Scottish Road Maintenance Condition Survey 20052006 by nne25858

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									                    THE HIGHLAND COUNCIL                                   Agenda
                                                                           Item
      TRANSPORT, ENVIRONMENTAL AND COMMUNITY                               Report
          SERVICES COMMITTEE – 17 August 2006                              No


                   Scottish Road Maintenance Condition Survey – 2005/06
         Report by Director of Transport, Environmental and Community Services


SUMMARY

This report updates members on the results of the Scottish Road Maintenance Condition Survey
carried out in 2005/06.



1.     Introduction

1.1    The Scottish Road Maintenance Condition Survey (SRMCS) was first carried out in 2002
       on a trial basis, and the results were used to develop a new Statutory Performance
       Indicator (SPI) which was introduced by Audit Scotland in 2003/04.

1.2    The survey is now in its 4th year and includes 31 out of the 32 Councils within Scotland,
       the exception being Glasgow City.
2.     Survey Details

2.1    WDM Ltd, an independent contractor, carries out the survey on a Scotland wide basis.
       Their survey vehicle is equipped with technology which measures:
           • Texture Depth (smoothness)
           • Rutting (wheel tracking)
           • Longitudinal Profile (ride quality)
           • Cracking


2.2    Work is ongoing to evaluate parameters that can relate cracking to actual distress on the
       road surface. Research by the TRL (Transport Research Laboratory) has produced a
       method, using existing survey techniques, for the assessment of edge deterioration and
       transverse shape of the road. It is hoped to introduce these measurements in the 2006/07
       survey.



2.3    The SRMCS has a requirement to survey the following roads each year:
            • 100% of A class roads
          • 50% of B class roads
          • 50% of C class roads
          • 25% of U class roads
      In Highland’s case these targets equate to approx 3,308km of our network or 49.7%.


2.4   Due to the extent of the Scottish road network there have been difficulties in achieving
      these targets, especially for the U class network. Work is ongoing to review the resources
      available to carry out the survey, together with the targets. It is currently proposed that
      from 2007 the target for U class roads will reduce to a 10% sample per year.


3.    Statutory Performance Indicator (SPI)

3.1   The Statutory Performance Indicator is defined as:
      “The percentage of the road network that should be considered for maintenance treatment,
      derived from a combination of established condition parameters that are measured at a
      network level.”

3.2   The survey data is presented in a map form and the following colour coding has been
      adopted to describe the three main conditions.


       Green        The road is in an acceptable condition
       Amber        The road condition indicates that further investigation should be carried
                    out to establish if treatment is required.
       Red          The road has deteriorated to the point at which repairs to prolong the
                    future life of the road should be considered.
3.3   As the SPI identifies the percentage of the road that should be considered for maintenance
      treatment it is calculated as the sum of Red and Amber lengths.


4.    Results from the SRMCS Survey 2005/06

4.1   The results for the Scottish Local Authorities are shown in Appendix A, and the key
      results are summarised below, with the results from the best, worst and average Authority
      for comparison purposes:

                                                      SPI
       Authority            Red          Amber                               Ranking
                                                      (Red + Amber)
       Shetland             4.38%        22.51%       26.89%                 1st (Best)
       Highland             8.09%        27.47%       35.56%                 8th
       Scottish Average     11.01%       32.08%       43.2%                  Average
       East Renfrew         16.54%       39.04%       55.58%                 31st (Worst)
4.2   The SPI is made up from the aggregated survey results for the different classes of road,
      and a breakdown of the overall SPI for Highland is shown below.


                      Total Length Red              Amber          Green          SPI
                      (km)
                                   3.25%            21.24%         75.51%
       A Class        1388                                                        24.49%
                                   (45km)           (295km)        (1049km)
                                   8.58%            29.38%         62.05
       B Class        976                                                         37.95%
                                   (84km)           (288km)        (609km)
                                   3.3%             14.55%         82.14%
       C Class        1439                                                        17.86%
                                   (47.4km)         (209km)        (1180km)
                                   12.71%           36.37%         50.92%
       U Class        2871                                                        49.08%
                                   (362km)          (1035km)       (1450km)
                                   8.09%            27.47%         64.44%
       Overall        6674                                                        35.56%
                                   (538km)          (1827km)       (4309km)



5.    Comparison with previous years

5.1   The SPI’s for Highland over the last three years are shown in the table below:


       Year         SPI
       2003/04      38.92%
       2004/05      30.47%
       2005/06      35.56%


5.2   On first analysis the condition of the road would appear to have improved by around 8%
      between 03/04 and 04/05, with a deterioration of 5% between 04/05 and 05/06. These
      fluctuations are clearly unrealistic and must be considered within the context of the
      sampling regime.


5.3    “A” class roads are surveyed in full each year and these are the only roads which allow a
      direct comparison year on year. “B” and “C” class roads have a 50% sample per year and
      thus require a two year period to sample all roads.


5.4   The SPI, for A Class Roads only, for the past 3 years are shown below:
                         Year                       SPI – A Class Roads
                         2003/04                    27.76%
                         2004/05                    25.67%
                         2005/06                    24.49%


      Although there is still a significant percentage of the A Class road network requiring
      treatment, the above results indicate steady improvement over the past 3 years.


6.    SRMCS – Conclusions

6.1   Although there are some moderate fluctuations in the SPI over the first three years of the
      survey, it has to be considered within the parameters of the sampling technique being used.
      Results are always likely to vary when different roads are being sampled, each year. This
      situation is not unique to Highland, and other Councils have recognised this issue.
      Discussions with Audit Scotland have concluded that the SPI should to be based on a two
      year rolling two year average.


6.2   If a two year rolling average was used the results for Highland would be as follows:

                             SPI
       Years
                             (2 year rolling average)
       2003/04 to 2004/05    34.69%
       2004/05 to 2005/06    33.01%



6.3   The two year rolling average appears to remove the fluctuations due to sampling, and the
      figures in 6.2 would indicate a modest improvement in the overall condition of the road
      network in the Highlands. It will however require data over a number of years to fully
      establish the trend in terms of road condition.


6.4   In terms of allocating funding for structural maintenance we have already adopted this
      principal of a two year rolling average.

6.5   As the survey develops to include new defect parameters, such as “edge condition”, “drop
      off” and “transverse profile”, we should see a more accurate assessment of the condition of
      our rural road network.
7.        Future Trends


7.1       The allocation for structural road maintenance saw a significant increase in 2006/07 and
          this was allocated on the basis of need, as determined by the road Condition Survey. The
          effect of the additional works will show up in future surveys, depending on the sampling
          regime, and it is hoped that we will continue to see an improvement in the overall SPI over
          the next few years.


8.        Resource Implications


8.1       There are no resource implications arising directly from this report.


9.        RECOMMENDATION

9.1       Members are asked to NOTE the results of the Scottish Road Maintenance Condition
          Survey for 2005/06.



Signature:

Designation:          Acting for the Director of Transport, Environmental and Community Services

Date:                 4 August 2006

Author:               J MacLennan

Background Papers None.
                                                                                      Appendix A

                                                                                  SRMCS results for 2005_06

           100%
           95%

           90%
           85%
           80%
           75%
           70%
           65%
           60%
           55%
           50%
           45%
           40%
Highland   35%
           30%
           25%

           20%
           15%
           10%

            5%
            0%
                                           2


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                                      Highland Council (Number 9)

								
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