UPS and FedEx are going to great lengths to deliver holiday packages on time - but it may not be enough

Between Thanksgiving and Christmas, Americans ship more than 1 billion packages.

This means it's peak season for the shipping giants UPS and FedEx.

Every year, both companies take extraordinary measures to make sure they are equipped to handle the additional traffic and there's always a last-minute scramble to get holiday packages delivered on time.

UPS is expecting to ship a record-setting volume of more than 700 million packages between Thanksgiving and Christmas - an increase of more than 70 million over 2015's record total. At the same time, FedEx is projecting a 10% increase over the more than 325 million packages it shipped last holiday season.

Last year both companies experienced delays due to an unexpected surge in online shopping. Here's a look at what UPS and FedEx are doing to try and prevent a holiday shipping disaster.

Bracing for the rush

In preparation for the peak shipping season, UPS has added - like last year - 95,000 seasonal employees along with fleets of leased aircrafts, trucks, and trailers. (UPS declined to comment on how many aircraft and trucks they are adding this year.) In addition, UPS has boosted its package processing capacity with temporary mobile delivery centers and more UPS Access Point locations, a company spokesperson told Business Insider in an email.

UPS also has a team of five meteorologists on staff at the company's Louisville, Kentucky World Port international air cargo hub keeping tabs on weather around the world.

Since the last peak season, FedEx has added an additional 12 million sq. ft. of sorting space including four new major distribution hubs in Tracy, California; Ocala, Florida; Metuchen, New Jersey; and Toronto, Canada.

FedEx has also hired 50,000 seasonal employees - down 5,000 from last year - to help cope with the increased volume. The company's vaunted air-freight operation has acquired 30 additional jets since last year's peak season.

However, even with this kind of preparation, plans can still go awry.

Last year, UPS resorted to renting hundreds of U-Haul moving vans to bolster its delivery fleets when shipping volumes pushed the capacity of its trucks to the limit. In fact, there were reports of concerned citizens calling law enforcement due to the unexpected presence of these U-Hauls in their neighborhoods.

Some packages in New Jersey and California even ended up in trucks parked outside of FedEx and UPS warehouses for days just waiting to be sorted.

But this year, both shipping giants are turning to technology to help them get through the onslaught of packages and avoid these kinds of past mishaps.

Big bets on new tech

UPS is banking on its new navigation, dispatch, and routing software called ORION - or On-Road Integrated Optimization and Navigation- to speed up delivery times and cut down on the number miles driven.

According to UPS, ORION's algorithm considers more than 200,000 ways to conduct a single route before settling on the most efficient course of action.

The system has taken more than a decade to develop and fully integrate into the Atlanta-based company's 55,000 North American delivery routes.

FedEx, on the other hand, has installed Enhanced Vision systems on 270 of its fleet of nearly 400 cargo planes. The infrared night vision system "will greatly improve pilots' ability to land in low visibility conditions and mitigate potential weather delays," a FedEx spokesperson told Business Insider in an email.

Despite all their efforts, though, both companies are sticking to their policy of suspending delivery guarantees in the final weeks leading up to Christmas.

FedEx plans to suspend its money-back delivery guarantee for FedEx Ground Nov. 28 through Dec. 24. At FedEx Express, there will be no guarantee on Nov. 23 and Dec. 19 through Dec. 24.

For UPS, there will be no ground delivery guarantees Nov. 27 through Dec. 3 and Dec. 18 through Dec. 24.