A roll-along survey is a method for operator to survey a long line. After the initial survey, the operator will leave one cable on the ground and move the instrument and cables forward. So there is always one cable overlap between two surveys.
Alternatively, the operator can divide the cable in half and only overlap 16 electrode spacing. In this way, the opearator could complete the survey faster.
FlashRES systems have roll along option for its cables, customers can specify which cable arrangement they prefer before they purchase the system.