Motor Vehicle Accident Case Study: The Dow Chemical Company's Use Of "six Sigma" Methodology

Company: The Dow Chemical Company

December 2005

The Problem:

In the United States, over the 11-year period from 1992 through 2002, motor vehicle accidents (MVAs) were the leading cause of occupational fatalities1. Work-related roadway deaths increased over this period, even as the number of all other occupational fatalities declined. In 2003, MVAs accounted for approximately 25 percent of all workplace fatalities--more than one and a half times the next largest single cause of death; contact with objects and equipment2. Yet, identifying and addressing the causes of MVAs continues to be difficult for employers, especially when the accidents involve numerous and varied driver characteristics, vehicle types and driving conditions.

For example, Bart, a safety manager at one of the business units at The Dow Chemical Company (Dow), wants to reduce the rate of MVAs throughout his divisions and operations. Before he can understand what changes to make, he must identify the root causes of MVAs among drivers. Although he has some theories, Bart does not know for sure what factors are causing or contributing to the employees' accidents. Only by determining the root causes can he implement with confidence the controls that will achieve positive results.

Bart also wonders whether the root causes of MVAs are the same across different operations and divisions in his business unit. If this is the case, he would like to design a program that is flexible enough to be implemented throughout the Company. In addition, he wants a program that produces results sustainable over a long period of time and encourages managers and employees to stay away from their old, unsafe patterns.

As a first step, Bart might refer to a similar project successfully undertaken by Dow's Hydrocarbons and Energy business unit (HC&E), which is discussed in the case study set out below. This project, which utilized a problem-solving methodology called "Six Sigma," offers an innovative way to address Bart's concerns and develop a sustainable program for reducing MVAs throughout the business unit.

A Solution:
The Dow Chemical Company's Innovative Use Of "Six Sigma"

Reducing MVAs is just one facet of Dow's overall commitment to safety and health. Dow is a science and technology company that develops, manufactures and provides chemical, plastic and agricultural products and services to customers in over 180 countries. In 1994, Dow adopted a set of voluntary 10-year environmental, health and safety (EH&S) goals designed to dramatically improve the Company's performance by 2005. One of these goals called for a reduction in the number of MVAs per million miles by 50 percent (from a 1994 base). As part of this initiative, HC&E launched a project in 2002 to reduce MVAs by its employees. HC&E procures the fuels and crude-oil-based raw materials and supplies, and the products and power that Dow uses in its global operations.

From September 1, 2001, to August 31, 2002, there were 25 work-related MVAs among HC&E employees. The drivers involved in the accidents were the sales and marketing personnel who drive to client sites and the employees who drive vehicles on-site at HC&E facilities. In addition to personal injuries, the MVAs contributed to lost sales and productivity while the HC&E employees were away from work recovering from their injuries. To reduce these negative consequences, HC&E management decided to launch an effort using the Six Sigma methodology to understand the causes of MVAs and implement continued improvements that would allow HC&E to meet the goal of a 50-percent reduction.

Dow has successfully used Six Sigma to address a number of EH&S improvements. The Company believes that using Six Sigma enables employers to develop program improvements based on measurement and analysis rather than on speculation and results in a more cost-efficient and sustainable fix that will yield benefits indefinitely. Rather than undertaking costly trial-and-error attempts at solutions, the Company is able to identify the root causes of safety concerns with confidence. Improvements can then be implemented in a systematic and sustainable way, not only in the business unit where the project took place, but also throughout Dow's other business units where the relevant conditions are substantially similar.

Step 1: Measure

To address the MVA problem, HC&E created an MVA project team. The team established an initial goal of reducing MVAs by 20 percent over a 12-month period to be followed by continuing reductions until the 2005 goal of 50 percent reduction was achieved. After creating a project charter, which defined the project's timelines and objectives, the team began to collect information on the variables associated with MVAs. These variables included factors related to the accident, the driver, and the vehicle driven, along with details of the accident itself.

Step 2: Analyze

After identifying the variables associated with MVAs, the team divided them into three categories of possible risk factors: methods, people, and environment. (See Figure 1.)

Figure 1. Possible MVA Risk Factors:
Methods People Environment
Not adjusting mirrors/seats Hurrying Slippery surface
Not "Aiming High" in steering Inattention to construction Reduced lanes
Not utilizing a spotter when backing Pulling forward before stopping/looking Heavy traffic
Not checking behind vehicle before backing Inattention while backing Unfamiliar area
  Left a running vehicle unattended  
  Using cell phone/radio  
  Not getting clear picture of surroundings  
  Driving on autopilot  
  Driving too fast for conditions  

Variables in the methods category were related to driving skills; risk factors in the people category were largely behavioral; and variables in the environment category were related to both the driver and the condition of the environment. The team next performed a root-cause evaluation that analyzed the probability of each risk factor occurring and determining whether it was measurable. The actual MVAs were then charted according to:

  • Site (i.e., off-site, on-site, business sites, plant within site);
  • Environmental conditions (e.g., weather, light);
  • Vehicle (i.e., Dow-owned or -leased); and
  • Moving backward or not.

Next, the team studied the police and accident reports of the MVAs and surveyed the drivers involved to determine which factors played key roles in the accidents. The analysis confirmed that the following three variables contributed to (i.e., were the root causes of) most of the Company's MVAs:

  • Not focusing on driving tasks in general;
  • Not having a clear picture of surroundings (e.g., not properly evaluating road conditions, other drivers); and
  • Not checking behind the vehicle before backing.

Through its analysis, the team determined that all of the accidents involving backing up were avoidable as were 81 percent of the other accidents.

Step 3: Improve

After determining the most significant root causes of the MVAs through the Six Sigma's analysis and validation steps, the team developed a series of driver procedures or steps to address the risk factors. For example, all drivers involved in MVAs are now required to complete a course on defensive driving and have their driving observed by a supervisor in an "in-car" driver improvement course. These drivers develop a "Learning Experience Report," which is shared with other HC&E employees. In addition, topics pertaining to driving are discussed at monthly environmental, health and safety meetings. Every employee must also review a 10-step "Arrive Alive" checklist (Figure 2) before driving a Dow-owned or -leased vehicle, and suggested procedures for backing up and guidelines for using cell phones are provided.

Figure 2. The Dow Chemical Company Vehicle Pre-Startup Checklist
10 Steps to Arrive Alive:
  1. I realize that my number 1 priority right now is to drive this vehicle safely and without incident to my destination.
  2. I have checked behind the vehicle for obstacles; it is safe to back this vehicle if needed.
  3. I am mentally and physically alert and am capable of making this trip.
  4. I have securely fastened my seat belt and adjusted it for proper fit.
  5. I am aware of the weather and realize that it can change during my trip. I will adjust my driving technique to allow for darkness, fog, rain, ice, etc.
  6. I will be alert for traffic and road hazards and adjust my driving to safely allow for them.
  7. I will obey all posted highway traffic signs.
  8. I have a good attitude toward my driving, and I will be courteous and allow for other drivers' mistakes.
  9. I am devoting my undivided attention to safely operating this vehicle, and I will not allow distractions to take my mind away from driving.
  10. I know the five keys to safe driving
    • Aim high in steering
    • Get the big picture,
    • Make sure they see you,
    • Keep your eyes moving, and
    • Leave yourself an out,
    and I will practice them as I drive to my destination.

To ensure that all Dow HC&E employees understood the root causes of MVAs, the team published the findings of the Six Sigma project in Drive to Zero, the HC&E business' monthly EH&S improvement web-based newsletter.

Step 4: Control

The final phase of the project required that controls be established to sustain the project's immediate MVA reduction and to develop further improvements in line with Dow's 2005 goals. The project team developed and held a series of specific presentations, some with general information geared to all drivers, and others with more in-depth information for drivers involved in MVAs and/or who drive over 30,000 miles per year in an assigned vehicle.

The project team also established new criteria for investigating future MVAs that provide for the continuing collection of relevant data. All MVAs are now the subject of root-cause investigations, and the findings are reviewed and tracked by an MVA reduction team. As new risk behaviors are identified, this team is responsible for developing appropriate corrective measures and employee education programs.

Results Of The Project:

The project was conducted during the 3rd quarter of 2002, and the improvements and control plan put into place beginning January 2003. For 2001 and 2002, HC&E experienced 23 MVAs each year (46 total); in 2003 and 2004, HC&E experienced 15 and 17 MVAs, respectively (32) for a 30 percent reduction. This number exceeded the 20 percent reduction established as the immediate goal by the project charter and placed the Dow HC&E business unit even closer to its 2005 goal of 50 percent fewer MVAs than it anticipated. Following this success, many of the training materials developed by the project team (e.g., Vehicle Pre-Startup Checklist shown in Figure 2) have been adopted for use at other Dow businesses. While only work-related MVAs have been tracked for this project, it is likely that the driver education initiatives have helped employees avoid accidents outside of working hours as well.

The project team believes that the Six Sigma methodology was a key factor in the project's success. Through Six Sigma, the project team was able to validate the root causes of the MVAs prior to implementing corrective actions, saving both the time and expense of studying and correcting factors that did not contribute significantly to the accidents. As a result, the MVA project team was able to achieve substantial improvements almost immediately. Moreover, the improvements that the team made to record keeping and data collection will help ensure that as root causes develop, they are identified and eliminated on an on-going basis.

Sidebar: Six Sigma Methodology:

The Greek letter lower-case sigma (σ) is used in mathematics to represent standard deviation (i.e., how much a process varies from its average value). Under the Six Sigma methodology, deficiencies are described in terms of "defects" per million opportunities, with the score of 6σ (six sigma) equal to 3.4 defects per million opportunities. Six Sigma uses the following four-step process known as MAIC (Measure, Analyze, Improve and Control) to significantly reduce defects in processes, products, and/or services:

  • Step 1: Measure - define the process to be improved and the defect for the project, and identify a clear and appropriate measure for the defect;
    Step 2: Analyze - determine the root causes of the defect;
    Step 3: Improve - develop solutions to address the root causes and validate process improvement; and
    Step 4: Control - implement a long-term strategy to ensure that the improvements are sustained.

The methodology can be applied to any process that allows the measurement of benefits and improvements in defect reduction, whether in the manufacture of a product, the delivery of a service, the control of costs or the management of injuries and illnesses.

Dow adopted the Six Sigma methodology to accelerate the Company's improvement in quality and productivity. Dow has expanded the use of this approach to help manage aspects of the Company's operations beyond production and quality, including the safety and health of its workforce. Some of the other projects to which Dow has applied the Six Sigma methodology include:

  • Reducing repetitive stress injuries;
  • Improving safety for visitors (especially contractors);
  • Reducing site-logistics risks; and
  • Improving off-the-job safety processes.

These projects have been key components of Dow's 2005 goals, which include reducing Dow's reportable injury and illness rate by 90 percent to 0.24.

As the example in the case study illustrates, Dow's EH&S function has found the Six Sigma methodology particularly useful in identifying and validating root causes that are hard to discern because of their subjectivity and in focusing improvements in a motor vehicles program in ways that caused measurable improvements. Moreover, since the Six Sigma process includes the implementation of controls to ensure that achievements are sustained over a long term, the Company expects to realize the benefits of its efforts for years to come.

The views expressed herein do not necessarily represent the official position or policy of the U.S. Department of Labor.

1National Institute for Occupational Safety and Health Publication Number 2004-137: Work-Related Roadway Crashes: Who's at Risk? [Note: This document is based on a September 2003 publication. It omits data for 2002. Those data are available from Bureau of Labor Statistics, "Census of Fatal Occupational Injuries All Worker Profile, 1992-2002" (PDF). For 2003, highway deaths were 24 percent of workplace fatalities (transportation incidents as a whole were 42 percent) and contact with objects and equipment accounted for 16 percent. From 2002 to 2003, highway deaths declined and deaths from contact with objects and equipment increased.)

2Bureau of Labor Statistics, "Census of Fatal Occupational Injuries, 2003 Data, Information on Deadly Work Hazards" (PDF).