Plans for a high-speed rail system for California have been mooted as far back as 1981. Serious planning began in the 1990s as a growing population saw an increase in the use of local transportation.

Such a system is now closer to reality than ever before; tenders for route sections were announced recently and construction work on the first aerial structure, the Fresno River Viaduct, began in June.

"We have environmentally cleared two project sections for high-speed rail. There are ten altogether that encompass the 800-mile project," says Annie Parker, information officer for the California High-Speed Rail Authority, which is responsible for planning, designing and building the project.

"One is the Merced to Fresno section and the other is Fresno to Bakersfield. What that means is that we are actually starting construction of high-speed rail, building a system near the city of Fresno near the Central Valley."

In August, the authority also released a request for qualifications for environmental and engineering services for the San Francisco to San Jose section and the San Jose to Merced route.

Another recent development is a partnership with Caltrain, a commuter rail system between San Francisco and San Mateo and Santa Clara counties, to electrify the 51-mile route that goes from downtown San Francisco to Diridon station in San Jose.

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"[Caltrain] is wildly popular because it's right along the Silicon Valley route," adds Parker. "Before, when we did work in the area, we assumed we were going to build a full, totally dedicated high-speed rail in the area.

"Now that we've decided to integrate with Caltrain - to keep costs lower - that will require some work on how it all happens. But we're having discussions and Caltrain is a partner."

California high-speed rail: section by section

As it encompasses such a large area, high-speed rail has been broken down into individual sections.

Each one has to undergo an environmental impact report before construction work can begin, and Parker is hopeful that this can be achieved for every route, with the exception of LA to San Diego and Merced to Sacramento, by 2017 - "a very ambitious schedule."

For San Francisco to San Jose, the proposed route will start at the Transbay Transit Centre and move south, with additional stations in Millbrae and San Jose as well as the possibility of stations in Redwood City or Palo Alto.

Moving west, the route will connect San Jose to Merced. Parker says: "We're starting work in the Bay area. The major feature here is there will be a station in the city of Gilroy. This will be built from the ground up.

"Gilroy is really excited about this as it's a real opportunity for them to connect with the Silicon Valley and the Bay area in a way they haven't before."

From Merced, a link will be created to Sacramento, which Parker classes as phase two and "the future".

"This is very close to businesses and the city hall; it will really be a hub in the area."

"There are a lot of existing [local transport] systems that are expanding and looking at opportunities to build out, so we're in talks with them to make sure that we are coordinating," she says.

At Merced, however, the high-speed rail will also branch off to Fresno. It will travel from the city, with a station planned for downtown Merced, direct into the city Fresno - which will also have a downtown station.

"This is very close to businesses and the city hall; it will really be a hub in the area," says Parker.

"Fresno is experiencing a revitalisation. There's already been interest from people about relocating but [at the moment] there's no real easy way to get there, apart from an airport."

Also forming part of phase two is a section called Central Valley Wye, which will take trains west to San Francisco and east to Sacramento. The Wye, which used to be part of the Merced to Fresno area, is being studied as its own environmental documents, says Parker. It has three alignments, or route plans, under consideration and a preferred alternative is expected to be announced by the end of the year.

Moving south from Fresno, high-speed rail will stop at a station in Bakersfield, with a station option under discussion in the Kings/Tulare region of the State. This would be near the city Hanford, which Parker says has a need for greater transport links.

There will also be an alternative route in the area, known as the Bakersfield F Street Station Alignment.

"We are having our first public meeting announcing the alternative and getting public feedback in August," says Parker.

"Once we decide upon on this, we can start building high-speed rail in the city of Bakersfield."

Towards LA and San Diego

As high-speed rail gets closer to LA and San Diego, it will include a line from Bakersfield to Palmdale, which, according to Parker, will be the most challenging route from an engineering point of view as it will have to go through the Tehachapi mountain range.

As such, preliminary alternatives have been identified, but the formal review process is yet to kick off.

In the original plans, the authority planned a Palmdale to LA route, but because of the length and scale of work, this was split in half, resulting in Palmdale to Burbank and Burbank to LA.

Parker says: "[For] Palmdale to Burbank we have our notice of intent and scoping meetings [and] we are now starting the formal environmental process, which will kick off next year.

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"There are a lot of professionals who live there but right now it's over two hours' drive from Palmdale to the Burbank area. High-speed rail will cut it down to approximately 15 minutes [and therefore] Palmdale is really enthusiastic about high-speed rail."

The Burbank to LA route, where public meetings will start very soon, will connect with LA Union station, a major hub in southern California for rail and bus services. For Burbank, Parker says the authority is keen to tap into plans to upgrade the city's metro services and fit into the "overall picture" of transportation.

From LA, a branch will take trains to Anaheim - the home of Disney Land - and add to an existing station that opened in December.

"From LA to San Diego; this is technically phase two of high-speed rail," adds Parker.

"Therefore, we will not get into serious work [and] will not start environmental work on that until we get phase one, San Francisco to LA, started."

Package by package

At present, high-speed rail is broken up into five construction packages. The first is a 29-mile stretch between Madera and Fresno. Significant construction for this, which includes two viaducts, one tunnel and a river crossing over the San Joaquin River, is expected to be completed by 2017.

In August 2013, the design-build contract for this was awarded to a joint consortium called Tutor Perini/Zachry/Parsons (TPZP), three California-based companies with extensive experience of working on civil infrastructure projects.

"They have been working to bring all the designs up to 100%, to acquire property in the area, to staff up [and] to sign third-party agreements such as utility relocation," says Parker.

Construction package 2-3 (CP2-3), a combined package, runs for 65 miles and is located in the Fresno to Bakersfield section. It is likely to include 23 high-speed rail structures and 36 grade separations.

The design-build contractor is a firm called Dragados-Flatiron, while Jacobs Engineering Group, based in Pasadena, has been awarded a $1.2bn contract to provide design services.

At the time of writing, the authority is in the process of finalising the request for proposals for construction package four

"This is another 22 miles, south from CP2-3 to Poplar Avenue, north of the city of Bakersfield," Parker explains.

"At the end of last year we received statements from five firms and we have determined that they are qualified to bid.

"The next step is to release the actual request for proposal, which is coming anytime [soon]."

Package five, meanwhile, is yet to be announced. However, there is no doubt a feeling of optimism and anticipation as high-speed rail begins its long journey.