The development of autonomous drive cars is beginning to mature and can be expected to be fully operational in time to deploy as part of this system. Taking the driver out of the equation enhances safety and reliability. 

The tubes are internally tagged with electronic location markers that allow the car to precisely determine it’s location and speed. Cars also communicate with other cars entering the tube to coordinate merges. The autonomous navigation procedures used on outside surface roads can also be used to facilitate linking cars into trains. 

Cars entering the guideway are timed to merge just behind a train and, while still accelerating, fall back to become the leader of the following train.  The headway, thereby, becomes part of the entrance ramp for obtaining merging speed. The opportunity to merge onto the guideway from an on ramp would occur about every 5 seconds.  

An exiting car, in the center of a train, will reverse the polarity on it’s magnetic couplings, repelling the cars to the front and back, creating a small opening from which to maneuver.

Solar Tubular Transit is a redesigned successor to 
Tubular Guideway Transit.


Air handling.

Schematic drawing of a dual direction Solar Tube. The approximate outside dimensions are 17 feet wide by 8 feet high. Shown are the solar panels on the roof, the three guideway truss walls with windows on the outside walls, the roadway with metal track ways, and the supporting pylon.

There are two imperatives affecting how to configure the flow of cars in the tube: throughput capacity and passive pneumatic air flow. In this presentation of STT, ten car trains with a four-second headway have been used as a conservative starting point. The large four-second headway may not be efficient enough, however, in generating the desired airflow.  Engineering and experience may determine that shorter headways are possible which would increase both air flow and throughput capacity. The more traffic in the tube, the more energy efficient it becomes. 

It would be possible to replace trains with a small headway between cars. Instead of ten car trains with a 4 second headway each car would have a .4 second headway or 41 feet at 70 mph. Although this is feasible using computer control it would make merges complicated and potentially risky. It adds the requirement to adjust the headway and speed of other cars in the traffic stream.

In off peak hours, shorter trains with less headway help sustain airflow.  The system can use algorithms to configure car/train patterns in response to usage. In high speed tubes and during times of low usage, it may be necessary to augment airflow with external air turbine assist. The goal is to always have the air in the tube moving near or at the same speed as the cars.


Schematic cross section sketch of a dual STT guideway. The vehicle on the right is in the normal position, centered in the guideway with wheels on the metal strips.

An emergency that causes the vehicle to stop in the guideway would, by software protocol, park the vehicle close to the center wall, allowing room for the passengers to exit if needed.

The Flow of the Cars in the Tube.

The Solar Tube.

Two tubes, sharing a center wall, form a bidirectional guideway elevated on pylons. The three walls of the tubes function as bridge trusses, carrying the span between pylons. The center truss carries the preponderance of the load while the outer trusses have window spaces allowing passengers to see to the outside from their cars. The midspan between pylons must not deflect downward under the weight of train/cars.  A dual direction tube is small, approximately 8 feet high by 17 feet wide in its outside dimensions and relatively lightweight.     (Note: a single lane of expressway is 11 feet wide.)

The floor in each tube is a flat roadway with two surfaces. Flat ribbons of steel provide low rolling resistance trackways and will act as a heat sink to keep the tires cool at high speeds. The rest of the road surface is flush with the tracts and provide traction when needed. 

Channels or tracks built into the roof give access to the solar panels for cleaning and maintenance by robotic or staffed track vehicles. 

An important advantage of the tube is that it protects from varying weather making it a reliable environment for operating vehicles at high speed and close tolerances. 

The tube’s interior walls are smooth to facilitate air flow and its walls, floor, and roof are insulated for sound and heat. The enclosed tube environment reduces thermal expansion and contraction of the roadway surface. Like historic covered bridges, the external covering protects the structural members from deterioration.

No flammable materials are used in the tube’s construction. 

Emergency exits, where people can leave the tube are at pylon locations. The tube will fit closely to the car vertically but be wide enough horizontally to allow riders to exit the car if needed.

Solar Tubular Transit is a good neighbor. Traffic in the tube will produce very little noise because the vehicles have quiet electric motors, are enclosed, sound buffered,  and run on smooth steel. Best of all, there is no pollution emitted. It will take traffic off sprawling expressways and cars out of endless parking lots returning now vacant zones to vibrant urban life.

Surfaces within the tubes are engineered to promote smooth airflow. The guideway has exits and entrance ramps which are open to the outside atmosphere. Due to the Venturi effect, the flow in the tube creates a slight negative pressure, drawing air into the tube. Any buildup of air within the tube will be self-limiting.

The cross section proportions of the car in the tube need to be calculated to allow air pressure adjustments when cars merge or move apart while still inducing maximum airflow. The tube/car proportions for a 70 mph guideway may not be the same as a 150 mph tube.

​​​​​    Solar Tubular Transit  

Jon Bogle  12/2015