A collar assembly for retrofitting a barrier to one or more bollards comprises a barrier and at least one collar adapted to fit around each of bollard. Each collar comprises two or more openings. Each opening is configured to receive a barrier mounting device or a securing element. Each collar has at least one securing element configured to affix the collar to the one or more bollards. Each collar has at least one barrier mounting device configured to attach the barrier to the one or more bollards. The barrier is mounted to each barrier mounting device.