A significant share of the attacks against
 targets in Route Packages V and VI has been against
 railroads. During the period January-August 1967,
 about 4,530 attack sorties -- 28 percent of the
 16,220 attack sorties flown in Route Packages V
 and VI -- delivered more than 9,300 tons of
 ordnance against the six railroad lines (see the
 tabulation below) located wholly north of the 20th
 Parallel (see Figure 2). More than three-fourths
 of this ordnance was delivered in the three-month
 period of June-August. The greatest weight of
 attack against northern lines was on the key
 northeast line leading from Yen Vien to Dong Dang.

During the eight-month period, 5,590 attack
 sorties delivered about 11,900 tons of ordnance
 against the railroad running south from Hanoi through
 Route Package IV to Vinh. This amounted to 56 percent
 of total ordnance delivered against railroads in
 North Vietnam. The changed focus of the campaign
 against railroads is apparent in the fact that
 while the Hanoi-Vinh line withstood almost 80
 percent of the weight of attack from January through
 May 1967, it took only about 35 percent of the
 attack during June through August. The following
 tabulation gives tons and shares of ordnance
 against each railroad by time period.*

* Six lines radiate from Hanoi. Traffic from
 Hanoi to Lao Cai, Dong Dang, and Thai Nguyen moves
 over the 11-kilometer segment to the Yen Vien yards.
 This segment is sometimes treated as part of the
 Hanoi-Dong Dang line.

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