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3.4 Effectiveness The lack of side specific underride collision data makes it difficult to evaluate the effectiveness of SUPDs. However, one UK study was identified in the literature review which addressed the effectiveness issue.
A 2005 UK report titled Integrated Safety Guards and Spray Suppression evaluated the benefits of improving current sideguards . The authors looked at the potential benefits generated by a smooth surface design and a lower ground clearance than current EU regulations. The evaluation was carried out using two methods: collision data analysis and computer simulation.
In order to establish a baseline for future predictions of benefits, a collision data analysis was performed based on data from three distinct UK sources: Road Accidents Statistics (STATS19 Returns), Heavy Vehicle Crash Injury Study (HVCIS) and Truck Crash Injury Study (TCIS). Data
from before the introduction of sideguards were compared with data from ten years later, when sideguards would have been installed on the majority of the UK fleet.
The data in Figure 17 were extracted from that report and shows the distribution of injury severity for bicyclist involved in all types of collision with a Heavy Goods Vehicle (HGV). In addition, the data in the table shows how the distribution has changed.
Figure 17: Summary of bicyclist casualties, UK, 1980-1982 and 1990-1992  Data in Figure 17 shows that the number of fatally and seriously injured bicyclists in collisions with HGVs decreased, which suggests that there have been improvements in secondary safety during that period. It can be seen that the total number of injured bicyclists after the sideguards were introduced decreased by 18.7%.
It is well understood that sideguards are primarily designed to protect VRUs in a very specific type of accident, when a VRU falls against the side of a moving heavy vehicle in the area between the wheels. Unfortunately, such collisions could not be identified from UK collision data. To account for such collisions, the authors of the report extracted collision data where both the bicyclist and HGV were going straight ahead in the same direction and the initial point of impact was to the nearside of the HGV. Data for this specific type of collisions is shown in Figure 18.
Figure 18: Bicyclist injury distribution from specific collisions, UK, 1980-1982 and 1990-1992  The reduction in the number of killed and seriously injured (KSI) bicyclists is substantial: 61% reduction for the fatally injured and 12.8% reduction for the seriously injured bicyclist. The large reduction in the number of KSI bicyclists suggests that the introduction of sideguards has provided substantial benefits to the bicyclists involved in going ahead collisions with HGV, where the initial point of impact was the nearside of the HGV. The authors noted that in other studied manoeuvres, the proportion of KSI bicyclist was virtually unchanged before and after the introduction of sideguards. This suggests that sideguards are effective for only the specific type of collision previously mentioned. For the cases where pedestrians and HGVs were involved, for the going ahead type of accident, a reduction of 20% was noted for the fatally injured pedestrians when sideguards were installed, but no reduction was observed for seriously injured pedestrians.
The computer simulation of the study took into consideration the specific type of collision where a bicyclist or pedestrian falls against the side of a HGV moving in a straight line and equipped with either traditional rail type or smooth integrated sideguards, as shown in Figure 19.
Figure 19: HGV models equipped with rail type (left) and smooth (right) sideguards 
The loads transmitted to, and the injury criteria sustained by bicyclists and pedestrians during
the simulations were compared for the two vehicles. The simulation results showed that:
The traditional rail type design was effective at preventing the upper body of vulnerable road users from being run over by the rear wheels; however, the results also showed that the VRUs can still sustain severe injuries which could be fatal, particularly head injuries resulting from contact with the ground; and For the model representing a VRU and an HGV fitted with smooth integrated sideguards, the general finding was that the VRU fell close to the moving HGV, which provided a greater potential for the upper VRU model appendages to fall under the sideguard and be crushed by the trailer wheels.
The analysis of national collision data of the UK report provided considerable evidence to support the simulation findings with regards to the effectiveness of current sideguards for HGVbicyclist collisions.
The report showed that while there are benefits to refining the design of current sideguards, these estimated benefits are small in comparison with those obtained by introducing sideguard regulations: It was found, through computer simulation and accident analysis that using a flat panel sideguard reduced the forces applied to vulnerable road users that collided with the side of an HGV. This reduction in forces was predicted to translate to a reduction in the number of pedal cyclists killed of between 0.2 and 1.5 per year with serious injuries reduced by 3.9 per year and slight injuries increased by 17.5 per year. It was also predicted that pedestrians may benefit from the changes with a predicted reduction of between 0 and 2.91 fatalities per year.
Using DfT casualty cost figures (RAGB, 2001) this translates to a financial benefit of between £0.581 million and £5.609 million per year. The benefits arising from ending vehicle exemptions included in current regulations was also evaluated. Based on STATS19 data, the authors predicted that approximately two VRU fatalities per year can be prevented if vehicle exemptions are eliminated. In UK, approximately 20% of HGV are exempted from sideguard regulations due to various clauses contained in the regulations.
3.5 Conclusions of Literature Review
Sideguard legislation for heavy vehicles was introduced in the EU 20 years ago with the specific purpose of protecting VRUs such as bicyclists and pedestrians from falling under the wheels and being run over by the wheels; similar legislation exists in Japan. Australia has contemplated the possibility of requiring sideguards for heavy vehicles, but based on collision statistics and implementation costs it could not justify this requirement. Canada and U.S. have no legislation regarding sideguards on heavy vehicles but there has been an increased interest in evaluating the benefits and drawbacks of considering legislation similar to the one that exists in the EU.
Even though sideguard legislation exists in many countries, a large number of heavy vehicles are still exempted from its requirements. There are many heavy vehicles which cannot have sideguards installed, due to their specific operational requirements. For example, it is estimated that in UK approximately 20% of the heavy vehicles are exempted. Such a situation will likely occur in other jurisdictions, based on the fleet characteristics. In North America for example, the
number of snow ploughs is significant and the diversity of these trucks will require careful consideration regarding sideguard design and installation.
Few changes have been made to sideguard regulation requirements in the past 20 years.
Numerous studies related to various heavy vehicle systems, including sideguards, have been undertaken and several recommendations have been made so that effectiveness of the sideguards is improved.
One of the recommendations was to lower the height of the sideguards. However, understanding the effects of such modifications requires extensive analysis so that the new designs do not interfere with the operation of the vehicles. It is anticipated that a lower sideguard will improve the protection of VRUs involved in collisions with heavy vehicles.
However, the lower the sideguard, the more likely it is that it will affect the operation of such vehicles. A known issue in Canada is certain rural rail crossings, where some heavy vehicles equipped with rear guards encountered difficulties in the past.
The sideguard design falls into two categories: rail type and smooth type. Each has its advantages and drawbacks and considering the operating environment is a key requirement for evaluating the best alternative in terms of strength, aerodynamic and material characteristics.
While collision data have been collected from different jurisdictions, a direct comparison cannot be performed due to significant differences, such as structural (country size, density and quality of the road network, population, etc) and socio-economic differences (vehicle composition, user behaviour, etc.) and road users composition (number of bicyclists, pedestrians, mopeds, etc.).
Nonetheless, the collected data clearly shows a much higher fatality rate for bicyclists in the EU, as presented in Table 17.
Table 17: Average bicyclist and pedestrian fatalities, all motor vehicles, selected data
While data for collisions involving heavy vehicles and VRUs are often difficult to obtain, Canadian data provided by Transport Canada  showed that between 2004 and 2006, the number of bicyclist fatalities that resulted from heavy vehicle-bicyclist urban collisions represented on average 13% of the total number of bicyclist fatalities resulted from heavy vehicle-bicyclist collisions and approximately 0.28% of the total number of road user fatalities.
Similarly, the number of pedestrian fatalities that resulted from heavy vehicle-pedestrian urban collisions represented on average 7% of the total number of pedestrian fatalities resulted from heavy vehicle-pedestrian collisions and approximately 0.9% of the total number of road user fatalities.
In urban collisions involving heavy vehicles, bicyclists and pedestrians, the front of the heavy vehicle (front, right front and left front) was the initial point of impact: in 42.9% of the cases for
bicyclist fatalities and 45.8% of the cases for pedestrian fatalities. The right side of the heavy vehicle (right middle, right rear and entire right side) was the initial point of impact in approximately 28.5% of cases for bicyclist fatalities and 6.3% of cases for pedestrian fatalities.
U.S. data obtained from FARS showed that between 2005 and 2007 the number of bicyclist fatalities that resulted from heavy vehicle-bicyclist collisions represented on average 10% of the total number of bicyclist fatalities resulted from all motor vehicle-bicyclist collisions and approximately 0.18% of the total number of road user fatalities. Similarly, the number of pedestrian fatalities that resulted from heavy vehicle-pedestrian collisions represented on average 6% of the total number of pedestrian fatalities resulted from heavy vehicle-pedestrian collisions and approximately 0.62% of the total number of road user fatalities.
The front of the vehicle was the initial point of impact in 48.5% of the cases for bicyclist fatalities and 71.6% of the cases for pedestrian fatalities. The right side of the vehicle was the initial point of impact in approximately 22.5% of cases for bicyclist fatalities and 7.9% of cases for pedestrian fatalities. Details regarding the exact location of the impact of the right side were not available.
The effectiveness of the sideguards on heavy vehicles has been demonstrated by a UK study, which showed significant reductions in the number of bicyclist fatalities from before the sideguards were introduced to after the sideguards were introduced. The study was performed using UK data and the extrapolation of the results may not be appropriate.
The general consensus is that sideguards are only part of the solution for improving the safety of VRUs in collisions with heavy vehicles. Numerous other measures have been proposed for improving the safety of VRUs involved in collisions with such vehicles. Some of these measures, presented at an APROSYS workshop in 2008, are illustrated in Figure 20.
4 VEHICLE CONSIDERATIONSSection 3 defined how side guards were conceived, designed and installed in Europe and Japan and presents some collision statistics relating to heavy vehicles and VRUs. Section 4 outlines the possible effects to Canadian truck and trailer operators and to VRUs if side guard devices were fitted to trailers and straight trucks in Canada.
4.1 Definitions 4.1.1 Tare Weight The empty weight of a container or trailer.
4.1.2 Gross Vehicle Weight Rating The gross vehicle weight rating (GVWR) is the is the maximum allowable total weight of a road vehicle or trailer when loaded including the weight of the vehicle itself plus fuel, passengers, cargo, and any trailer tongue weight.
4.1.3 Gross Vehicle Weight The gross vehicle weight (GVW) is the actual weight of a truck, trailer, or tractor including the tare weight and the weight of the fuel, passengers, cargo and any added tongue load.
4.1.4 Straight Truck Vehicle which carries cargo in a body mounted to its chassis, rather than on a trailer towed by the vehicle.
4.1.5 Tractor The tractor, or power unit, is the towing vehicle in a combination vehicle. It generally does not have any inherent cargo carrying capacity.
4.1.6 Fairing An accessory mounted to the body of a vehicle or aircraft designed to reduce aerodynamic drag.
4.1.7 CO2 production Engine and exhaust after-treatment manufacturers use many methods to reduce the levels of pollutants that are released from a diesel powered vehicle s tailpipe. All but one of the major pollutants can be reduced by using combinations of exhaust gas re-circulation (EGR), variable geometry turbo chargers, catalysers, selective catalytic reduction (SCR), alternate fuels, particulate traps and computer controlled engine management that alter timing and combustion temperatures. However, the only way to reduce the amount of CO2 from an engine s exhaust stream is to reduce the amount of fuel burned in that engine or to change the type/grade of fuel being burned in that engine.