Traffic congestion is sure to cause any driver aggravation. Getting stuck on the road will cause you to lose time, and you'll also waste fuel as your engine idles. However, a recent study suggests that these conditions can also improve a state's road safety record.

Michael Sivak and Brandon Schoettle of the University of Michigan Transportation Research Institute, compared the road crash fatality rate of all 50 states as well as Washington, D.C. The researchers also determined how these deaths compared to a state's overall fatality rate as well as fatality rates from five leading diseases.

The nation's capital is notorious for gridlock conditions on the road. Earlier this year, the District of Columbia earned the unenviable distinction of having the worst traffic in the nation in an analysis by the Texas A&M Transportation Institute.

This analysis determined that the average D.C. commuter in 2014 spent an extra 82 hours a year in traffic, with the daily drive taking an average of 34 percent longer than it would under free flowing conditions. It also estimated that drivers in the city wasted 35 gallons of gasoline each year and spent $1,834 on this fuel and other congestion costs.

The UMTRI study suggests that sluggish traffic conditions help cut down on the risk of serious crashes. Sivak and Schoettle determined that Washington, D.C. has both the lowest road crash fatality rate as well as the fewest traffic fatalities as a percentage of all deaths. The fatality rate was 3.1 per 100,000 people, while crash fatalities accounted for 0.4 percent of all deaths in the District of Columbia.

Massachusetts had the second lowest traffic fatality rate at 4.9 per 100,000 people. This state was followed by New Jersey (6.1), New York (6.1), Rhode Island (6.2), Washington State (6.3), and Alaska (6.9).

Massachusetts also had the second fewest traffic fatalities as a percentage of all deaths at 0.6 percent. Other states where traffic fatalities made up a small share of all deaths included Rhode Island (0.7 percent), New Jersey (0.8 percent), and New York (0.8 percent).

Sivak and Schoettle say the states with the lowest crash fatality rates and fewest road deaths as a percentage of all fatalities were generally in the northern Atlantic seaboard and bordering the Pacific Ocean. Connecticut was in the top third of states with these low figures, along with Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, Ohio, Oregon, Pennsylvania, and Wisconsin.

States in the northern Rocky Mountains, the South, the Southwest, and the Dakotas had the highest traffic fatality rates and the most crash fatalities as a percentage of all deaths. Montana had the highest traffic crash fatality rate at 22.6 per 100,000 as well as the most crash deaths as a share of all fatalities at 2.4 percent.

Mississippi and North Dakota each had the second highest crash fatality rate of 20.5 per 100,000 people. Both of these states also had the second highest percentage of crash deaths, with these fatalities making up 2 percent of all deaths in each state.

The national average fatality rate for road crashes was 10.4 per 100,000 people. These fatalities made up 1.3 percent of all deaths in the United States.

In addition to these calculations, Sivak and Schoettle also compared crash fatalities to the fatality rates and percentages from five major diseases in each state. These illnesses included Alzheimer's disease, cancer, heart disease, lung disease, and stroke.

The study found that crash fatalities were considerably less common than these causes of death. That nationwide fatality rate per 100,000 people was 26.8 for Alzheimer's disease, 40.8 for strokes, 47.2 for lung disease, 185 for cancer, and 193.3 for heart disease.

However, crash deaths still made up a substantial share in the comparison. Traffic fatalities were equal to 5.4 percent of the deaths caused by heart disease, 5.6 percent of those caused by cancer, 21.9 percent of those caused by lung disease, 25.4 percent of those caused by stroke, and 38.6 percent of those caused by Alzheimer's disease.

Fatality rates for these diseases varied widely from state to state. Sivak and Schoettle say heart disease and cancer are more common in the eastern half of the United States, while lung disease and stroke are generally most common in these states and the Midwest. The Midwest and some Western states usually had higher fatality rates from Alzheimer's disease. The West had the lowest fatality rates related to disease in general.

For this reason, crash fatalities compared to disease fatalities in a wide variety of proportions. Sivak and Schoettle noted that while crash fatalities were equal to only 13.3 percent of deaths caused by Alzheimer's disease in Washington State, they were equal to 91.4 percent of deaths caused by the disease in New Mexico.

In 46 states, crash fatalities were equal to more than 25 percent of deaths caused by Alzheimer's disease. Crash deaths exceeded this percentage when compared to stroke in 30 states and when compared to lung disease in 18 states.

Although the National Highway Traffic Administration is predicting that overall traffic fatalities in the United States will be higher in 2015 as travel increases in the nation, these deaths have been trending downward in recent years. Richard Read, writing for the automotive site The Car Connection, says crash fatalities will likely continue to decline as vehicles' anti-collision technology improves.

Sivak and Schoettle say the data for their study came from the NHTSA as well as the Centers for Disease Control and Prevention. The study used data from 2013, the most recent year with available statistics from the NHTSA.