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.
| 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.
| 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 4.2 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.
| Item | Cost (£m) |
|---|---|
| Capital | |
| 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 |
| Revenue | |
| 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 4.4 RCI by network percentage for Scottish local roads (2009)
