Economic, Environmental and Social Impacts of Changes in Maintenance Spend on Local Roads in Scotland

4 Local Road Network in Scotland

4.1 Extent and nature of network

Table 4.1 shows the length of the local road network in Scotland as used for the analyses.

Table 4.1 Scottish local roads network length
Local Authority Road Class Network length (Carriageway km)
A Class roads 7,611
B Class roads 7,486
C Class roads 10,619
Unclassified roads 25,907
Total 51,623

Source: RCI condition reports

The Scottish local road network[2] carries less than 65% of all traffic and less than 40% of all Heavy Goods Vehicle (HGV) traffic in Scotland, whilst being more than 90% of the total length of the Scottish road network.

4.2 Amount of travel

The most recent traffic data for Local Authority roads in Scotland (for 2009) was obtained from Scottish Transport Statistics2 and used to derive the total distance travelled on the network, summarised by road type, used in this study (shown in Appendix C). Table 4.2 shows the 2010 levels of traffic on local roads in Scotland2. For the 20 years represented in this study (2010 - 2030) traffic growth rates from the National Road Traffic Forecasts (NRTF) have been used. These growth rates (shown in Appendix C) are for each vehicle type (Cars, Light Goods Vehicles, Heavy Goods Vehicles and Buses) and vary through the 20 years analysis period.

For the economic analysis the traffic count for heavy vehicles has been assumed to be for articulated commercial vehicles.

4.3 Accident trends

Accident data was extracted from the STATS19 database for the period 2005 to 2009 was extracted. The data in STATS19 is populated from police reports taken at the scene of road accidents. From 2005 the data has included contributory factors for each accident recorded in the database. This data has been analysed to determine the number of accidents on the Scottish Local Authority road network, resulting in death or serious injury, by contributory factors that may be influenced by changes in road maintenance spend. The results of this analysis are shown in Figure 4.1. Note that accidents can have more than one contributory factor associated with them so this data should not be aggregated to determine the total number of accidents in any given year.

The data shows that the single largest contributory factor to serious and fatal injuries is slippery road conditions (due to weather), with deposits on the road being the second largest and a poor or defective road surface being the third largest contributory factor.

Table 4.2 Traffic on Scottish local roads by vehicle type (2010)
Road Type Traffic (Million vehicle kilometres)
Cars 2 wheel motor vehicles Buses Light Goods Vehicles (LGV) Heavy Goods Vehicles (HGV) All motor vehicles
Major local roads
Non-trunk A roads - urban1 3,722 19 96 509 153 4,499
Non-trunk A roads - rural1 6,033 65 107 1,080 450 7,735
All major local roads 9,755 84 203 1,589 603 12,234
Minor roads (B, C and Unclassified)
Urban roads1 6,400 59 215 1,054 126 7,854
Rural roads1 5,193 50 82 1,352 207 6,884
All minor local roads 11,593 109 297 2,406 333 14,738
All roads
Urban roads1 10,122 78 311 1,563 279 12,353
Rural roads1 11,226 115 189 2,432 657 14,619
All local roads 21,348 193 500 3,995 936 26,972

Note: 1. Source: Scottish Transport Statistics.

Scottish Transport Statistics uses the Department for Transport classification of urban and rural roads which is based on population. The classification used here is based on built up/non-built up areas.

Similarly the data for fatal accidents on the Scottish Local Authority road network was investigated to determine the number of accidents by the prevailing lighting conditions. This data is shown in Figure 4.2. Note that most accidents occur during daylight hours, since traffic flows are higher compared to night time.

Figure 4.1 Accidents causing death or serious injury by contributory factor

Figure 4.1 Accidents causing death or serious injury by contributory factor

Figure 4.2 Numbers of fatal accidents by lighting levels

Figure 4.2 Numbers of fatal accidents by lighting levels

4.4 Budgets

The most recent expenditure data available for this study is the 2009/10 outturn costs (Audit Scotland, 2011). Table 4.3 shows the costs for all local roads and Appendix C shows the results for the 8 Local Authorities considered in the detailed analysis in this study.

Table 4.3 Expenditure on local roads in Scotland (2009/10)
Item Cost (£m)
Traffic Calming 2,987
Road Safety 8,521
New Road Schemes 11,757
Lighting 20,629
Structural Maintenance 109,906
Other 34,477
Total capital 188,277
Road Construction 1,370
Structural Maintenance 65,432
Environmental Maintenance 13,950
Winter Maintenance 92,261
Lighting 53,449
Safety Maintenance and Emergency Patching 33,880
Routine repairs 42,895
Total revenue 303,236
TOTAL 491,513

Key points made by Audit Scotland (Audit Scotland, 2011) are:

  • The figures translate to an average cost per kilometre of £9,400. This compares with an average cost per kilometre on the Scottish trunk road network of £47,500.
  • Road maintenance expenditure has increased by £54m since 2005, taking account of general inflation. However, when the higher specific rates of road construction inflation are considered, road maintenance expenditure on local roads has fallen by £76m.
  • Structural maintenance might be funded from capital or revenue expenditure. There has been a trend towards it being funded from capital expenditure in recent years.
  • Different Authorities adopt different cost accounting systems to define activities and record costs. For example, costs for repairs to structures might be captured in structural maintenance (capital or revenue) or 'other' in Table 4.3.

4.5 Network condition

The Scottish Road Maintenance Condition Survey (SRMCS) is a survey of the local roads in Scotland (SCOTS, 2010). The machine-based (SCANNER) surveys measure the surface condition in terms of:

  • Rutting (average of near-side and off-side wheelpaths)
  • Roughness (Longitudinal Profile Variance - 3m and 10m wavelengths)
  • Texture (near-side wheelpath)
  • Whole carriageway cracking

These condition measurements are combined into a Road Condition Index (RCI) and the RCI values are assigned to show poor ('Red') condition, in need of investigation ('Amber') condition and good ('Green') condition. Figure 4.3 and Figure 4.4 summarise the condition of local roads in Scotland in 2009.

Figure 4.3 RCI by road length for Scottish local roads (2009)

Figure 4.3 RCI by road length for Scottish local roads (2009)

Figure 4.4 RCI by network percentage for Scottish local roads (2009)

Figure 4.4 RCI by network percentage for Scottish local roads (2009)