[Reading Science] Why Are Road Sign Distances Different from Navigation Distances?

'Dorowonpyo' located near Donghwa Department Store in Gwanghwamun, Seoul.
Photo by YouTube screenshot

[Asia Economy Reporter Kim Jong-hwa] Nowadays, it is difficult to find a destination without navigation. In the past, when there was no navigation, maps were essential. Drivers would look at maps before departure and find their destinations by looking at road signs while driving.

Therefore, many drivers understood the numbers or meanings displayed on road signs. However, these days, most drivers rely on navigation and often do not even know the concept of the numbers shown on road signs.

In particular, many do not know from where to where the distances indicated on road signs are measured. When it says "Seoul 30 km," people tend to think, "There are 30 km left from here to Seoul." But Seoul is vast, so aren’t you curious about which part of Seoul is 30 km away?

First, you need to understand the meaning of the numbers on road signs that you must know. There are road numbers commonly seen on national roads. These road numbers are odd for north-south direction roads and even for east-west direction roads.

For example, "National Road No. 43," which connects Sejong City to Goseong in Gangwon Province, is a north-south national road. Also, "National Road No. 22," which connects Jeongeup in Jeollabuk-do to Suncheon in Jeollanam-do, is an east-west road running diagonally from the west coast.

For east-west roads, the west is the starting point, and the east is the end point. For north-south roads, the south is the starting point, and the north is the end point. This is designed with unification in mind, making the south the starting point.

Highway terminus sign. [Photo by YouTube screen capture]

When indicating remaining distance, there is also a starting point and an end point. For national and local roads, the remaining distance is indicated based on each road’s reference point, called the "Doro Wonpyo (道路元標, Starting point of mile posts)," and for expressways, it is based on the "Interchange (IC)." Famous tourist spots use parking lots or landmarks, and express buses or trains use departure and arrival terminals or stations as the reference points.

These standards are specified in Article 50 of the Enforcement Decree of the Road Act and Article 23 of the Enforcement Rules. According to these laws, one Doro Wonpyo must be installed in each special city, metropolitan city, special self-governing city, and city or county. The criteria include "administrative centers such as metropolitan city halls, special self-governing city halls, provincial offices, city halls, and county offices," "transportation hubs," and "other historical and cultural centers."

According to these criteria, Seoul’s Doro Wonpyo is located next to Donghwa Duty-Free Shop on Sejongno near Gwanghwamun, Busan’s is next to the flower bed at the front gate of Busan City Hall, and Daegu’s is inside Gyeongsang Gamyeong Park. When referring to distances between regions, it means the distance between these Doro Wonpyo points. However, for expressways, the reference is the IC, not the Doro Wonpyo.

Therefore, even for the same section, the indicated distance may differ depending on whether you use the expressway, the national road, or what kind of public transportation you use. For example, the distance between Seoul and Daegu on the expressway is 294 km between Yangjae IC and Dongdaegu IC, but on the national road, it can exceed 300 km because it indicates the distance from the Gwanghwamun Doro Wonpyo to Gyeongsang Gamyeong Park in Daegu.

'Dorowonpyo' located in 'Gyeongsang Gamyeong Park', Daegu.
Photo by YouTube screen capture

Also, when using express buses, the distance indicated on road signs and the distance announced inside the vehicle may differ. The distance announced inside the vehicle is from the departure terminal to the arrival terminal, while the road sign distance is to the IC. For high-speed trains, it is the distance to the station.

On expressways, a road sign saying "Seoul 30 km" means there are 30 km left from the location of the sign to Seoul Yangjae IC. On national roads, "Seoul 30 km" means there are 30 km left to the Gwanghwamun Doro Wonpyo.

Now do you understand why the remaining distance announced by navigation and the distance indicated on road signs differ? Remember that even-numbered roads and odd-numbered roads start from the southwest and end in the northeast, and that expressways use IC as the reference point while national roads use the Doro Wonpyo as the reference point.