FORMULA ONE- The worldâ„¢s largest spectator sport. What makes it so good? Cars, Drivers and their experience and most of all, the race track which helps these high techniques cars zoom at an excess of 320 kmph safely with the minimum of injuries or zero injuries in case of a crash or an accident. These tracks with their high tech safety barriers and other safety features which go into the making of the track like the use of CSAS( Circuit And Safety Analysis System) and barrier crash test makes it so safe and thrilling to watch.
Success is all about being in the right place at the right time Â¦.. and the axiom is a guiding principle for designers of motorsport circuits. To avoid problems you need know where and when things are likely to go wrong before cars turn a wheel â€œand anticipating accidents is a science.
Take barriers, for example, there is little point erecting them in the wrong place â€œbut predicting the right place is a black art. The FIA has developed bespoke software, the Circuit and Safety Analysis System (CSAS), to predict problem areas on F1 circuits.
Where and when cars leave circuits is due to the complex interaction between their design, the driverâ„¢s reaction and the specific configuration of the track, and the CSAS allows the input of many variables-lap speeds, engine power curves, car weight changes, aerodynamic characteristics etc â€œto predict how cars may leave the circuit at particular places. The variables are complex. The impact point of a car continuing in a straight line at a corner is easy to predict, but if the driver has any remaining control and alters the carâ„¢s trajectory, or if a mechanical fault introduces fresh variables, its final destination is tricky to model.
Modern tyre barriers are built of road tyres with plastic tubes sandwiched between them. The side facing the track is covered with conveyor belting to prevent wheels becoming snagged and distorting the barrier. The whole provides a deformable Ëœcushionâ„¢ a principle that has found its way to civilian roads. Barriers made of air filled cells, currently under investigation may be the final answer. Another important safety factor is the road surface. Racing circuits are at the cutting edge of surface technology, experimenting with new materials for optimum performance.
The tracks used in motor sport all are designed to meet certain standards. If a new circuit will ever be used for an international event, its design and layout must be approved by the FIA, before any construction commences. For a permanent circuit, a member of the FIA must inspect it no more than 90 days before a World Championship event, giving adequate time to implement changes.
All design criteria, for curves and straight sections, do not mean the actual track itself, but the actual trajectory followed by the cars whilst racing. Track width on a permanent circuit should be at least 12 metres and should not exceed 15 metres. This avoids bad congestion in corners by limiting the width of the approach to the corner, and having a wide enough track through the corners. There should be 3m minimum clear space along both sides of the track, usually consisting of grass. The maximum length of any new permanent circuit should not exceed 7km to allow drivers to be able to familiarize themselves with all corners on the track. The minimum length of a Formula One circuit will not be less then 3.5km, with the race being no longer than 2h45min. Cross fall across the track for drainage purposes should not exceed 3%, or be less than 1.5%, either from edge to edge or from the centerline to each edge.
The geometry of the track should be designed using the formulae set out by the FIA in Appendix O to the International Sporting Code section 7. These formulae give design criteria for longitudinal profile, visibility, curves, track edges, runoff areas and starting grid specifications. Curves must not get tighter as the turn progresses unless the speed through the corner is less than 125kph, and should preferably have an increasing radius. The maximum number of cars allowed to start in an international race takes all the above geometrical constraints into account, along with the types of cars competing. The number of cars allowed to practice is 20% greater than the number actually allowed to start.
The criterion for barrier placement is stated in section 8 of the above code. If "the probable angle of impact is less than 30o then a continuous, smooth, vertical barrier is preferable, and where the probable angle is high, a system of deceleration (eg. gravel bed) and stopping (eg. tyre barrier) devices should be used." (FIA Appendix O, in appendix 2)
The emergency response during a motor sport event is one of the most important aspects of safety. When all other safety aspects such as vehicle, and track safety have no more to offer a driver, any further help must come from emergency services. It is vital that drivers can be extracted from damaged vehicles and given the best possible medical care as soon as possible. The 'Recommendations for the supervision of the road and emergency services, Appendix H to the International Sporting code', states the FIA procedures in detail, which will be only covered briefly here.
Any international event should be supervised from a race control centre. This room should be in contact with all marshaling and observation point at all times, and should also have access to emergency services from outside the race such as a helicopter for an evacuation. The Clerk of the Course supervises all emergency procedures from here, after personally ensuring the road is clear of obstacles, is closed to the public and that all observers, marshals and emergency personnel and equipment are in the correct positions.
There must be enough observers placed around the track such that all sections of the road can be constantly monitored. Each observation post must be able to communicate by sight with the posts on either side and must be no more than 500m from each other. These observers must be protected from the vehicles and debris but still able to access the track quickly in the event of an emergency. Every post must have communications equipment, a set of flags, oil absorbing material, brooms, spades and fire extinguishers. At least one of the observers must be trained in first aid. The observers must warn drivers of any adverse track condition, report any incident to race control and maintain a section of track and return it to race condition following an incident.
The observers communicate with drivers by using flags. Yellow flags indicate danger, red flags indicate that the race has been stopped prematurely, a yellow flag with red vertical stripes indicates deterioration in adhesion such as oil or a pool of water, a green flag indicates an all clear after a yellow. A white flag indicates a slow moving vehicle ahead, a blue flag indicates to a slower car that they are about to be lapped. A black flag with a white number indicates that the car with that number must stop in the pits on the next lap, an orange circle on the black flag indicates a serious mechanical problem that may endanger other drivers. A black and white flag divided diagonally shown with a number is a warning for unsportsmanlike behaviour, it is shown only once. All the warning flags can be shown stationary, waved or in the case of yellow, double waved depending on the danger ahead or the urgency of the message. In poor visibility, coloured lights may replace the flags. The use of yellow, blue and white flags are at the discretion of the flag marshals, while the clerk of the course must authorize all others. The marshals must ensure that they do no exaggerate or under emphasize the danger ahead, to ensure the drivers will always respect the flag signals.
If it is necessary to temporarily stop racing, but not stop the race, a safety car is used. This car has yellow flashing lights in its roof and takes control of the race when directed by the Clerk of the Course. No cars may overtake another, or the safety car unless directed by the safety car to do so. If allowed to pass, the car must continue at a reduced speed until it catches the rear of the line of cars behind the safety car. The safety car will only be brought out in the event of a major incident requiring course workers on the track and emergency vehicles on the track, such as tow trucks and ambulances. While the safety car is out, the track is on a full course yellow, with a single yellow flag being displayed at every observation point.
In the event of an accident, two marshals must be on the spot almost immediately, each with a fire extinguisher, fire being the number one priority. Medical crews cannot work in fire and the fire marshals are not permitted to move an injured driver. They must clear the track of debris and oil. A fire-fighting unit should be next on the scene and be able to completely extinguish any remaining fire. The medical crews should be next, arriving as quickly as possible to stabilize an injured driver. A manned portable fire extinguisher should be placed every 150m along the track, with unmanned extinguishers every 50m in between. Marshalâ„¢s post should have reserve fire extinguishers. As well as portable fire extinguishers, it is recommended that every 300m, there is an installed fire extinguisher of 60kg capacity with a 200m hose. The extinguishant must be able to be released quickly, leave no slippery residue, have minimum effect on visibility, have low toxicity and be highly effective. BCF (Diflourochlorobromomethane) extinguishers are most commonly used.
The race tracks must have a medical management system with all necessary resources for first aid care. It should provide medical transport in and around the circuit with provision for evacuation to a hospital. Any hospital that may be receiving injured drivers must have a pre-arranged signed contract to supply and have waiting, at least a traumatology specialist, an emergency abdominal specialist and an emergency vascular specialist. For international Formula races there must be a permanent medical centre, usually near the race control building. During a race meeting, at least two anesthetists/resuscitation doctors and two surgeons skilled in spinal injuries and trauma must staff the medical centre. One of the doctors should also be skilled in the treatment of burns. Depending on the level of the medical centre, the response crews and the track design, it may be necessary to have a helicopter waiting and running for the entire race meeting. The track should be equipped with Fast Medical Intervention Vehicles (FMIV) carrying all necessary medical equipment. It must be powerful enough to carry out the first lap behind the field with out being caught by the leaders. The driver must be an experienced race driver, the passenger must be a Doctor trained in resuscitation. The extrication team must have all the necessary equipment to extract an injured driver from a damaged vehicle as quickly and safely as possible.
CIRCUITS OF THE WORLD
CIRCUIT AND SAFETY ANALYSIS SYSTEM (CSAS)
Predicting the trajectory and velocity of a racing car when it is driven at the limit within the confines of a racing track, is now the subject of a great deal of analytical work by almost all teams involved in racing at all levels. However, predicting the trajectory and velocity of a car once the driver has lost control of it has not been something the teams have devoted a great deal of time to. This can now also be analyzed though in the same sort of detail, to assess the safety features of the circuits on which it is raced. The two tasks are very different, and the FIA had to start almost from scratch when it set out to develop software for its Circuit and Safety Analysis System (CSAS).
The last two decades have seen a steady build up of the R&D effort going into vehicle dynamics modeling, particularly by those teams that design and develop cars as well as race them. The pace of development has been set by the availability of powerful PC's, the generation of vehicle and component data, and the supply of suitably qualified graduates to carry out the work.
Their task is to be able to model and predict the effects of every nuance of aerodynamic, tire, engine, damper etc., characteristic on the speed of their car at every point on a given circuit. The detail in the model will only be limited by available dynamic characteristics and track data, and will require a driver model to complete the picture. However, they are only interested in the performance of the car while the tires are in contact with the tarmac, and the driver is operating them at or below their peaks.
Fig.1. Examples of straight trajectories.
Fig.2. Examples of all possible trajectories.
Fig.3. Stopping distances in the run-off area, highlighting points where the run-off is inadequate to stop the car.
Fig.4. Residual velocity, perpendicular to the boundary of the run-off area.
Fig.5. Residual velocity, perpendicular to a 2-row tyre barrier, after impact with it.
The FIA, on the other hand, starts to be interested in what happens when the driver exceeds the limit and is unable to recover control of the car, or when something breaks and the computer model almost literally falls apart. Knowledge of the speed of the car all around a circuit is needed, but the precise speed differences due to small improvements in some car characteristic have little affect on the outcome of this analysis. Major changes in lap speeds, due for instance to the effects of tire competition or regulation changes are relevant, and so CSAS has a lap simulation as its core, to generate speed profiles for any circuit and any class of racing car. It is a fairly elementary simulation compared to those in use for performance prediction by teams, but is regularly updated with engine power curves, Pacejka tire coefficients, typical aerodynamic characteristics, and weight changes. Checks that the speed predictions are sufficiently accurate can be made by comparison against speed data supplied from a typical car.
Circuit details are supplied in AutoCAD. This software was chosen because of the ease of adding modules to perform the CSAS-specific operations, and also because the majority of circuit maps are supplied by the circuit designers in this format. CSAS is run via the AutoCAD interface, with additional tool bars corresponding to the CSAS-specific applications. Circuit information is in multiple layers, e.g., left side of track, right side of track, curbs, run-off areas, access roads, removable barriers, permanent barriers, being the most relevant. The track edges can be modified using the AutoCAD drawing tools - the addition of a chicane is simply a few click-and-drag operations of the mouse! The operator draws the racing line on the track (an automatic routine for doing this is being investigated, but the manual approach is currently preferred as knowledge of whether drivers clip curbs or avoids a bumpy section of track, provides a better match of speed profiles) and selects the calculation of the speed profile. Generally, the speed is calculated every 3 meters around the track, which provides adequate resolution, at each of these points a prediction of the trajectory of an out of control car is made.
A driver's natural reaction, once he realizes that he has no further hope of regaining control, is to stamp on the brakes and bring the car to a halt before hitting anything. A car with its wheels locked up, whether it is travelling forwards, backwards or sideways, or spinning, will tend to travel in a straight line unless it hits something (Fig.1). Thus, the most likely trajectory is a straight line, tangential to the racing line at the point control is lost; all circuit safety criteria are currently based on this trajectory assumption. However, if the driver does not give up and tries to catch the car while it spins, or to influence which way it goes, or if a component failure substantially takes over the steering of the car, there is a possibility that some lateral forces will be generated by the tires (they could be up to 4g on a Formula 1 car), in which case the trajectory will be curved, just as if the car was cornering. However, the curved trajectory will probably not follow the curve of the track (Fig.2).
These "unpredictable" trajectories are the hardest to plan for, without lining the whole circuit with run-off areas and barriers. In many cases e.g., if a wing fails on the straight that causes the car to turn into the wall lining the straight, the car cannot accelerate to a high speed perpendicular to the wall, and the speed is scrubbed off by sliding along it. Spectacular though this may be, this sort of accident tends not to lead to high impact decelerations or injuries to the driver. However, in a high-speed corner, the car can end up going off in a direction that until then has not been predicted and so is not protected. Zonta, in the accident in Brazil in which he received leg injuries, tried to collect his BAR after he lost it on a bump in the 4th-gear Ferradura and struck a section of Armco instead of the tire barrier erected to protect cars in that corner. He was not meant to hit the barrier at that location. CSAS is being developed to be able to predict the impact velocity for any possible trajectory.
Another example of unpredictable trajectories occurred on the Circuit de Catalunya, during the Spanish GP in 1997. Morbidelli accelerated his Minardi out of the pit lane and lost control of it as he joined the track, possibly due to the speed limiter cutting out suddenly. He accelerated across the full width of the Start/Finish straight into the concrete wall, fortunately without collecting anyone else travelling at top speed on the straight. He hit the wall head-on at just under 50kph, performing a near perfect FIA frontal crash test!
Having established the speed at any point on the track, CSAS calculates the trajectory of a car leaving the racing line and the distance traveled along it. The path of the car is initially on the track, subsequently on a run-off area, if one exists, and may finally impact a barrier. The boundaries of all these features are set up from the circuit plans, in AutoCAD. The circuit criteria guidelines have been established such that under normal or average conditions, the car will stop before it reaches a barrier. Under abnormal conditions this may not happen, and in certain locations on circuits it may not be possible to provide adequate run-off - Monaco, or indeed any street circuit, is the classic case of this - hence the need for barriers. The deceleration characteristics for an out of control car on the track and on any type of run-off area are set in CSAS and may be quite complex relationships based on speed. One of the purposes of fitting Accident Data Recorders (ADR) to Formula 1 and Formula 3000 cars is to gain real deceleration data. With data gained over the last four years, it has been possible to analyze it statistically and derive "normal" characteristics for wet and dry tracks and for gravel beds. These characteristics are used in CSAS to determine how large the gravel beds need to be and to establish the likely impact velocity with a barrier, where it is not possible to install an adequate run-off area. CSAS plots the trajectories, and the ends of these lines form the desired limits of the run-off areas, which can be compared with existing or planned boundaries. Discrepancies show up immediately on the screen (Fig.3).
Faced with sections of run-off areas that do not stop a car before it reaches the edge of the area, the circuit designer has a number of options. If he cannot extend the run-off, one option is to modify the corner to reduce the speed, however, the critical trajectories are often those of a car that loses control under braking, when it maybe necessary to reduce the top speed on the preceding straight - the result is often the unpopular chicane. Alternatively, barriers can be placed along the critical edges of the run-off area. CSAS calculates the impact velocity, perpendicular to the boundary, in the absence of a barrier (Fig.4). Barrier characteristics have been measured for a number of barrier configurations, particularly for a variety of tire barrier arrangements. Conservative characteristics based on the test results are used in CSAS to calculate the resultant velocity of the car after it has penetrated the barrier i.e. the velocity the car will impact the solid boundary behind the barrier (Fig.5). This velocity or, to be more precise, the residual energy in the car, is what the crushable structures on the car will have to absorb without injuring the driver.
One issue that CSAS addresses is whether the critical case for stopping a car is under wet or dry conditions. In the dry, initial speeds are higher but on-track deceleration is greater than in wet conditions. Wet or dry, the gravel beds perform pretty well the same. Based on the data available to date, the indication is that the critical case is under dry conditions.
The worst scenario for any safety engineer is when a car "flies". Whether it is a big sports or GT car, with excessively pitch sensitive aerodynamics, or an open-wheeled car touching wheels with one ahead of it, if a car leaves the ground it is almost impossible to provide a means of decelerating it. It will decelerate due to aerodynamic drag, and CSAS can assess this case provided the drag characteristics are known as the car tumbles through the air. Gravel beds that cause light cars with wide tires to skip through them (a sort of "ducks and drakes" effect) do not seem to exhibit very different overall deceleration rates from beds where the car stays in contact. Although the deceleration is reduced while the car is in the air, it is much higher when it lands and digs in, and the average deceleration is very much the same.
CSAS has facilitated the synthesis of the results from a number of safety R&D programs that are gradually putting motorsport safety on a sound scientific basis. It uses the actual speed of the cars at any point on a circuit, representative deceleration rates on- and off-track, and tested barrier performance to size and specify circuit safety features. Changes to the specification of the cars, particularly those that increase top speed or cornering speed, and changes to the layout of tracks can be monitored for their effect on the size of run-off areas and barrier specifications. Any class of car can be evaluated by inputting its performance parameters to the lap simulation and obtaining a speed profile, such that the grading of circuits and their suitability for particular classes of racing can be studied.
The development of CSAS is ongoing. Routines to facilitate and speed up the application are being studied and the database for the performance of the various circuit safety features is continuously updated and added to, to ensure that any variations in the deceleration parameters, e.g. due to an extra tire groove, are taken into account. It is an invaluable tool at the design stage of new circuits, avoiding much of the need to revise either track or run-off areas after the circuit has been built, and is providing detailed insights into how existing circuits can be upgraded in the continual quest for greater safety.
The ideal crash barrier is no barrier at all. However, the only applications of this in motor sport are at Bonneville and the Black Rock desert, used for Land Speed Record attempts. At these sites there are several miles in every direction between the track and the mountains and, even through a telephoto lens the vehicles seem a very long way away from the spectators and viewers. Barriers are necessary on race circuits to enable spectators and TV cameras to get close enough to the action, without being exposed to the danger of being hit by an out of control car.
The problem is little different from stopping a train ploughing into the platform and injuring potential passengers when the driver has left the braking too late. The buffer is equipped with energy absorbing devices (large spring/dampers), which engage with similar devices on the front of the train. The energy is absorbed and dissipated and the train brought to a halt without damage or too great a shock to the passengers. Provided the capacity of the joint energy absorbing system is adequate. Road and racing car barrier systems work in a similar fashion: both cars and barriers have energy absorbing devices, which engage and dissipate the kinetic energy of the car. However, while trains are perfectly aligned, buffer to buffer, by the rails, cars can hit a barrier pointing in any direction, at any height, and either spinning, rolling, tumbling end over end, or some complex combination of all of them. The energy must be dissipated without either subjecting the car to loads that cause the driver protection structure (safety cell) to fail and injure the driver by intrusion, or subject the driver to decelerations that cause internal injuries or result in him striking the safety cell, especially with his head. The magnitude of the energy to be absorbed and dissipated increases as the square of the speed: at 100kph it is the equivalent of dropping the car from a height of 78 meters; at 200kph - 314 meters; at 300kph - 707 meters. Loss of control of a racing car at the end of a straight is the equivalent of falling from an aircraft flying at a height of nearly one kilometer.
The mechanisms used by the car and barrier energy absorbing systems vary. The Formula 1 Technical Regulations stipulate a series of tests on frontal, rear and side impact structures that results in short, stiff, sacrificial structures that dissipate energy by material failure. The highest performance of these tests - the frontal impact test - generates peak loads of 460KN (60g), 300KN (40g) average, and dissipates the energy equivalent to a fully loaded car travelling at 50kph in little over 0.5 meters. Barriers tend to be more like train buffer systems, behaving like spring/dampers. They absorb energy by deflection, dissipating some of it via the damper part, and storing and releasing again the remainder, via the spring. This latter causes rebound, Some barriers also slow the car by momentum transfer: the car collects heavy parts of the barrier, and by the principle of conservation of momentum, its speed is reduced proportional to the increase in the mass of the car plus the barrier. Fig.1 shows a car hitting a two-row tire barrier, spaced in front of a three-row barrier. When it hits the first rows it collects an ever-increasing mass of tires, which combines with the mass of the car to reduce its velocity by momentum transfer, prior to impacting the second set of tires. In fact, most barriers combine momentum transfer, material failure, spring and damper in a complex interaction. Pure material failure (crushable) barriers such as Armco and foam blocks, have not found the favor one might expect as they are one-shot systems, and there is a racing requirement to replace barriers as soon as they are damaged. Spring/damper barriers usually recover, to be capable of absorbing further impacts.
By far the biggest challenge facing a circuit barrier designer is to come up with a construction that accommodates a variety of angles of impact and is stiff enough when impacted with the front or rear of the car, but not too stiff when hit with the full length of the car traveling sideways. Modern single-seaters have sharp pointed noses, reinforced to absorb frontal impacts. They are just like stilettos, and tend to penetrate barriers like a knife through butter. There is not much substantial behind the nose to engage with the barrier until the wheels, which if attached with CFRP suspension offer little resistance. It is not until the side pods are reached, or the wheels jam into the front of the side pods, that there is anything to really slow the car. In a side impact however, the wheels and side pods, which are full of impact structure and crushable radiators and exhaust, engage over 3 meters of a barrier. Both cases must be catered for and the barrier characteristics are inevitably a compromise. No one-barrier system is ideal for all situations, and the solutions vary according to the site on a circuit. It is not possible to accurately predict how and where a car will impact, but it is possible to make reasonable estimates of where they are most likely.
Fig.1 - 2-row tire, momentum transfer barrier
Fig.2 - Inclined impact with concrete wall
Straights are a particular case. Due to the increased probability of component failure at high speeds, and the opportunity for overtaking (and therefore running into another car) that they provide, accidents do happen on straights. It is normal to place the barrier close to the track edges as this prevents a high velocity being developed perpendicular to the barrier. Most of the velocity, and hence energy to be dissipated is along the barrier - see Fig.2. Even if the car accelerates sideways at around 4g, crossing the full width of the track, it will only manage to hit the barrier with a perpendicular component of velocity of around 80kph. The driver will, even in this extreme case, normally be all right, but it is desirable that the car does not rebound back onto the track in front of other cars. Instead, it should slide along the barrier, shedding and destroying parts and dissipating its energy as it does so. Concrete walls provide these characteristics very effectively and this is why they are still the best solution for straights. They are also used universally on ovals, in spite of the potential for perpendicular impact velocities in excess of 100kph due to the width of the track and the geometry of the turns (CART and IRL cars are built with greater energy absorbing capacity than road circuit cars).
Temporary road circuits are often built using connected concrete blocks, as are sometimes used as temporary barriers on roads. When a car hits one of these, it may actually move one or more blocks, each of which weighs over a ton. The action of moving the block increases the instantaneous effective mass of the car, and hence reduces the velocity by momentum transfer. The friction between the block and the ground then dissipates the energy in the car and block. Moving a block just 0.5 meters may well halve the severity of the crash pulse. Concrete looks pretty unforgiving as a barrier material, but in the right application it serves very well. It also withstands impacts without much damage, and so does not require refurbishment or replacement before racing can continue.
Lining the edges of the track with a rigid wall does not work once the geometry of the circuit causes perpendicular impact velocities above about 60-80kph i.e. when straights lead into corners that require the cars to brake heavily to reduce the speed of entry. In these cases the barrier itself must be able to absorb significant amounts of energy, but even the best barriers are not yet able to stop a car from high speeds in a short distance. The approach taken is to use as much space as is available to slow the car. Run-off areas are provided to generate a low level of deceleration (around 1g), and to enable the driver to attempt to sort it out and rejoin the track, and the boundaries are lined with barriers, the specification of which is determined by the likely residual velocity and the direction of impact. The thickness of the barrier is one of the most critical parameters that determine its performance - the greater the distance available to decelerate the car, the lower the average deceleration g-level and the softer the barrier can be constructed. However, if the barrier is too thick and soft, the car may penetrate it so deeply that the barrier face reaches the driver's cockpit and injures him, or traps him and hinders rescue. Similarly in an oblique impact, where the velocity along the barrier is high, penetrating the barrier can snag the car, and then the car stops so abruptly that the driver is injured by the high deceleration, or the car turns over. Examination of the videos of Jacques Villeneuve's Eau Rouge accidents at Spa in 1998 and 1999 show a barrier subjected to high speed oblique impacts, fortunately ones in which the barrier design protected him well.
Race circuit barrier development has historically been based heavily on systems developed for public roads and has not, until recently, been backed up by tests on specific racing barriers. It was not until Jackie Stewart ignited the whole motor racing safety issue in the late 1960s that barriers were considered necessary. Until then, with much of motor racing taking place on closed public roads, earth banks, railway sleepers, concrete retaining walls and straw bales were considered adequate to protect the spectators, and it was up to the drivers to avoid hitting them or the unprotected buildings, bridges and trees that lined many circuits. Many drivers paid with their lives, and spectators were all too often victims as well. The first attempt to use barriers employed Armco barrier, as developed for and still used extensively on public roads. This will deform up to 0.5 meters when impacted, with the formed steel rails and posts both deforming plastically with little rebound. Armco is however a one-shot system, and rails and posts must be replaced after an accident. After Jochen Rindt's fatal accident at Monza, in 1970, in which his Lotus T72 penetrated under the Armco, it fell out of favor. However, that was before cars were developed to absorb and withstand major impacts, and it is still used effectively at some circuits, especially close to the track as at Monaco, when there is no run-off space and where they have trained teams of Armco repairers ready to leap into action following an accident. It offers some impact attenuation and will accommodate oblique impacts nearly as well as a concrete wall.
Tire barriers were first used in the USA, and started to be adopted in Europe in the 70s. They gained favor as being an extremely practical way of building barriers in a variety of configurations and of providing a reasonable degree of protection. Used tires are plentiful in every country in which motor racing takes place, barriers can be assembled by unskilled labor in a range of thickness and module lengths, and tires weather well and survive minor impacts without damage and so do not need replacing regularly. All this adds up to a feasible, low cost barrier system. The only serious, practical problem is that they collect rainwater and provide ideal breeding grounds for mosquitoes! Tires deform as springs, and so there is some rebound. However, energy is dissipated by the action of tearing the tires (especially where they are bolted together), friction between the tires, and by the friction between the tire stack and the ground
However, the assessment of the impact performance of tire barriers was based on accident outcomes rather than any scientific tests, until the 90s when the FIA started impact trolley tests at the CSI Laboratory in Italy, and GM carried out tests at Wayne State University in the USA. These early tests looked at the effects of the various tire-stacking configurations that were popularly employed, the connection systems between the tires (e.g. bolting, strapping, chains), and the number and placing of the rows of tires. The impact trolleys all had blunt, rigid impactor faces and so provided comparative data rather than the actual performance of a racing car hitting the barrier.
When Senna died at Imola in 1994, there followed a surge in barrier concepts offered to the FIA for consideration. Many of these were commercial systems used on roads or new concepts utilizing materials manufactured by the company promoting the idea. The FIA decided that a new barrier test procedure was needed to represent better the impact by a stiff, sharp-nosed single-seater. The Transport Research Laboratory (TRL) in the UK, was commissioned to develop this test and to use it to evaluate the performance of existing barriers and the better ideas that had emerged in the aftermath of Senna's accident. The test would become the method by which any novel barrier system could be evaluated.
Fig.3 - 3-row tire barrier with tube inserts and conveyor belting
Fig.4 - Deceleration v distance for 3-row tire barrier with tube inserts and conveyor belting
TRL designed a special impact trolley, weighing 780kg, running on road wheels and tires. The front represents a slim monocoque to which is mounted an F3000 nose - a new one for each test. Test instrumentation is also mounted on the trolley, which is accelerated by a cable to the test speed and released to impact the test barrier. This is mounted in front of a massive, immovable concrete block. High-speed cameras record the impact. Initial tests were carried out at 60kph to avoid destroying the test trolley, and then raised to 80kph for the better performing barriers.
Ideally, barriers would be tested through a range of impact angles. However, once the impact is other than perpendicular to the barrier, the dynamics of the trolley come into effect and significantly alters the outcome. To accurately simulate the dynamics of a single-seater racing car one needs just that: a single-seated car. Even using damaged and repaired F3000 cars for the tests would be prohibitively expensive. There is an additional problem in that racing tires have such a high cornering stiffness that they react to any road surface irregularity and steer the car, making it extremely difficult to guide it automatically even at 80kph. Barrier tests in the USA on an IRL car resulted in a spectacular crash, but not against the barrier! Data from CART and IRL cars on ovals has shown that drivers consistently survive side and rear impact that generate of the order of 150g, without injury, thanks to current seat and head protection padding. The critical impact direction is head-on and about 30 degrees either side. A well-restrained driver should be uninjured in a frontal impact of 30g, and this should increase to at least 40g if he is wearing a HANS device. Thus it was decided that a frontal test is the critical case for barrier design.
Tests were carried out on three rows of tires, to evaluate:
Â¢ Tire fixing methods - straps and bolts
Â¢ Separating the front 2 rows from the rear row
Â¢ Inserts in the tires - foam cylinders and plastic tubes
Â¢ Additional mass by fitting smaller tires inside the primary tires
Â¢ Fitting conveyor belting to the impact face
The resulting deceleration traces were analyzed to determine the energy absorbed by the barrier, the energy absorbed by the nose cone, stored (rebound) energy, and peak and average decelerations. Fitting plastic tubes inside the tires (the tubing used is similar to that used for underground gas mains) doubled the energy absorbed by the barrier. Conveyor belting contributed little in a frontal impact, in fact it slightly increases the rebound, but it does prevent the car snagging in an oblique impact.
The best configuration of barrier - bolted tires, tubes and conveyor (see Fig.3) - was tested at 80kph (77% more energy), at which speed it absorbed nearly 80% of the trolley's energy, the nose absorbing the rest, without exceeding 30g - See Fig.4 - the final peak is the nose crushing. Fig.5 is a section of the high-speed film of the test, with the sequence running from right to left, at 20 millisecond intervals.
The car is brought to a halt from 80kph in just 2 meters - the depth of the barrier plus the length of the nose cone crush - averaging 12.5g. If the two energy-absorbing systems could generate a steady 30g for the 2 meters available, the car could be stopped from 123kph. If the driver can stand 40g, this goes up to 143kph. These figures give some indication of the potential and difficulties of barrier and car design.
Fig.5 - High-speed film of trolley impact with 3-row tire barrier with tube inserts and conveyor belting. 20ms frame intervals, right to left
A number of other, proprietary barrier configurations have been tested, but the results are confidential to the companies involved. In many tests the effect of the sharp nose cone has surprised the designers! A design approach that is popular is embodied in the Airfence system, developed as a temporary barrier for roads works, used in critical areas at Monaco for instance, where the available space is limited. The barrier is made up of air filled cells that exhaust through metering orifices when impacted, in much the same way that an airbag works. The barrier is made of strong, flexible plastic, and provided the car does not penetrate it, it recovers for further use.
In the USA, with its many high-speed oval tracks, the search is on for a barrier that provides some impact absorption in the perpendicular direction, while retaining all the good qualities of a concrete wall i.e. no damage, no snagging along the wall, no rebound. A barrier that deflects up to 0.5 meters while retaining a smooth profile would about halve the massive g-levels sometimes experienced during impacts. Meanwhile, in Europe work is underway to increase the absorbed energy during a head on impact. Not only must the magnitude of the resulting crash pulse be defined, but its shape can have an effect on the injury outcome. Advanced, high-performance barriers must be developed hand-in-hand with the safety features on the cars, driver protection systems and be based on biomechanics research into human tolerances. Component failure at the end of a straight, or two cars touching early in the braking area, provides the most critical safety conditions for both the run-off area and the barriers. If the cars become airborne across the run-off area, they may arrive at the barrier with little loss of speed. The challenge is to ensure the driver is not seriously injured and the spectators are untouched.
With all the effort going into barrier research, the safety of competitors and spectators still comes down to ensuring that the correct and latest safety systems are installed and maintained at circuits around the world. The effort and negotiating skills needed to achieve this are enormous.
The purpose of this seminars is to show how the advanced technology of the worldâ„¢s fastest and largest spectator-sport can be used in the normal superhighways and expressways setting standards of safety for the general public who drive on the highways. Use of barriers similar to those used in formula one can reduce the amount of injury in case of accidents on these highways. Even the use of CSAS (Circuit and Safety Analysis System) can be used to build safer highways.
As for F1 different circuits and different conditions present challenges for all connected with the engineering side of F1 and it is those who predict and cope best with these complications who eventually triumph.
Â¢ F1 Technology and the Sport
Â¢ F1 Racing magazine
Â¢ Autocar Magazine
First of all I thank the almighty for providing me with the strength and courage to present the seminars.
I avail this opportunity to express my sincere gratitude towards
Dr. T.N. Sathyanesan, head of mechanical engineering department, for permitting me to conduct the seminars. I also at the outset thank and express my profound gratitude to my seminars guide Mr. Mohan.C.C for his inspiring assistance, encouragement and useful guidance.
I am also indebted to all the teaching and non- teaching staff of the department of mechanical engineering for their cooperation and suggestions, which is the spirit behind this report. Last but not the least, I wish to express my sincere thanks to all my friends for their goodwill and constructive ideas.
2. TRACK DESIGN
3. CIRCUIT AND SAFETY ANALYSIS SYSTEM (CSAS)