A method of operating an automated storage and retrieval system, the automated storage and retrieval system comprising: - a rail system (108,108') comprising a first set of parallel rails arranged in a horizontal plane (P,P') and extending in a first direction, and a second set of parallel rails arranged in the horizontal plane (P,P') and extending in a second direction which is orthogonal to the first direction, which first and second sets of rails (110, 111) form a grid pattern in the horizontal plane (P,P') comprising a plurality of adjacent grid cells, - a central control unit configured to receive, transmit and process data signals of a plurality of container handling vehicles (2,3) for handling storage containers of the automated storage and retrieval system, each container handling vehicle (2,3) comprising a vehicle body (101a, 201a, 301a, 601a) a wheel assembly (101b, 101c, 201b, 201c, 301b, 301c, 601b, 601c) provided on the vehicle body (101a, 201a, 301a, 601a), the wheel assembly (101b, 101c, 201b, 201c, 301b, 301c, 601b, 601c) being configured to move the vehicle (2,3) along the rail system (108,108') in both of the first direction and the second direction, a vehicle control unit configured to receive data signals from, transmit data signals to and process data signals of the central control unit, and a proximity sensor system configured to detect another container handling vehicle (2,3) of said plurality of container handling vehicles (2,3) and determine whether or not it is within a predetermined distance, wherein the method comprises: - detecting with the central control unit that access of a first container handling vehicle to a target cell, which is one of the plurality of grid cells, is blocked by a second container handling vehicle, - transmitting a data signal from the central control unit to the vehicle control unit of the first container handling vehicle commanding the first container handling vehicle to move into the target cell when the second container handling vehicle is beyond said predetermined distance. - a rail system (108,108') comprising a first set of parallel rails arranged in a horizontal plane (P,P') and extending in a first direction, and a second set of parallel rails arranged in the horizontal plane (P,P') and extending in a second direction which is orthogonal to the first direction, which first and second sets of rails (110, 111) form a grid pattern in the horizontal plane (P,P') comprising a plurality of adjacent grid cells, - a central control unit configured to receive, transmit and process data signals of a plurality of container handling vehicles (2,3) for handling storage containers of the automated storage and retrieval system, each container handling vehicle (2,3) comprising a vehicle body (101a, 201a, 301a, 601a) a wheel assembly (101b, 101c, 201b, 201c, 301b, 301c, 601b, 601c) provided on the vehicle body (101a, 201a, 301a, 601a), the wheel assembly (101b, 101c, 201b, 201c, 301b, 301c, 601b, 601c) being configured to move the vehicle (2,3) along the rail system (108,108') in both of the first direction and the second direction, a vehicle control unit configured to receive data signals from, transmit data signals to and process data signals of the central control unit, and a proximity sensor system configured to detect another container handling vehicle (2,3) of said plurality of container handling vehicles (2,3) and determine whether or not it is within a predetermined distance, a vehicle body (101a, 201a, 301a, 601a) a wheel assembly (101b, 101c, 201b, 201c, 301b, 301c, 601b, 601c) provided on the vehicle body (101a, 201a, 301a, 601a), the wheel assembly (101b, 101c, 201b, 201c, 301b, 301c, 601b, 601c) being configured to move the vehicle (2,3) along the rail system (108,108') in both of the first direction and the second direction, a vehicle control unit configured to receive data signals from, transmit data signals to and process data signals of the central control unit, and a proximity sensor system configured to detect another container handling vehicle (2,3) of said plurality of container handling vehicles (2,3) and determine whether or not it is within a predetermined distance, - detecting with the central control unit that access of a first container handling vehicle to a target cell, which is one of the plurality of grid cells, is blocked by a second container handling vehicle, - transmitting a data signal from the central control unit to the vehicle control unit of the first container handling vehicle commanding the first container handling vehicle to move into the target cell when the second container handling vehicle is beyond said predetermined distance.