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NSAR Safety Critical Assessments

PRB Consulting offer a range of Railway Safety Critical Assessments. Our Assessors are competent to undertake the following assessments in line with Network Rail standards and the Rail Training Assessment Services (RTAS) Rules.



All Assessments are conducted by NSAR Licensed competent Assessors.



Important Announcement from Network Rail – From September 5th, 2020


Following instructions from Network Rail, from September 5th, 2020, the following arrangements will no longer be permitted for competency assessments:

  1. Candidate Coss and the Assessor Only
  2. Candidate COSS, + 1, + Assessor (with the exception of roles which are the operational norm to be COSS +1 i.e., AP, NP, S&T Tester/Assistant and are evidenced as such)
  3. Manufactured work activities such as non-obtrusive: (list is not exhaustive)
  1. Two or more probationary assessments being completed in the same location at the same time. Both probationary COSS’s form the same workgroup. The 1st (P)COSS briefs the group with the 2nd (P)COSS within the workgroup. The 2nd (P)COSS then briefs the same group with the 1st (P)COSS forming part of the workgroup.
  2. Similarly, a candidate being assigned an ES and COSS role on a shift that would not be required if the workplace assessment had not been requested. Where the arrangements are Candidate, + 1, + Assessor and the +1 switches roles/relieves the candidate only for the purposes of either or both competence workplace assessments.
  3. Questioning most of the assessment criteria rather than observing work activity.


In addition, Assured Provides are unable to:


  1. Plan to complete workplace assessments for more than two candidates within the Assessors 12-hour shift will not be permitted.
  2. Plan to complete workplace assessments for more than one candidate within the Assessors 8-hour shift will not be permitted.
  3. Assessors must witness the COSS briefing and access and egress from the site of work in order to observe as many elements of the assessment as possible.
  4. The Assessor shall not be considered as part of the workgroup but are required to sign RT9909, F01, task risk briefings and any other documentation that the site requires.
  5. There must be a minimum of three people within the workgroup, including the COSS and excluding the Assessor. This may need additional planning by Sponsors to make sure workplace assessments are planned to take place on shifts with the required work group members. Assured Providers and Assured Trainer/Assessors are required by the RTAS Rules to make sure they are providing Assessors to complete workplace assessments that meet these requirements.
  6. Where the COSS is working alone (effectively acting as an IWA) the criteria for a COSS Workplace assessment cannot be met.
  7. COSS working alone questions (reference IWA within the COSS workplace assessment records) must always be asked by the Assessor and answered by the candidate during a COSS workplace assessment unless there are restrictions recorded in Sentinel that prevent the individual from working alone.


The Assessment Candidate Sponsor MUST have arrangements in place to provide another Controller of Site Safety for the work activity in the event that the Coss Candidate is deemed ‘No Longer Competent’


It is PRB Consulting company policy to request payment for all Assessments in advance of the planned Assessment Date.