A railway bridge weighing more than 4,000 tons was not built directly over the tracks it would eventually serve. Instead, Hamburg's new Sternbrücke was completed away from the railway and then transported through the city in one extraordinary overnight operation.
The journey covered only about 1,600 feet, but the route left almost no room for mistakes. At the narrowest sections, the enormous steel structure passed buildings with roughly 16 inches of clearance. More than 100 specialists worked in shifts as the bridge moved slowly through the Altona neighborhood, as per a report by The Pulse.
How can a bridge this heavy be transported?
The new Sternbrücke is a tied-arch railway bridge, with its steel arches curving inward above the deck. It measures about 354 feet in length and roughly 69 feet across, while its steelwork weighs approximately 4,060 tons.
Moving something of that size required a very different approach from ordinary road transport. The bridge was supported by 48 self-propelled modular transporters, known as SPMTs. These hydraulic platforms are used for exceptionally heavy loads, including large industrial equipment and ship sections.
For the Hamburg operation, the transporters were linked beneath the completed bridge. Their combined 1,088 wheels distributed the enormous load across the road as the structure made its way through the neighborhood.
The movement was deliberately slow. The convoy traveled at a maximum speed of around half a mile per hour, turning what might normally be a short road journey into an operation that occupied most of a night.
How did it squeeze between the buildings?
The weight was only one part of the engineering challenge. The route passed through an established part of Hamburg where buildings stood close to the roadway. In the tightest locations, the gap between the bridge and nearby walls was only about 16 inches.
That tiny margin meant the transport system had to be capable of making constant adjustments. The SPMTs could steer their axles individually, allowing the bridge to move sideways as well as forward. The entire load could also rotate around its center and make corrections during the journey.
Before the move began, survey marks were placed along the road so its position could be monitored. The bridge's movement was watched throughout the operation.
Preparations also extended beyond the transporters themselves. Street signs had to be unbolted, lamp brackets were removed and steel plates were placed across sections of the roadway.
The move took place at night, beginning in the evening and continuing until the following morning.
Why was the bridge built somewhere else?
The unusual transport was closely connected to the importance of the railway underneath. The route between Hamburg's main station and Altona carries regional, long-distance, commuter and freight services. Keeping that railway operating for as long as possible was therefore a major consideration.
Rather than constructing the replacement bridge directly over the active railway, crews assembled the Sternbrücke completely at a prepared site a few hundred yards away.
That allowed railway traffic to continue while the new structure was being built.
Once the old bridge was ready to be removed, the railway could be closed during a planned period. The existing structure could then be taken out and the completed replacement transported into position.
The strategy meant that the major interruption to the railway could be concentrated into a defined construction window instead of leaving the line unavailable while the new bridge was built.
What happened after the bridge reached its destination?
Reaching the site did not mean the project was finished. The bridge had traveled on its transporters at a height of about 20 feet above the ground. This allowed it to clear its final supports before being lowered into position.
Afterward, the transporters were driven out from beneath the structure. The steel then had to be permanently connected to the concrete at both ends using bolts and grout. Railway crews also had to restore the track itself, including sleepers and ballast, followed by the overhead wiring. That work continued through the end of the month. So while the bridge's overnight journey provided the most dramatic part of the project, it was only one stage in turning the enormous steel structure into an operational railway bridge.
Why did the replacement matter?
The new bridge replaced a structure dating from 1926 and followed a lengthy public discussion over the need for a replacement. Project manager Janna Widmaier said afterward that the lift had gone smoothly. The scale of the operation is perhaps easiest to understand through its numbers. A finished bridge weighing around 4,060 tons was moved approximately 1,600 feet through a residential district, supported by 48 hydraulic transporters and 1,088 wheels.
At certain points, only 16 inches separated the moving steel from nearby buildings. The decision to assemble the bridge away from the railway and transport it afterward also reflected the need to limit disruption on one of northern Germany's busiest rail corridors.
For several hours, the completed bridge was no longer simply a construction project sitting beside the railway. It became an enormous moving load navigating Hamburg's streets with carefully controlled precision.
Once the transporters disappeared and the bridge was lowered onto its supports, the most extraordinary part of the operation was over.
What remained was the less dramatic but essential work of connecting the steel, rebuilding the railway and preparing the new Sternbrücke to carry trains.
FAQs
How far did the bridge travel?About 1,600 feet.
How many wheels carried it?
1,088 wheels.
