Call it brilliant marketing or call it a happy coincidence -- either way, Elon Musk's The Boring Company has just bagged a big contract to connect Chicago O'Hare Airport to the city's downtown Loop district.

To do it, he'll be building a "Loop" of his own.

Loop, as we discovered at The Boring Company (TBC) press conference in L.A. last month, is the name of Musk's latest transportation brainchild, a system of tunnels bored through solid rock that can be used to transport passenger "pods" along underground highways at speeds approaching 150 miles per hour.

An offer they couldn't refuse

Late last year, Musk announced on Twitter that TBC would be one of four companies bidding on the Chicago transportation contract, and just a little over six months later he's come out on top. Musk's promise to pay for building his O'Hare-Loop Loop out of pocket, and recoup his costs by charging usage fees for the service, was likely key to the company's success.

As The Chicago Sun reports, Musk has promised that his Loop will carry passengers from downtown to the airport (an 18-mile trek) in 12 minutes flat, at a cost of $20 to $25 per ticket. An anonymous source confirmed to the Sun that TBC is estimating the project's cost at "less than $1 billion."

That's an ambitious goal. Other urban public transportation costs in other cities have sometimes topped the $1 billion mark per mile of tunnel constructed. Still, taking the $1 billion projection at face value and using it as a ceiling amount on the cost of the project, assuming 16 passengers per pod paying $20 to $25 a head, it could take Musk anywhere from 2.5 million to 3.1 million trips to pay for the project -- not counting any financing costs, and assuming full capacity on each trip.

However, consider that O'Hare is the third busiest airport in the country, shuttling nearly 80 million passengers through its doors every year. If each of those passengers used Loop just once, the revenue would suffice to pay for Loop's construction in less than one year. Additionally, TBC will be able to sell advertising on board its pods, and sell goods and services to passengers in transit, which could further shrink the payback period on Musk's investment.

What this means for investors

Musk is financing Loop primarily out of his own pocket, and the company is not publicly traded. Still, there are at least two ways investors should be looking at Loop -- one medium-term, and one much further out.

Musk is hoping to begin construction of Chicago's Loop as soon as he receives all the needed permits, perhaps as soon as three to four months from now. Medium-term, construction could be complete, and Loop operational, within 18 to 36 months.

Again, this seems an ambitious schedule for a major urban public transportation project. Still, if Musk can pull it off, the Chicago Loop project could provide a financial boost to Musk's most famous company, Tesla (NASDAQ:TSLA). TBC has confirmed that it will be buying the pods that will run passengers through Loop's tunnels from Tesla. Depending on how many pods we're talking about (and it could be a lot, to accommodate those 80 million O'Hare passengers), that could mean a sizable revenue boost for Tesla, albeit along with attendant capital investment costs to build the new type of vehicle.

Longer term, if Loop proves out as a concept in Chicago, it has the potential to remake the transportation market in other cities, and indeed throughout the U.S. -- depressing sales of personal automobiles, helping sales of mass transit vehicles such as Loop's pods, and providing Tesla with a captive market for one of its products.

Ultimately, Musk envisions Loop as less of a Point A-to-Point B shuttle service such as Chicago is envisioning, and more of an underground highway network connecting hundreds or even thousands of small stations for boarding and offloading passengers. The closer he gets to that goal, the more revenue for Tesla, and the greater the danger of investing in car companies other than Tesla.