Swing Test Report. Impact Testing

Transcription

1 Phone: Fax: Windermere Avenue Toronto, Ontario M6S 3K4 Swing Test Report Requesting Agency: None GENERAL INFORMATION Date: November 29, 2004 Time: 9:00am 11:00am Location: Palmerston Park Whitby, Ontario Weather: Temperature: Overcast 4.3 degrees Celsius Consultant: Scott Belair Purpose: To determine the impact properties of the belt, enclosed and tire swings and evaluate the swing use zones necessary and compare that the relevant safety standards in the United States and Canada (i.e. impact absorbing and necessity of use zones prescribed). Testing Device: Impact Testing All impacts tests were performed with use of a size C headform specified in the Federal Motor Vehicle Safety Standard No Page 1 of 10

2 Test Procedure and Guidelines: Both American Society for Testing Materials (ASTM) 1487 and Canadian Standards Association (CSA) Z614 specify ASTM F1292 for head impact data as related to protective surfacing material. ASTM F1292 states that head impacts in excess of 200 GMAX and 1000 HIC are associated with lifethreatening and debilitating injuries. Also, the ASTM F1148 states a test method for determining the impact properties of a swing as seen below. This test method entails that an unloaded swing seat shall be pulled back and dropped into the headform from 60-degrees. The CPSC Handbook for Public Playground Safety (1981 publication), Volume II also published nearly identical criteria. The key difference being that the CPSC document required that a swing shall impart a peak acceleration in excess of 100 G s to the test headform. It should also be noted that serious head injuries (non-life threatening) can be sustained with HIC scores in excess of 700 (despite 1000 being the CSA and ASTM thresholds). These types of injuries may include cerebral contusion, loss of consciousness, and possible brain hemorrhaging 1. Other types of devices which have a head impact measurement include: hockey helmets, bicycle helmets, bull-riding helmets. All of these noted devices have thresholds in excess of 200 GMAX. 1 Source: ASTM F Page 2 of 10

3 Using these criteria, a relative measure of safety of head impact can be assessed from contact with a belt, enclosed or rotating style swing. It should be noted that this test provides a calculation of the severity of head impact. These test should not be interpreted to mean that impacts below the specified threshold numbers will not cause injury. Although it would certainly be acceptable to eliminate all known injuries with one test method, at the time of this test there is no known test to accurately predict the likelihood of other types of injuries (i.e. long-bone, neck, whiplash, impacts to the abdomen or other parts of the body, etc.). Other injuries can result based on the nature of an impact, rather than the severity of impact. For instance, a person can stand on the ground, trip and break a bone, or fall from a great height and suffer little or no injury at all. These types of injuries (i.e. long bone, neck, etc.) could also be caused by more traditional types of swings and more traditional types of playground equipment (i.e. this would not be unique to the "biggo" swing). Although some impacts were conducted unloaded (as per ASTM test method), many impacts were conducted with greater than kg (175 lbs.) of weight and impacts were conducted from approximately 90-degrees from horizontal. Some impacts were conducted with multiple to-fro s prior to impact (rather than single raise and drop). This was done to simulate the most adverse condition of use (i.e. the worst case scenario). Each impact test conducted has a notation to indicate unloaded, or loaded. All impacts were conducted from approximately 90-degrees from horizontal. User measurements - Height Weight User - 182cm (6 0 ) kg (175 lbs.) Page 3 of 10

4 Swing #1 Type: rotating swing (tire swing) Pivot point = 225cm Y = 145cm 2Y = 290cm (CSA) Y cm = 327cm (ASTM) Swing #2 Type: belt swing Pivot point = 345cm Y = 290cm 2Y = 580cm (CSA) 2X = 690cm (ASTM) Swing #3 Type: enclosed swing (baby swing) Pivot point = 236cm Y = 165cm 2Y = 330cm Page 4 of 10

5 Testing Results: Swing #1 Impact # Gmax (Peak) HIC Conditions swing #1, unloaded swing #1, unloaded swing #1, unloaded swing #1, unloaded swing #1, unloaded swing #1, loaded swing #1, loaded swing #1, loaded max swing #1, loaded Swing #2 Impact # Gmax (Peak) HIC Conditions swing #2, loaded swing #2, loaded swing #2, loaded Swing #3 Impact # Gmax (Peak) HIC Conditions swing #3, unloaded swing #3, unloaded swing #3, unloaded swing #3, unloaded swing #3, unloaded swing #3, unloaded Page 5 of 10

6 Other Testing Information: Page 6 of 10

7 Definitions: G The acceleration due to the earth s gravity at sea level, having a standard value of 9.8 meters per second (32 feet per second). Accelerations are expressed in units of g, where 1 g = the acceleration due to gravity Gmax the maximum acceleration of a missile during an impact, expressed in g units. HIC Head Injury Criterion, a specific integral of the acceleration time history of an impact. It is used to determine the relative risk of head injury. HIC interval the time interval within the acceleration-time history of an impact over which the HIC integral is evaluated. Impact contact caused by a moving object (for example, a swing) striking another object (for example, a headform or user) and during which one or both bodies are subject to high accelerations. Page 7 of 10

8 Swing #1 Protective surfacing zone/use zone evaluation evaluation ASTM use zone (shown in cm) CSA protective surfacing zone roll after total distance required (cm) special conditions Trial # swing #1, loaded swing #1, loaded swing #1, loaded swing #1, loaded swing #1, loaded *Horizontal distance to landing measured from centre of static swing to front of foot. **1.8 meter no-encroachment zone also required under CSA Standards. Swing #2 ASTM use zone (shown in cm) CSA protective surfacing zone roll after total distance required (cm) special conditions Trial # swing #2, loaded swing #2, loaded swing #2, loaded swing #2, loaded swing #2, loaded *Horizontal distance to landing measured from centre of static swing to front of foot. **1.8 meter no-encroachment zone also required under CSA Standards. Swing #3 ASTM use zone (shown in cm) CSA protective surfacing zone roll after total distance required (cm) special conditions Trial # swing #3, loaded swing #3, loaded swing #3, loaded swing #3, loaded swing #3, loaded *Horizontal distance to landing measured from centre of static swing to front of foot. **1.8 meter no-encroachment zone also required under CSA Standards. Page 8 of 10

9 Additional information: Typical landing point End of CSA protective surfacing zone End of CSA no encroachment zone Page 9 of 10

10 Professional Opinion: Rotating swings ASTM F of Y + 72 inches (where Y equals length of swing chain from pivot point to top of swing seat) and CSA Z requirements of 2 x Y are greater than what is actually required. With a single user, a rotating swing is near impossible to jump from given that the swing begins to tip (as seen in photo below). This makes jumping near impossible as the downward force necessary to propel a jump also leads to that side of the rotating swing lowering or tipping. During testing it was impossible to even jump from the rotating swing. Any potential fall during single use will be downwards with very little to no horizontal distance traveled. Multiple occupancy at a tire swing does not create a need for more space. Multiple users serve to add significant weight to the swing and thus prevent the swing from reaching heights up and around the pivot point. 1.5 x Y would be a more realistic area for protective surfacing than either the ASTM or CSA requirements. However, the CSA protective surfacing zone requirements are more realistic as compared to ASTM. However, given the 1.8 meter no-encroachment zone requirement, the ASTM use zone method may be less expensive as the ASTM method has user flow throughout the play area built in to the use zone requirement. To-fro swings ASTM F requirement of 2X (where X equals distance from pivot point to protective surfacing) and CSA Z requirement of 2 x Y (where Y equals the distance from the pivot point to the top of the swing seat) are both reasonably accurate (there will be some variation based on user dimensions and swing toprail height, etc.). The CSA requirement is preferable given that after landing the user will roll and would still be within the 1.8 meter protective surfacing zone. Whereas, with the ASTM spacing methodology, a user could hit within the use zone, but roll into other users, pedestrians, or other play equipment. Enclosed swings ASTM F requirement of 2W (where W equals the distance from the pivot point to the top of the swing seat) and CSA Z requirement of 2 x Y (where Y equals the distance from the pivot point to the top of the swing seat) are both far too excessive. Page 10 of 10