National Expressway 1

National Expressway 1, also known as the Trans-Golden Arc Highway (Zhenian: 금호고속도로; Geumho Gosokdoro) and alternately referred to as The Expressway in some contexts, is the oldest by groundbreaking date and single most heavily-traveled within the Zhenian expressway network. Traversing through almost the entirety of the Golden Arc region as well as adjoining areas from Gwangseong in Namhae Province to Zhuhae in Balhae Province, it passes through many of the largest Zhenian cities and industrial centers. It is given the route number 1, in light of the historical and economic significance of the route to the nation. It is widely considered the single most important expressway in the nation, hence earning its nickname 'the artery of Zhenia'. Traversing through an entire length of 5,508.87 kilometers all the way from Gwangseong to Zhuhae, it is also one of the longest expressway in the nation, with a maximum speed of around 120 km/h enforced by speed cameras across most of its segments.

The construction of an expressway spanning through most of the Golden Arc region has been one of the most important objectives in approaching infrastructure since the early 16th century, as a means to lighten the over-saturation of passenger rail demand along the region. Although a considerable portion of its segments were predated by historical auto trails and routes, the expressway broke ground in 1549 AC and the entire route was open to the public in 1556. Since its opening in 1556, it has been augmented and supported by several alternative routes following its general direction, including National Expressway 35.

Name and numbering
Given the expressway designation number '1', National Expressway 1 was also the only expressway in the National Expressway network to be exempt from the numbering scheme; this exception was made with the consideration of the symbolism as well as the historical and functional significance of the highway in the network itself, as the road was the only expressway entirely traversing the Golden Arc region from end to end and thus served as the backbone of the entire network. Had the exception not been made, what is now National Expressway 1 would have been broken down to a handful of segments that connect regional cities.

National Expressway 1 is officially referred to as the "Trans-Golden Arc Highway", due to the road traversing the near-entirety of the Golden Arc.

Danguk Peninsula
The expressway starts from its eastern terminus, located just 2.5 kilometers southwest of the Port of Gwangseong. The road winds west from Gwangseong's urban areas and bypasses the Bukdu Mountains to the route's direct north, briefly entering Namhae Province in the process. The route curves to the northwest in Gwanseo Province and enters Gyeongin Province through suburban and rural areas southeast of Chungju. Winding between Lakes Payang and Jungsan, the road passes through Hansan and enters metropolitan Daedo via the southeast. Within most of Daedo, however, the road passes underneath the urban areas through the Daedo Underground Highway System (DUHS), around 45 meters beneath the surface. Its underground Daedo segment forms the single longest tunnel segment in the entire route, at 37.1 kilometers of continuous tunnel, until resurfacing as aboveground segments in northern Daedo.

Exiting Daedo from its north, the expressway winds north along the Danbon River, passing through several major cities in northern Chungmu Province, including Arisu and Bukwon. It crosses into Haegeum Province, in which it crosses through many of the population centers in the province, most notably Gaeseong. The route makes a generally southwestern turn shortly after crossing into Haegeum Province, following the general direction of the Gulf's coastline. After Gaeseong, much of the expressway traverses the coastal plains and inland cities in Haegeum Province west of Gaeseong's suburbs. The expressway crosses into Bukhwa Province and ultimately into continental Zhenia by crossing the 3,135-meter Daesang Bridge on the Weisu River.

Continental Zhenia
The route enters Hanam after crossing the Weisu River, directly crossing through the city's urban area from northeast to southwest before making its way further southwest. It briefly crosses into Namhwa Province through the 3.4-kilometer Songguo tunnel, passing around 4.4 kilometers west of Osong Mountain, until crossing into Shinhang. While the route does not directly enters the high-density urban areas of Shinhang as per local legislation, it is connected with the city center via supporting branch roads of the network, as well as throughways traversing Shinhang. South of Shinhang, it passes through the inland rural areas of Namhwa Province, before entering Imhae Province.

The expressway slides northwest of Namgyeong's city center and makes a smooth tilt further to the west, eventually entering Jinhae. Upon entering Jinhae, the expressway makes a turn to the south.

Balhae Peninsula
South of Jinhae, the expressway enters Balhae Province through Hamyang, after which it cuts through the general direction of the peninsula.

History
While the construction of infrastructure spanning the entire Golden Arc region has always been within the priorities of Zhenian governments since the Empire of Zhenia, the need for an arterial road along the Golden Arc was called for since the beginning of the 16th century AC. While National Roads Route 35 and Route 45 had formed initial road networks along the Gulf of Danguk, plans for a broader route capable of handling more traffic were being drawn out before the Second Great War. While most land acquisitions had been made before the beginning of the Second Great War and segments of the route within Gyeongin Province broke ground in 1523 AC, construction came to a halt with the Second Great War, as most resources were redirected to continuing the Zhenian war effort in the Tarsis-Hanmaric region.

While the construction sites remained more or less intact during the Second Republic, it was the Kim Shimin Administration of the Third Republic that reinstated plans for a broader, straightened-out highway spanning the Golden Arc region. Specifics in the route, however, were significantly revised from pre-war construction plans: unlike pre-war plans, the highway would start from Gwangseong instead of Jin-Nampo given the significance of Gwangseong's ports, while the same was done with Zhuhae over Suripo, and the highway would overall run most of its routes inland instead of being mostly along the Gulf's coastline. Referring to what would be the Trans Golden Arc Highway as "the number-one priority for road infrastructure towards Zhenian economic resurgence", plans for the highway received more attention from the government than any other highway in the network. This was partly because of the sheer length of the route as well - with the entire plan spanning almost 10,000 kilometers, it was set to be one of the longest and most important routes in the entire network.