How can vehicles maintain positioning when GPS becomes unreliable? TERN’s Independently Derived Positioning System (IDPS™) enables vehicles to derive and maintain an understanding of where they are from within, including through tunnels, dense cities, parking structures, and other challenging environments.

Dan Ronan expected a brief conversation when he hosted Shaun Moore, CEO and Co-Founder of TERN, who had joined SiriusXM’s Road Dog Trucking to discuss a new approach to positioning. The segment was planned for roughly ten minutes, enough time for a few questions about the company and its technology before the program moved on.

Instead, the conversation expanded across the hour-long program. Ronan kept returning to the same underlying idea, testing it against the places and situations every driver understands: Chicago’s layered streets, long tunnels, dense cities, commercial fleets, and the systems that depend on knowing where a vehicle is. His interest was not driven by a longer list of features. It grew as he understood TERN’s architecture and began considering what that architecture could make possible.

“The core thesis of the organization is that we are taking position from the satellites in space and bringing it back down to Earth, turning vehicles into providers of position, not just consumers.”
– Shaun Moore

Ronan paused over the implication. “The vehicle actually knows where it’s at?” he asked. He had already offered a concise assessment of what he was hearing: “It sounds remarkable.”

That exchange captures a familiar progression. People often begin by trying to place TERN beside technologies they already know. Is it another navigation system? A different GPS receiver? A way to recover a lost signal? Those comparisons make sense because the prevailing architecture of positioning has been largely invisible to the people who depend on it. Once the architecture becomes clear, however, the comparison changes. The question is no longer what TERN replaces. It is what becomes possible when a vehicle can maintain an understanding of where it is from within.

How Can Vehicles Maintain Positioning When GPS Becomes Unreliable?

For decades, modern mobility has relied on an effective and familiar model. Signals from satellites and other external infrastructure provide information that receivers use to calculate position. Navigation, routing, driver assistance, fleet operations, and many other systems build on that position. GPS is an extraordinary public infrastructure, and it remains a valuable input for vehicles around the world.

The limits of any externally delivered input become visible when the operating environment changes. A vehicle may enter a tunnel, move beneath several levels of concrete, travel between tall buildings, or leave mapped roads for industrial or remote terrain. Signals may be obstructed, degraded, or delayed by terrain and structures. Increasingly, they can also be deliberately disrupted through GPS jamming or GPS spoofing. The issue is not that GPS has ceased to be useful. The issue is that systems built on continuous position still need continuity when a particular input becomes unreliable.

TERN approaches that requirement at the architectural level. TERN’s Independently Derived Positioning System (IDPS™) enables a vehicle to derive, maintain, refine, and use an understanding of its position from within. External technologies can continue to contribute useful information, but they are no longer the sole authority on which position depends. The source of position moves to the intelligence of the system itself.

This changes the usual sequence. Instead of receiving a position, losing it, and attempting to recover it, the vehicle maintains continuous positioning as an ongoing process. Position is derived from within as movement, terrain, and vehicle behavior data are analyzed to determine a precise position across changing conditions. The result is not simply a route that survives a momentary interruption. It is a positioning intelligence layer designed to persist.

That is the direct answer to the question at the center of Ronan’s interview. Vehicles can maintain positioning when GPS becomes unreliable by using an architecture in which position is independently derived and continuously refined within the vehicle. 

Why Dense Cities Expose the Limits of Conventional Vehicle Positioning

Ronan’s first practical example was Lower Wacker Drive in Chicago. The choice was immediate and intuitive. Lower Wacker is a network of roadways beneath the city, with multiple levels, concrete overhead, limited views of the sky, and streets running above and beside one another. Drivers know the experience: a map can hesitate, place the vehicle on the wrong level, or catch up only after a turn has passed.

Dense cities present related challenges even when a vehicle is not underground. Tall buildings can obstruct or reflect satellite signals. Elevated roads and stacked interchanges create several plausible positions within a small horizontal area. Parking structures add repeated ramps and levels beneath concrete. A latitude and longitude may be close, yet still fail to answer the operational question that matters: Which road, level, lane, or direction is the vehicle actually occupying?

Moore used Lower Wacker to make the difference tangible. Because IDPS™ derives position through the vehicle’s interaction with movement and the physical environment, the system can maintain a three-dimensional understanding of the vehicle’s path. In the interview, he described knowing that a vehicle was on the second level, taking a particular turn, and moving toward a bridge even where conventional satellite reception was constrained.

These conditions are sometimes treated as unusual edge cases, but they are ordinary parts of modern transportation. Cities continue to build upward and downward. Vehicles pass through garages, delivery bays, underpasses, tunnels, industrial sites, and complex interchanges every day. A positioning architecture intended for intelligent mobility has to account for the environments vehicles actually occupy, not only the open roads where external signals are strongest.

What Happens When a Vehicle Enters a Tunnel?

Once Ronan understood the Lower Wacker example, his next question followed naturally: What about a tunnel? He mentioned the Baltimore Harbor Tunnel. Moore responded with another example from the interview, describing a request from an automotive supplier to demonstrate the system in the Tokyo Bay Aqua-Line, a long tunnel beneath the water. The point was not the spectacle of the location. It was the continuity of position from entry to exit.

A tunnel removes access to the open sky, but it does not stop the vehicle from moving through physical space. Its motion continues. The relationship between the vehicle, its path, and the surrounding terrain continues. An independently derived architecture uses that continuity rather than waiting for an external signal to return.

The operational value is straightforward. Navigation can continue to place the vehicle along the correct route. Vehicle systems retain a coherent understanding of where the journey is occurring. Fleet operators do not have to accept a gap simply because a truck moved underground. More advanced vehicle functions can continue to reference position as a persistent input rather than treating a tunnel as a blank section between two reliable points.

Tunnels also illustrate why positioning continuity is the more important concept. The objective is not to prove that a vehicle can traverse one difficult location. It is to establish an architecture that maintains spatial understanding as conditions change repeatedly across a journey. Open sky, dense city, covered roadway, parking structure, remote terrain, and tunnel are not separate positioning problems. They are successive operating conditions for the same vehicle.

Positioning Is Infrastructure. Navigation Is an Application.

Part of the difficulty in explaining this shift is that people encounter position most often through a map. When the blue dot is correct, the system appears to work. When it jumps or disappears, the problem is described as a navigation problem. That language blends two distinct layers.

Positioning answers, “Where am I?” Navigation uses that answer to help determine, “How do I get where I am going?” The distinction is simple, but it matters. Navigation is one application built on position. Driver assistance, logistics, emergency response, infrastructure management, fleet awareness, autonomous functions, and defense operations also depend on a reliable understanding of where vehicles and systems are.

This is why people do not depend on GPS itself. They depend on position. GPS has become one of the most important ways that position is delivered, but the need is larger than any single technology. Transportation networks require continuity. Emergency responders require awareness. Fleets require reliable operational information. Intelligent vehicles require a spatial foundation that other systems can trust.

Seen from that perspective, position is not a convenience added to a vehicle. It is an infrastructure layer supporting everything above it. When that layer is intermittent, the effects travel upward. A route can become uncertain. A fleet view can develop gaps. A vehicle function can lose the spatial context needed to make a sound decision, especially as vehicles become more autonomous. When the positioning layer remains continuous, those systems have a stronger foundation on which to operate.

Ronan’s questions expanded because he was no longer evaluating a feature. Once he understood that TERN was addressing the infrastructure layer, the examples multiplied. Commercial trucks, personal vehicles, tunnels, urban streets, defense, and national infrastructure all rely on the same foundational truth: the world runs on position.

Vehicle Positioning Is Becoming Continuous Intelligence

The shift is especially relevant as vehicles become more software-defined. Automotive software already manages a growing range of functions, from energy and performance to safety, driver assistance, connectivity, and the in-vehicle experience. These systems do not operate in isolation. They depend on shared intelligence about the vehicle and its environment.

Positioning is becoming part of that intelligence. TERN’s architecture is not limited to producing a coordinate for a map. Its core capabilities include:

  • Vehicle-Derived Positioning determines and maintains position independently.
  • Vector Positioning provides continuous three-dimensional spatial awareness.
  • Zero Start derives absolute position without prior location or external assistance.
  • Motion Intelligence learns from movement, terrain, behavior, and conditions.
  • Adaptive Continuity predicts, confirms, corrects, and refines position.
  • Expanded Terrain supports roads, trails, industrial sites, and remote terrain.
  • Seamless Integration supports existing vehicle platforms and software stacks.
  • Continuous Spatial Intelligence maintains an uninterrupted understanding of place.

Together, these capabilities allow a vehicle to establish position, maintain three-dimensional spatial awareness, refine its understanding, and continue across changing environments.

The order matters. Architecture comes first. Capabilities emerge from the architecture. Products and integrations apply those capabilities to particular vehicles and operating requirements. Markets expand as the same foundation supports new forms of mobility and operational intelligence. Products will evolve, but the architectural shift from externally delivered position to vehicle-derived positioning is more durable.

For automotive manufacturers, this creates a different foundation for software-defined vehicles. Position can become a persistent intelligence layer available to navigation, advanced driver assistance, vehicle controls, fleet services, and future applications. External systems remain part of the environment, but the vehicle is no longer limited to consuming their output. It can maintain and use its own continuous spatial understanding.

This also explains why TERN is not a GPS replacement, a backup navigation system, or a workaround for weak signals. Those descriptions begin with an existing product category and place TERN inside it. TERN’s IDPS™ changes the underlying assumption. It allows the vehicle to take greater responsibility for knowing where it is, which is a broader architectural change than improving any one navigation experience.

From Position to Operational Intelligence

Once position becomes continuous intelligence, its value extends beyond the individual vehicle. A fleet can maintain awareness across changing environments. Transportation operators can preserve route continuity. Vehicles can report position with greater consistency. Other systems can use a more persistent spatial foundation to understand movement, readiness, conditions, and operational context.

The same architecture has implications across mobility, autonomy, emergency response, critical infrastructure, and defense, although the operational priorities differ. In commercial transportation, continuity supports efficient movement, accurate deliveries, and fleet awareness. In public safety, it supports response and coordination. In defense, it supports freedom of movement, mission continuity, readiness, and operational awareness in GPS-denied environments. The architecture remains the foundation; the application reflects the mission.

TERN has tested and demonstrated elements of this approach in demanding settings, including testing by the U.S. Department of Transportation, demonstrations during U.S. Army evaluations, operational testing in denied environments, OEM pilots and fleet engagements, and complex terrain testing. TERN is also a NATO DIANA cohort member and has received TIME Best Inventions recognition. These proof points matter because foundational infrastructure earns trust through disciplined testing, not through claims of novelty alone.

The larger implication is not that external positioning technologies disappear. They remain useful and, in many situations, highly effective. The change is that they can become inputs to a more resilient system rather than the sole source of authority. Position is transformed from a signal a vehicle receives into intelligence the vehicle continuously creates, confirms, and uses.

The Conversation Changes When the Architecture Becomes Clear

The most revealing part of the SiriusXM interview was not a technical detail. It was the way Ronan’s questions changed. He began by asking what TERN was and how it worked. He moved quickly to whether the vehicle actually knew where it was. Then he tested the idea against Lower Wacker Drive, the Baltimore Harbor Tunnel, long tunnels beneath Tokyo Bay, consumer vehicles, and broader transportation needs. Understanding the architecture did not end the discussion. It gave the discussion more places to go.

TERN sees the same shift in conversations with automotive manufacturers, government agencies, defense organizations, fleet operators, investors, and industry partners. People initially try to compare the system with technologies they already understand. Once they recognize a different architecture, they stop asking what TERN replaces as well as how it works and begin focusing on the bigger picture: what TERN enables.

That is why a ten-minute interview expanded across an hour-long program. Ronan understood that the technology was not merely restoring a familiar capability in difficult conditions. It was moving the source of position into the intelligence of the vehicle itself. From that point, tunnels and dense cities were no longer isolated problems. They were examples of a broader requirement for continuous positioning.

The world runs on position. Transportation, logistics, emergency response, critical infrastructure, intelligent vehicles, and defense all depend on it. As those systems become more capable, the positioning layer beneath them has to become more intelligent as well. TERN’s work begins with that foundation: vehicles stop simply consuming position and start understanding where they are.

FAQ: Vehicle Positioning and Positioning Continuity

Use this section on the published page and mirror the visible wording exactly in FAQPage structured data. Each answer is concise enough for retrieval while retaining TERN’s architecture-first framing.

How can vehicles maintain positioning when GPS becomes unreliable?

Vehicles can maintain positioning when GPS becomes unreliable by using an architecture that derives and continuously refines position within the vehicle. TERN’s Independently Derived Positioning System (IDPS™) uses the vehicle’s movement, terrain, behavior, and changing conditions to maintain an understanding of where it is. GPS and other external technologies can remain valuable inputs, but they are not the sole authority on which position depends.

Why does GPS become unreliable in tunnels and dense cities?

GPS depends on signals reaching a receiver from satellites. Tunnels, concrete structures, tall buildings, stacked roads, and other obstructions can block, reflect, or degrade those signals. GPS remains useful where signals are available, but vehicles and the systems built on position still need continuity as operating conditions change.

Can vehicles maintain positioning inside tunnels and parking structures?

Yes. An independently derived positioning architecture can maintain position as a vehicle moves through tunnels, parking structures, covered roads, and other environments without an open view of the sky. The vehicle continues to measure and refine its understanding of movement and place rather than waiting for an external signal to return.

What is vehicle positioning?

Vehicle positioning is the foundational process of determining and maintaining where a vehicle is in physical space. It may include horizontal and vertical position, direction, movement, and relationship to the surrounding environment. Navigation, driver assistance, fleet operations, autonomy, and other systems use positioning as an underlying source of spatial information.

How is positioning different from navigation?

Positioning determines where a vehicle is. Navigation uses that position, along with a destination and route information, to guide the vehicle or driver. Navigation is an application. Positioning is the infrastructure layer that navigation and many other vehicle systems depend on.

Why is positioning important for software-defined vehicles?

Software-defined vehicles rely on shared, persistent intelligence about the vehicle and its environment. Continuous positioning can provide spatial context for navigation, advanced driver assistance, vehicle controls, fleet services, and future applications. When positioning is maintained as a software-enabled intelligence layer, capabilities built above it can operate with greater continuity.

Does TERN replace GPS?

No. TERN does not seek to replace GPS. GPS and other external technologies can remain useful inputs. TERN changes how position is determined by enabling vehicles to derive and maintain an understanding of where they are from within, so no single external source has to serve as the sole authority.

Editor’s note: This feature draws from an interview between SiriusXM host Dan Ronan and TERN CEO and Co-Founder Shaun Moore. The conversation has been condensed and placed in narrative context, while quoted language is preserved from the edited transcript.