5.4.1 USRN
The Authority Address Custodian and the Authority Street Custodian should have an information exchange process in place. This helps to ensure that the information on additions or changes to the type 1, 2 and 4 Street Records generated by the LLPG is fed into the NSG via the LSG. In a two tier authority administrative area, the District Councils should work together to ensure a consistent approach within a Local Highway Authority, see Appendix G.
5.4.2 Record type
For details of which role is responsible for the creation and maintenance of each Record type, see Section 5.3.3.
For details of the data flows which reflect the exchange process referred to in Section 5.4.1 see Appendix G.
5.4.3 Extremity points
When a Street is initially entered into the ASG the extremity points should be identified to a maximum tolerance of 50m for Street STATE = 1 – Under construction. Each Authority Address Custodian must try to ensure this tolerance is improved over time to a tolerance for Street STATE = 2, 4 or 5 of at least 10m for agreed Street Records which match in the NSG and the ASG. This can be done when more reliable mapping becomes available or when information is received through the exchange process described at Section 5.4.1.
5.4.4 Tolerance
The tolerance Field is the radius of the influence of the chosen coordinate point and its value encompasses all likely definitions of the end of the Street.
The value of tolerance must take into account the quality of the recorded coordinates. The tolerance for each Record is normally 1m. However with high definition mapping and imagery the Authority Address Custodian should try to achieve a tolerance of 0.1m.
The tolerance Field has a maximum permitted value depending on the Street state code. For full details, see Table 1. Closed Records do not have to be retrospectively corrected. Only new Records created after 1st October 2013.
Table 1 - Maximum permitted tolerance values:
1 - Under Construction
50m
2 - Open
10m or half the carriageway width whichever is the smaller
4 – Permanently Closed
10m if closed date is later than 1 October 2013
5 - Street for addressing purposes only
10m