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2003 NATIONAL ROAD MAINTENANCE CONDITION SURVEY RESULTS PUBLISHED

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The report of the 2003 National Road Maintenance Condition Survey ...
The report of the 2003 National Road Maintenance Condition Survey

on the condition of roads and footways in England and Wales

(available here) presents information on both the

surface condition and structural condition of roads. Surface

condition is measured using a visual survey of defects and machine

based surveys of wet road skidding resistance and the English trunk

road network. The structural survey uses a machine to measure the

deflection of a road under a standard load.

KEY RESULTS

Visual condition

In July 2000, the government set out its transport strategy in

'Transport 2010 - The 10 Year Plan'. This included the target to halt

the deterioration in the condition of local roads, i.e. non-trunk

roads, in England by 2004. This target is monitored by a surface

condition 'defects index' which is derived from results of the NRMCS

visual survey. The index is set at 100 for the base year 1977, based

on conditions in England and Wales. A significant decrease in the

index indicates an improvement in the road condition.

Figure 1 shows that the defects index for English local roads fell

between 2000 and 2002 but rose slightly from 107.6 to 108.4 in 2003.

In order to reflect sampling error, ranges are calculated within

which the true average defects index lies with a 90 per cent

probability. Where the confidence ranges (as represented by the small

dotted lines) overlap it is generally not possible to say with

confidence that the condition in one year is different from that in

the other. The increase in the index in 2003 is not statistically

significant, and statistical analysis shows that there has been a

significant improvement in local road conditions in England between

2000 and 2003; that is, the net fall in the index is unlikely to be a

result of sampling error and probably reflects a real improvement in

road conditions.

A defects index for England is not available prior to 1998 so the

index for England and Wales is included as an indication of the

earlier trend.

The length of local roads in England accounts for 90% of all local

roads in England and Wales and so it is not surprising to find that

the trend in visual condition in England is similar to that in

England and Wales (see Figure 2).

The local roads defects index for England and Wales rose from 106.4

in 2002 to 106.7 in 2003. None of the changes observed in the overall

index since 2000 are significant and so there is a possibility that

the long-term trend of deteriorating visual road condition has

stopped.

Changes in conditions vary across the different road types as shown

in Figure 3. In recent years, real improvements - as indicated by

significant falls in the index - have been seen on built-up principal

and built-up classified roads. These improvements coincide with

deterioration of non built-up unclassified roads which tend to be

country lanes. The 4 point reduction in the index for built-up

unclassified roads, which are generally through residential areas and

account for 40 per cent of all local roads, will have contributed

most to the reduction in the overall defects index since 2000.

In 2003, the defects index for non built-up unclassified roads is

141.3 and is by far the highest of any road class, signifying the

greatest deterioration in conditions since the survey began in 1977.

The defects index of 84.3 in 2003 on non built-up principal roads is

the lowest of any road class and signifies the greatest improvement

since 1977.

Figure 4 shows that around half of the defects index for built-up

roads was a result of major deterioration to the whole carriageway,

i.e. not just in the wheel tracks. Rutting contributed to 40 per cent

of the index on non built-up principal and classified roads, i.e. non

built-up local au thority owned A, B and C roads. Major deterioration

also has a large effect on non built-up unclassified roads, as does

edge deterioration since these tend to be roads without kerbs.

In practice, rutting alone would not generally be treated on

unclassified roads and so the contribution is assumed to be zero.

Structural condition

To supplement results on visual road condition, structural surveys

are carried out to determine the proportion of the major road network

whose structural condition has reached the point at which close

monitoring is needed to see whether maintenance is required. Although

results for English motorways and all purpose trunk roads are no

longer available, Figure 5 shows that until 2001 in England,

motorways consistently had the lowest percentage needing close

monitoring and principal roads the highest. The percentage of

principal roads requiring close monitoring increased for the fourth

year in a row and stands at 17.2 per cent in 2003.

Figure 6 shows corresponding figures for Wales and as with England,

motorways have the lowest percentage needing close monitoring and

principal roads the highest. In 2003, 15.6 per cent of principal

roads needed close monitoring, an improvement of almost 2 percentage

points. The percentage needing close monitoring on motorways has

increased from 3 per cent in 1993 to 9 per cent in 2003.

The National Assembly for Wales has the target that by 2004-05 no

more than 13 per cent of the all purpose trunk roads network should

need close monitoring of its structural condition. Following an

improvement in structural condition for the first time since the

survey began in 1993, its value in 2003 was 11.2 per cent.

Skidding resistance

Road safety is improved when roads have a satisfactory level of

skidding resistance. The skidding resistance of major roads is

assessed when the road surface is wet and compared with an

investigatory level that is set for t he characteristics of the

particular length of road. Where the skidding resistance is below the

investigatory level, the road is not necessarily unsafe but it does

show that further investigationis required. This would include an

assessment of the safety record for the length of road to see if

maintenance is needed. Latest results for England are shown in Figure

7.

As with structural condition, the percentage needing further

investigation is lowest for motorways and highest for principal

roads. In particular, 34 per cent of principal roads in London and 27

per cent in metropolitan authorities needed further investigation to

determine if remedial treatment in relation to skidding resistance is

required. Figure 8 shows the latest skidding resistance results for

Wales.

Trunk roads in England

Highways Agency results from machine based surveys of the surface

condition of the English trunk road network are published here for

the first time. These are derived from comparisons of the severity of

each type of defect with thresholds representing levels of condition

where treatment may be required. Results represent the percentage of

the network where the threshold for at least one aspect of condition

has been exceeded. In 2003, 5 per cent of motorways in England needed

further investigation to see if maintenance is required. This rises

to 8 per cent on all purpose trunk roads.

Footways, verges and kerbs

Along with the condition of roads, the NRMCS also collects visual

survey information on the condition of footways, verges and kerbs on

all local roads and, prior to 2003, on all purpose trunk roads as

well. Results are therefore no longer available for all road classes

(excluding motorways). However the relatively short length of all

purpose trunk roads means their exclusion from the survey makes

little difference to the overall total and comparisons between recent

figures for non-trunk roads and historic figu res for non-trunk roads

and all purpose trunk roads should provide a relatively consistent

picture of changes over time.

Figure 9 shows that the percentage length of footways affected by

deterioration (a combination of various defects on the footway) has

risen steadily since 1995 to the highest level since records began in

1977. However, there are signs that the steady rise in the number of

'trips' (spot conditions per 100 metres posing potential danger to

pedestrians) since the mid 1990s may have been halted.

1. Figures are for local roads from 1999. Prior to that they include

all purpose trunk roads although this will have little effect on the

overall total.

The percentages of verges and kerbs affected by deterioration are

shown in Figure 10. The percentage of verge area which is

disintegrating or deformed has varied considerably over the years and

it is difficult to make conclusions about current trends. The

percentage of kerb lengths which need replacing or resetting fell in

2003 to its lowest level since the survey began.

Maintenance expenditure

Levels of maintenance expenditure on local roads in England were

fairly stable in the early 1990s but were around some 25 per cent

lower towards the end of the decade (see Figure 11). During this

period, visible conditions on local roads worsened. Since then,

funding has increased and this has been followed by the recent

overall improvement in conditions.

Backlogs

The government, in its response to the Select Committee on Transport

last year, undertook to publish updated estimates of the backlog in

English local highway maintenance. These figures are still being

finalised and it is hoped to publish them soon.

Note

The annual NRMCS is supported by the Department for Transport, the

Local Government Association, the National Assembly for Wales and the

Highways Agency.

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