The VEM-20 is sized for a full size SUV that is 7ft wide and 18ft long. The 20ft diameter composite caterpillar shape cylinder module is designed for 15psi ovepressure and an 8.5+ Richter. It does not have a catastrophic failure mode. The elevator is designed to lift and lower an 8,000 pound vehicle by hydraulic lift at approximately 1ft/second using mostly non-ferrous materials for most of the structure for corrosion resistance and radar avoidance. The lift is activated by a wireless pocket transmitter like a garage door clicker and powered by the battery banks/diesel generator in the CAT 25 Support Module. The ground level over the lift platform is a rectangular pan holding soil and gravel form the surrounding area to blend in without a strong visual signature. The hudraulic system can also be operated by a manual pump from inside for an emergency escape. On the bottom of the elevator shaft is the moon shaped space on the one side of the vehicle platform to decontaminate the vehicle before it enters the tunnel. Contaminants are pumped to the surface after collection in the elevator sump.

The composite tunnel connecting the VEM to another module such as an Earthcom 32 is curved to shield the radiation that would otherwise enter the living structure. The curved tunnel performs the same as a right angle entranceway restricting gamma and neutron radiation transport. The tunnel is compoundly curved to remove tensile loads and allows only a non-catastrophic failure mode. the tunnels clear opening is 10ft wide x 10ft high. Each end of the tunnel contains a triple axis seismic joint.