The effect of on-off switches on passengers in crashes is twofold.
On the one hand, it would have been essentially impossible to install passenger air bags in pickup trucks where infants and children have no place to ride but the front seat, without some sort of manual or automatic technology to suppress air bag deployments for child passengers. Since on-off switches became available in 1996-98, whereas advanced, automatic suppression technologies were not phased in until 2003, the switches in essence made it possible to equip pickup trucks with passenger air bags seven years earlier, helping to save hundreds of adult lives.
On the other hand, as we have seen, the switches are often left on for children, potentially exposing them to a deploying air bag, and leaving them at greater risk than in a vehicle that has no air bags or suppresses their deployment. They are often left off for adults, depriving them of any protection from air bags. On-off switches are less effective than an ideal suppression system that always, automatically turns air bags off for children and on for adults.
Thus, the effect of on-off switches can be expressed as “a cup half full,” relative to the fatality risk in trucks without any passenger air bags, or as “a cup half empty,” relative to trucks with advanced air bags that deploy for adults but not for children.
Either way, however, NHTSA is unable to quantify the effect on child passenger fatalities. Children 12 years old and younger have a “non-quantifiable but increased risk” [18] of fatalities due to the air bag. Since the risk is non-quantifiable, we cannot estimate the lives saved because drivers turned off the passenger air bag for children. Nor can we estimate the lives lost because the passenger air bag was turned on for children. As of July 1, 2003, NHTSA’s Special Crash Investigation program has documented 4 cases where a child in the front seat of a pickup truck has been killed in a low-speed crash by the passenger air bag. Three of these trucks were equipped with on-off switches and the switches were left on. The children were 2 months, 2 years, 5 years, and 8 years old. The position of the switch in the truck where the 5 year old was riding is unknown. The infant was properly secured in a rear-facing child safety seat, the 2-year-old was unrestrained, the 5-year-old was unrestrained and sitting on the lap of a passenger, and the 8-year-old was unrestrained.
The effects on adult fatalities are estimated as follows:
Adult Lives Saved/Lost as of December 2001 in Model Year 1996-2001
Pickup Trucks with Passenger Air Bag On-Off Switches
In the Fatality Analysis Reporting System (FARS), there were 8,873 pickup trucks with passenger air bag on-off switches involved in fatal crashes from 1996 to 2001. There were 729 adults sitting in the right front position killed in pickup trucks with a passenger air bag on-off switch that only had adult passengers in the front seat. Some of these passengers were protected by the air bag because the air bag on-off switch was turned on and some were not because the switch was turned off.
To calculate the number of fatalities, we must first calculate the effectiveness of air bags that are off 17 percent of the time. Air bags are 12 percent effective in reducing adult fatalities in all crashes, [19] but the survey found that 17 percent of the time the passenger air bag was turned off when only adult passengers are in the front seat of pickup trucks. Therefore, passenger air bags in these trucks are 12% * (1 – 17%) = 9.96% effective in reducing fatalities.
Since there are actually 729 adult fatalities in pickup trucks with the switches, in crashes where only adult passengers sat in the front seat, then there would have been 729 / (1 - 9.96%) = 810 adult fatalities in these trucks if they did not have passenger air bags. If the switches in these trucks were always turned on to protect the adult right front passenger, then there would have only been 810 * (1 - 12%) = 712 adult fatalities. That is a reduction of 810 – 712 = 98 fatalities.
But since the switches are turned off 17 percent of the time, there were only 810 - 729 = 81 lives actually saved. Therefore, if the switches were always turned on when an adult right front passenger was present, then there would have been an additional 98 – 81 = 17 adults saved in these pickup trucks.
In summary:
Adult Lives Potentially Saved/Lost Over the Life of One Model Year Cohort of
Pickup Trucks All Equipped with Passenger Air Bag On-Off Switches
Passenger air bag on-off switches became standard equipment on most pickup trucks in model year 1998. These trucks are relatively new and have had only a few years of exposure, but about half of these vehicles will still be on the road in 15 years. In this section, we will calculate the number of lives that will be saved over the life of one model year cohort of pickup trucks that are all equipped with passenger air bag on-off switches.
A good surrogate for the number of fatalities that will occur over the life of a model year cohort of pickup trucks is the fatalities that occur in one calendar year in pickup trucks of any model year. In FARS 2001, there were 832 right front adult fatalities in all pickup trucks that had only adult passengers in the front seat. Some of these trucks are equipped with a passenger air bag and an on-off switch, a few others are equipped with just a passenger air bag, and still others are not equipped with a passenger air bag. Below, the number of fatalities that occurred in these pickup trucks is subdivided into four groups by type of equipment available:
(1) 519 not equipped with a passenger air bag,
(2) 283 equipped with a passenger air bag and on-off switch,
(3) 15 equipped with a passenger air bag, but not equipped with a on-off switch,
(4) 4 equipped with a passenger air bag, unknown if equipped with on-off switch,
(5) 11 unknown if equipped with passenger air bag.
The first step is to calculate the number of potential fatalities that would have occurred if none of these trucks had been equipped with a passenger air bag. Since pickup trucks with a passenger air bag and on-off switches are 9.96% effective in reducing adult fatalities, there would have been 283 / (1 - 9.96%) = 314 fatalities in group (2) if these trucks were not equipped with a passenger air bag and on-off switch.
Since air bags are 12 percent effective in reducing fatalities, there would have been 15 / (1 – 12%) = 17 fatalities in group (3) if these trucks had not been equipped with a passenger air bag.
Let us assume that the trucks in group (4) had a passenger air bag and did not have an on-off switch. Since air bags are 12 percent effective in reducing fatalities, there would have been 4 / (1 – 12%) = 5 fatalities in group (4) if these trucks had not been equipped with a passenger air bag.
Let us assume that none of the trucks in group (5) were equipped with a passenger air bag. Then there would be 519 + 314 + 17 + 5 + 11 = 866 adult fatalities over the life of one model-year cohort of pickup trucks, if the trucks did not have passenger air bags.
If we repeat the analysis, using FARS 2000 instead of FARS 2001 data as a baseline, it produces an estimate of 82 lives saved by air bags and switches and 17 additional adult lives lost over the life of the trucks. Using the 1999 data produces an estimate of 79 lives saved by air bags and switches and 17 additional adult lives lost. Using the 1998 data produces an estimate of 74 lives saved by air bags and switches and 15 additional adult lives lost. Therefore, on average there will be 80.25 adult lives saved over the life of one model-year cohort of pickup trucks all equipped with passenger side air bags and on-off switches and the switches were turned off 17 percent of the time. Also, on average there will be 16.75 adult lives lost due to the air bag being turned off over the life of one model-year cohort of pickup trucks all equipped with passenger side air bags and on-off switches.
Adult Lives Potentially Saved/Lost Over the Life of Model Year 1996-2001
Pickup Trucks with Passenger Air Bag On-Off Switches
To estimate the adult lives saved/lost due to the air bag being turned off over the life of model-year 1996-2001 pickup trucks with on-off switches, we must first estimate the percentage of pickup trucks with on-off switches for model year 1996-2001 trucks.
Initially, manufacturers furnished on-off switches in almost all pickup trucks equipped with passenger air bags, beginning with some Ford Rangers in 1996 and extending to all models with passenger air bags by 1998. However, beginning with model year 2000, some crew cab pickup trucks were offered with passenger air bags but not on-off switches because the rear seat could accommodate a rear-facing infant seat. Since then all manufacturers have produced crew cab pickup trucks with rear seat areas big enough to accommodate rear-facing infant seats, so that these trucks do not have on-off switches. Table 2a lists the crew cab trucks without switches and shows the model year when they were first introduced without switches.
Using the FARS data, we estimated the percent of pickup trucks with switches by model year. Table 34 shows the estimated percent of pickup trucks in fatal crashes with the switches by model year. The passenger air bags were optional in the 1996 Ford Ranger and there is no way to identify which Rangers had passenger air bags. Therefore, we shall assume that no pickup trucks had switches in model year 1996. In FARS 1997 and 1998, 50 percent of model year 1997 pickup trucks had switches. That grew to 99 percent of model year 1998 trucks, but has dropped since the introduction of crew cabs with rear seat areas big enough to accommodate rear facing infant seats. If the switches are turned off 17 percent of the time, the result will be (80.25 * 0%) + (80.25 * 50%) + (80.25 * 99%) + (80.25 * 89%) + (80.25 * 90%) + (80.25 * 81%) = 329 adult lives saved over the life of model years 1996-2001 trucks. If the current rate of the switches turned off continues for these trucks, the result will be (16.75* 0%) + (16.75 * 50%) + (16.75 * 99%) + (16.75 * 89%) + (16.75 * 90%) + (16.75 * 81%) = 68 additional adult fatalities over the life of model years 1996-2001 trucks.
Table 34: Percent of Pickup Trucks with Switches
| Model
Year |
Percent
with Switches |
|---|---|
1996 |
0% |
1997 |
50% |
1998 |
99% |
1999 |
89% |
2000 |
90% |
2001 |
81% |
Adult Lives Potentially Lost Over the Life of All (Model Year 1996-2012) Pickup Trucks
Equipped with Passenger Air Bag On-Off Switches
On-off switches may remain as standard equipment on pickup trucks until model year 2012. But by model year 2004, all crew cab pickup trucks except Ford Ranger and Mazda B Series will not have on-off switches. In FARS 2001 and 2002, 35 percent of model year 2001 pickup trucks are crew cab (excluding Ford Ranger and Mazda B Series crew cab trucks). So let us assume that in 2004-2012, 35 percent of pickup trucks will be crew cabs without switches, as in model year 2001. Let us assume that the percentage of crew cab pickup trucks without switches will increase linearly from 2001 to 2004. Therefore, 76 percent of model year 2002 pickup trucks will have switches and 70 percent of model year 2003 pickup trucks will have switches.
Besides the crew cab pickup trucks, advanced air bags are now being developed that can make the switches unnecessary by minimizing the risks to infants and children. On-off switches in pickup trucks allowed drivers to minimize the risk to infants and children well before the introduction of advanced air bags that automatically reduce the risk to infants and children. So the adult lives potentially saved over the life of all pickup trucks with on-off switches will not extend beyond model year 2007 when all new pickup trucks will be equipped with advanced air bags. However, let us also assume that manufacturers will continue to equip regular and extended cab pickup trucks with switches thru 2012. Then if the switches continue to be turned off at the current rate, that will result in 68 + (16.75 *76%) + (16.75 * 70%) + (9 * 16.75 * 65%) = 190 additional adult fatalities over the life of those 17 model years of trucks.
All of the preceding calculations are based on the assumptions that the 17 percent of air bags turned off in the 2000 survey is an accurate estimate of the national average and that in the future 17 percent of air bags will be turned off for adult passengers. If the national average were not 17 percent, then the estimates of additional adult fatalities would be affected. If the average were less, then adult fatalities would be reduced. If higher, then more adult lives would be lost. Also, programs to increase public awareness of the recommended use of the switches could reduce the percentage of switches turned off for adults and reduce the number of lives not saved. In addition, if advanced air bags function as intended, there will be no need to turn the switches off. This would probably affect the public perception of the need to turn the switches off and alter the agency guidance on the use of switches, further reducing the percentage of switches turned off. Finally, the estimated number of vehicles with factory-installed switches could decrease, between now and 2012, if manufacturers believe they are no longer needed.