San Antonio residents and visitors would be able to make one-way trips from downtown to the Pearl and back in under two minutes, and from downtown to the San Antonio Airport in under 10 minutes, if Elon Musk’s proposed tunnel becomes reality, officials said Wednesday.

New details of the Alamo Loop Project that is expected to cost between $241 million to $298 million were discussed during Wednesday’s update from the Alamo Regional Mobility Authority (RMA) staff to the RMA board of directors. 

The update comes after a March 16 meeting in which the RMA’s board took the next steps with The Boring Company for the high-capacity transportation project aimed to reduce traffic. 

Renee Green, Bexar County’s director of public works, told the board Wednesday that the estimated time to design and construct the project would be less than 36 months. All funding for the project would come from The Boring Company, she emphasized, and not be funded by taxpayer money. 

“It will assist with growth congestion, which is currently projected to be about $20 billion short, meaning we will not have enough money, taxpayer money, to build out all the transportation needs that we have to address this,” she said. 

In the presentation, Green said that out of 30 million visitors the city sees per year, more than 10 million landings occur at San Antonio International Airport. Based on that, the Boring Company estimates the projected annual net revenue could be as high as $25 million per year. 

“These revenue projections would require, obviously, more detailed study for reasonableness and accuracy. That’s what the ridership and revenue study will tell us,” said Green. “Is this a realistic estimate?”

The Alamo Loop Project would be a high-capacity, one-way underground tunnel of 7.6 miles long that will run under U.S. 281, which the RMA says can transport customers via direct routes faster than traditional transportation systems in Tesla vehicles, including newer ones as they become available. 

According to Green, with 100 vehicles, there is an average daily capacity of 32,000 passengers, with the maximum at 4,500 per hour. The fare would be between $10 to $12. With 350 Tesla vehicles operating, 112,000 people can commute daily, and 15,750 per hour from the airport to downtown. 

It is unknown if self-driving vehicles will transport passengers or if drivers will operate the vehicles, confirmed Monica Ramos, public information officer for the office of the county manager.

“This is an extremely efficient system. You don’t have any cross traffic, you’re not stopping at each location, you’re either pulling in or pulling out of the tunnel system,” said Green. 

Passengers would board and deboard at designated stations, although passengers may be dropped off at their ultimate “last-mile” destinations. Stations will be one of three different types, depending on station location: sub-surface stations that passengers and cars can access via an escalator; open-air stations; and surface stations.

“Every trip is an express trip with little-to-zero wait time. … The project can provide an equivalent capacity to both bus and rapid transit for a fraction of the operating costs that we’re talking about, while providing reliability and solving a lot of the last-mile difficulties that you see with traditional transit systems by utilizing underground rides where the system will supplement any plan for ongoing transit type projects and is not expected to replace them,” said Green, emphasizing traditional transit is still a “necessary, critical” part of the community, and that the tunnel projects are not competing for the same ridership for tunnel projects. 

Tunnels would be constructed using an Earth Pressure Balance Tunnel Boring Machine launched at station locations, with multiple machines operating at any time. Tunneling can run 24 hours a day, seven days a week, Green said. 

The tunnels are expected to be 30 to 50 feet deep. 

For safety, emergency egress shafts, or stairs, will be built along the tunnel every half- mile. The tunnel system, Green said, would not utilize  live electric thirdrails like subways, will not contain any touch hazards and will be well-lit, in case of an evacuation. 

The project would be designed in accordance with the National Fire Protection Association’s 130 design standards. System ventilation would remove smoke and cameras would monitor the system always. Green added that the tunnels will be lined with water-tight gaskets to protect against groundwater infiltration. 

The planning level route is along the Artesian Zone of the Edwards Aquifer, Green said, adding the Texas Commission on Environmental Quality does not require special permitting within the zone. In a route study, other potential environmental issues will be identified. 

Also in phase one of the engineering process, the implementation plan will study geological information, and a subsurface feasibility study will be conducted to determine any underground obstacles that would result in risk. If risk is identified, Green said, The Boring Company would pause all plans and “walk away. … Unless they themselves want to pay or subsidize [improvement].”

By this time, utility coordination will begin and a design launch site will be determined. The RMA will also begin to undergo a ridership and revenue study, based on the route study. 

In design and pre-construction steps, 60% of design principles, such as civil, structural, mechanical and architectural, will be reviewed in the collective project to determine constructibility and refine the final product. At 85% design,  The Boring Company will respond to internal and external feedback provided by stakeholders and make any minor adjustments to the design. Final plans will then be submitted for the issuance of any applicable permits.

Green discussed benefits of the project, including lowering congestion anticipated in 2050. 

“There’s still a lot of need… The goal is to be able to put more money back into the community, back into areas that may not qualify for funds,” said Green. 

So far, The Boring Company has developed a comprehensive assessment of the project’s viability, after which management decided to pursue the opportunity. 

“The system is expandable as demand grows with no disruption to the existing transportation service,” said Green. 

She added the system will help move people without increasing emissions. 

“Our community was just bumped up from marginal to moderate. So we do have to start looking at emission reduction strategies. And this is one way to go,” she said. 

Avatar photo

Raquel Torres

Raquel Torres is the San Antonio Report's breaking news reporter. She previously worked at the Tyler Morning Telegraph and is a 2020 graduate of Stephen F. Austin State University.