That has been proposed for the desert southwest of the US.
Trenches. Specifically covered trenches. It is a lesson in, how do you build cost effective tunnels in the desert?
You carve out shallow trenches, build walls and use prefabricated vaulted covers, think concrete Quonset huts, and bury the newly formed tunnel. You are now weather tight.
Road crossings could be handled by deepening the trench or ramping the road. Either solution will work based on the circumstances.
In addition to the insulating effect of the overburden, the tunnel roof can be insulated to keep the tunnels from overheating. In addition to providing a mechanism for sand control, buried air shafts would allow natural ground cooling to further cool down hot outside air being used to ventilate the tunnel.
Emergency access points can be easily designed and built into the structure. Emergency ventilation directly to the outside can be readily incorporated at regular intervals to properly ventilate the tunnel in case of a train fire to prevent choking smoke from spreading beyond the fire scene.
Being a shallow buried modular structure any major track or infrastructure repairs could be done by removing the overburden and uncovering the tracks.
In the long run this would be a more cost effective solution that would reduce the ongoing maintenace costs for the system.
So forget I ever said anything. Most modern rail supporters do not care about cost effective solutions because it is not their money paying for it.
MADRID — Imagine driving in snow at night, but instead of snow, it’s a sand storm. Beyond this decreased visibility, imagine the sand getting stuck up in the tires, slowing speed, and the normally smooth roads become bumpy and unyielding. Suddenly, out of nowhere, a torrential rain storm comes pouring down, flooding the roads and muddying your view even more. Now, picture all this at 320 kilometers (200 miles) per hour. This is the perspective of the new high-speed rail conductors who will soon be driving across Saudi Arabia. Preparing for these hazards is the task set to Spanish engineers.
Last year, the Saudi Railways Organization awarded the contract for the final phase of completing, running and maintaining the Haramain High-Speed Rail Project to multiple Spanish infrastructure, construction and technology companies. Haramain means “two holy places” in Arabic; in this case, they are Medina to Mecca, the birthplace of the Prophet Muhammad and the location of the revelation of the Quran. This pilgrimage is called Hajj and is obligatory for all Muslims who can afford it.
With an estimated 1.6 billion Muslims in the world and growing, there’s no doubt why the Haramain project is especially important to this consortium of Spanish companies. This project could give Spain recognition as the worldwide expert in high-speed railways.
The Haramain railway will allow millions of pilgrims yearly to cross the 444 kilometers between their two holiest cities in less than three hours, but not without careful planning. The huge technical challenges include dust and sand storms, large temperature swings, shifting dunes, and passenger volumes that could reach 160,000 people per day — and even higher during the Hajj pilgrimage. The Saudi authorities predict the railway will serve three million passengers a year.
Started in 2009, with a cost of more than 12 billion euros, it is set to open to the public in late 2014 or early 2015. Besides the two holy cities, it will have three other stops, two in Jeddah for commuters — one in the center and one at the airport — and one in the still-under-construction King Abdullah Economic City, a residential, industrial and commercial macro-complex covering 169 kilometers (105 miles) of the previously desolate desert in this, the geographical giant of Arabia.
So, how do you build 444 kilometers (276 miles) of railway in seemingly impossible conditions in the middle of the desert? With loads of research, technology and design.
First, everything, including the stations and tracks, is designed to withstand the extreme range of temperatures in Saudi Arabia, which can go from the freezing point up to more than 50 degrees Celsius (122 degree Fahrenheit.) The power of the sun in the desert means, while not this extreme, the temperature can change dramatically from day to night. The electrified double track will include induction motor air conditioner loads, which control the speed of the motor, allowing temperature regulation. The compensator in the substations also regulates the 80- to 100-percent humidity levels, intense solar radiation and dust.
The project is also being built around the idea of tackling its heavy load, including more durable equipment and more frequent maintenance schedules. The Spanish team is calling it “An ‘AVE’ for the desert,” after the Spanish-owned, high-quality, high-speed rail that runs through most of Europe. There will be tourist and business classes, with all exclusive design elements and adapted for the Saudi Railway Organization’s special requirements. “This project consolidates Talgo’s position as the Spanish leader in the design, manufacture and maintenance of high-speed trains, and as a clear leader at a global level,” says Carlos de Palacio, president of Talgo, the company that is supplying the 350 trains ordered for the project.
But the biggest challenge of all is also the tiniest — the sand. Never has a project like this been tackled in the desert, particularly dealing with rapidly-changing weather conditions like wind, temperature and sudden deluges of rain. The power system for the electric train tracks is called a ballast. When sand gets into the ballast, it can make weight distribution uneven and can prevent drainage. There isn’t a lot of rainfall in this desert, but, when it falls, it falls hard, fast and heavy. It’s predicted certain points along the 444 kilometers will have a much bigger problem with the sand. Routes run north and south, with many kilometers running along the Red Sea coastline. The sea causes wind that brings sand clouds. This wind also forms and moves sand dunes. The Spanish consortium is building protection walls and fencing to block the sand build-up along these points. These barriers are made out of bituminous asphalt concrete, which is known to be more durable, with the added bonus of being successful at blocking the train’s noise on the other side.
They are also incorporating ditches to control the amount of sand collected. Slab tracks or railways ties are added to some sections to further prevent ballast contamination and to increase stability.
Spanish technology and innovation giant Indra is in charge of designing and constructing the state-of-the-art, touch-free, mobile, wireless technology available both on-board and off to passengers and employees alike.
One of the most important technologies goes into training staff to handle the abnormal weather conditions. Indra has created simulators with real environmental conditions for engineers, as well as drivers and other personnel, to test the new functionality under various conditions. “The environment is comprised of a combination of different types of simulators, depending on the type of railway personnel to be trained,” Indra’s spokesperson says.
Spanish construction company OHL, along with two smaller Spanish construction companies, will be in charge of the building of the superstructure and bases of the track and it mechanisms. In addition, they have been put in charge of 12 years of maintenance. OHL is also working on the Ankara-Instanbul high-speed line and the Marmaray Project, which will link Europe and Asia, also through Turkey. The company is also involved in negotiations for projects in Brazil, the US and the UAE.
Spanish-owned Adif and Renfe will be in charge of the operations management. They say that this contract “intensifies their internationalization processes and values the implicit recognition of their technical expertise in high-speed rail.”
“It would also be our first experience building a high-speed line abroad. Our point of reference is the Spanish network, which is one of the most advanced in the world,” says Antonio Gonzalez Marin, president of Adif. There’s no denying that the Spanish public transit system is an example globally. It’s quick, efficient and well-connected. Renfe, which runs the Spanish trains that branch out like arteries from Madrid’s stations, has set the goal over the next to years of opening to new international markets, making this project a wonderful start.
The contract with the Spanish consortium is for 6.74 billion euros, which will be reinvested in these struggling Castellano construction and infrastructure companies. While Spain’s name is in the mud in many ways these days, this project could give the country recognition as the king of high-speed rails — surely one of the public transports of the future and maybe a small step out of this seemingly endless hole of the crisis.
Photos: Saudi Railways
