A project to build an expressway connecting Sejong and Anseong is progressing well and is expected to meet the completion target by June 2024.

The project broke ground in December 2019. It will cost 3,111.2 billion won.

The project involves the 55.86 km portion between Sejong and Anseong, and the Osong branch line linking Yeongi Junction to Osong, a new satellite city. The Sejong-Anseong section is part of the Seoul-Sejong expressway.

The Sejong-Anseong section will be connected with the Pyeongtaek-Jaecheon Expressway at the planned Namanseong junction, connecting it with the Seoul-Busan Expressway at the planned Dongcheonan Junction, and linking the Dangjin-Yeongdeok Expressway at the planned Sejong Junction.

The Sejong-Anseong section will have major facilities, such as Junctions at Sejong, Yeongi and Dongcheonan, five interchanges at five locations — Sejong, Yeongi, Dongcheonan, Seounipjang and Geumgwang Hi-pass, two resting areas at Yeonggi and Dongcheonan, and two sleeping shelters at Cheonan and Namanseong.

It will also have 87 bridges, stretching 11,352 meters in total length on the main line, and three bridges, totaling 845 meters on the Osong branch line as well as 24 tunnels, totaling 17,993 meters in length on the main line.

Three tunnels totaling 2,312 meters on the Osong branch line will be constructed.

The section between Sejong and Yeongi junctions will be made into four lanes for both directions, while the portion between Yeongi and Namanseong Junctions will be built to accommodate six lanes.

The design velocity of the Sejong-Anseong expressway is 120 km per hour, while that of the Osong branch line is 100 km per hour.

A first section of the Sejong-Anseong expressway is a 5.48 km-long portion, to be built by Namkwang Construction.
A second, stretching 5.96 km-long, will be constructed by Hanwha E&C.

A third part, 5.5 km-long, will be done by Lotte E&C while a fourth, 4.82 km-long portion will be implemented by DL E&C.

A fifth, 5.62 km-long section will be built by KCC E&C while a sixth, 7.52 km-long portion will be constructed by Daewoo E&C.

A seventh, 5.46 km-long section will be done by SM Samwhan Corp. while an eighth, 5.22 portion will be implemented by POSCO E&C.

A ninth, 4.1 km-long section will be built by Hyundai Engineering Co. while a 10th, 6.18 km-long portion will be done by Doosan Heavy Industries & Construction.

The 6.21 km-long Osong branch line will be done by Hanjin Heavy Industries & Construction Co.

The project to build an expressway between Seoul and Sejong is one of the current government’s state mega projects, designed to support balanced national development and ease traffic congestions along the Gyeongbu (Seoul-Busan) and Jungbu (Seoul-Daejeon) expressways.

If the Seoul-Sejong expressway is completed and opened to traffic, it will take one hour and 14 minutes, a reduction of 34 minutes, instead of current one hour and 48 minutes for motorists to commute from Seoul to Sejong.

The value of public benefits from 30-year-old pubic use of the expressway is estimated at 3,772.4 billion won. It will also reduce logistics costs and traffic accidents.