reduce the degradation of the polymer.
Installation of each pile location is carried out within a 180m-long moving work area which minimises disruption to pedestrians and road users. The road is only closed during the installation of the beam, which takes place at the end of a predefined pile construction section of 10-20 pile locations.
At this point the mobile construction rig carrying the individual superstructure section is driven into place. Using the rig enables the very precise installation of the beam while surveying beacons are used by a surveyor during the superstructure installation to identify any small movements. Once in place steel bracing is installed 500mm below the split cradles for stable support before the walls are lifted into position and secured. Where wayside equipment is required, one wall is replaced by a steel grid platform which is braced against the columns with an option for additional columns available for heavier equipment.
"As it is a modular system, it is easy to put up and it quickly pays for itself," says Mr Nigel Walrond, principal consultant, integrated systems, at Mercury Rail. "Its design also means that you won't have to close down roads for weeks at a time as the structure is built, which can turn the public against a project. This is what happened in Jakarta with its metro line. The system minimises the impact on the public and existing buildings and structures."
For station platforms the support structure is a lattice design which allows passage underneath while maintaining the same longitudinal footprint as the track structure. Retrofitting a platform area to the elevated structure requires an 8.5m superstructure to allow passage under the 4m pile spread, a 2.35m-wide platform area, a 6m escalator approach to the platform, and space for passenger channelling, which is dependent on the expected usage of the station.
Passengers can only access the platform when a train is approaching with platform screen doors separating passengers from railway infrastructure, improving safety. The platform itself is 25% smaller than conventional elevated platforms because of the proposed reduction in train size for the system.
Saul says that while the trains are smaller they will be designed to maximise space to provide comparable capacity with existing systems. He added that Mercury is in discussions with manufacturers about developing a suitable solution.
"We have a strong relationship with a rolling stock manufacturer and have worked on how the weight of the rolling stock would impact the system," Saul says. "We have found that it is more than capable of accommodating 22 tonne axleloads, and to go any higher than this it would simply require increasing the pile size."
Another important consideration for the project for Saul and Walrond is its capability to provide socio-economic payback. Saul says that the simplicity of LCSTS's design means that installing the system is within the capabilities of local workers with up to 95% of the labour required for the project available locally.
The structure also uses sustainable materials, specifically E-crete, a low-carbon concrete for each superstructure, wall and column component. This again can be produced locally and the production process is proven to reduce CO2 emissions by 60% compared with conventional Ordinary Portland Cement-based concrete.
The cost of the system is of course dependent on the location. However, compared with traditional elevated structures, LCSTS uses 60% fewer materials, which reduces costs significantly, without sacrificing stability. "If one pile gets hit by a car or a truck, you have still got three to provide the support," Saul says.
The modular design of the structure also reduces construction costs and simplifies the process with only six engineers required to install a single section of the structure. The city is able to fund construction in stages enabling the generation of revenue when only a portion of the infrastructure is complete.
Reductions in material costs are similarly possible by removing walls, which reduces the weight of the structure and are attractive for applications outside of urban areas. In this case communications and signalling cables are relocated to the base of the structure from conventional application in the box-section void. Maintenance outlay is also reduced by adapting equipment used for construction such as the construction rig for track inspection and by utilising the latest techniques and affordable but state-of-the-art inspection vehicles.
There are also options to tailor the structure's design to a particular environment and meet cities' concerns about how it will look within the existing environment. "Traditionally low-cost structures are not as aesthetically pleasing so we have looked at designing the façade of the structure to fit in with the local situation," Walrond says. "This will increase the time it takes to build and the cost, but it is an option to deliver something that suits the local surroundings."
Saul says Mercury is targeting LCSTS at projects in the Middle East, Africa and Asia, with Malaysia and Vietnam considered key target markets, and Saudi Arabia another attractive proposition. "They are more interested in the safety aspects of the system's approach than the low-cost element," Saul says, adding that in general the reception for LCSTS has been overwhelmingly positive. "We have had a lot of feedback from presentations and they are encouraged that we are looking to do things differently, and taking a fresh approach to this problem."
Saul's experiences in the rail industry began with Jarvis Rail in Britain in 2000 and he has subsequently worked in Saudi Arabia and Australia. Walrond has a similar background, beginning with Docklands Light Rail in the 1990s, then spending time in Asia, before moving to Australia.
Both say they see Mercury Rail as an opportunity to give something back to the industry and "to provide a solution that makes a difference." They would not reveal who is backing Mercury Rail financially, but emphasised that the project's investors are "100% committed" to making it a success.
With their drive and determination to deliver, LCSTS is likely to be a new consideration for urban rail developers as they let contracts in the next few years and may become a key feature of efforts to combat congestion, particularly in areas where the cost of doing so have proven prohibitive.
"Many people work in the railway industry and have ideas, but tend to focus on something that will look good," Saul says. "They don't often get the chance to do something that is a legacy project and will still have value in 50 years."