The government has declared that from 2005/06 automated surveys will check the condition of all local authority roads. But will the technology work? Mark Hansford investigates.
There can be little argument that the state of Britain's local roads is one of the biggest transport issues facing government today. Survey after survey shows that funding is insufficient to prevent further deterioration, let alone make good the repairs backlog.
Britain's roads are in bad shape and the situation is only growing worse.
Only last month an ICE survey of local authorities estimated that local roads, footways, cycleways and street lighting need a massive £8.3bn of outstanding maintenance work, up almost £1bn on last year. This survey echoed that by the Asphalt Industry Alliance (AIA) earlier in the year in which 91% of local authority highway engineers said councils were compromising road safety by under funding road maintenance.
But what can engineers do when faced with a funding shortfall that, according the AIA survey, means roads are on average resurfaced just once every 76 years rather than the recommended 10 to 20 years?
The first problem councils must overcome is that current estimates of the backlog are just that - estimates.
At present they use a number of different systems for condition assessment, some of which are more objective than others.
Best value performance indicators were introduced in April 2000 to raise performance and ensure that English authorities systematically monitor local road conditions, but do not provide robust data.
Without hard figures, the government is not going to provide hard cash, says John Ekins, past chairman of the Association of Municipal Engineers and former county surveyor for Hampshire.
'The provision of accurate, consistent and reliable condition data at local, regional and national levels is vital if the funding levels for highway maintenance are to be sustained against other demands on national and local resources, ' says Ekins.
'The highway maintenance community has to grasp this challenge if it is to retain credibility with the decision makers at all levels of government.'
The Department for Transport (DfT) agrees, and has turned to automated surveys for the solution (NCE last week). Automated surveys - which measure surface condition at normal road speed via cameras and lasers mounted on a highway maintenance vehicle - are already the norm for trunk roads and will become the norm on all principal local roads from next year. Their use would then be widened to non-principal local roads in 2005/06.
The automated TRACS Type Survey (TTS), named after the Traffic-speed Road Assessment Condition Survey (TRACS) developed by the Highways Agency, is said to be adequate for modern designed roads where it is safe to assume lasting foundations.
But there are fears the technique is not yet ready for use on local roads where foundations are an unknown quantity and where simply getting access to the surface may be a problem.
'The big problem with this system is that you are only assessing the section of road beneath the sensor, ' says Simon Brightwell, director of testing specialist Aperio. 'Now that's okay on the M25 where there are no parked cars. But it is not the same in city centres or in rural areas where most of the defects are edge defects. These vehicles will really struggle to map those.
'Before TTS can be rolled out to this area it needs a lot more development, ' adds Brightwell.
But consultant Babtie, which recently splashed out £1M on its own TTS machine for use on its Highways Agency contracts, believes too much is being made of these problems.
'In cascading this technology down to non-principal roads there are problems to be addressed. There will be problems in busy town areas, and at present the system cannot deal with verge damage. But at the end of the day, it is not a 100% science, ' says Babtie technical director Ed Lawrence.
'Our view with regard to parked cars is that we are concerned about the condition of the road as traffic uses it. It is not a significant problem - just go where the traffic goes, ' he adds.
'And that is the Scottish view as well.'
Scottish authorities already use TTS. Last year Clackmannanshire was surveyed in its entirety to gauge how much of the network TTS could reach - 99% coverage was achieved.
'Scotland gives us confidence that as long as you take the attitude that it's not going to be precise, TTS allows you to improve the consistency of results - and that is difficult to achieve with the coarse visual inspection (CVI), ' says Lawrence.
Lawrence and Ekins accept that assessing verge damage remains a problem, and it is here that the majority of the research between now and 2005/06 will be focused.
Before the start date, Ekins' team also needs to find a way to bring costs down. The high initial cost of a TTS machine means surveys work out at around £30/km, marginally higher than the cost of the traditional CVI.
Longer term research, to allow TTS to completely replace the CVI by 2007/08, will focus on ways to enhance cracking measurement and analysis systems.
It will also look at other road surface types and other aspects of road surface. And it will aim to find ways of detecting other visual surface defects and means of using texture and other defects as a proxy for skid resistance.
Yet Brightwell is yet to be convinced. He wants the DfT to widen the use of technology so that the visual data - such as rutting and cracking - provided by TTS is complemented by structural data that can be collected by ground penetrating radar (GPR).
'Its all very well having TTS surface condition data. But at the most basic level you need to know if your road is thick or thin, multi-layer or single, ' says Brightwell.
'The alternative to GPR has been to take cores and guess in between. But that's pretty hopeless in an urban environment.
Our experience working in London has been that on any 1km of road you can find up to 50 construction changes. You need a lot of cores to measure that.
'So our philosophy is, yes, use TTS to replace the coarse visual inspection. But ideally you'd run a GPR survey maybe every five years, ' says Brightwell.
He refers to AmeyMouchel which, on taking on maintenance of the Highways Agency's Area 5 - covering the M25 - immediately commissioned a map of the road's construction with GPR.
'If you think that's the jewel in the crown of the Highways Agency's network and people still don't have accurate reference points and construction details, you can see why everybody needs GPR, ' says Brightwell.
Lawrence accepts that GPR - or the more traditional deflectograph test - has a place when it comes to detailed inspection of a problem area, but does not believe it is cost efficient to use over the entire network.
For him, TTS is more than enough to identify trouble spots.
'When GPR or a deflectograph indicates a structurally weak road there will generally be other, surface, characteristics that reflect that condition. If you don't have them, then as an engineer you would be suspicious.
And you certainly wouldn't dig it up just on the basis of the deflectograph.'
Ekins is confident that TTS will work. If not, engineers will have a tough time arguing for more maintenance cash, he says.
Herts finds the dream team
Hertfordshire County Council's highway maintenance backlog typifies that faced by councils across the country. It is rated as a top performing highways authority, yet every year it estimates that its road network depreciates by £50M - despite an annual spend of £30M on network enhancement and £20M on maintenance.
'We would argue that we are a three star service with a network that has a huge number of deficiencies and never enough money to do what the public wants, ' says environment director Mike Palmer.
And this public demand is growing. The county has a dedicated highway fault hotline, and the council's new service charter sets demanding targets - such as hazardous potholes to be repaired within 24 hours of receiving an alert.
To handle this extra pressure Palmer got his councillors to agree to a bold way forward - a public private partnership.
In October 2002 it joined forces with consultant Mouchel and contractor Amey Lafarge to set up Hertfordshire Highways. This partnership brings together 1,000 staff who are fully integrated - you will see no workmen bearing Mouchel or Amey Lafarge logos. But integration is more than cosmetic - key to the partnership is that everything is shared. All parties have access to a common database and work to an integrated works programme. Decisions are made by those best placed to make them, and work carried out without delaying for client approval.
The partnership is pioneering a 'walk and build' system, where Amey Lafarge is free to carry out 'standard' works, such as footpath reconstruction or putting in pedestrian crossings, direct from standard specifications without involving a time consuming design and approvals stage.
Palmer believes the partnership pays dividends - crucial when it comes to budget negotiations with councillors.
'At £4bn, the highway is the county's most valuable asset.
With this partnership we will be able to prove better than ever that we're improving the asset.'