The network hierarchy is user defined, based on usage and not dependent on the current road classification system. A resilient network has been developed and has the highest priority.
We've set our own standards for the frequency of its highway safety inspections. The frequencies have been determined for each network hierarchy, using a risk based approach based on usage, that is, the hierarchy with the most usage has the highest inspection frequency. These have been approved by elected members.
Each part of the network is assigned a hierarchy which relates its importance to usage. These hierarchies are stored in SAMS and records are kept of hierarchy changes.
Hierarchies need to be as dynamic as possible and regularly reviewed to reflect changes in network characteristics and functionality, so that maintenance policies, practices and standards reflect the current situation rather than the use expected when the hierarchy was originally defined and or last modified.
Highway inspectors are able to evaluate their inspection routes when changes occur in characteristics and functionality and, as a result, they can make recommendations for a hierarchy review as they see appropriate.
Footway and cycleway hierarchies can be different to carriageway hierarchies and therefore some roads have different hierarchy classifications and potentially different inspection frequencies for carriageways, footways and cycleways.
Frequency of inspections
Carriageways
- Resilient network
Category: Priority network required to maintain economic activity and key services
Frequency of inspection: 1 month
- Network hierarchy 1
Category: annual average daily traffic flow >= 9000
Frequency of inspection: 1 month
- Network hierarchy 2
Category: annual average daily traffic flow >= 6000 and < 12000
Frequency of inspection: 1 month
- Network hierarchy 3
Category: annual average daily traffic flow >= 3000 and < 8000
Frequency of inspection: 1 month
- Network hierarchy 4
Category: remaining strategic regional routes, main distributor roads and secondary distributor roads
Frequency of inspection: 1 month
- Network hierarchy 5
Category: remaining link roads
Frequency of inspection: 3 months
- Network hierarchy 6
Category: Remaining local access roads that are not a cul-de-sac
Frequency of inspection: 1 year
- Network hierarchy 7
Category: Remaining local access roads that are a cul-de-sac
Frequency of inspection: 1 year
Footways
- Hierarchy: 1A
Category: Prestige area
Frequency of inspection: 1 month
- Hierarchy: 1
Category: Primary walking route (including shared use facilities)
Frequency of inspection: 1 month
- Hierarchy: 2
Category: Secondary walking route (including shared use facilities)
Frequency of inspection: 3 months
- Hierarchy: 3
Category: Link footways
Frequency of inspection: As for carriageway
- Hierarchy: 4
Category: Local access footways
Frequency of inspection: As for carriageway
Cycleways
- Hierarchy: A
Category: Carriageway – contiguous or shared
Frequency of inspection: As for carriageway
- Hierarchy: B
Category: Footway – contiguous or shared
Frequency of inspection: As for footway
The inspection due date will generally default to the 15th of the month for each inspection.
Where carriageway and footway hierarchies intersect, for example, at pelican or zebra crossings, bollards or other defined crossing points at junctions, the higher inspection frequency should always take precedence in determining the inspection frequencies, defect definition and responses. This principle should also apply to intersections between carriageways and cycle routes and between cycle routes and footways.
Tolerance levels for safety inspection frequency
Tolerance levels:
- inspection frequency: monthly (tolerance: plus or minus 10 days)
- inspection frequency: quarterly (tolerance: plus or minus 15 days)
- inspection frequency: annually (tolerance: plus or minus 30 days)
Structures safety inspections are not carried out on a specific frequency and are a reactive process which will only occur after an event, such as a flood or after an enquiry.
Before an inspection takes place, each section of the route is assessed for its availability and whether it is safe to complete the inspection. If, for any reason, part or all of the route cannot be inspected, then the inspection is recorded as suspended, and the reasons and photographs recorded as appropriate. The route or route section is then reprogrammed for inspection at the next available opportunity. If sections of a route continue to be unavailable due to the presence of street works or parked vehicles, then it may not be practicable to inspect those parts of the highway that are obstructed to the same standard as the rest of the highway.
The process is shown in the following flowchart:
Are inspections safe to complete?
Top of the chart begins: Is it safe to inspect?
- If "Yes", then is the route available for inspection?
a. If "Yes", then record and start inspection
b. If "No", then suspend inspection - record, document and photograph the reasons and reprogramme the inspection
- If "No", then suspend inspection - record, document and photograph the reasons and reprogramme the inspection.
Due to the differences in categories between carriageways, footways and cycleways, it may be necessary in certain instances to inspect each element at different times. Conversely, there will be instances where the frequencies for each are the same. These elements may, therefore, be inspected at the same visit.
Link footways are linking local footways through urban areas and busy rural footways. They are not interlinking footways, which are, for example, footways between 2 housing estate roads.
We will ensure that the routes include the existing highway network and any newly adopted highways, where appropriate. These will be added to the inspection routes as necessary.