The Scottish Government

Page: [1] [2] [3] [4] [5] [6] [7] [8]

Appendix B

Summary of IHIE Guidelines for Motorcycling

Surface Grip and Consistency

Motorcycles have a much greater need for a consistent and high level of grip from the road surface than twin-track vehicles, especially on wet surfaces and in areas requiring braking and steering. Riders adopt an angle of lean to negotiate a corner that is related to speed and curvature - changes in grip can destabilise the machine in this situation. Any deviation from a consistently level surface can seriously impair the motorcycle's road-holding ability, increasing the risk of a crash. Unpredictable changes in the road environment that calls for rapid deceleration or braking while cornering can cause the motorcycle to "sit-up" and take a tangential line away from the bend.

Design Points

The recognition and understanding of the dynamics of motorcycle behaviour, when considered during planning and maintenance of roads, can play a significant role in lessening the risk to motorcyclists.

To reduce sudden variations in steering or braking requirements and minimise the consequences of any loss of control the following points should be considered:

• Consistent horizontal alignment to minimise changes in steering angle;
  
• Whenever possible position pedestrian and cycle crossings away from bends to allow motorcycles to brake and stop in a straight line and improve driver and rider sight lines;
  
• Ensure consistent skid resistance properties, particularly on bends;
  
• Terminate anti-skid surfacing on straight sections of road;
  
• Avoid using different surfaces, for example granite setts, to emphasise a change of circumstances at turning points such as junctions and mini roundabouts;
  
• Thermoplastic markings rarely have the same skid resistance properties as the surrounding road. Arrows and destination markings on roundabouts or bends are of concern to riders. Consistent and informative advance warning and direction signs should minimise the need for such surface signing. Careful consideration should be given to large areas of hatching;
  
• Specifications for and positioning of in-road and roadside furniture, including impact characteristics when struck by a fallen or sliding body. The principal should be to minimise the number of obstacles;
  
• Gentle changes in vertical alignment, both to minimise potential loss of tyre adhesion and optimise drainage;
  
• Allow for higher eye level of riders when positioning street furniture or planting vegetation, especially at junctions;
  
• Use battered kerbing as standard in rural areas to minimise potential injury to a sliding body;
  
• When redesigning existing road layouts consider the position and level of utility covers, especially on bends and within braking areas. Avoid forcing riders to over-run them whenever possible;
  
• Use of safety barriers and protection of support posts. The UK Highways Agency has issued an Interim Advice Note on Road Restraint Systems (IAN 44/02) in preparation for a new performance based standard, which will bring UK safety barrier guidance in line with European standards;
  
• The desirability of a "clear zone" on the outside of bends on higher speed rural roads - whenever possible position warning signs in advance of bends or as far as practicable from the carriageway;
  
• Consistent signing along a route, where the severity of the hazard is proportionate to the level of signing, so rider and driver expectations are met. If the road can "deceive", warnings are required;
  
• The role that probable future levels of maintenance may have on continued safety should be considered, particularly if design features require higher levels of maintenance than the road is realistically going to receive;
  Those authorities introducing LRT systems must give careful consideration to the destabilising effect that the rails can have on motorcycles and cycles.

Priority Junctions and Roundabouts

Measures to optimise sight lines are very important at priority junctions and roundabouts. A high proportion of crashes between motorcycles and cars in urban situations are due to emerging drivers failing to see the oncoming motorcycle. This potential problem can be mitigated with steeper entry angles and narrower entry widths - which as well as improving visibility for the driver has the effect of reducing entry speed. A balance will need to be struck between capacity and safety.

Highway Maintenance

The role of the maintenance engineer is critical to motorcycle safety, perhaps more than for any other mode:

• In providing a consistent road surface;
  
• In keeping roads clear of contamination and debris;
  
• In maintaining visibility, especially at bends and junctions;
  
• In ensuring best practice in maintaining road signs, road studs and markings;
  
• In implementing maintenance policies that focus on preventative action;
  
• In designing winter maintenance regimes that keep the needs of riders in mind;
  In ensuring that road works are safe for all users.

A good quality surface makes for a safer, more pleasant experience for most road users; it is an essential requirement for motorcyclists. Factors affecting motorcyclists include: skid resistance, surface contamination and debris, drainage gullies, road markings and road studs all of which should be considered from the motorcyclist's viewpoint.

Surface Contamination and Debris

The consequences of loss of grip are usually more severe for motorcyclists. Loose grit and gravel are a major concern for the rider and routine highway maintenance should be planned to reduce the amount of debris left on the highway. To counter this:

• Engineers should give more consideration to finished surface dressing sites to reduce the hazard caused by excess material in the days after work has been completed;
  
• Storage of gravel at the roadside, which could spill onto the carriageway, should be avoided;
  
• Under the code of practice for maintenance management it is recommended that surface inspections are carried out regularly. The opportunity should be used to locate areas of unused carriageway where loose material accumulates and identify these areas for priority sweeping;
  
• The spillage of diesel, oil and other similar substances on the roads is of great concern to the motorcyclist. Even the use of absorbent granules to remove these spills can be a hazard. At sites where this is a regular problem consider warning signs;
  
• Loose chipping warning signs need to be prominent, with consideration being given to yellow backing boards or high visibility signs.

Visibility

"Looked but failed to see" is a common contributing factor in accidents involving motorcycles and other vehicles. This can become a problem at sites, particularly junctions where planted areas or hedges are overgrown. This can be countered by an improved maintenance regime or modifying the type of planting.

Road Markings and Road Studs

The use of road markings needs to be carefully assessed with regard to the motorcyclist. The position and skid resistance value of edge lining, rumble strips, large arrows and hatched centre line marking can catch out the unwary particularly in the wet. Laying new markings on top of old can exacerbate this problem as can the practice of blacking out redundant markings. Where possible old markings should be burned or planed off.

Many different types of road studs are now available. Newer types are more visible and may be more suited to routes well used by motorcyclists, due to the lower level of illumination provided by motorcycle headlamps and the fact that the lean of a motorcycle negotiating a bend can take the headlight beam away from the hazard.

Rutting

Badly rutted surfaces cause particular problems in wet conditions because, in addition to rapid change in level, they retain water and increase the risk of aquaplaning. Use warning signs as an interim measure pending performance of a programmed maintenance scheme.

Potholes

Potholes can be one of the most dangerous hazards for motorcyclists and cyclists. Adequate inspection and repair regimes should deal with the vast majority but the public should also be encouraged to report defects. An efficient reporting regime can be beneficial. Reactive maintenance can be reduced by a switch to planned maintenance that caters for the higher vulnerability of motorcycles and their riders as resources permit.

Re-texturing

The various techniques of surface roughening such as grooving which are used to give a texture or improve drainage, must be carefully considered and when used require adequate signage to give the motorcyclist ample warning of this hazard.

Highway Drainage

Inadequate or compromised highway drainage creates wet patches and water pools causing slippery surfaces and increases the risk of aquaplaning. This can be a problem where non-highway water runs across the highway often as a result of blocked gullies or inadequate drainage schemes. Such areas should be noted for remedial action and gullies should be inspected and cleaned regularly.

Lighting

At night consistent road lighting is essential to enable any standing water, potholes or uneven utility covers to be seen in time to take evasive action. Therefore roads departments need a thorough and timely inspection and repair regime for road lighting.

Service Covers

One of the most regular problems encountered by motorcyclists is that of service covers. Designers and maintenance engineers should take every opportunity to reassess the use of steel service covers in the carriageway and, where re-location is impossible, consider replacement with high skid resistance covers. This is particularly important where covers lie on the riding line during a change of direction. The British and European standard on this topic is currently under review with the intention of including a requirement for skid resistance. This does not preclude retro-fitting improved surfaces to covers that can't be moved and utility companies should be encouraged to fit "skid proof" types during renewal of apparatus.

Road Works

The positioning and construction of temporary road signs can create a hazard for motorcyclists when negotiating roadworks, while poorly constructed re-instatement, temporary or otherwise, can pose severe stability problems to riders, especially at low speed. Areas of substandard road lighting can pose an even greater risk during road works. Missing or defective lighting should be repaired prior to commencing work.

Traffic Calming Schemes

Certain types of traffic calming features, for instance horizontal build-outs, vertical humps, speed tables and the use of block paving or stone setts can cause a variety of problems for riders, including difficult level and wheel path changes. Careful consideration to the design and location of traffic calming measures is required if they are not to be counter-productive. In addition effective and well maintained lighting is essential especially at vertical features such as road humps and plateau.

Page: [1] [2] [3] [4] [5] [6] [7] [8]