TRAIN GENERATED AIR CONTAMINANTS IN THE TRAIN CREW'S WORKING ENVIRONMENT

ABSTRACT

This document contains data on the levels of air contaminants in the train crew's working environment. Measurements were made in locomotive cabs and cabooses of freight trains travelling through long tunnels and over mountainous terrain. In addition, measurements were performed in long-hood forward locomotives during through freight operations and in switchyard locomotives. The data from this study indicate that the breathing environment of railroad operating crews is acceptable within the guidelines of the published Occupational Safety and Health Administration (OSHA) standards.
Appendix A covers the sources of air contaminants in the railroad environment and Appendix B gives a detailed description of the measurements in this study. A review of related studies is given in Appendix C.

APPROACH

From a literature survey of air contaminants in railroad operations the sources of the contaminants are compiled in Table 1. In addition, applicable OSHA standards were examined. In an initial effort to limit the scope of the study, pilot measurements of air contaminant levels under selected worst case situations were made, namely freight trains in tunnels.

This selection was based on information contained in publications of prior investiga­tors who found the highest levels of air contaminants in tunnels.
As explained in greater detail in Appendix A, the locomotives' diesel engine is the main source of crew space air contaminants and production of contaminants increases proportionally with engine size. Consequently, the primary objective was the measurement of air contaminants produced by the largest engines in the longest tunnels.

Measurements of air contaminant levels in locomotives and cabooses were made during 39 trips through tunnels that varied in length from 0.75 to 7.8 miles. These tunnels are listed in Table 2.

Measurement trips lasted from 30 minutes to 2 hours, with 20 to 30 minutes in a tunnel. The total trip distances range from 15 to 60 miles. The numbers of each type of locomotive sampled are as follows: EMD [SD-45 (1), SD-40-2 (5), SD-40 (2), GP-9 (4), GP-38 (2)] and GE [U-33 (3), U-30 (1)].

Additional measurements were performed in situations where either no previous data was available (long-hood forward locomotive and switchyard locomotives) or where it was thought desirable to check the accuracy of previously recorded data (locomotive and caboose in through freight service). These measurements were performed, under contract, by Scott Environmental Technology, Inc.
(Scott).


The Scott measurements were comprised of eight through freight trips of distances from 130 to 240 miles. Sampled during these trips were cab-front locomotives, cabooses, long-hood forward locomotives, helper locomotives in tunnels, and switchyard locomotives.

These trips lasted from nine to twelve hours. The following loco­ motive types were sampled: SD-45 (2), GP-38-2 (2), SD-40 (2), SW-7 (1), SD-35 (1), and NW-2 (1) . A compilation of all the trip infor­mation is given in Appendix B.

For all of the measurement trips the following contaminants were measured: carbon monoxide, nitric oxide, nitrogen dioxide, total particulates, total hydrocarbons, and total aldehydes. These contaminants were measured for the following reasons: (1) data
can be compared with results of other investigators who have measured some or all of these contaminants; and (2) highly reliable and accurate instrumentation is available for measurement of these contaminants.

Specific hydrocarbons, particulates, and aldehydes were not measured because continuous and fast responding techniques are not available for these contaminants. Sulfur dioxide was not measured because a sensitive, continuous technique was not available and the SC level can be calculated from the sulfur content of the diesel fuel.

MEASUREMENT INSTRUMENTS


The measurement instruments utilized during the TSC studies were sensitive, highly reliable, battery operated, and portable. These characteristics were dictated by the low levels of air con­taminants to be measured, the rough environment encountered in rail­ road operations, and the lack of space and power in locomotive cabs and cabooses.

These instruments also permitted flexibility in measurement location with minimum set-up and break-down time.
Table 3 lists the instruments used. This equipment was calibrated at the beginning and end of each day of measuring. Samples in the locomotive cab were taken at the brakeman’s seat and at the console in front of the engineer. In the caboose, samples were taken at
the rear conductor's desk.

Table 4 lists the measurement devices used by Scott. The Scott instruments were extremely sensitive, and featured continuous operation and fast response. The equipment was powered by a portable generator. Scott sampled from the sampling location to the instru­mented test car through a teflon line. Measurements were taken in the same locomotive and caboose locations as the TSC measurements. Scott also sampled the air in the cupola of the caboose. Instrument calibrations were made at least every hour.

RESULTS

Tables 5, 6, 7, and 8 summarize the results of the TSC and Scott measurements. In addition, the OSHA standards are presented. The values presented are the maximum levels measured over a time period in a particular sampling location. The reference measure of exposure (OSHA standard) for most substances is the "8-hour time weighted average" (TWA) in one 8-hour work shift for a 40 hour work week.

Table 5 summarizes the peak levels measured by TSC and Scott in 39 separate measurements in locomotive cabs and caboose passing through the long railroad tunnels (20-30 minutes). Also summarized in Table 5, are the peak levels measured by prior investigators in locomotive cabs and cabooses in tunnels. A dis­cussion of these other investigations is presented in Appendix C. The values shown in columns 3 and 4 for carbon monoxide and nitric oxide levels appear to exceed the OSHA standards, but this is not the case since the contaminants’ concentration reached these levels for periods of only 20 and 30 minutes respectively while the trains were in a tunnel.

Because the measurements were taken only during the time the trains were in the tunnels, an 8-hour time weighted average cannot be reported as such. However, if a crew member making a tunnel trip was exposed for the remainder of the 8-hour work shift to normal air contaminant levels, such as those summarized in Table 8, then an approximate 8-hour time weighted average can be calculated. Using this procedure the 8-hour TWA's for various numbers of tunnel trips were calculated and are presented in Table.6. The data used in these calculations were taken from Tables 5 and 8.

As can be seen from Table 6, the calculated 8-hour averages for a combined tunnel trip and normal working day yields an 8-hour time weighted average well within OSHA standards. Also shown in Table 6 are the 8-hour time weighted averages for five tunnel trips during a normal working day. These levels are within OSHA standards. Generally, helper locomotive crews make only three to four trips a day through these long tunnels and their exposure levels are within OSHA standards.

Table 7 presents the results of measurements in long-hood for­ ward road-haul and switchyard locomotives. Comparison with Table 5 and 6 shows that the maximum levels measured are several orders of magnitude lower than those found in tunnel operations. In further comparison with Table 8, which presents the 8-hour time weighted averages measured in locomotives and cabooses during typical through freight operations, the long-hood forward locomotives were not found to differ significantly from cab forward locomotives. In fact, in all operations except tunnels, the maximum levels of some con­taminants occurred when crew members smoked.


