DC Feedback: Locomotive cab temperatures

Study shows cabs hotter than 90 degrees 88 percent of the time during August 2000

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This month's installment deals with the question of temperatures in locomotive cabs.

What is the BLE doing in regards to an air conditioning standard for locomotive cabs?

Locomotive engineers are forced to work in temperatures hotter than 90 degrees nearly 90 percent of the time during summer months, according to preliminary results of the Brotherhood of Locomotive Engineers' three-year survey of locomotive cab temperatures.

In August of 2000, 88 percent of locomotives surveyed by BLE members had ambient in-cab temperatures that were 90 degrees Fahrenheit or higher. Over a 12-month period, cab temperatures averaged 90 degrees or higher 20 percent of the time (in locomotives without working air conditioners), and above 100 degrees five percent of the time.

This data is part of the BLE's ongoing study into the need for a maximum temperature limit inside locomotive cabs. Scientific studies have proven that worker performance reaches its lowest levels during periods of extreme heat. The purpose of the study is to provide data for the use by the Rail Safety Advisory Committee (RSAC) in developing a high temperature standard in locomotive cabs.

The best way to regulate in-cab temperature is by air conditioning. The carriers, however, have been loath to implement an air conditioning standard due to cost. Regular exposure to temperatures above 86 degrees, however, can cause fatigue, nausea, dizziness, heat exhaustion, heat stroke and even death if the body loses its ability to cool itself.

Opening a door or window to lower cab temperatures is unsafe, the BLE report concludes. Opening windows leaves locomotive engineers unprotected from projectiles and harmful diesel exhaust fumes. In addition, there were several reports of mosquito swarms entering locomotive cabs in cases where windows were left open.

The BLE In-Cab Temperature and Humidity Survey began in the summer of 1998. BLE members in 29 states participated in the survey, equipped with hygro-thermometers provided by the BLE's National Legislative Office headquartered in Washington, D.C. The engineers who participated have provided more than 2,500 useable temperature and humidity ratings, which is the basis for the temperature readings provided above.

For more details, please read the following summary of the In-Cab Temperature and Humidity Survey, which was prepared by the BLE's Washington D.C. office.

BLE In-Cab Temperature and
Humidity Survey, 1998-2001

This draft summarizes the information collected as of August, 2001 by BLE members on temperature and humidity in locomotive cabs.

Beginning in the summer of 1998, and continuing now, BLE members have been participating in data collection for the In-Cab Temperature and Humidity Survey. In this time, more than 2,500 useable temperature and humidity ratings have been recorded. Over three years, in 29 states, 24 hours a day, temperature and humidity readings were measured and recorded at three locations in the locomotive cab: the engineers' side, conductors' side, and center of the cab. Measurements were made in locomotives both with and without air conditioning. Outside (ambient) air temperature and humidity were also recorded at the time interior recordings were made. Persons who were collecting data were instructed to insure that the data collection process did not hinder safe train operations.

Participating BLE divisions were issued a hygro-thermometer with identifying number, provided written instructions facilitating consistency of data collection, given standardized reporting forms with detailed fields for information entry and instructed to measure the temperature and humidity at the locations detailed below. These measurements were made at three hour intervals, three times during their shift. The specific locations were:

1. Outside the cab;

2. Engineer's side at "belt buckle" level, in a sitting position;

3. Conductor's side at belt buckle level; and

4. Center of the cab, approximately four feet off the cab floor.

We asked that they note any unusual circumstances that may affect the interior cab temperature/humidity, including mechanical problems such as failed air conditioners or weather stripping problems and unusual weather conditions. We requested the position of windows (open or closed) be recorded.

The geographic diversity of the readings provides a good picture of cab temperature/humidity conditions and indicates an accurate picture of the differences between locomotive cabs with and without air conditioning. Twenty-five percent of the temperature readings were taken between midnight and 7:59 a.m., 46 percent of readings were taken between 8:00 a.m. and 3:59 p.m. (covering the period when the heat is likely to be greatest) and the remaining 29 percent were taken between 4:00 p.m. and 11:59 p.m.

The purpose of the study was to provide data for the use of the Rail Safety Advisory Committee (RSAC) in developing a high temperature standard in locomotive cabs. Within the RSAC, two significant questions arose:

1. How hot and humid does it get in locomotive cab?

2. Are high temperatures affecting safety and health?

To answer the last question, BLE has documented cases of heat related illnesses experienced by locomotive engineers while occupying locomotive cabs and believes there is considerable evidence to support a decrease in human performance (safety) when exposed to hot environments.

Heat contributes significantly to fatigue as well. It is understood that cold temperatures can adversely affect human performance. In hot temperatures, particularly those above 86 degrees Fahrenheit (F), fatigue, nausea, dizziness, heat exhaustion, heat stroke and even death can result when the body loses its ability to cool itself.

During RSAC discussions, information was introduced utilizing the Federal Railroad Administration's (FRA) accident statistics generated in the years 1992 to1997. The information reported was based on cause codes associated with "human factor" accidents. There are only a few data points in this accident category. Overall, accidents are a rarity in our industry but, there is a relationship between these human performance accidents and ambient temperature; that is to say that accidents of this type will peak at the low temperature extremes and at the high temperature extremes (in this case, over 90 degrees Fahrenheit)

While our data was not seeking and, therefore, shows no correlation, other studies have demonstrated that accident rates increase in extreme temperatures. In fact, FRA data from 1994 shows that accidents in July and August, two of the hottest months of the year, are the fourth and third highest, respectively. FRA data also shows that Yard accidents are highest between 6 a.m. and 10 a.m., and mainline accidents are highest between 10 a.m. and 2 p.m. This mainline information correlates precisely with the times when sun exposure is at its peak. Human factors yard acidents peak between 4 p.m. and 6 p.m., coinciding with a low point in alertness, according to circadian rhythms, and with the time period when heat effects from peak exposure would be felt.

The BLE data indicates that 20 percent of temperature readings fell above 90 degrees Fahrenheit, most of them in the months of August and September. Five percent of all of the data collected showed inside cab temperatures above 100 F, ranging as high as 123.1 F with a humidity reading of 16.1 percent. In this one measurement the outside-the-cab temperature was 108 F at 22.2 percent humidity. There were frequent reports of temperatures over 110 F. Of note is that in August of 1999, 64 percent of data collected showed temperatures above 90 F at the engineers' side. In August of 2000, this number increased to 88 percent. Temperatures above 80 F occur as early as March, and above 90 F as early as April. These high temperatures continue through the summer and into the fall, ending in October.

Air conditioning in cabs can reduce temperatures an average of 10 to 12 F, with the possibility of reducing temperatures as much as 20 F or 25 F, bringing temperatures well above 90 F into the range where they are much less likely to affect performance, or cause heat related illnesses.

Data reporting sheets contained space for comments from engineers. The necessity of closed windows was noted in several cases when under the heat and humidity conditions, open windows would have been preferable. Several reports of mosquito swarms fell into this category. Engineers also expressed concern with rocks being thrown at the cab, as well as other conditions like diesel fumes or dust in the air. Closed windows would also provide additional protection from diesel fumes and noise; occupational hazards for locomotive engineers.

We have also collected several reports of engineers leaving cab doors open to cool the cab, allowing even greater exposure to dangerous noise levels, diesel fumes and dust, and adding to the risk of being struck by a projectile. It was also noted that opening windows in locomotive cabs designed for air conditioning provided poor ventilation and relief when the air conditioning failed to function properly.

Extensive study may be required to establish conclusively that air conditioned cabs can improve employee alertness and health. The potential to decrease accidents and incidents by maximizing human performance is without question. A reduction in exposure to other occupational hazards, including diesel fumes, dust and noise, would be a benefit of air-conditioned locomotive cabs.

The BLE continues to gather data on this critical issue and will pursue this effort with increased vigor, knowing the need exists and is being demonstrated by the survey data.

Thanks to all who continue to participate in this study.

2001 Brotherhood of Locomotive Engineers