This chapter of the appendix describes subjective safety effects of five measures under the category of road maintenance.
1.2.1 Ordinary resurfacing of roads
Ordinary resurfacing denotes the normal replacement of existing road surface with new surface, for example in the form of re-asphalting. Elvik and Vaa (2004) do not clarify if resurfacing of tracks for walking and cycling is included under the measures. It is included in this report.
No studies are available which directly have evaluated the effects of resurfacing of roads and tracks on subjective safety. However, different handbooks, cycle strategies and reports describe indirectly the possible effects especially regarding what happens to subjective safety if resurfacing is not carried out. This is
summarized in table 1.19.
According to Karan et al. (1976), Cooper et al. (1980), Cleveland (1987) and Anund (1992), re-asphalting of roads affects driving speed, especially where the evenness of the road surface is improved. In this respect, an increase of speed up to 10 km/h has been detected, but more typical values are 2-5 km/h.
Compared to car drivers, cyclists are more sensitive to evenness, holes and cracks on road surface (Andersen 2002). In this respect, cyclists with slim wheels are especially more sensitive (Staten vegvesen 2003a). Thus, Staten vegvesen (2003b) has some supplementary standards for operation and maintenance of tracks for walking and cycling. In addition, guidelines for cycle path inspections have been developed to record flaws or shortcomings that would then form a basis for immediate measures to the road network (Statens Vegvesen 2004).
Nevertheless, surveys among the road users show that cyclists and pedestrians are displeased with the operation and maintenance of tracks for walking and cycling both in summer and winter. A question about the quality of the road surface is included in the summer survey (Staten vegvesen 2007).
Bad maintenance of the road surface results in several problems regarding subjective safety. Firstly, it increases the fear of accidents as a result of holes in the road surface. Erke and Elvik (2007) describes that holes in the asphalt, slippery roads, high curbs etc. contribute to accidents of pedestrians and cyclists. A questionnaire to 590 Norwegian cyclists involved in accidents showed for example that 4.5 % of the 375 single accidents were caused by holes in the road surface (Bjørnskau 2005). According to earlier studies from Norway, Denmark and Sweden the percentage of cycle single accidents caused by bad design, operation and maintenance is 30-50 % (Bjørnstig 1987, Borger and Frøysadal 1993, Frøysadal 1988, Hvoslef 1993, Larsen 1991).
Secondly, the result may be that cyclists are forced to use roads instead of cycle tracks. This will integrate motor vehicles and vulnerable road users with an
increased feeling of unsafety (Amundsen and Kolbenstvedt 2008, Staten vegvesen 2003a).
Thirdly, cyclists and motor vehicles will probably try to steer around evenness, holes and cracks in the road surface, which in some situations will give conflicts and reduce the distance between vehicles and cycles.
Fourthly, evenness, holes and cracks on road surface may distract cyclists and make it more difficult to cycle. This can have a negative effect on the feeling of safety (Transport- og Energiministeriet 2007). In other words ordinary resurfacing may reduce the required task of cycling. In table 1.19 this is indicated by
improved skills.
Finally, the service level for vulnerable road users is reduced in general if the ordinary resurfacing of roads and tracks is not carried out regularly.
Table 1.19. Possible effects of ordinary resurfacing of roads on subjective safety.
Traf
fic volume
Heavy vehicle Vulnerable road users Speed Distance Crossing distance Paths Separation/integration Intersections, design Crossings, number Road conditions Sight Road Light Thoughtfulness Skills Personally protection Total
- - - ↓ ↑ - - ↑ - - ↑ - - (↑) - ↑ ?
TØI report 1009/2009 Based on these considerations, it is concluded that bad road surface maintenance probably reduces subjective safety. In other words, ordinary regular resurfacing of roads and tracks can particularly contribute to improved subjective safety of bicyclists.
1.2.2 Improving the evenness of road surface
Improving the evenness of road surface involves filling potholes on the road surface, sealing large cracks, repairing damage following frost heave and other measures in areas where the road surface is abnormally uneven. The difference between this measure and the previous measure is that this measure deals with spots or short sections where a particular unevenness has occurred on the road surface (Elvik and Vaa 2004).
Table 1.20. Possible effects of improving the evenness on subjective safety
Traf
fic volume
Heavy vehicle Vulnerable road users Speed Distance Crossing distance Paths Separation/integration Intersections, design Crossings, number Road conditions Sight Road Light Thoughtfulness Skills Personally protection Total
- - - ↓ ↑ - - ↑ - - ↑ - - (↑) - ↑ ?
TØI report 1009/2009 Like ordinary resurfacing of roads no studies regarding the effects of repairing the road surface on subjective safety have been made.
Ordinary regular improvement and repairing of road surface are very similar measures, and therefore the effects on subjective safety are quite identical. The effects are summarized in table 1.20 and were clarified in chapter 1.2.1:
− Speed: Speed increases.
− Distance: Distance may decrease because it is not longer necessary that vehicle drivers and cyclists try to steer clear of evenness, holes and cracks in the road surface.
− Separation: Separation will in some situations be improved because cyclists no longer are forced to use the road instead of cycle tracks.
− Road condition: Road conditions are improved which will reduce the fear for single accident as result of holes in the road surface.
− Skills: The required task of cycling will be reduced which can improve subjective safety.
It is concluded that improving the evenness of road surfaces may contribute to improved subjective safety of vulnerable road users especially cyclists.
1.2.3 Improving road surface friction
No studies about possible effects of improving road surface friction on subjective safety of vulnerable road users have been found.
Table 1.21. Possible effects of improving friction on the subjective safety.
Traf
fic volume
Heavy vehicle Vulnerable road users Speed Distance Crossing distance Paths Separation/integration Intersections, design Crossings, number Road conditions Sight Road Light Thoughtfulness Skills Personally protection Total
- - - ↓ ↑ - - ↑ - - ↑ - - (↑) - ↑ ?
TØI report 1009/2009 If improving of road surface friction is carried out as a part of an ordinary regular resurfacing or as a part of improving the evenness of road surfaces, which is normally the case, the measure will have the same effects on subjective safety as these two measures. This is summarized in table 1.21. Changing from normal road surface to road surface with extra good friction solely does not influence
subjective safety in any significant degree.
Provided that the measure also improves the evenness of the road surface, it is concluded that subjective safety is improved especially for cyclists.
1.2.4 Winter maintenance of roads
The most important winter maintenance measures are snow clearance, sanding and salting (Elvik and Vaa 2004). This chapter focuses on roads without separate tracks for cycling and walking while the next chapter deals with winter
A review of 21 Norwegian studies from 1979 to 1998 which deal with subjective safety in different ways shows that slippery and icy road conditions increase the percentage of road users feeling unsafe (Amundsen 1999, Amundsen et al. 2000). In other words, winter maintenance of roads contributes to improved subjective safety. For example Ragnøy (1985) has studied drop of accidents among 514 old pedestrians in Oslo. 71 % stated that they went out as pedestrian less frequently in winters than in summers. 50 % of them stated slippery pavements as the reason. Erke (2008) concludes in a study about accidents among elderly pedestrians that winter maintenance improves the feeling of safety while walking among elderly pedestrians.
Some possible effects of good winter road maintenance are discussed in the following and summarized in table 1.22.
Good mobility is the main objective of the majority of winter maintenance measures. Thus, a number of studies have evaluated how different winter maintenance measures affect speed. These studies indicate that winter
maintenance measures increase the average speed of traffic up to 7 km/h. The increase in speed depends on how large improvements in friction the car drivers think the measures giver. During snowy weather, speed is reduced greatly by 10- 15 km/h (Elvik and Vaa 2004).
The distance between vulnerable road users along/on the road and motor vehicles are reduced by bad winter maintenance. The reason is that snow and ice at the road shoulder forces cyclists in particular to cycle more to the left on the road and more close to the motor vehicles (Erke and Sørensen 2008). In addition to the reduced distance, it also leads to more conflicts and disputes between vehicle drives and cyclists if the road is so narrow that motor vehicles cannot pass the cyclists. For example a survey by Trygg Vesta shows that cyclists on the road irritate over 70 % of the interviewed vehicle drivers (VG 2009).
Table 1.22. Possible effects of winter maintenance of roads on subjective safety.
Traf
fic volume
Heavy vehicle Vulnerable road users Speed Distance Crossing distance Paths Separation/integration Intersections, design Crossings, number Road conditions Sight Road Light Thoughtfulness Skills Personally protection Total
- - (↑) ↓ ↑ - - - ↑ - - (↑) - ↑
TØI report 1009/2009 Like maintenance and improvement of the surface, good winter maintenance improves road conditions which consequently reduce the fear of accidents due to icy and slippery roads.
Improved road conditions also reduce the required tasks for cycling, which may improve subjective safety. In table 1.22 this is illustrated by improved skills. Finally, improved road conditions that make cycling possible in winter and improve subjective safety consequently encourage more people to cycle in winter
(Bergström and Magnusson 2003), which itself improve subjective safety because more volume of cyclists increases the vehicle drivers’ attention.
Both the literature study and the qualitative considerations show that winter maintenance of roads increases subjective safety of vulnerable road users. 1.2.5 Winter maintenance of pavements and foot and cycle paths Winter maintenance of pavements, foot and cycle paths and other public areas includes the same measures as winter maintenance of roads, i.e. snow clearance, sanding and salting (Elvik and Vaa 2004).
As described in the previous chapter, different studies conclude that icy and slippery road conditions in general are associated with increased feeling of
unsafety. Pedestrians and cyclists are more sensitive to “difficult” road conditions, so this correlation should be also considered for foot and cycle paths.
A study about winter maintenance of cycle paths in Sweden concludes that temperature, precipitation, and road condition are the most important factors for those who choose to cycle to work in summer but not in winter. By improving winter maintenance service levels on cycle tracks, it might be possible to increase the number of bicycle trips during winter by 18 %, representing a corresponding decrease in the number of car trips by 6 %. They have also found that snow clearance is the most important maintenance measure. Less motor vehicle traffic and more cycle traffic improve subjective safety of vulnerable road users
(Bergström 1999, 2002, Bergström and Magnusson 2003).
No or bad winter maintenance of tracks for walking and cycling force vulnerable road users to use roads instead of tracks. This integration of motor vehicle and vulnerable road users reduces the feeling of safety.
Table 1.23. Possible effects of winter maintenance of pavements, foot and cycle paths and other public areas on subjective safety.
Traf
fic volume
Heavy vehicle Vulnerable road users Speed Distance Crossing distance Paths Separation/integration Intersections, design Crossings, number Road conditions Sight Road Light Thoughtfulness Skills Personally protection Total
(↑) - ↑ - - - - ↑ - - ↑ - - (↑) - ↑
TØI report 1009/2009 Good winter maintenance of tracks for walking and cycling improves road
conditions which consequently simplifies the task of walking and cycling, and therefore reduces the fear for accidents due to icy and slippery roads.
The qualitative considerations are summarized in table 1.23. Both the literature study and qualitative considerations show that winter maintenance of pavements, foot and cycle paths as well as other public areas increases subjective safety of vulnerable road users.