Emergency services call for removal of bollards at Clissold traffic filter Drawing of Clissold Crescent traffic filter. Image: Hackney Council. The Town Hall is set to remove bollards at a recently introduced traffic filter at Clissold Crescent after emergency services asked for them to be taken away. The majority of the traffic filters brought in under the council’s Low Traffic Neighbourhoods (LTNs) programme are not physical closures but allow emergency vehicles to travel straight through. The news was delivered to residents at a recent ward forum, which saw a mix of views from people for and against the closures.