1. EMIS 7305: Systems Reliability, Supportability  And Availability Analysis Project Presentation Air Break System in Trucks Prepared by: Abdullah Alnujaidi Aziz Qari FahadShabi

2. Table of Contents • Introduction • Project Description • Project Objective • Air Brake System Effectiveness • System reliability • Injury severity • Injury Risk • AirBrake System Operation Availability • Analysis of crash distribution • Conclusion

3. Introduction • Air Brake system is a Safety System that prevents the wheels on Trucks from locking up or ceasing to rotate while breaking by using air pressure. • Foundation brakes are the most common air-brake systems found in trucks and buses and work the same way as in rail cars. • The following components are exclusive to a foundation air-brake system in a truck or a bus: • Air compressor: Pumps the air into storage tanks to be used in the brake system • Air compressor governor: Controls the cut-in and cut-out point of the air compressor to maintain a set amount of air in the tank or tanks • A rotating road wheel allows the driver to maintain steering control under heavy braking by preventing a skid and allowing the wheel to continue interacting with the road surface. • Today most of the trucks have Air Brake System, and customers attend to buy Trucks that have this safety system.

4. Project Description • This project studied the effectiveness of the Air Brake System in trucks, and the different between trucks that have the air brake system with air compressor and the one with air compressor governor. • The project also shows that the air brake System effects differently depend on the type of the truck. • The Air Brake System decreases road accidents and passengers injury, but its increases accidents in some parts of countries as they attend to drive faster and danger because the truck is fitted with Air Brake System. • In crashes between heavy trucks and light vehicles, most of the fatalities are the occupants of the light vehicle. A reduction in heavy truck stopping distance should lead to a reduction in the number of crashes, the severity of crashes, and consequently the numbers of fatalities and injuries.

5. Project Objective • The goal of this study is to determine the use and the benefit of the Air Brake System, and the failure of it. • Also clear the effectiveness on trucks depends on the type based on statistical analysis, and shows the history of accidents with the Air Brake System and the advantages and disadvantages. • The purpose of an air brake system on heavy duty vehicles is to convert air pressure to mechanical energy to activate the foundation brakes. Federal • Motor Vehicle Safety Standard 121 dictates how this is to be done for over-the-road vehicles.

6. Air Brake System Effectiveness • Air Brake System reduced the risk of multiple vehicle crashes by 18% and reduced the risk of runoff road crashes by 35% and as the National Highway Traffic Safety Administration (NHTSA) study found that Air Brake System increased stopping distance on loose gravel by 22%. • On high traction surfaces, many Air Brake System equipped trucks are able to attain braking distances better and in a shorter time than those that would be easily possible without the benefit of Air Brake System. • Assessment of differences in occupant injury risk and injury severity between crashed vehicles with Air brake system without adjusting for differences in other factors between the comparison vehicle groups, the table below shows the different in occupant injury risk or severity between vehicles with Air compressor and withAir compressor governorAir brake system. N represents the number of crashed vehicles.

7. A log linear model with Poisson error structure for the variability in the counts of occupant casualties fitted to the data with the form given in equation 1: ln (Nijk) = β0 + βi + βij + βik + βijk In equation 1, Is the vehicle model index, j is the Air Brake System presence indicator, k is the injury level index and Nijk is the cell crash count. The percentage reduction in injury or severity injury associated with the presence of ABS in vehicle model is given by equation 2: ∆i = 100 (1-exp (βijk)) %

8. System reliability • System reliability often depends on the effort of many individuals, making reliability a public good. It is well-known that purely voluntary provision of public goods may result in a free rider problem: individuals may tend to shirk, resulting in an inefficient level of the public good. • In this study I will show the system to the first failure in the brakes and which distribution will fit with the study. • 10 brakes were tested and the life time for them as shown below in hours: 1287 1051 920 711 1172 975 671 521 759 850

9. β = 4.402

11. Estimates of Probability Density Functions

12. Probability Distribution Functions

16. Injury severity • In this table, it lists the driver injury severity by vehicle Air Brake System presence for each of the vehicles in the study it shows that there were sufficient data for seven vehicles models to allow assessment of the effects of the Air Brake System on driver injury severity using the contingency table analysis method.

19. Injury Risk • Analysis of the effects of Air Brake System on the risk of driver injury given crash involvement was carried out in the same manner as for injury severity above. This table all vehicles models by Air Brake System presence and the level of driver injury for injury risk calculation for eleven models.

23. Air Brake System Operation Availability

29. Analysis of crash distribution

33. Conclusion and Summary • The study has attempted to quantify the effectiveness of Air Brake System in terms of both primary and secondary safety. Some of the estimates of the effect of Air Brake System have achieved statistical significance. • The US insurance institute for highway safety (IIHS) has conducted several studies aiming to determine if cars equipped with Air Brake System are involved in more or fewer fatal accidents. • Results from this study suggested that Air Brake System might have some benefits in reducing driver injury severity in some specific vehicle models. Although none of the results were statistically significant, four out of seven vehicle models assessed showed an estimated reduction in injury severity associated with Air Brake System presence. • The distribution of crash involvement by crash type for Air Brake System equipped vehicles was statistically significant different from the distribution of crash involvements by crash type for non Air Brake System equipped vehicles. • This study has attempted to access the effectiveness of Air Brake System in reducing vehicle occupant injury risk and injury severity through the analysis of real crash outcomes described in mass crash data. Also effects of Air Brake System were measured in terms of their effect on crash type distributions.

34. Questions?