Tainan Railway Dig Uncovers 19th Century Roads Built With Sugar Fragments

A sugar district's history emerges beneath Dongmen Road

Road foundations containing sugar fragments, broken ceramics and roof tiles have been uncovered near Sin Lau Hospital on Dongmen Road in Tainan's East District, revealing an unusual connection between the city's streets and its sugar economy nearly two centuries ago.

The discovery came during construction to move a section of Tainan's railway underground. The Tainan Municipal Administration of Cultural Heritage said the remains appear to belong to important thoroughfares built in the first half of the 19th century, when Taiwan was administered as a prefecture of Fujian under the Qing Dynasty.

Archaeologists compared the location and alignment with an 1875 map of Tainan and identified a likely connection to the Bullock Cart Road. Historical context and the map suggest that construction or renovation took place around 1836, during the reign of Emperor Daoguang.

The roadbeds consist of mixed mud mortar, with gaps between stones and compacted layers packed with mortar, ceramic fragments, tile pieces and sugar. Researchers interpret that combination as a practical use of materials that workers could obtain easily and cheaply in an area known for sugar production.

Tainan's cultural heritage administration says the team has documented the location and temporarily relocated the materials so the railway project can continue. Plans call for the remains to be presented later as part of a new parkway cultural project, connecting a modern transport corridor with the roads that served the city long before industrial sugar factories and dedicated sugar railways.

A Qing era account adds a striking detail to that connection: sugar was described as so plentiful in the district that summer heat could bring a sweet smell out of its streets. The discovery gives that historical description a physical setting, where the materials of everyday trade became part of the road itself.

What workers packed into the road

Mud mortar formed the base of the uncovered structures. This compacted earth mixture could be stabilized with natural binders and covered with successive layers, providing a foundation before modern asphalt became the familiar material for urban roads.

Workers filled crevices with mortar and small, hard pieces of broken pottery and roof tiles. Fired clay fragments resist wear, helping create a tougher surface. Small spaces between fragments could also form channels through which water could escape, improving drainage.

Sugar was part of the material wedged into gaps, rather than a separate surface covering. Its likely role was practical rather than decorative: in a district that processed and traded sugar in bulk, fragments were among the small pieces available for road work.

Historical roadbeds often incorporated local waste and byproducts to help bind and stabilize their surfaces. Tainan's mixture fits that pattern of reuse, bringing together earth, mortar, broken household or building materials and remnants of a major local commodity.

The mixture also suited a road that might need repeated repairs. Mud mortar combined with shards and sugar pieces would have produced a firm but workable surface that crews could patch. Local kilns and households supplied broken pottery and tiles, while sugar processing and transport offered another possible source of material.

The account of streets that smelled sweet

A Qing official chronicle described summer heat drawing sweetness from the streets of the sugar district. The historical account linked rising steam with sugar mixed into the road and sugar scattered nearby:

During one summer, steam rose from the roads. It reacted with sugar mixed into the road and with sugar scattered nearby, and the air filled with a sweet aroma.

The description presents sugar as part of the street environment, extending beyond mills, storage buildings and goods awaiting transport. It is consistent with the archaeologists' interpretation that sugar was available in quantities large enough for road crews to mix it into filler alongside pottery and tile.

Sugar could have been spilled, crushed and pressed into the ground as people worked and carts moved through the area. Processing waste offers another possible explanation for how fragments reached the construction mixture. Both possibilities connect the road to the routine movement and handling of sugar.

The chronicle's sensory detail also helps make the find understandable. A road foundation can appear to be little more than layers of earth and rubble. The description of sweet summer air places those layers within a working district, where a traded product affected the surroundings as well as the economy.

How the road was dated to around 1836

The 1875 city map provides a key reference for identifying the remains. Researchers found that the road's alignment and location correspond to the route marked as the Bullock Cart Road, linking the excavated foundations to a named historical thoroughfare.

The estimated construction or renovation date is earlier than the map. Archaeologists combined the cartographic comparison with historical context and the materials at the site to place the work around 1836, within the first half of the 19th century.

Emperor Daoguang's reign lasted from 1820 to 1850. Tainan remained a regional centre for agricultural commerce during that period, with goods moving into and out of the city using transport drawn by animals. A road built or repaired around 1836 would have served that traffic.

The chronology connects the road's likely working life with the later record used to identify it:

• 1820 to 1850: Emperor Daoguang's reign, the period associated with the road's likely construction or renovation.
• Around 1836: The estimated date of construction or refurbishment, based on historical context and the map comparison.
• 1875: The date of the Tainan map showing the Bullock Cart Road alignment matched to the excavated remains.

Bullock carts were slow but dependable. The road's name suggests a route used by heavy carts carrying sugarcane, processed sugar, ceramics and other goods toward warehouses and ports in the Tainan area. Such traffic called for sturdy surfaces that could be repaired with readily available materials.

From cane fields to factories and railways

Sugar shaped Tainan's economy over several centuries. During the Qing era, farmers grew cane on the plains surrounding the city. Small mills and boiling houses processed it into crystalline sugar, syrup and molasses, while coastal trade carried that output to regional markets.

Historical descriptions of workers, carts and sacks moving through streets and storage yards show how closely production and transport were tied to daily urban life. The excavated road belongs to that earlier system, when local materials and practical building knowledge supported the movement of agricultural goods.

Under Japanese rule, sugar production later expanded through industrial factories and private railways built to transport cane. Historic surveys cite more than forty factories and an extensive network of sugar rail lines connecting fields, mills and ports.

Tainan's Yongkang district became home to a major factory complex with its own narrow rail lines, housing and community spaces. Production and export became more standardized under the new regime, while pathways and patterns of labour retained roots in the previous century.

The Dongmen Road foundations provide a tangible connection between those stages. Roads reinforced with pottery, tile and sugar fragments preceded the large factory and railway networks of the 20th century. Industrial expansion developed above an older landscape of cart routes and locally built infrastructure.

Broken tiles and sugar remnants also show the resourcefulness involved in maintaining that landscape. Materials associated with homes, kilns, processing and trade could be reused in road construction instead of being discarded. The city's sugar economy affected what moved along the streets and what went into making them.

Why sugar residues could survive underground

Sugar dissolves in water, making its reported presence in an old roadbed an unusual part of the discovery. The explanation depends on the conditions around the material: mortar and compacted earth can create protected pockets where fragments have less contact with flowing water.

A fragment embedded and sealed within the road mixture may experience limited water infiltration. Reduced exposure can help preserve residues that would otherwise dissolve more readily in an open, wet setting.

Crystallized sugar can also partly dissolve and then recrystallize when moisture comes and goes and the surrounding mixture dries. Over time, that process can leave detectable residues within the fabric of the road.

Microscopy is one way to investigate such material. Researchers can examine the mixture for crystals or small rounded deposits and document where they occur. Chemical spot tests can then screen for carbohydrates, the family of substances that includes sugars.

Laboratory methods such as high performance liquid chromatography and mass spectrometry can detect sucrose and its breakdown products, glucose and fructose. These techniques help separate and identify the chemical substances present in a sample.

Stable isotope analysis can sometimes help distinguish cane sugar from other plant sources by examining carbon signatures. Sugarcane and many grasses share similar signatures, so this approach requires careful sampling and controls. Infrared spectroscopy offers another method, identifying chemical groups associated with carbohydrates in material preserved among minerals.

Together, these methods provide a toolkit for determining whether granular material in crevices is sugar or another organic filler. The explanation of the find describes these possible techniques without specifying which laboratory tests were used on the Dongmen Road remains.

Sugar residues, ceramic shards and tile fragments also help reconstruct worksite behaviour. Household refuse and kiln waste could supply the fired clay, while spilled sugar or processing waste could supply sugar fragments. Crews using materials close at hand could pack those pieces into gaps to firm up the surface.

Construction brings buried heritage into view

Taiwan's modern infrastructure projects frequently expose traces of older settlements and industries. Salvage archaeology, also called rescue archaeology, is the response used when remains are encountered in a construction area and must be investigated while work schedules continue.

Teams map discoveries, collect samples and record the layers in which objects and structures are found. Their time can be limited, making documentation central to preserving information before construction changes the site.

Tainan has experienced this process on a much larger scale at the Southern Taiwan Science Park. Excavations there uncovered dozens of archaeological sites across a wide area, helping researchers reconstruct ancient settlement patterns and food practices, including the spread of rice and millet cultivation.

Investigators refined techniques such as soil flotation, which uses water to recover seeds and other small remains from excavated soil. These methods produced information that routine excavation could miss, demonstrating how the way a site is examined affects what can be learned from it.

The Cultural Heritage Preservation Act provides a legal framework for preservation in Taiwan. Its implementation operates alongside construction schedules and budgets. Rescue excavations preserve knowledge through records and samples, but pressure from deadlines can compress the time available for investigation.

The Dongmen Road discovery brings that tension into a specific urban setting. The cultural heritage administration says the team completed documentation and moved the materials for safekeeping, allowing the underground railway work to proceed while retaining the remains for later study and public presentation.

What the planned parkway could show

Archaeologists documented the road's layers, photographed its alignment and recorded the combination of mortar, pottery, tile and sugar before removing sections of the foundation. Temporary relocation is a common response when remains cannot stay in place during major construction.

The immediate aim is to keep the materials safe and intact while heavy equipment continues the railway work. Plans call for them to be incorporated into a parkway cultural project after the railway is completed. No date for that display was given.

A parkway project of this kind typically creates a landscaped corridor where preserved features are displayed at their original location or reassembled nearby. Interpretive panels can explain how the road was constructed, the materials it contains and its place in Tainan's history.

The proposed presentation could connect the roadbed with bullock cart transport, the local sugar economy and the reuse of ceramics and tiles from homes and kilns. Together, those subjects would help visitors understand why these fragments were found in the same structure.

The sweet aroma described in the Qing chronicle might also inspire an educational recreation. Any recreated scent would need to be labelled as an interpretive device, rather than presented as a feature that has survived in the excavated road.

Public display offers a way to connect preservation with everyday use of the future corridor. The railway would operate below ground, while the road remains above could give residents a visible record of an earlier transport system and the work that sustained it.

What the discovery means for Tainan residents

Tainan's sugar trade left traces beyond warehouses and commercial records. The discovery suggests that remnants of the commodity became part of the physical streets, filling gaps alongside pieces of household pottery and roofing.

Residents could eventually see how roads were built before asphalt, why broken ceramics were useful and how an abundant local product influenced construction choices. The planned display could also explain the sequence of rescue archaeology: discovery, recording, temporary relocation and later presentation.

Community programmes and school visits could connect younger audiences with objects and structures from their own city. A road foundation offers a concrete starting point for explaining how farming, processing, transport and building work depended on one another.

Tainan's identity has long been associated with trade, religion and craftsmanship. The railway excavation adds an older working landscape to that picture, connecting a handcrafted road with the industrial sugar networks that followed it.

The surviving foundations and the chronicle's description of sweet summer streets tell the story in different ways. One preserves materials beneath the city; the other describes the atmosphere of a district where sugar was handled in abundance. Bringing the remains into a public space would keep that history visible as the railway moves underground.

Key Points

• Road foundations containing sugar fragments, broken ceramics and tiles were discovered near Sin Lau Hospital on Dongmen Road in Tainan's East District.
• The remains are associated with the first half of the 19th century, with construction or renovation estimated at around 1836 during Emperor Daoguang's reign.
• The alignment matches the Bullock Cart Road shown on an 1875 map of Tainan.
• A Qing official chronicle described summer steam and sugar giving the district's streets a sweet aroma.
• The Tainan Municipal Administration of Cultural Heritage says the remains were documented and temporarily relocated so underground railway construction could continue.
• Plans call for later presentation within a parkway cultural project, with no display date given.
• The discovery connects local road building and material reuse with Tainan's sugar economy before its expansion into industrial factories and dedicated railways.