The Bannan Line: Stitching Two Cities Together Underground Over 26.5 Kilometers

30-Second Overview: The Bannan Line is not merely a blue route that shuttles passengers across Taipei City. It began with an early concept of a line from Banqiao to Songshan, underwent route adjustments, underground negotiation, and phased opening, and ultimately became a 23-station underground high-capacity system stretching from Dingpu to the Nangang Exhibition Center. What it shortens is not just a commute, but a metropolitan area’s imagination of “where one place ends and another begins.”

On December 24, 1999, the Ximen Station to City Hall Station segment, and the Banqiao Line’s Ximen Station to Longshan Temple Station segment, began operations on the same day. ¹ At that time, the Bannan Line did not yet look like the complete entity it is today. It first stitched Ximen, Taipei Main Station, Zhongxiao East Road, and the Xinyi Planning District into an east-west underground backbone, and the following year pushed the operational endpoint to Kunyang. ¹

On July 6, 2015, the Dingpu Station to Yongning Station segment opened, pushing the western end of the Bannan Line further into Tucheng. ² Today, the BL Bannan Line runs from Dingpu Station to Nangang Exhibition Center Station, spanning 26.5 kilometers with 23 stations in total, all underground. ³

What makes this line most worth writing about is that it connected three originally distinct lifestyles onto the same timetable: residential commuting from Banqiao and Tucheng, commercial and transfer activities in central Taipei, and the railway and industrial nodes of Nangang. The number of stations is merely the result; what truly changed the city is that these rhythms began to interlock on the same day.

Image: Jiahwang / Wikimedia Commons, CC BY-SA 2.5. The image shows the Taipei MRT C371 EMU, taken at Beitou Station, and is not a train exclusive to the Bannan Line. ⁴

Not Just a Line, But a City Choice Repeatedly Modified

The predecessor of the Bannan Line was not a fixed blue line map from start to finish. According to records from the Taipei Metro Engineering Bureau, the early blue line concept was from Banqiao to Songshan, later evaluated for extension to Nangang, with reasons including serving commuting trips in Songshan, Nangang, and Xizhi, and guiding balanced development of the Taipei metropolitan area. ¹

This change reveals a often-overlooked aspect of metro planning: routes are determined by distance, commuting demand, and urban direction. It simultaneously answers three questions: “who needs to commute,” “where should be connected,” and “in which direction does the city wish to grow.” By crossing Zhongxiao East Road to the east, the Bannan Line also rewrote Nangang from the urban periphery back into the central narrative of metropolitan transportation.

The engineering at the time was not conducted on blank land. The Nangang Line advanced along Zhonghua Road, Zhongxiao West Road, and Zhongxiao East Road, passing through densely populated commercial districts, near Taipei Main Station, the Executive Yuan, and the Control Yuan, and had to pass beneath the North Gate. Consequently, official sources described this section of the project as a route with higher construction difficulty. ¹

📝 Curator’s Note: The first major turning point of the Bannan Line was not the opening of a specific station, but engineers finding a new path within the gaps of an existing city. The metro does not push the city down to rebuild it; rather, when the city refuses to make way, it learns to pass through underground.

Why the Nangang Section Changed from Elevated to Underground

The Nangang Section best illustrates how local life and engineering planning pull against each other. Official data indicates that the revised Nangang Line was originally planned to switch to an elevated structure at the exit of the Dongxin Street Tunnel, crossing the Taiwan Railways Administration (TRA) main line before heading to Nangang. From the late 1970s to the early 1990s, this plan changed due to local proposals and multiple coordinations. The Taipei City Council had proposed changing the approximately 1.75-kilometer section from Xiangyang Road to Nangang Road to underground, after which the Executive Yuan’s Public Construction Supervisory Committee ruled that the section from east of Houshanpi to Kunyang Station, including Kunyang Station itself, would be underground. ¹

Going underground may look like a simple landscape choice, but it actually involves exchanges of land, transportation, and local development. An elevated structure can quickly form a visible transport corridor, while going underground keeps roads and streetscapes on the surface but increases engineering difficulty and cost. The final decision to hide the Nangang Section underground meant the city chose a less conspicuous method in exchange for the continuity of surface space.

This also explains why the Bannan Line is often hard to see on the surface. On Zhongxiao East Road, you see shops, arcade walkways (qilou), and traffic, but it is difficult to read from the streetscape that a high-capacity railway lies beneath your feet. Its urban effect is an invisible corridor that does not interrupt surface life, allowing people to continuously cross administrative districts and commercial zones.

Two Phased Openings: First Connecting the City Center, Then Pushing the Eastern End to Nangang

The birth of the Bannan Line adopted phased opening. On December 24, 1999, the City Hall to Ximen and Ximen to Longshan Temple segments began operation first. On December 30, 2000, the City Hall to Kunyang segment followed. ¹ This sequence is interesting because it first allowed the most densely populated city center’s east-west axis to start operating, pushing the endpoint toward Nangang, rather than waiting for the entire line to be completed before passengers could use it.

Source: Taipei Metro Co., Ltd. Route Introduction. ³

Image: Taipei Metro / Wikimedia Commons, authorized under the Taipei Metro Government Website Open Data Announcement, with source attribution required. ⁵

Phased opening made the Bannan Line an infrastructure learned by citizens in segments. Passengers first became familiar with movement between Ximen, Taipei Main Station, Zhongxiao Fuxing, and City Hall, before incorporating Kunyang, Nangang, and further west Banqiao and Tucheng into the same daily routine. The impact of the network did not only appear on the day of completion. Each movement of the endpoint added more “places one can conveniently visit.”

In 2015, the Dingpu Station to Yongning Station segment opened, increasing the operational length by 1.9 kilometers. The Taipei Metro Company listed this event in its chronology. ² The extension from Banqiao to Tucheng meant the Bannan Line was no longer just an east-west axis within Taipei City, but became a long-distance commuting corridor spanning Taipei City and New Taipei City.

Image: Taiwan Junior / Wikimedia Commons, CC BY-SA 3.0. Taken at Taipei Main Station First Platform on May 3, 2007. ⁶

Convenience Does Not Mean Everyone Profits Equally

The Bannan Line indeed brings foot traffic, but there is no automatically established equation between “increased foot traffic” and “increased commercial district revenue.” Taking the Longshan Temple commercial district as an example, research from the National Taiwan University Library’s Master’s and Doctoral Dissertation Database found that after interviewing business owners and consumers, everyone generally agreed that the metro made transportation more convenient, but this convenience did not necessarily directly convert into business revenue. The study also pointed out that the pedestrian connection between metro exits and the neighborhood was still insufficient. ⁷

This gap is important. The metro bringing people to a station does not mean people will walk into every alley. If there is a lack of clear and comfortable pedestrian paths between the station body, exits, temples, old shops, arcade walkways, and markets, travelers may only transfer underground without truly entering the surface commercial district.

The change the Bannan Line brings to local areas truly occurs after traffic is redistributed. The question becomes: who can absorb the crowd, and who can only watch the crowd pass by? The Longshan Temple research reminds us that the metro must work together with commercial district marketing, heritage and religious activities, hygiene and safety, and surface environment planning. ⁷ A line can bring people, but it cannot replace local decisions on how to welcome them.

📝 Curator’s Note: The metro is most easily misunderstood as a machine that dumps crowd traffic into commercial districts. In reality, it is more like an amplifier. Whatever the alleyway dynamics, shop nature, and local memories were like before opening, they will be amplified after opening.

Land Next to Stations Begins to Learn Metro Pricing

The Bannan Line also changed how people imagine housing. Research focusing on the Longshan Temple Station to City Hall Station section of the Bannan Line analyzed passenger entry/exit volumes at each station, surrounding announced land values, and administrative district housing price indices, finding that after the metro appeared, commercial real estate had a more positive response than residential properties. The study pointed out that station areas might shift toward commercial use due to increased foot traffic, while residential areas moved outward from the station. ⁸

This is not a simple story of “metro opening means housing prices must rise.” Another policy analysis pointed out that metro real estate price changes often concentrate around the opening period; as the network becomes more complete and convenience becomes universal, the original sense of scarcity also decreases. Metro-adjacent housing is not a guarantee of perpetual price increases. ⁹

Newer TOD (Transit-Oriented Development) research places this matter within the urban system. Research indicates that Taipei had already established land use regulations equivalent to TOD in 1983; development within a 500-meter radius of major public transport stations could obtain floor area ratio bonuses, treating land value capture as a policy tool to support public transport. ¹⁰

In other words, the Bannan Line is not just a transportation construction. It also made the land around stations begin to be treated as a venue for negotiation among public transport, urban renewal, and private development. Below the station body is the platform; above or beside it may be malls, offices, residences, and walking spaces. The true scope of the underground railway has never been limited to the tunnel.

A Cultural Facility Disappearing Into the Streetscape

The English introduction from the Taipei Metro Engineering Bureau specifically emphasizes that metro space includes not only stations and trains, but also underground streets, plazas, walking spaces above station bodies, and linear parks under elevated sections. It describes the metro as part of urban life, not just a means of transport. ¹¹

In the case of the Nangang Line, official data mentions that the ventilation shaft and multi-functional pedestrian underground street at Zhongxiao Dunhua Station were transformed into the public art piece “Tree River.” The station design of the Nangang Line also adopted a concise method to reduce impact on the urban landscape, then created new urban landmarks through public art. ¹¹

This design produced a counter-intuitive result for the Bannan Line: an all-underground route continuously changed the visual and walking experience on the surface. It does not announce its existence via elevated bridges, but translates the underground system into surface urban life through exits, underground streets, ventilation outlets, signage, artworks, and foot traffic.

During Nangang Line construction, the engineering team also handled heritage preservation issues. The English official page states that during construction, stone and wooden pillars of the foundation of Taipei’s old city wall were discovered; some components were excavated, repaired, and displayed at the location of the Zhongxiao West Road underground street. ¹¹ This meant the metro’s underground engineering was not just burying a new system, but also bringing physical evidence of the old city into new public spaces.

Nangang Is Not the End, But Another Kind of Urban Rhythm

The significance of the Bannan Line extending eastward cannot be summarized merely as “getting to Nangang is faster.” The Metro Engineering Bureau points out that the Nangang Depot is located around Xiangyang Road and Dongxin Street, providing functions for train parking, maintenance, and cleaning; the top slab of the depot also reserved space for development. The Nangang Line was also planned to form transfer functions with the TRA Zhonggan Line in Songshan and Nangang. ¹

The Nangang East Extension Section itself was not a one-time completed endpoint. The approximately 2.5-kilometer extension from Kunyang to Nangang Station adopted a shield tunnel, featuring Nangang Station and Nangang Exhibition Center Station, of which approximately 725 meters were within the TRA right-of-way, forming a three-rail integration with HSR and TRA. Responding to construction schedules and Nangang traffic diversion needs, the Engineering Bureau first opened the Kunyang to Nangang Station segment on December 25, 2008, and then opened the Nangang to Nangang Exhibition Center Station segment on February 27, 2011. ¹²

The Nangang here does not share the same urban rhythm as the commercial streetscapes of Zhongxiao Dunhua. It connects railways, depots, exhibitions, and industrial spaces. The Bannan Line puts these different rhythms into a route understandable by the same passengers, making “going to Nangang” feel less like going to the urban periphery and more like going to another work scene within the same metropolitan area.

Image: Robert S. Donovan / Wikimedia Commons, CC BY 2.0. Taken at Taipei City Hall Station. ¹³

The significance of Nangang Exhibition Center Station is not merely pushing the blue line further east. The Metro Engineering Bureau listed the station building design of the Bannan Line separately for Nangang Station and Nangang Exhibition Center Station, placing Nangang Exhibition Center and Nangang Technology and Software Park within the same set of urban design context. The station body thus became an entrance where industry, exhibitions, and transfers could recognize each other, rather than just an underground box responsible for boarding and alighting. ¹⁴

📝 Curator’s Note: What is most noteworthy about the Nangang Section is not “how many stations the endpoint extended,” but how the opening sequence divided traffic diversion, rail integration, and exhibition industries into different timelines to connect to the network. The eastern end of the city therefore became not a fixed endpoint, but an interface gradually being used out.

A route becomes the backbone of a living circle not because the endpoints are so lively, but because the intermediate transfers and stops are stably used. Taipei Main Station stacks railways, another metro line, and the airport MRT at the same underground node; Zhongxiao Fuxing intersects the commuting directions of the Bannan Line and the Wenhu Line; Nangang connects the metro with TRA, exhibition activities, and industrial spaces. These nodes give the Bannan Line an effect exceeding its own station spacing: passengers may not alight at every station, but can put a more distant city into the same schedule via transfers.

Image: NG LAU Hears / Wikimedia Commons, CC BY-SA 4.0. Taken at Taipei Main Station on August 12, 2019. ¹⁵

The Taipei Metro Company’s ridership statistics include the Bannan Line in the high-capacity system statistics. Official data simultaneously provides annual and monthly totals for high-capacity routes, but does not break out the Bannan Line’s single-line numbers; therefore, this article does not mistake the high-capacity total for the Bannan Line’s single-line ridership. ¹⁶

This statistical limitation also reminds us that the importance of the Bannan Line lies not just in single-line客流 rankings. Its role is more like a network backbone, connecting different routes, stations, and living circles through transfers. Calculating how many passengers a line has is certainly important. Understanding how many people a line enables to put different places into the same day may be closer to its urban value.

✦ “What is truly shortened is not just the distance between two stations, but the boundary of ‘that place is not my living scope’ in people’s minds.”

Questions Left by the Blue Route

The success of the Bannan Line cannot be written as an urban fairy tale without cost. Research has pointed out that station commercialization may push residential areas outward, and transportation convenience may also cause land and housing prices to re-stratify. ⁸ Commercial districts gaining foot traffic may also bear the pressure of exit dynamics, tourism-ification, and the repackaging of local original life. ⁷

TOD research reminds us that if public transport and land development lack supporting measures for pedestrian environments, mixed use, and public interest, it may only be “development near the metro,” rather than a complete transit-oriented city. ¹⁰ The Bannan Line brought people closer; the city still must answer whether people can safely, comfortably, and with reason walk the final 500 meters.

Therefore, the core question of the Bannan Line is not “whether it changed Taipei,” but “who was given the change.” The Engineering Bureau decided the route and construction methods, the Metro Company maintains schedules and station bodies, local commercial districts absorb foot traffic, developers recalculate land values, and passengers vote with their daily movements. Everyone holds only a small segment, but the entire blue line is the result produced jointly by these small segments.

The Final 500 Meters Are Where the City Truly Catches People

The Bannan Line brings people to the station exit; the road behind is still completed by the city itself. Whether the exit faces the market, whether the underground street can clearly connect to the arcade walkways, whether the elderly, people pushing strollers, and those with mobility impairments can avoid detours—these determine whether the metro’s convenience truly reaches daily life. The Longshan Temple research has already pointed out that the insufficient pedestrian connection between exits and neighborhoods is one reason why transportation convenience did not automatically become commercial district revenue. ⁷

Therefore, the surface engineering of the Bannan Line is worth viewing in the same article as the tunnel engineering. Rain shelters, pedestrian signals, arcade walkways, public art, underground street connection points, and commercial district signage around stations are all the grammar that translates “arriving at the station” into “arriving at the place.” They will not appear in the colored lines of the route map, but they determine whether a passenger finally remembers a neighborhood with character, or just a node suitable for transferring.

Here lies the Bannan Line’s homework for the future. TOD should not be measured only by floor area ratio bonuses, but also ask whether the station area has diverse uses, continuous pedestrian environments, and public spaces that do not exclude original residents. ¹⁰ The metro brought the city closer; the city still must decide what to leave behind after getting closer.

Conclusion: The Underground Line, The Shared Daily Life On The Surface

On December 24, 1999, the Bannan Line first connected Ximen, Longshan Temple, and City Hall. In 2000, it reached Kunyang. In 2015, it extended further to Dingpu. ^{1 2} Each opening was a moment when an endpoint was incorporated into daily life.

Today, passengers see the blue circle logo, train doors, and the next station broadcast on the platform. Fewer people think about how this line was once re-discussed between elevated and underground, once had to pass beneath the North Gate, and was once expected to be used to balance the development of the Taipei metropolitan area. ¹

The counter-intuitive nature of the Bannan Line lies here: the more successful it is, the more it seems to not exist. When people from Banqiao can go to Nangang to work on the same day, and people from Nangang can go to Longshan Temple to eat, the city no longer treats this as an engineering miracle, but takes it for granted.

This taking-for-granted is not naturally formed. The Bannan Line is an underground seam line that was planned, fought for, excavated, preserved, and then repeatedly used out by people riding every day. The Bannan Line did not eliminate the differences between Taipei and New Taipei; it merely added a road that can be traveled back and forth between these differences.

The blue line on the route map has only one color, but the map of life has many layers. Some alight at Longshan Temple to buy breakfast, some transfer at Zhongxiao Fuxing to the office, some switch to buses at Kunyang, some complete their day’s work at Nangang Exhibition Center. The Bannan Line puts these different purposes into the same direction, and the city thus becomes larger than administrative district boundaries in daily round trips. This is the route’s quietest yet deepest achievement: it gradually turned cross-city movement that previously required special arrangements into a daily routine that needs no explanation, and let the boundaries of a metropolitan area unfold anew between footsteps and trains, becoming a shared experience verified every day.

Further Reading

• Taipei Metro Co., Ltd. Route Introduction: View the current network and the Bannan Line’s station count and length.
• Taipei Metro Engineering Bureau Bannan Line Route Explanation: View the Nangang Line engineering history and underground decision-making.

Image Sources

Image File: File:Taipei MRT Train C371 3CarSet No 3398.JPG, Author Jiahwang, Wikimedia Commons, Creative Commons Attribution-ShareAlike 2.5 Generic. Image taken at Beitou Station on July 24, 2006; this article embeds via Commons hotlink, does not download the image.

Image File: File:MRT Taipei Main Station Platform 1 20070503.jpg, Author Taiwan Junior, Wikimedia Commons, CC BY-SA 3.0. This article embeds via Commons hotlink, does not download the image.

Image File: File:2023 Taipei MRT official map.png, Copyright holder is Taipei Metro, used according to Government Website Open Data Announcement.

Image File: File:Taipei City Hall Metro Station Platform.jpg, Author Robert S. Donovan, Wikimedia Commons, CC BY 2.0. This article embeds via Commons hotlink, does not download the image.

Image File: File:Platform 3 & 4, MRT Taipei Main Station 20190812.jpg, Author NG LAU Hears, Wikimedia Commons, CC BY-SA 4.0. This article embeds via Commons hotlink, does not download the image.

References