Explanation of how HCC make decisions on which roads to resurface
To get the best from the available budget, we use a data-driven asset management approach to start the process but this is always tempered by the judgement and experience of our engineers.
We carry out a condition survey on all our roads once a year (in addition to safety inspections). We put this condition data into a sophisticated computer modelling programme along with information on how busy the roads are, what they are made of, what works we have got planned for them and any defects we have fixed. The model then predicts how each road will perform over the coming years, what treatments we might want to consider and how soon. This allows us to build a picture, not just of the current condition of the network, but of the likely future condition under different strategies. This gives our engineers a good place to start as they visit the potential sites to refine the programme of works that we will eventually deliver.
In particular, this approach is very helpful in picking ‘stitch in time’ preventative treatments for roads which, while they don’t look bad now, will deteriorate soon; this means we can get in early and maintain them for much less than it would cost to go in and fix them once they have failed. Our programmes look to strike a good balance between fixing poor roads and maintaining as many as we can to stop them becoming ‘poor’.
What data do we use?
Annual condition surveys – all roads every year
- A, B &C roads: we use SCANNER (Surface Condition Assessment for the National Network of Roads). SCANNER is an automated survey undertaken at normal traffic speeds by special vehicles equipped with HD cameras and laser and radar units to identify roughness and surface defects, texture, rutting, edge defects and cracking; it also records the roads geometry (e.g. radius and cross-falls), GPS coordinates and creates a video record.
- On unclassified roads we use CVI (Coarse Visual Inspection). CVI is a driven inspection undertaken by qualified specialist inspectors from a slow-moving vehicle; it identifies issues with Edges, Kerbs, Joints, Cracking, Rutting and various other defects.
- We also use other technical surveys occasionally: These include ground penetrating radar (GPR) surveys, various road deflection measures and core samples. In the early years of the modelling process we did a complete GPR survey of the whole network supported by some of these other surveys to give construction information. This does not change over time so does not need repeating but these additional surveys are now used on a case by case basis to help designs.
All of these technical surveys are undertaken on our behalf by survey companies who specialise in this sort of work. Individual companies vary from year to year as we tender the work to get the best value for money but they all work to the same nationally-agreed specifications.
Traffic, HGVs, Bus Routes
- We use this data to help determine how busy the routes are, how quickly they will wear out and how many people will benefit from work to maintain them – busier routes benefit more people so have a higher priority.
- We use actual traffic count data where we have it (most of the A road network and many busier local roads); where we don’t have counts, we use estimated values based on the type of road and its location. We also use scheduled bus routes to help identify busier roads and land-use mapping to help identify areas where there will be high concentrations of HGVs since they do more damage to roads than cars do.
Maintenance history: potholes, patches, historic treatments and planned future treatments
- Information from Confirm (our computer based record of works undertaken) tells us about potholes and other defects Ringway have dealt with, either via inspections or public reports and also other faults logged that were not urgent and so have not yet been fixed. This allows us to factor in how much a road is likely to cost us in the future if we do not fix it.
- Our programme management databases hold information on historic schemes going back to 2005 although the older information is less detailed; this helps in planning and selecting future treatments. They also hold what we are planning for future years so each review and revision of the programme is an evolution of the previous version rather than starting from scratch.