DOCSLIB.ORG

Schaeffler Symposium 2018

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Schaeffler Symposium 2018 2018 Schaeffler Symposium 9/6/2018 Intelligent Active Roll Control INTELLIGENT ACTIVE ROLL CONTROL SHAUN TATE 1 2018 Schaeffler Symposium 9/6/2018 Intelligent Active Roll Control Production Experience & Awards Series Production – 12V BMW 7 Series 2015 BMW 5 Series 2017 RR Phantom 2018 Series Production – 48V Bentley Bentayga 2015 Audi SQ7 2016 Porsche Panamera 2017 Porsche Cayenne 2017 Bentley Continental 2018 Award‐Winning System German Innovation Award Vehicle Dynamics International Award Auto Test Sieger PACE Award 2016 2016 2016 2017 Feature to Product Mapping Stationary Ride Comfort Feature Adaptive Suspension Setup Agility & Stability Conditions Improvement Control Response Clearance Vertical Acceleration Exit Base Stability / Roll Leveling Acceleration Steering Products ‐ Easy Loading Easy Entry Easy Parking Adapt Ground Adapt Wheel Increase Articulation Load Reduce Acceleration Reduce Lateral Reduce Yaw Adapt Self Adapt Steering Dynamic Body Trailer iARC 2 2018 Schaeffler Symposium 9/6/2018 Intelligent Active Roll Control Market Trends & Features Trend 3: Large Trucks/SUVs/Vans for improved comfort and more safety Weight Trend 2: HEV/EV for improved comfort and system availability Vehicle Trend 1: SUV for improved comfort and agility Vehicle Center of Gravity Selling Features Using Schaeffler iARC System Feature Driving Dynamics Comfort Features ADAS Support L3 / Active Safety ‐ Roll Into m Lane Mode ‐ Self Steering Yaw Ride Stability Body Tilt Control Control Emergency Split Free Speed Road Vehicle Class ‐ Stability Active Control Dynamic Steer Off Dynamic Low Smooth Control Active Acc. Enh. Steering Enh. Trailer Dynamic Stabilization Ratio Maneuverability Corner Changes Control Sports Car Luxury Sedan / Coupe SUV Trucks / Off‐Road Vehicle 3 2018 Schaeffler Symposium 9/6/2018 Intelligent Active Roll Control Dynamic Body‐Roll Control Passive Comfort Sport ► Control body‐roll‐angle relative to lateral acceleration, steering angle input and vehicle speed ► Angle Enhancing body‐roll‐control performance using roll acceleration, strut accleration or suspension displacement signals Roll ► Supporting different tuning modes Lateral Acceleration m/s2 Adaptive Self‐Steering Behavior M FA>M RA M FA<M RA ► Adaptation of roll‐moment distribution through look‐up tables (e.g. relative to vehicle speed) ► Support of different tunes through mode selections ► Enhanced performance opportunities through integration with ESC by adaptation of roll‐moment‐to‐road‐conditions or stability rating relative to dynamic vehicle reference model 4 2018 Schaeffler Symposium 9/6/2018 Intelligent Active Roll Control Improved Ride Comfort & Off‐Road Capabilities ► Reduction of copying behavior through wheel‐force decoupling between left and right ► Increased suspension articulation through reduced‐static‐roll stiffness ► Enhanced dynamic comfort control using wheel acceleration and displacement sensors System Evolution Generation 1 Generation 2 Design 2 November 2015 Launch Bentley Bentayga 1st Generation 48V 1200 Nm 48V Split Gears External ECU 48V Design 3 Design 1 June 2020 July 2015 Launch Generation 2 Launch BMW 7 Series 48V + + 1st Generation 1400 Nm 12V 12V Torque Sensor 900 Nm Elastic Decoupling Unit Torque Sensor External ECU Elastic Decoupling Unit Fully Integrated Modularity Performance Product Cost 5 2018 Schaeffler Symposium 9/6/2018 Intelligent Active Roll Control Gen 2 Attributes ► Nominal voltage 48V ► Nominal torque up to 1400 Nm ► CAN, CAN FD or FlexRay Communication ► Power on demand with 90% efficiency ► Integrated torque sensor (optional) ► Road disturbance rejection up to 12 Hz ► Integrated decoupling device (optional) ► Plug and play / maintenance free ► ø 91 x 311 mm (without bars) ► Total weight 12 kg + roll bars Harness to ECU Torque Sensor Housing Brushless DC Motor Angle Sensor Planetary Gear Sets Decoupling Unit Stabilizer Bushing Stabilizer Bar Top Level Control Strategy Body Roll Agility & Handling Lateral Acceleration Roll Torque Torque Roll Steering Angle Distribution Vehicle Speed Front Rear Torque Torque iARC Front iARC Rear Front Rear Speed & Speed & Wheel Angle Angle Motion Wheel Disturbance Acceleration Observer Comfort 6 2018 Schaeffler Symposium 9/6/2018 Intelligent Active Roll Control Simulation Environment Vehicle Level Subsystem Level Vehicle / Chassis Driving Maneuver Linear, non‐linear, … Constant Radius, Double Lane Change, … Teamwork Tire Driver Type Chassis Systems Pacejka, F‐Tire, … economic, sport, … iARC, iRHA, iRWS… Chassis Controller for Simulation Low & High Level Controller Simulation Vehicle Data Test Rig Converter Verification Conversion of K&C Data for K&C analysis in Kinematic & Compliance (K&C) Model CarMaker™ 7 2018 Schaeffler Symposium 9/6/2018 Intelligent Active Roll Control Simulation Example Passive Vehicle iARC Vehicle Simulation Example Oversteer Understeer 8 2018 Schaeffler Symposium 9/6/2018 Intelligent Active Roll Control Simulation Example Passive Vehicle iARC Vehicle Simulation Example Passive Vehicle iARC Vehicle 9 2018 Schaeffler Symposium 9/6/2018 Intelligent Active Roll Control 10.
Load more

Recommended publications
  • Electronic Stability Control Systems for Heavy Vehicles; Proposed Rule
    Vol. 77 Wednesday, No. 100 May 23, 2012 Part III Department of Transportation National Highway Traffic Safety Administration 49 CFR Part 571 Federal Motor Vehicle Safety Standards; Electronic Stability Control Systems for Heavy Vehicles; Proposed Rule VerDate Mar<15>2010 18:07 May 22, 2012 Jkt 226001 PO 00000 Frm 00001 Fmt 4717 Sfmt 4717 E:\FR\FM\23MYP2.SGM 23MYP2 mstockstill on DSK4VPTVN1PROD with PROPOSALS2 30766 Federal Register / Vol. 77, No. 100 / Wednesday, May 23, 2012 / Proposed Rules DEPARTMENT OF TRANSPORTATION New Jersey Avenue SE., West Building A. UMTRI Study Ground Floor, Room W12–140, B. Simulator Study National Highway Traffic Safety Washington, DC 20590–0001 C. NHTSA Track Testing Administration • Hand Delivery or Courier: West 1. Effects of Stability Control Systems— Phase I Building Ground Floor, Room W12–140, 49 CFR Part 571 2. Developing a Dynamic Test Maneuver 1200 New Jersey Avenue SE., between and Performance Measure To Evaluate [Docket No. NHTSA–2012–0065] 9 a.m. and 5 p.m. ET, Monday through Roll Stability—Phase II Friday, except Federal holidays. (a) Test Maneuver Development RIN 2127–AK97 • Fax: (202) 493–2251 (b) Performance Measure Development Instructions: For detailed instructions 3. Developing a Dynamic Test Maneuver Federal Motor Vehicle Safety on submitting comments and additional and Performance Measure To Evaluate Standards; Electronic Stability Control information on the rulemaking process, Yaw Stability—Phase III Systems for Heavy Vehicles see the Public Participation heading of (a) Test Maneuver Development (b) Performance Measure Development the SUPPLEMENTARY INFORMATION AGENCY: National Highway Traffic section 4. Large Bus Testing Safety Administration (NHTSA), of this document.
    [Show full text]
  • Design, Analysis and Optimization of Anti-Roll Bar
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Directory of Open Access Journals Pravin Bharane et al. Int. Journal of Engineering Research and Applications www.ijera.com ISSN : 2248-9622, Vol. 4, Issue 9( Version 4), September 2014, pp.137-140 RESEARCH ARTICLE OPEN ACCESS Design, Analysis and Optimization of Anti-Roll Bar Pravin Bharane*, Kshitijit Tanpure**, Amit Patil***, Ganesh Kerkal**** *,**,***,****( Assistant Professor, Department of Mechanical Engg., Dnyanganga College of Engg. & Research, Pune) ABSTRACT Vehicle anti-roll bar is part of an automobile suspension system which limits body roll angle. This U-shaped metal bar connects opposite wheels together through short lever arms and is clamped to the vehicle chassis with rubber bushes. Its function is to reduce body roll while cornering, also while travelling on uneven road which enhances safety and comfort during driving. Design changes of anti-roll bars are quite common at various steps of vehicle production and a design analysis must be performed for each change. So Finite Element Analysis (FEA) can be effectively used in design analysis of anti-roll bars. The finite element analysis is performed by ANSYS. This paper includes pre-processing, analysis, post processing, and analyzing the FEA results by using APDL (Ansys Parametric Design Language). The effects of anti-roll bar design parameters on final anti-roll bar properties are also evaluated by performing sample analyses with the FEA program developed in this project. Keywords: FEA, Anti Roll Bar, APDL, Design Parameters. I. INTRODUCTION Anti-roll bar, also referred to as stabilizer or ensure directional control and stability with adequate sway bar, is a rod or tube, usually made of steel, that traction and braking capabilities [1].
    [Show full text]
  • COMPARATIVE STUDY of VEHICLE ROLL STABILITY Final Report
    COMPARATIVE STUDY OF VEHICLE ROLL STABILITY Final Report Contract No, FH-11-9577 Phase V T.D. Gillespie R.D. Ervin May 1983 Tuluicol RwDocuumtati'm P- I. RepmNo, Z Accessim (lo. 3. Recipient's Cedmq (lo. I 4. Title d Subtitie 5. RvtDate COMPARATIVE STUDY OF VEHICLE ROLL STABILITY May 1983 6. P-mag Orqmir.ri.r, Cdr 8. Per4emiag OmdmRm No. 7. kihu's) T.D. Gillespie and R.D. Ervin UMTRI-83-25 9. Pduming Orl.niadir Nuad Mess 10. Work Uait No. The University of Michigan 1 Transportation Research Institute 2901 Baxter Road - - 7 (Phase V) Ann Arbor, Michigan 48109 13. Trr ef RW 4p.,iocl had 12 Wag4mnq Nu ad Ahss U.S. Department of Transportation Final 2118183-5/18/83 Federal Highway Administration ' Washington, D.C. 20590 1'. Srmwing Amyae 1.6. Abshct The roll stability levels of a broad range of motor vehicles were determined using computer simulation. The input data needed for these calculations were obtained from both direct measurements and from pre- viously published information. The vehicles of interest covered the range from subcompact passenger cars through heavy-duty truck combinations. The results are discussed in the light of two issues, namely: 1) the roll stability levels of step-van-type trucks used by the bakery industry relative to the stability levels of other vehicles and I 2) the influence of width parameters on the roll stability of heavy truck combinations. 17. Key Wrb roll stability, passenger I 18- D's"hM ] cars, light trucks, bakery trucks, I I heavy-duty trucks I UNLIMITED I 19.
    [Show full text]
  • The Roll Stability Control ™ System
    ROLL RATE BASED STABILITY CONTROL - THE ROLL STABILITY CONTROL ™ SYSTEM Jianbo Lu Dave Messih Albert Salib Ford Motor Company United States Paper Number 07-136 ABSTRACT precise detection of potential rollover conditions and driving conditions such as road bank and vehicle This paper presents the Roll Stability Control ™ loading, the aforementioned approaches need to system developed at Ford Motor Company. It is an conduct necessary trade-offs between control active safety system for passenger vehicles. It uses a sensitivity and robustness. roll rate sensor together with the information from the conventional electronic stability control hardware to In this paper, a system referred to as Roll Stability detect a vehicle's roll condition associated with a Control™ (RSC), is presented. Such a system is potential rollover and executes proper brake control designed specifically to mitigate vehicular rollovers. and engine torque reduction in response to the The idea of RSC, first documented in [10], was detected roll condition so as to mitigate a vehicular developed at Ford Motor Company and has been rollover. implemented on various vehicles within Ford Motor Company since its debut on the 2003 Volvo XC90. INTRODUCTION The RSC system adds a roll rate sensor and necessary control algorithms to an existing ESC system. The The traditional electronic stability control (ESC) roll rate sensor, together with the information from systems aim to control the yaw and sideslip angle of a the ESC system, help to effectively identify the moving vehicle through individual wheel braking and critical roll conditions which could lead to a potential engine torque reduction such that the desired path of vehicular rollover.
    [Show full text]
  • Design, Analysis and Optimization of Anti-Roll Bar
    Pravin Bharane et al. Int. Journal of Engineering Research and Applications www.ijera.com ISSN : 2248-9622, Vol. 4, Issue 9( Version 4), September 2014, pp.137-140 RESEARCH ARTICLE OPEN ACCESS Design, Analysis and Optimization of Anti-Roll Bar Pravin Bharane*, Kshitijit Tanpure**, Amit Patil***, Ganesh Kerkal**** *,**,***,****( Assistant Professor, Department of Mechanical Engg., Dnyanganga College of Engg. & Research, Pune) ABSTRACT Vehicle anti-roll bar is part of an automobile suspension system which limits body roll angle. This U-shaped metal bar connects opposite wheels together through short lever arms and is clamped to the vehicle chassis with rubber bushes. Its function is to reduce body roll while cornering, also while travelling on uneven road which enhances safety and comfort during driving. Design changes of anti-roll bars are quite common at various steps of vehicle production and a design analysis must be performed for each change. So Finite Element Analysis (FEA) can be effectively used in design analysis of anti-roll bars. The finite element analysis is performed by ANSYS. This paper includes pre-processing, analysis, post processing, and analyzing the FEA results by using APDL (Ansys Parametric Design Language). The effects of anti-roll bar design parameters on final anti-roll bar properties are also evaluated by performing sample analyses with the FEA program developed in this project. Keywords: FEA, Anti Roll Bar, APDL, Design Parameters. I. INTRODUCTION Anti-roll bar, also referred to as stabilizer or ensure directional control and stability with adequate sway bar, is a rod or tube, usually made of steel, that traction and braking capabilities [1].
    [Show full text]
  • 45Th ANNUAL LAW ENFORCEMENT VEHICLE TEST and EVALUATION PROGRAM
    45th ANNUAL LAW ENFORCEMENT VEHICLE TEST AND EVALUATION PROGRAM VEHICLE MODEL YEAR 2020 Alex Villanueva, SHERIFF 1 TABLE OF CONTENTS CONTENTS PAGES PREFACE 3 ACKNOWLEDGEMENTS 4 - 5 TEST VEHICLE DESCRIPTION 6 - 7 VEHICLE SPECIFICATION 8 - 18 VEHICLE DYNAMICS EVALUATION (32 LAP HIGH SPEED COURSE) 19 - 41 CITY COURSE EVALUATION 42 - 53 BRAKE EVALUATION 54 - 55 ACCELERATION EVALUATION 56 - 58 HEAT EVALUATION 59 - 62 COMMUNICATION EVALUATION 63 - 71 ERGONOMICS EVALUATION 72 - 100 FUEL EFFICIENCY EVALUATION 101 2 PREFACE The Los Angeles County Sheriff’s Department first implemented its police vehicle testing program in 1974. Since that time, our department has become nationally recognized as a major source of information relative to police vehicles and their use. It is our goal to provide law enforcement agencies with the information they require to successfully evaluate those vehicles currently being offered for police service. The Los Angeles County Sheriff’s Department is proud to publish this information, via the internet, to all law enforcement agen- cies. Since the inception of our vehicle testing program in 1974, we have continually refined our efforts in this area in order to provide the law enforcement community with the most current information available. During the 1997 model year testing, the Sheriff’s department expanded its existing criteria to include an urban or city street course. This course consists of multiple city block distances punctuated by the various types of turns normally found in most inner city environments. The city street course is designed to simulate the conditions encountered by most officers working in typical urban communities. The test is only conducted on vehicles offered with a factory “police package”.
    [Show full text]
  • Glossary of Suspension Terms
    Chapter 2: Glossary of Terms Chapter Two: Glossary of Suspension Terms RIT Baja SAE Introduction This glossary of terms is intended to provide a brief and accu- rate description of both conceptual and component terms used in design, manufacturing, and tuning of R.I.T. Baja SAE Suspension Systems. For quick referencing this chapter is divided into two sec- tions. The first section of the chapter focuses on theoretical concept definitions used in describing the analysis and design of off-road suspension system dynamics. The second segment contains compo- nent descriptions and visual references . Figure 1: (2005-2006)SLA A- Arm Rear Suspension Chapter 2: Glossary of Terms Glossary of Suspension Theory Terms Camber A measurement of wheel angle relative to vertical as viewed from the front or rear of the car. In a double A-arm system, camber is dictated mainly by control arm geometry. Positive Camber occurs when the top Negative Camber occurs when the of the tire tips away from the chassis. top of the tire tips towards the chassis. Commonly, a system in droop will Commonly, a system in compression have positive camber. will have negative camber. Figure 2: Positive Camber Figure 3: Negative Camber Toe A measurement of wheel angle relative to the centerline of the car as viewed from top. Toe can be measured by comparing the vehicle centerline to front of tire distance with the vehicle centerline to rear of tire distance. In a double A-arm “steerable,” or front suspension system, this is controlled by tie-rod length in conjunction with the steering system.
    [Show full text]
  • Truck Handling Stability Simulation and Comparison of Taper-Leaf and Multi-Leaf Spring Suspensions with the Same Vertical Stiffness
    applied sciences Article Truck Handling Stability Simulation and Comparison of Taper-Leaf and Multi-Leaf Spring Suspensions with the Same Vertical Stiffness Leilei Zhao 1, Yunshan Zhang 2, Yuewei Yu 1,*, Changcheng Zhou 1,*, Xiaohan Li 1 and Hongyan Li 3 1 School of Transportation and Vehicle Engineering, Shandong University of Technology, Zibo 255000, China; [email protected] (L.Z.); [email protected] (X.L.) 2 Shandong Automobile Spring Factory Zibo Co.,Ltd., Zibo 255000, China; [email protected] 3 State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130022, China; [email protected] * Correspondence: [email protected] (Y.Y.); [email protected] (C.Z.); Tel.: +86-135-7338-7800 (C.Z.) Received: 16 December 2019; Accepted: 31 January 2020; Published: 14 February 2020 Abstract: The lightweight design of trucks is of great importance to enhance the load capacity and reduce the production cost. As a result, the taper-leaf spring will gradually replace the multi-leaf spring to become the main elastic element of the suspension for trucks. To reveal the changes of the handling stability after the replacement, the simulations and comparison of the taper-leaf and the multi-leaf spring suspensions with the same vertical stiffness for trucks were conducted. Firstly, to ensure the same comfort of the truck before and after the replacement, an analytical method of replacing the multi-leaf spring with the taper-leaf spring was proposed. Secondly, the effectiveness of the method was verified by the stiffness tests based on a case study. Thirdly, the dynamic models of the taper-leaf spring and the multi-leaf spring with the same vertical stiffness are established and validated, respectively.
    [Show full text]
  • Vehicle Handling Dynamics: Theory and Application
    Contents Preface .......................................................................................................................... xi Preface to Second Edition .......................................................................................... xiii Symbols........................................................................................................................ xv CHAPTER 1 Vehicle Dynamics and Control .........................................1 1.1 Definition of the Vehicle.....................................................................1 1.2 Virtual Four-Wheel Vehicle Model ....................................................1 1.3 Control of Motion...............................................................................2 CHAPTER 2 Tire Mechanics .................................................................5 2.1 Preface.................................................................................................5 2.2 Tires Producing Lateral Force ............................................................5 2.2.1 Tire and Side-Slip Angle.......................................................... 5 2.2.2 Deformation of Tire with Side Slip and Lateral Force ........... 7 2.2.3 Tire Camber and Lateral Force................................................ 8 2.3 Tire Cornering Characteristics............................................................9 2.3.1 Fiala’s Theory........................................................................... 9 2.3.2 Lateral Force..........................................................................
    [Show full text]
  • Global Tech Talk Release: Comfortable and Agile – Audi's Eaws
    Global tech talk release: Comfortable and agile – Audi’s eAWS technology turns SUVs into quick-change artists We're publishing a “Tech talk” series to share more about the people and technology behind our cars – who and what makes an Audi an Audi. We hope you enjoy the series! To see all "Tech talk" articles, click here. • System available on four top-of-the-line models of Audi SUV family • Controllable stabilizers help reduce body roll • High demand proves customers’ enthusiasm • Nürburgring record drive underscores dynamic qualities INGOLSTADT, August 28, 2020 – How do you provide a large SUV with sporty road-holding properties and minimal body roll without impairing ride comfort? Audi has resolved this by implementing electromechanical roll stabilization (eAWS). Assisted by the 48-volt onboard electrical system and powerful actuators, the stabilizers on the front and rear axle can be actively controlled according to the driving situation. As a result, the models retain their high level of ride comfort in straight-line driving. By contrast, in cornering and load alteration situations, they impress with enhanced lateral dynamics combined with minimal body roll. The technical advantages of Audi’s electromechanical solution: it is energy-efficient, operates in near-real-time and is virtually maintenance-free due to the absence of hydraulic elements. What challenges do large SUV models pose to chassis engineers? Customers of larger SUVs are thrilled by their many practical elements – from ample space in the cabin to cutting-edge chassis technologies to powerful engines and advanced control and assistance systems. Plus, an SUV can deliver superb performance off paved roads.
    [Show full text]
  • Active Roll Control (ARC): System Design and Hardware-In- The-Loop Test Bench
    Active Roll Control (ARC): System Design and Hardware-In- the-Loop Test Bench A. SORNIOTTI, A. MORGANDO and M. VELARDOCCHIA* Politecnico di Torino, Department of Mechanics Correspondence *Corresponding author. Email: [email protected] Abstract. The first part of the paper describes the targets related to the design of an Active Roll Control (ARC) system, based on the hydraulic actuation of the anti-roll bars of an automobile. Then the basic static and dynamic design principles of the system are commented in detail. The second part of the paper presents the Hardware-In-the-Loop (HIL) test bench implemented to evaluate the designed system. In the end, the main experimental results are summarized and discussed, also from the point of view of the integration of ARC with Electronic Stability Program (ESP). Keywords: Active Roll Control; Hardware-In-the-Loop; Handling; Comfort 1 Targets and Fundamentals The first target of the Active Roll Control (ARC) system is the reduction of the roll angle for small values of vehicle body lateral acceleration during semi-stationary manoeuvres. This target improves the comfort feeling transmitted by the vehicle to the passengers. In addition, it reduces the variation of the characteristic angles, especially camber angle, between the tires and the road plane during vehicle turning. It can provoke, according to the characteristics of the suspensions, a substantial improvement of vehicle dynamics in semi-stationary manoeuvres. The second target of the ARC system is the reduction of body sideslip angle and body yaw rate oscillations during dynamic manoeuvres, like step steer or double lane change. This target can be reached through a dynamic variation of the roll stiffness distribution between the two axles of the car.
    [Show full text]
  • Superelevation and Body Roll Effects on Offtracking of Large Trucks
    TRANSPORTATION RESEARCH RECORD 1303 Superelevation and Body Roll Effects on Offtracking of Large Trucks WILLIAM D. GLAUZ AND DOUGLAS W. HARWOOD Past research has shown that vehicles, especially large trucks, Current AASHTO criteria for intersection and channeli­ offtrack on curves and turns; at low speeds the rear axles track zation geometrics and for pavement widening on horizontal inside the front axle (negative offtracking), and at sufficiently curves consider only low-speed offtracking. The design of high speeds the reverse is true. New research shows that typical intersection and channelization geometrics is properly a func­ amounts of superelevation tend to increase low-speed, negative offtracking of trucks by 10 to 20 percent. Superelevation also tion only of low-speed offtracking, because truck operations tends to reduce the amount of high-speed outward offtracking. at intersections usually occur at low speeds. Pavement cross­ The magnitude of the superelevation effect is independent of slope effects on offtracking can generally be ignored in the speed. The superelevation effect is greater with more heavily design of intersection and channelization geometrics because loaded trucks, trucks with newer tires, and trucks with larger roll normal pavement cross-slopes are small. Turning roadways steer coefficients. This research also shows that body roll affects at channelized intersections do not require much superele­ both high-speed offtracking and the superelevation contribution to total offtracking. Trucks with softer suspensions are more af­ vation because operations there usually occur at low speeds. fected. The net effect is to increase outward offtracking at normal However, pavement widening at horizontal curves should and high speeds and to slightly increase negative offtracking at consider both low-speed and high-speed offtracking, as well very low speeds.
    [Show full text]