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Home > Safer roads for motorcycles > Chapter 7. The need for roadside safety zones

Research from several countries show the need for a safety zone next to the roadway for all road users but in particular motorcyclists. Roadside safety zones free from obstacles such as trees, barriers, and poles create a more forgiving environment. It allows motorcyclists to take evasive action if something unexpected happens on the road. Several studies describe that higher demands on the roadway and roadside width will increase safety. (51, 65).

The WHO states that roadside hazards (such as trees, posts, barriers, poles, unprotected gullies etc) represents a significant risk for motorcyclists. A crash involving a roadside hazard is 14 times more likely to be fatal than a crash to the ground with no physical contact with a fixed hazard (9).

The definition of a safety zone for motorcycles will not always be the same as for motorists (9). Studies from NZ and Australia conclude that many of the roadside measures such as poles and barriers provide protection for cars but can be fatal and hazardous to motorcycles. All studies show that a removal of roadside hazard would reduce the injury risk for all road users but especially for motorcycles.

The World Bank states that the road environment has a particular influence on the risk of crashes for motorcyclists and lists one of the contributing factors to be roadside hazards (30). To cater fully for the needs of motorcyclists, the road design needs to consider the type and placement of street furniture, including how safe they are in the case of a motorcyclist crash. It is crucial to minimize the number of obstacles, especially on bends, and to use poles that do not shear off leaving sharp remains or protrusions that could snag a fallen rider. On higher-speed roads consideration must also be given to the “swept path” of the rider leaning into bends to avoid roadside features and oncoming traffic.
A policy recommendation from the ITF Forum in 2018 concludes that each road infrastructure element presents a unique level of crash risk, with the level determined by/dependent upon how the element was originally designed and its condition (31). Different scenarios were collated, iRAP risk factors were applied to each of these to demonstrate the effects the design or condition of infrastructure elements have on the likelihood of a crash occurring and the severity of a crash should it occur. The results indicated that the likelihood of a crash occurring increased as various road infrastructure elements were either at minimum standards (e.g., lane width and curvature) and/or if more than one element was in good or poor condition. The results indicated that in addition to the roadside objects crash severity risk factor, the distance from the lane and available paved shoulder width contributed to crash severity.

The Norwegian Road Safety Handbook states that safety zones beside the roads without fixed hazards will reduce the number of serious run-off crashes in rural and urban areas and that the need for a roadside safety zone is higher in curves (51).

Possible solution
The research consistently shows that roadside safety zones without fixed hazards reduces the risk of serious crashes for motorcyclists. As such, roadside safety zones should be included in national design standards and implemented to improve safety. This is particularly important for high-speed roads. The higher the allowed speed is and the number of vehicles using the road, the greater the need is for a safety zone beside the edge of the road. SWOV recommends safety-zones varying from 2.5 meters (on roads with speed limit of 60 km/h to 14.5 meters on roads with a speed limit of 130 km/h (66).

A forgiving roadside design guide was published in November 2012 by CEDR. It is mainly focusing on the safety for motorists but a design guide for motorcyclists would be an excellent way forward (67).

Paved shoulders (which are clear of gravel and debris) offer the safest option for a recovery zone (32). They allow a motorcyclist to take evasive action without losing friction.

The need for a paved recovery zone, especially in curves, is highlighted in a Swedish study (68). The study conducted tests where tests based on accident crash data to identify the performance characteristics of different motorcycles and their riders. At speeds between 60- 80 km/h, the riders required at least 1.5 seconds to react, counter steer and recover from an avoidance manoeuvre. The times were longer in curves and required significant lateral acceleration to ensure vehicle stability. While reference acceleration for passenger cars in smaller curves are approximately 0,2 g (g force), motorcyclists will require at least 0.4 g -to 0.5 g, to ensure stability.

Lateral displacements of the motorcycles were 0.6-1 m during the avoidance manoeuvres which indicates that there is little chance to avoid a fixed hazard positioned 0.5 m from the lane edge. A Life Cycle Cost model was also developed in the project with a paved shoulder in outer curves with different recovery areas widths instead of a guardrail. The construction costs would be lower than the cost of one minor injury accident for the curve.

Another reason mentioned above is the need to minimize the gravel from unsealed shoulders which causes many motorcycle crashes (36, 38, 69). They also provide space for vehicles which need to stop due to break down or any other reason. Four persons per year are killed on Swedish motorways and 2+1-roads after they´ve stopped on the narrow shoulder. The width is allowed to be 0,5 meter on rural roads and on 2+1-roads with a side barrier where the allowed speed is 100 km/h (VGU 2022, Thus, the Swedish Transport Administration urges all road users to leave the road as soon as possible when the vehicle stops (70). The recommended width on a hard shoulder on motorways in the UK is 3,3 meters.

Roadside safety zones which are free from obstacles next to the roadway reduces the severity of motorcyclist injuries in the event of a crash, particularly on roads with high-speed limits. According to WHO, roadside hazards (trees, posts, barriers, poles, unprotected gullies etcetera) represents a huge risk for motorcyclists. A crash involving a roadside hazard is 14 times more likely to be fatal than a crash to the ground with no physical contact with a fixed hazard. The definition of a safety zone for motorcycles will not always be the same as for motorists (9). Studies from NZ and Australia conclude that many of the roadside measures such as poles and barriers provide protection for cars but can be fatal and hazardous to motorcycles. All studies show that a removal of roadside hazard would reduce the injury risk for all road users but especially for motorcyclists.

American research looking at US motorcycle crashes, concludes that the risk of a motorcyclist dying as a result of impacting a tree as opposed to impacting a W-Beam barrier is double, i.e., there is half the risk of dying colliding with a roadside barrier as opposed to running off the road and colliding with a tree. Similarly, the risk of dying when striking a signpost, utility pole or other support is 1.5 times the risk of dying when striking a W-beam (98).

Data from Australia where crashes with roadside obstacles were compared to crashes with barriers shows that trees were significantly associated with a greater fatality risk than barriers, where collisions with trees are around 3.5 times more likely to result in a fatality than striking a barrier. Poles were also likely to be associated with a greater fatality risk than barriers. Other types of fixed objects were not found to be significantly associated with a greater or lesser fatality risk than barriers (122).

Collision data for the Strategic Road Network, SRN in UK, between 2015 and 2019 inclusive, indicates that 60% of all collisions which involved a motorcyclist colliding with a feature in the roadside, such as signs, lighting columns, telegraph or electricity poles and trees, resulted in fatal or serious injuries. For the same period, collisions involving cars colliding with a roadside feature resulted in 30% fatal or serious injuries. This demonstrates the vulnerability of motorcyclists when roadside features are present (22).

Possible solutions for safer roadsides
The English design guide for motorcyclists has an action plan in four steps to reduce the injury risk with obstacles on the roadsides: remove the hazard – relocate the hazard- reduce the hazard – protect the hazard (22).

The Slovenian guidelines has a similar approach: identification of danger – remove danger – move danger – protect from danger – indicate danger. The Slovenian guidelines also includes general conditions and a method of setting up safety equipment (guard rails with MPS, impact pads and passive safety poles) for motorcyclists. The locations that are mentioned are curves and exits from (38).

The Norwegian Handbook has a section about possible conflicts and proposes that there is a joint review through a planned road system from the various users’ point of view, that look at the risks and what can be the resulting consequences. Where there are different options available, attempts should as far as possible be made to describe what the various solutions can result in in terms of future motorcycle crashes as a part of the basis for decision when safety is being assessed against other considerations and against costs. The decision maker needs to know what a chosen solution means risk-wise and where motorcyclist safety conflicts with safety of other road users. If road safety is threatened when considered against other, such as aesthetics or financial limitations, the choice of solution and choice of risk must be taken at a sufficiently high level and the decision maker must take responsibility for a conscious choice of risk of future crashes (36).

All available national guidelines have similar advice and examples to improve motorcycle safety in curves. They are:

  • avoid trees near the road and if they are planted – at what distance.
  • eliminate vegetation and whatever impairs forward visibility to detect hazards.
  • remove fixed hazards and minimize objects on the roadsides.
  • install objects as far away from the road as possible.
  • consider the use of passively safe road furniture.
  • avoid placing road furniture on the outside of curves like barriers, lamp poles, and road signs,
  • choose barrier type with minimum injury risk for motorcyclists and install them as far as possible from the edge of the roadway.
  • install flexible w-beam barriers with MPS and attach pole and post padding where barriers, poles and posts can’t be relocated.
  • look at other measures like flatten ditches and embankments and smoothing and covering rock cuts with soil.

The risk of a motorcycle crash is highest in curves. If posts and signs must be installed in curves, the injury risk can be minimized by using posts and poles that are frangible for motorcyclists which otherwise is not the case. These kind of passive safety poles, PSP, are used in several countries, for example Slovenia, Germany, Australia, Austria, and England. In Germany and Slovenia, they are used frequently as a part of the guidelines for motorcycle safety in curves where a lot of crashes have occurred. Evaluation shows that the PSP pollards can reduce the likelihood of crashes on these roads (123-124).

Possible solutions
The use of PSP is described in detail in the Slovenian guideline (38). They are seen as efficient since they are made of materials and designed structurally so that they have less rigidity than metal and thereby offer greater elasticity (temporarily) and plastic deformation upon impact. They are designed so that above the line of the ground they have no sharp external edges. Their surfaces have the largest possible radii of curvature within the geometric constraints and in relation to parts of the human body. They don’t break or become damaged upon impact leaving hard and sharp edges. The passive safety poles are also a method to help the riders to keep the right line on the road.

In Slovenia the passive safety poles are installed where:

  • In the event of impact with a motorcyclist the installation of guard rails would cause greater harm than if there were no guard rail,
  • In the event of impact with a motorcyclist the installation of traffic signs with or without a guard rail would cause greater harm than if they had not been installed,
  • The carriageway has a large-radius blind curve and
  • Junctions are not easily visible.

Passive safety poles are installed on the shoulder or verge of the carriageway to indicate the flow of the road and/or draw attention to possible danger. They are situated on the outer side of the curve at regular intervals depending on the radius of the curve and are white. Passive safety poles are used as a “self-explaining” visual guidance for motorcyclists (as well other drivers) through curves and serve as pro-active measures for road safety.

Visibility is particularly important for motorcyclists. Unlike other larger vehicles on the road, motorcycles have a small profile which makes them difficult to see, especially if obscured by roadside features such as plantings, fencing, barriers, signage, or parked vehicles. A motorcycle can also be hidden by a part of a car, most frequently the A-pillars that supports either side of the windscreen and are known to create blind spots for drivers. Motorcyclists also need to see the road clearly ahead to avoid any hazards such as surface defects or other vehicles. The need for good visibility must be considered at intersection and roundabout design. The need for good visibility is mentioned in all national guidelines, as well as the global recommendations from the World bank and WHO.

Possible solutions
Several guidelines have included measures to improve the visibility of motorcycles. These are the most common measures mentioned in Norway, Slovenia, Australia, and England.

  • Ensure a clear view for road users at critical locations such as roundabouts, intersections or on curves.
  • Sight zones must be free of sight reducing obstacles so that motorcyclists can see and be seen.
  • Vegetation, noise barriers, guardrails and signs must not be placed in such a manner that motorcycles partly or fully «disappear» behind. This is especially important in intersections and curves.
  • Intersection design must provide crossing traffic the opportunity to see the whole motorcycle in the entire sight zone.
  • T-intersections should be constructed so that those required to yield will see traffic from the side, not frontally.
  • Consider if right turn lanes/deceleration lanes can be separated from through lanes. or be removed.
  • Install longer keep clear zones, especially at uncontrolled intersections to provide greater visibility for motorcyclists and other road users.
  • Trim vegetation where visibility is impaired especially at curves and intersections.
  • Introduce advanced stop lines for motorcyclists in urban areas which have reduced crashes with 39% in Malaysia and Indonesia (22, 32, 36, 38).
  • Open bus lanes for motorcycles to improve their visibility and reduce the risk of injuries (8, 21, 33, 125).


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