Author Archives: Vera Bosco

Hurricanes and Transportation Systems

Hurricanes and their impacts

When speaking about hurricane impact, usually the first things that come to mind are flooded streets, stranded people awaiting rescue, and damage to buildings. These are the most immediate impacts, but they are far from being the only ones. Hurricanes, as any other natural disaster, can have catastrophic consequences to the regions they hit.

Hurricanes are classified based on the Saffir-Simpson Hurricane Wind Scale. From this scale, hurricanes can be classified in 5 categories based on the maximum sustained speed they present. Category 5 hurricanes are among nature’s most potentially devastating disasters. While they receive their classification due to their destructive winds (157mph or higher), their strength can result in gigantic waves and catastrophic storm surge.

Flood victims are evacuated as floodwaters from Harvey rise Monday, Aug. 28, 2017, in Houston. (AP Photo/David J. Phillip)

Unlike other natural disasters such as tornados, hurricane damage is not restricted to the region it makes landfall. Hurricanes produce heavy wind and rain hundreds of miles away from the eye of the storm. Moreover, storm surges and heavy rainfall can cause as much damage as the strong winds. Massive storms can bring damage to many states at a time, as it was the case for Hurricanes Katrina, Rita, Ike, and Sandy.

Year 2017 has been presenting a very busy hurricane season, with many strong, potentially catastrophic hurricanes making landfall in the continental USA. The first massive hurricane of the season was Hurricane Harvey, that caused horrible destruction to multiple cities in Texas. Just weeks later the Caribbean and Florida were struck by Hurricane Irma. Finally, a couple of days ago, Hurricane Maria devastated Puerto Rico as a Category 4.

Hurricane Predictions

Hurricane predictions have come a long way. The forecast errors of both intensity and path reduced dramatically over the years. As is the case of any unpredictable natural event, errors occur and are larger the further away the event is.

Looking at Hurricane Harvey, for example, we know that it made its first landfall in the continental United States on August 25th, around 9:30 PM. The landfall was between Port Aransas and Port O’Connor, northeast of Corpus Christi. The National Weather Center issued a hurricane warning for Hurricane Harvey on August 25th at 4 PM (Figure 1) that covered more than half of the Texas coast, from Port Mansfield to Sargent, Texas. Hurricanes are so devastating that less than 6 hours before this catastrophic event the most accurate warning given covered around 300 miles of coast.

Figure 1: Hurricane Warning and Tropical Storm Warning for Hurricane Harvey on August 26

Moreover, Houston was not even in the Hurricane warning area, but rather in the Tropical Storm warning area. The city is actually around 160 miles from the landfall location and the damage that Hurricane Harvey caused to the city was monstrous. Figure 2 shows the flooding levels for Houston area.

Figure 2: Flooding caused by Hurricane Harvey

Hurricane impact on transportation systems

Hurricanes impacting road transportation system is pretty obvious. Before a hurricane, the road transportation system is chaotic due to evacuation procedures. During and after a hurricane, flooding closes the roads, many times leaving the population stranded.

A question asked by many after the chaos that took over Houston after Hurricane Harvey late August was: why was the city of Houston not evacuated?

The answer given by specialists is that due to the massive population in the city and the relatively short lead time between the knowledge of the strength of the storm and the expected landfall, evacuating would most likely cause more damage than good.

The example given to sustain this argument is that from Hurricane Rita. Back in 2005, a couple of weeks after Hurricane Katrina destroyed the city of New Orleans, Hurricane Rita was expected to hit Houston as a Category 5 hurricane (Katrina was a 3 when it hit landfall in New Orleans). Needless to say, the entire city wanted to evacuate.

Hours before the hurricane hit, 2.5 million people fled Houston at the same time during a triple digit heat wave. Traffic was absolute chaos, with traffic jams of over 20 hours, classified by some as the largest gridlock in U.S. history. More than 100 evacuees died in the exodus, mostly by heat stroke during all these hours stuck in the car. A tragic occurrence during the evacuation was a bus transporting elderly people from a nursing home exploded, killing 24 people.

The catastrophic impact expected from the Category 5 hurricane, however, never occurred. Rita made landfall much further east than predicted, closer to the Louisiana border, as a Category 3 hurricane. Even though Hurricane Rita did cause substantial damage ($12 billion), critics say that the evacuation caused more deaths than the storm would have caused.

But what about air traffic? Or maritime transportation? They are just as impacted by hurricanes as road transportation.

Flights must be cancelled and rescheduled, causing huge logistics impacts. Delays and cancelled flights cost both the airlines and the passengers, and after a hurricane it takes days for the airline schedules to go back to normal.

As for maritime transportation, the impact is massive for all agents involved. Ports need to end their activities, store equipment, secure vessels, and evacuate, while all the ships that were scheduled to dock at the port during the time of the storm must make a decision: wait on high seas until the hurricane passes and the port reopens, or find a new port to dock and unload its cargo or passengers.

For cargo ships, sometimes simply monitoring the storm from behind and waiting for it to go through is the best option. Other times the best decision is to reroute to a port that is not on the path of the storm. While rerouting is rather expensive and dependent on availability from other ports, sometimes waiting for the storm to pass will cause massive loss due to delays.

But what about when it is a cruise ship? These vessels have to take into account their passengers need. Their passengers 1) need to be fed for extra days – huge extra cost, 2) have other matters to attend to “on ground” and, most importantly, 3) will suffer horribly with the sea-sickness caused by being aboard a stranded ship on a windy and stormy sea.

Again, let’s take Hurricane Harvey as example. The Port of Galveston, a very busy port, especially in terms of cruise ships, shutdown and ordered its evacuation on August 24th. On August 26th, one day after Hurricane Harvey made landfall, Port of Galveston announced that it would probably open either August 29 or 30. However, the damage was much more severe than the first assessment led on, and the port could only open September 1st and only for vessels with less than 33 feet draft.

During the days that the Port of Galveston was closed, four cruise ships that were scheduled to dock at the Port of Galveston were stranded, along with over half a dozen of commercial ships. All the four cruise ships, that combined carried over 20 thousand passengers, rerouted to the Port of New Orleans or Miami.

All in all, hurricanes are massive weather events that have the potential to cause enormous impact and disrupt different aspects of every-day life. I am particularly fascinated by studying the impacts and how to mitigate them.