The Asian Development Bank of Manila has approved a $100 million loan and a technical assistance grant for a major road improvement project in South Korea.

The project is intended to create a balanced, efficient transportation system that will improve accessibility and mobility in the country, according to bank officials. About 240 miles of rural roads will be paved and some will be widened into four lanes. The government also is repairing roadside drainage and shoulders and replacing dilapidated bridges.

ADB's loan represents about 35 percent of the total cost of the project. The loan has a repayment period of 24 years, with no payments due for the first four years. Interest will be determined by the bank's pool-based variable lending rate system.

In conjunction with the project, ADB is helping the Korean bureau of public roads set up a road safety program and prepare a highway manual with a technical assistance grant.

The Asian Development Bank also has approved a $15.5 million loan to Laos for a water power project.

The project will install a hydropower plant on the Xeset River, a tributary of the Mekong River in the southern province of Saravane. The project's components includes a concrete dam 33 feet high and 260 feet wide to span the river; a powerhouse with five turbines; a system of tunnels that will direct water to the powerhouse; and engineering consulting work.

Most of the electricity generated by the project will be sold to Thailand to earn an estimated $5 million per year, according to ADB.

The project's total cost is about $39 million. Apart from ADB, cofinancing is being provided by the Swedish International Development Authority, the United Nations Development Program, and a local agency called Electricite du Laos.

The project is scheduled to be completed by June of 1991.