Instead of a whole capsule for transportation in the vacuum tube, as we get to see in the pictures of all Hyperloop models, how about a two-wheeler type equivalent of the same?
It shall of course have a compressor in the front in order to deal with the air pocket that is formed on the front during traveling in the supersonic wind tunnel (which is what a Hyperloop tube is) and a propulsion system behind to minimize the effect of the shockwave tail resulting at the back - both of these parts will be required in the design to work in accordance with the main goal of the vacuum tube, that is, to reduce the aerodynamic drag to 0.1%. Also, magnetic levitation (maglev) is found to be the most efficient and controllable form of locomotion for such a mode of transport and thus this is what this vehicle must use underneath to slide over the tracks. Maglev also works at the highest distance from the ground and (with particularly the passive maglev) modern designs with electromagnetic bearings or Lawrence Livermore's patented "Inductrack" concept, frictional losses through eddy currents and electromagnetic drag can be reduced.
Now this two-wheeler type equivalent (let us name it "loopbike" for now, shall we?) moving inside the vacuum tube is by no means a substitute to the main Hyperloop passenger capsule model but it can help a great deal by being an option along with the main pod and in making this mode of transportation more available around the world until we solve the critical issues related to a larger pod design. This can be a possibility largely because this loopbike system can function at a smaller scale with the same concept, and hence, implementation time and cost on building infrastructure can be greatly reduced. This way it can be constructed comparatively easily even in the economies which otherwise cannot afford a full-fledged Hyperloop transport system. As for more developed economic zones they can function alongside the bigger passenger pod.
Fig. A mock-up design of a loopbike concept.
The loopbike if implemented alone can be made smaller given the lesser number of passengers they will be carrying (one or two maximum). Hence, it will not have the tube wall close to its surface which can help deal with the Kantrowitz limit by not choking the airflow. Hence, the pressure drag and development of a shockwave at the tail can be resolved. Looking at it from another angle, this can also help with the concern of implosion by the thousands of kilograms of atmospheric pressure outside in case of a structural compromise, when the inside of the tube is a vacuum.
Also, magnetic levitation as mentioned above is the most efficient and thus the most futuristic locomotion technology suited for this mode of transportation, but it is also power intensive when propelled at higher speeds and required to reduce the induced magnetic or electromagnetic resistances. Given the smaller scale of loopbike maglev technology can easily be adopted and the necessary power can be provided.
The above factors greatly address the two crucial concerns of safety and cost-effectiveness related to the implementation of the Hyperloop transportation system.
As the entire system is track-dependent the traffic can easily be controlled since not everyone at every time will be able to use the tracks and, advisably, people shall be renting the loopbikes. The parking can be arranged in a manner similar to how we put the trolleys one behind the other on a separate strip beside the tracks at favorable locations.
A mesh of tubes can be constructed where loopbikes are the only available and chosen version of the Hyperloop transportation system, connecting a large number of places while still being financially viable.