Norfolk Southern Corp., the Norfolk-based railroad and transportation company, said yesterday that its profit jumped 21 percent in the fourth quarter but fell sharply for all of 1987 as the result of a restructuring charge.

The company said its profit fell 67 percent in 1987, to $172.4 million (91 cents a share) from $518.7 million ($2.74) a year ago. The decline resulted mainly from a special restructuring charge of $620.4 million taken in the third quarter.

If the special charge is excluded, Norfolk Southern said, its 1987 net would have been $524.2 million, up 1 percent from the year before.

Revenue for the year edged up 1 percent, to $4.11 billion from $4.08 billion in 1986.

Norfolk Southern said that in the fourth quarter it earned $173.7 million (92 cents), up from $144.2 million (76 cents). The company said the increase was due in large part to increased revenue, which rose 5 percent to $1.06 billion from $1.01 billion in the year-earlier period. Revenue from transporting coal increased 10 percent, building-material revenue rose 14 percent and metals revenue was up 42 percent.

Fourth-quarter earnings also were boosted by an after-tax gain of $23.7 million from the sale of Norfolk Southern's shares in Piedmont Aviation Inc., and by the favorable settlement of tax-related issues that added $11.5 million. Ryland Group Inc., the Columbia-based home builder, said its earnings increased 20 percent in 1987 to $31.2 million ($2.46) from $26.1 million ($2.02) a year earlier. Revenue increased 27 percent to $847.9 million from $666.2 million in 1986.

In the fourth quarter, Ryland's earnings decreased to $4.8 million (37 cents) from $7.3 million (56 cents) as the effects of the company's acquisition of M.J. Brock, which reduced fourth-quarter earnings by $2.5 million.

Fourth-quarter revenue rose 8 percent, to $201.2 million from $186.5 million.

Washington Gas Light Co. said it earned $39.4 million ($2.27) in 1987, up slightly from $29.3 million ($2.29) a year ago. Revenue during the year fell to $683.8 million from $722.1 million in 1986.

WGL, which recently proposed a 15 percent rate increase for District customers that could raise gas prices for residential gas users by as much as 22 percent, said it earned $20.3 million ($1.18) in the fourth quarter, up 12 percent from $18.2 million ($1.07) a year ago. Revenue in the quarter fell to $197.8 million from $206.9 million.

Citizens Savings Bank FSB of Silver Spring said it earned $3.1 million ($1.56) in 1987, its first year as a public company, compared with $2.8 million in 1986, when per-share figures were not applicable. For the fourth quarter, the bank earned $703,000 (35 cents), up slightly from $693,000 a year ago, again with no applicable per-share figures.