The Barriers at Gate X17 on Castle Street and at Berry Street also had reinforced sangars, fortified guard houses, for Army and later UDR support. These gates were considered to be of highest risk because of their location at the interface of the city centre and west Belfast. By this period, the British Army had begun surveillance operations Widgeon and Deerstalker, and these sangars were part of a wider military intelligence network - nodes where information could be sent and received via radio contact and were used as control points for access to the Segment. Castle Street also had a blast wall capable of withstanding 10lbs worth of commercial explosives erected in 1983 and was permanently manned by 4 soldiers in direct radio contact with Queen Street RUC station. It also had the first installation of CCTV, with a camera placed high on a lamp post outside the Hercules Bar and a monitor located inside the sangar.

At the four main gates - Castle Street, Donegall Place, Royal Avenue and High Street  - searchers were responsible for operating security equipment such as X-Ray scanners, sound detectors to pick up detonation devices and 'sniffers' - instruments that detected odours from explosives. The CSU was reluctant to operate these and was also concerned about the gradual withdrawal of static military support from most of the gates. This lead to industrial action by the CSU at various times, using strikes and 'go-slow' tactics to negotiate improvements to their working conditions. As a result, some gates remained closed at peak times and the relationship between the CSU and their employers, the Northern Ireland Office, became strained.

In September 1982, the Army were replaced by the Ulster Defense Regiment (UDR) and, by October, static armed guards on evening duty were removed from all but the Castle Street and Berry Street gates. Continual review of the situation led to Castle Street being opened up for buses leaving the city westwards, and buses were permitted to drop off and collect passengers within the Segment.

Further changes included replacement of the 20ft high breeze block sangar located directly outside the Hercules Bar on Castle Street with a less obtrusive structure, and smaller search points were erected at Royal Avenue and High Street clear from shop fronts, channelling shoppers towards the nearby businesses. In 1983 the gate at the junction of Berry Street and Castle Lane was moved eastwards to exclude the Presbyterian church from the Segment. Holes in the wall of the church can still clearly be seen, showing where this gate was located. Minutes from the CCSC meeting from October 1983 state that 'progress on lowering the security profile and returning to normality in Belfast city centre continues to be steady, unspectacular but nonetheless significant' (The National Archives, file CJ 4/5162).