A case study of current safety practices for Calder Park Race Complex.
Nascar, Auscar, HQ Holdens, Touring cars, drag racing, and sometimes truck racing.
Safety Aspects of the track design.
Calder Park is a race complex designed for many different forms of motor sports. It is located about 20km north west of Melbourne. The Thunderdome is used for NASCAR, AUSCAR and HQ Holden oval track racing, a style of racing developed in the United States. The Thunderdome being the only such oval track built outside of the US. The National circuit at Calder is used for V8 Supercars, 2 litre super tourers and occasionally truck racing. There is also a short course, incorporating a section of the National Circuit, which is used for Club races and practice. The Thunderdome can be incorporated into the National Circuit for a very long course, although this has not been done for a number of years. The straight on the National Circuit is used for the Drag strip, capable of safely running Top Fuel Dragsters. See diagram above.
The Calder Park complex follows all national procedures and regulations for motor sport in terms of design and equipment. The Thunderdome's design and safety regulations come directly from the American racing scene who have had far more experience and time to develop the best regulations. Unless there have been specific modifications to suit local conditions, the regulations are American. Calder Park will be studied as an example of current practices, due to both its variety of motor sport and the willingness of its staff to aid the researching of this project.
The National Circuit has sections of concrete barriers, tyre barriers, sand traps and runoff areas. The Concrete barriers are very strong, well reinforced slightly tapered walls approximately 1.2m high and 30cm thick. The walls are capable of deflecting any foreseeable impact during racing, perhaps with the possible exception of a racing truck hitting at a high velocity and high angle. see right.
The walls are set a few metres from the racing surface to give drivers some room for error, making the track more forgiving. There are breaks in the concrete walls to allow safety crews to have access to the track while remaining protected from the vehicles, see right.
Catch fences, set a number of metres behind the concrete walls, similar to those on the Thunderdome, but not as high protect the spectators. The catch fences on the National track consist of 100mm steel poles set in concrete, joined with four 12mm steel cables, and covered with cyclone mesh. see right. The fences here are designed mainly to catch debris, as the cars are unlikely to jump the walls, although it can happen. The gap between the wall and the fence is used like an emergency road for protected access to the track.
The curved entrance to the pits has a row of tyres over the concrete wall in the event of a vehicle entering the pits too fast. The tyre barriers, both on the national circuit, and the pit area of the Thunderdome, consist of 4-6 tyres chained together and encased in plastic, Figure 25. These barriers are very effective in absorbing energy in the event of an impact. Tyre barriers are used extensively in Formula One in rows up to three deep, and on the more unforgiving Indy cars circuits up to 6 rows deep.
The Drag Strip, which is the main straight of the National circuit, has concrete barriers over almost the entire length to deflect drag cars. Drag cars usually hit at very high speeds, but at relatively slight angles. Tyre barriers cannot be used on this situation. It is safer for the drivers involved to slide along the walls than to be caught by an energy absorbing wall. It is the same on the Thunderdome and all similar oval tracks and drag strips, both here and overseas. The drag strip has an escape road that continues in a straight line out of the race complex. If the brakes and parachutes used to slow a drag car fail, it will happen at the peak speed of the vehicle, which is usually over 450km/h for a Top Fuel class drag car. The escape road gives the cars an extra 2-3km over which to slow down safely.
The track surface is renewed approximately every five years on average. The drivers give feedback to the track organisers if a section of the track is not to their liking, or is deteriorating. The track surface is swept and vacuumed with a pair of street sweepers before any major booking such as V8 practice or a race event. The textured surface of the tracks fills with rubber, oil and dirt, which should be removed as regularly as possible. There is, however, a problem on the National Circuit due to the drag races. Drag cars lay down so much rubber on takeoff and during the 'burnout's', that the track becomes smooth with rubber. This rubberised section of the track has good grip when the track is dry, but when there is water on that section of the track, the rubber becomes dangerously slippery. Australian touring car legend, Peter Brock, says that the rubber causes big problems. "In the dry you wouldn't know, in the wet you can get into the main straight there and be wheel spinning until almost the end of the straight with just small applications of power. The car would just spin like a top unless you were extremely careful". The track safety officer, Paul King, said that if the complex was being designed again, the drag strip would be separate from the National Circuit. To minimise the danger to racers, large race events are not scheduled immediately after a drag meeting if possible, giving the rubber a chance to wear off during practice sessions, and touring cars are not run there in wet conditions.
The Thunderdome is an oval track with banked turns, designed for NASCARS. The superelevation of the bank is 44.5% or 24 degrees at each of the ends. Around the entire outside of the track is a continuous reinforced concrete wall of similar dimensions to the walls on the National Circuit. The walls are placed on an angle to remain perpendicular to the track, see right. The only time a concrete wall has ever been breached on the Thunderdome was many years ago when a truck race was held on the track. A wayward truck hit the wall at the top of the embankment and smashed a hole through the wall, although, luckily, the truck was deflected back onto the track.
Wherever there are spectators around the track, they are protected by very high catch fences. The catch fences on the Thunderdome are designed to catch a NASCAR travelling at full speed which jumps the wall. Unlike the fences on the National Circuit, the catch fences on the Thunderdome are on the top of the concrete walls. They consist of 100mm steel poles connected by six 12mm steel cables, overlaid with 100mm square steel mash, see right. The ends of the cables are securely fastened to concrete foundations and tensioned.
Around the inside of the Thunderdome is a similar concrete wall, but there are gates for safety crews, see photo, which protect them, yet are quick and easy to open. See right. There is also a grass strip between the track and the wall. The pit lanes are separated from the track by a grass strip, with all pit vehicles and crew behind a concrete wall. Tyre barriers protect all exposed walls. Of the three pit traffic lanes, there is a speed limit of 80km/h in the two inside pit lanes, with the outside lane having an unrestricted speed limit.
The Thunderdome has required regular maintenance over the years since it was built due to uneven settling of the earth banks causing dips and bumps on the track itself. Some sections of the track have been scheduled for resurfacing in the near future. The Thunderdome cannot be swept before races as the sweepers, similar to normal street sweepers, cannot operate on such a steep slope. To ensure the track is as clean as possible, any debris and dirt is washed to the bottom of the banks with water, where it can then be swept up. The biggest problem at the top of the track are the 'marbles'. These are small pellets of rubber from the tyres of the cars. Their own momentum carries them to the top of the track where they stay. If a car runs too high and into the marbles, they are like running on ball bearings and give virtually no grip.