PHNOM PENH: Nearly nine centuries ago, Chinese builders laid massive granite slabs across a tidal estuary in Fujian province, even as Khmer engineers were constructing stone-arched bridges along the road network of the Angkorian Empire.
Built in different environments and for different purposes, China’s Anping Bridge and Cambodia’s Spean Praptos, commonly known as Kampong Kdei Bridge, remain striking examples of advanced 12th-century engineering.
A group of ASEAN journalists visited the Anping Bridge in Anhai town, Jinjiang, on September 22, where a Chinese guide explained how ancient builders overcame soft seabed conditions, tidal currents and the difficulty of moving stones weighing several tonnes.
Anping Bridge connects Anhai town in Jinjiang with Shuitou town in Nan’an. Both county-level cities are administered by Quanzhou, in Fujian province.
Construction began in 1138 during the Southern Song dynasty and was completed in 1152. Work therefore began 888 years ago, while the completed bridge has stood for approximately 874 years.
The bridge extends approximately 2.25km and is between 2.9m and 4m wide.
It is also known as Wuli Bridge, or Five-Li Bridge, because its length was equivalent to approximately five traditional Chinese li.
“The longest stone slab reaches about 11m, and the heaviest weighs about 25 tonnes,” the guide told the journalists as they walked along the ancient structure.
Without modern cranes, builders transported granite by boat and used rising and falling tides to position the slabs above the piers.
Some local accounts suggest that part of the stone came from Kinmen and nearby islands, although the source of all the granite has not been conclusively established.
Anping Bridge also employed a “sleeper-log foundation” technique.
Builders laid wooden logs across soft mud and placed heavy stones above them, gradually forcing the foundation down towards a stable load-bearing layer.
Oysters growing around submerged sections helped bind and protect the stonework from waves and erosion.
They did not produce an adhesive liquid, as sometimes described; their shells accumulated around the masonry and strengthened its exterior.
The builders used three pier designs to respond to different currents: rectangular, single-pointed or half-boat-shaped, and double-pointed boat-shaped piers.
Official descriptions generally identify 360 piers — 290 rectangular, 44 single-pointed and 26 double-pointed — although some accounts count 361. The bridge has 362 water openings.
Anping Bridge supported trade and travel between Quanzhou and areas further south, reflecting the prosperity created by maritime commerce during the Song and Yuan periods.
In 2021, it became one of 22 component sites of the UNESCO-listed “Quanzhou: Emporium of the World in Song–Yuan China”.
Cambodia’s Kampong Kdei Bridge presents an important comparison from approximately the same period.
Located at Kampong Kdei in Chi Kreng district, Siem Reap province, the approximately 87m bridge is associated with the reign of King Jayavarman VII and the road network that connected Angkor with other parts of the Khmer Empire.
Unlike Anping’s long granite beams resting on hundreds of piers, Kampong Kdei was built from laterite blocks with more than 20 corbelled arches.
Its nine-headed naga balustrades combine engineering with Khmer religious symbolism and artistic identity.
The two bridges provided different solutions to similar challenges.
Anping served a maritime trading system and relied on tides, timber foundations and current-specific piers, while Kampong Kdei carried travellers across a river on the Angkorian land network.
Their survival demonstrates that ancient bridges were not merely transport infrastructure, but enduring expressions of economic power, technical knowledge and cultural identity. - Phnom Penh Post/ANN
