«National Research Conseil national Council Canada de recherches Canada Centre for Surface Centre de technologie des Transportation Technology ...»
National Research Conseil national
Council Canada de recherches Canada
Centre for Surface Centre de technologie des
Transportation Technology transports de surface
Side Guards for Trucks and Trailers
Phase 1: Background Investigation
Road Safety and Motor Vehicle Directorate
275 Slater Street, Ottawa
Ontario K1P 5H9
J. D. Patten, P. Eng.
C. V. Tabra, P. Eng.
Project 54-A3861 Projet 54-A3861 Technical Report Rapport technique March 1, 2010 CSTT-HVC-TR-158
UNCLASSIFIED NON CLASSIFIÉEi CSTT-HVC-TR-158
SIDE GUARDS FOR TRUCKS AND TRAILERS
PHASE 1: BACKGROUND INVESTIGATION
Prepared for /Prepare pour:
Road Safety and Motor Vehicle Directorate Transport Canada 275 Slater Street, Ottawa Ontario K1P 5H9 Centre for Surface Transportation Technology Centre de technologie 2320 Lester Rd. des transports de surface Ottawa, Ontario K1V 1S2 Canada Technical Report Rapport technique CSTT-HVC-TR-158 CSTT-HVC-TR-158 Copyright 2010. This document contains confidential information that is proprietary to NRC s Centre for Surface Transportation Technology. No part of its contents may be used, copied, disclosed or conveyed to any party in any manner, in whole or in part, whatsoever without prior written permission from NRC s Centre for Surface Transportation Technology.
National Research Council Canada Centre for Surface Transportation Technology ii CSTT-HVC-TR-158 This report reflects the views of its authors, and not necessarily those of Transport Canada.
National Research Council Canada Centre for Surface Transportation Technology iii CSTT-HVC-TR-158 ABSTRACT A study was conducted by NRC-CSTT to understand the state of heavy vehicle side guard use in the European Union (EU), Australia, Japan and North America. Publicly available information relating to side guard design, strength and installation was gathered and analyzed for countries currently requiring the devices. Collision data records were also analyzed to determine the effectiveness of the guards. Finally, heavy vehicle considerations and aerodynamic effects were reviewed to better understand how side guards would affect Canadian road users and operators.
National Research Council Canada Centre for Surface Transportation Technology iv CSTT-HVC-TR-158 Any mention of specific vehicle make, model or brand in this document is done so as a means to present factual information that was obtained from publicly available sources. Neither vehicle testing nor model-to-model comparisons were conducted by NRC-CSTT as part of this study.
As such, no comment is made on the suitability of any particular vehicle or commercial product for any particular application, use or task.
Vehicle side guards (also referred to as lateral protective and side underrun protection devices) are intended to provide protection to vulnerable road users (VRUs) such as pedestrians and cyclists, and in some instances motorcyclists, against the risk of falling under the sides of the vehicle and being caught under the wheels.
Additionally, certain flush side fairings (or side skirts) may provide environmental benefit through improved fuel efficiency over a range of operating points, based on the reduction of aerodynamic drag on certain types of vehicles Side guards have been legislated on certain motor vehicles, trailers and semi-trailers in various countries in the EU and Japan.
Transport Canada wished to undertake an investigative study of the feasibility of requiring protective side guards on large trucks and trailers operated in urban Canadian environments and also to understand any environmental benefits of flush side fairings.
NRC-CSTT performed a background investigation and data collection exercise on side guard use in the EU, Japan, Australia and North America. The review included current use of side guards, types of devices used (including material types, design, attachment mechanisms), the types of vehicles on which they are used, reported effectiveness of side guards, collision statistics and lessons learned from jurisdictions that have legislated the use of these devices.
In Canadian 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.
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 in the US heavy truck-VRU collisions. 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.
Based on data from the EU, the number of deaths and serious injuries for VRUs when involved in an incident with heavy vehicles has been reduced since the introduction of side guards.
However, it is not clear if this reduction is entirely related to side guards or if side guards are but one of the contributing factors.
The statistical data from the EU revealed there was a greater reduction in severe injuries and death for bicyclists than for pedestrians during the reporting period. UK s Transport Research Laboratory (TRL) modelling showed that sideguards offered a potential for improved protection to VRUs.
National Research Council Canada Centre for Surface Transportation Technology vi CSTT-HVC-TR-158 Side guards are only part of the solution to reducing severe injury caused by heavy truck and VRU collision incidents. It is not clear if side guards will reduce deaths and serious injury or if the guards will simply alter the mode of death and serious injury. For example, VRUs may strike the guards and then be ejected or diverted into another lane of traffic to suffer a serious injury as part of secondary event with another vehicle or with the road/sidewalk surface.
Side guards alone will not eliminate serious injuries. City buses have lower built-in side skirting than side guards found on most trailers yet there are still incidences of pedestrians and passengers being killed as they slip and fall under the wheels of moving city buses.
It is a common belief that side guards will reduce traffic slowdowns due to a decrease in fatal or serious injury events. However, side guards will not necessarily prevent incidents, they will simply minimize the risk that VRUs will be dragged under the wheels of the vehicle. Therefore, since anyone who strikes a heavy vehicle, with or without side guards, will likely sustain some form of injury, there is no evidence that traffic congestion will be lessened by any amount.
Since bicycles and pedestrians are not permitted to travel along divided highways, there is a lower risk of an incident involving a tractor trailer combination vehicle and a VRU. Although tractor and trailer combination vehicles spend the vast majority of their time driving on divided highways, they do enter urban areas to deliver and pickup goods. Therefore, the addition of side guards, that are principally intended to save lives, may rarely come into contact with the VRUs they are intended to protect for the vast majority of the vehicle s intended duty cycle. The majority of heavy vehicle and VRU collisions do not occur along the side of the vehicle and side guards are only one component of reducing injuries from truck-VRU collisions.
At present there is no way to accurately quantify the potential reduction in VRU death or serious injury as a result of side guard installation.
Operations The height, strength and location of side guards affect their ability to minimize the severity of incidents. Aerodynamic properties are also affected by these factors. If a side guard regulation is adopted in Canada it should stipulate a maximum ground clearance, a minimum strength requirement and define the areas of installation on heavy vehicles above a certain gross vehicle weight rating (GVWR).
It is not clear if the addition of side guards will alleviate, or exacerbate the issue of snow, ice and mud collection on the underside of heavy vehicles.
If a side guard regulation is adopted in Canada it will be important to define a list of candidate vehicle types and to consider which vehicles cannot perform their intended duties with a side guard in place. The number of vehicle type exemptions should be minimized in order to maximize the effectiveness of a side guard regulation.
There may be technical challenges to fitting continuous flush mount side guards and skirts/fairings to special commodity vehicles and to trailers equipped with self steer axles.
Environmental Although similar in appearance, a clear distinction should be made between devices that are intended to protect vulnerable road users and devices that are intended to reduce fuel consumption via a reduction in aerodynamic drag.
Additionally, there may need to be a clear distinction between devices that would be useful for inner city trucks and those aimed at highway trucks. Many of the aerodynamic benefits of flush side fairings that could be achieved on highway vehicle installations could potentially be detrimental to smaller and slower inner city vehicles. Similarly, many of the safety benefits that could be achieved with the addition of rail style side guards to inner city trucks would be detrimental to the drag coefficient of highway vehicles travelling at higher speeds.
There is sufficient test data from other countries to conclude that flush side fairings/skirts on heavy vehicles improve aerodynamics via a reduction in the vehicle s coefficient of drag. The amount of the reduction in drag depends highly on the installation, the vehicle and the speed at which the vehicle is travelling.
Regardless of safety issues, the use of flush side guards or belly fairings on highway transport trailers could reduce the volume of diesel fuel consumed every year. It is estimated that industry wide use of flush mount side skirts/fairings could result in a total savings of over 400 million litres of fuel every year in Canada, and a total reduction of CO2 of 1.1 million tonnes annually.
Installing rail style side guards on highway trailers would be counter productive to other global initiatives that are currently aimed at reducing greenhouse gas emissions and fuel consumption.
Since operators may have to pay for the devices and reduce payload by approximately 114 kg (250 lbs), the impact to their operations could be minimized if the devices were sufficiently aerodynamic to provide payback periods of two years or less.
Attempts were made to predict the reduction in CO2 levels from traffic congestion if all trucks had side guards, thus reducing injury events requiring emergency vehicles and road closures.
Since side guards may only alter the mode of incident or type of injury, it is impossible to predict if traffic slowdowns, and hence engine idling and CO2 production, would be reduced. More importantly, even if the amount could be predicted, it is clear that any reduction in CO2 as a result of fewer truck/VRU injury events would be insignificantly small compared to the total amount of CO2 released in Canada every year from motor vehicles.
TABLE OF CONTENTSTable of Contents
List of Figures
List of Tables
3 Jurisdictional Review
3.1 Current Regulations
3.1.1 European Union
3.2 Types of Devices
3.2.1 Side Guard Design
3.2.3 Materials and installation
3.3 Collision Statistics
3.3.1 European Union
3.5 Conclusions of Literature Review
4 Vehicle Considerations
4.1.1 Tare Weight
4.1.2 Gross Vehicle Weight Rating
4.1.3 Gross Vehicle Weight
4.1.4 Straight Truck
4.1.7 CO2 production
4.1.8 Drag and Coefficient of Drag
4.2 Types of Add on Devices
4.2.1 Devices Designed Primarily to Reduce Aerodynamic Drag
4.2.2 Devices Designed Primarily to Improve Safety
4.3 Variations in Fairing/Side Guard Design and Construction
4.4 Implementation cost
4.4.1 Flush mount versus rail style
4.5 Environmental benefits
4.5.1 How fuel is consumed in a heavy truck
4.6 Aerodynamics of Side Mounted Devices
4.6.1 Drag Coefficient
4.7 Reduced idling due to reduction in collisions
4.8 Operator Considerations
4.8.1 Access to underbody equipment
4.8.2 Brake Cooling
4.8.3 Added tare weight to trailers and trucks
4.8.4 Interference with self steer axles
4.8.5 Collection of snow, ice, mud and debris
4.8.6 Break angle and Interference around Snow and Ice
4.9 Canadian Statistics
4.10 Cost benefit, fuel savings and CO2 emissions
4.11 Fleet replacement and exceptions
4.12 Other safety considerations
List of Acronyms/Abbreviations
LIST OF FIGURESFigure 1: R73 dimension requirements 
Figure 2: Mercedes Atego 1218 (2002 model)
Figure 3: Volvo FM9-260 (2002 model)
Figure 4: Scania tractor and semi-trailer (Japanese market)
Figure 5: Mercedes truck and semi-trailer
Figure 6: Volvo truck and semi-trailer
Figure 7: DAF CF 65.220 (2002 model)