A heat wave continues to make life uncomfortable – for most people, anyway – from the Great Plains to the Great Lakes. Well-above-normal temperatures and oppressive mugginess will have people feeling like they’ve stepped into a sauna as soon as they go outside. This dangerous combination of high heat and humidity should be taken seriously by carriers and shippers. It can affect driver health. Interestingly, it may also impact freight trains carrying cargo.
Temperatures cracked 100° yesterday, July 17, in many parts of Oklahoma and Kansas. The intense heat will spread in all directions today, baking places such as Oklahoma City, Wichita, Topeka, Minneapolis, Des Moines, St. Louis, Little Rock, Memphis, Nashville, Louisville, Cincinnati, Indianapolis, Chicago, Milwaukee, Detroit, Columbus (Ohio), Raleigh, Norfolk and towns in between. Record may not be broken everywhere. However, widespread highs in the mid-90s to just above 100°, plus humidity so thick it can be cut with a knife, will have the heat index going beyond 110° in many areas.
Buckled tracks in the United States. Image: U.S. Department of Transportation
It could get just hot enough to cause some rails to warp a bit under the pressure of the heat. FreightWaves contributor Jim Blaze is a railway commerce expert who has decades of practical experience and training in both rail economics and railway track maintenance standards and procedures. Blaze said because main line railway tracks – infrastructure of rail, fasteners like spikes and plates, and ballast – are subject to extremes of both cold and heat, they sometimes buckle. These buckles are called “sun kinks” when they occur as a result of extreme heat. The resulting deformation of tracks can trigger derailments.
When repairing or laying new steel rails, structural and track engineers use complex mathematical equations that recognize the extreme historical temperature range at each location. They adjust the rail length before welding them together at joints by heating the two rail sections to a neutral rail temperature. This accounts for rail expansion at these joined track sections during extreme heat, as well as for possible rail contraction (pull aparts) on extremely cold days. Temperatures as high as 110° degrees are often outside the top range. When excessive heat occurs, railway track inspectors go to greater lengths to inspect tracks ahead of oncoming trains.
Railroad engineering departments and train operators coordinate “slow orders,” reductions in speeds in order to avoid derailments when air temperatures exceed 100°. At an air temperature of 110°, the temperature of the rails themselves can often reach 140°. Slowing down the trains can delay them by at least 30 minutes over a 50- to 70-mile track route. The impact for freight shippers is that some of their cargo may be delayed or could miss connecting freight train movements.
The same precautions are applied to passenger trains. The Chicago Tribune reported this morning, July 18, that Metra planned to slow down its trains as a safety precaution during this heat wave. Metra is the commuter railroad serving Chicago and northeastern Illinois. The commuter rail service slows trains by about 10 mph when temperatures top 95°. Also, the state’s road authority warned all drivers to look out for buckling pavement that can result from the sizzling heat.
Another side effect of the heat is stress on driver health. Heat kills more people each year in the U.S. than any other weather-related hazards. According to the latest U.S. Natural Hazard Statistics report, extreme heat killed an average of 136 people per year from 1989 through 2018, compared to 30 for extreme cold.
It doesn’t take long for sunstroke, heat cramps or heat exhaustion to kick in during hot, very humid weather. Your body becomes less efficient at cooling itself down. In order to stay as healthy as possible, it’s very important for truckers to pack extra water for their hauls. They should drink plenty of water and other non-alcoholic beverages, even when they don’t feel thirsty. They should also wear light-colored, loose-fitting clothes in case they are outside for a lengthy period of time. Light colors reflect more heat than dark ones, and loose clothes will help the body “breathe” better. Also, they should limit/eliminate time spent outdoors during breaks. Instead, finding air-conditioned spaces is the advice given.
Hot, extremely humid air can also become stagnant and hazy, trapping pollutants in the lower atmosphere near the ground. This can make breathing difficult, especially for drivers with heart or respiratory conditions.
SONAR Critical Events: Extreme heat risk areas for July 18 through July 21, 2019.
The heat wave will continue in the Great Plains and Midwest on Friday, July 19, while spreading into parts of the Northeast and New England where it will linger through the weekend. The National Weather Service has issued Excessive Heat Warnings and Heat Advisories for cities that are not used to experiencing this kind of heat and humidity very often, including Minneapolis, Chicago, Milwaukee, Detroit, Washington, D.C, Baltimore, New York City and Boston.