Inside the world’s most expensive megaproject that cost £341bn | World | News
From new soaring bridges in China to vast rail networks carving through Europe’s mountains, the world is packed with jaw-dropping infrastructure megaprojects that showcase human engineering ambition at its boldest. Yet, despite the eye-catching scale of developments elsewhere, it is the US’s Interstate Highway System that stands as the most expensive project ever built.
Spanning the entire nation and even into the Caribbean, its staggering cost still dwarfs even the most futuristic projects now taking shape around the globe, despite being formed just under 70 years ago. Also known as the Dwight D. Eisenhower National System of Interstate and Defense Highways, this is the network of controlled-access highways that extends throughout the US mainland, as well as routes in Hawaii, Alaska and Puerto Rico. Spanning over nearly 49,000 miles, it is the backbone of American transportation.
While planning began in the late 1930s under Franklin D. Roosevelt (FDR), the system as we know it today was championed by Dwight D. Eisenhower. His passion for a national highway network arose from two life-altering experiences. The first was his 1919 convoy, when, as a young Army officer, President Eisenhower participated in a transcontinental motor convoy that took 62 days to cross due to muddy, impassable roads. Then, during World War 2, he was impressed by Germany’s high-speed road network, the Autobahn, which enabled the rapid movement of troops and supplies.
As a result, President Eisenhower signed the Federal-Aid Highway Act of 1956, which authorised the construction and established a funding model where the Federal Government paid 90% of the costs.
Unlike the earlier US Numbered Highway System, the interstates were designed to be all freeways, with nationally unified standards for construction and signage. While some older freeways were adopted into the system, most of the routes were completely new.
Construction of the original Interstate Highway System was proclaimed complete in 1992. The system has continued to expand and grow as additional federal funding has enabled the addition of new routes and many future Interstate Highways are currently either being planned or under construction.
According to NeuroJect, it has cost the American taxpayer an eyewatering $459billion, or £341billion.
The official name includes “Defense Highways” because the system was designed with national security in mind. During the Cold War era, it was intended to allow for the mass evacuation of cities in the event of a nuclear strike. It also ensures that the military can move heavy equipment and troops quickly across the continent.
The system follows a strict grid-based numbering logic that helps drivers navigate without a map: a North-South route uses odd numbers that from west to east, such as I-5 (West Coast), while an East-West route uses even numbers that increase from south to north, such as the I-90 (North). Loops or bypasses have three digits starting with an even number, like the I-495 (Capital Beltway), while spurs have three digits starting with an odd number, like the I-190 (New York.
The longest route is the I-90, stretching 3,020 miles from Seattle to Boston, while the shortest is the I-110 in El Paso, Texas, at just 0.92 miles.
