Abstract: The G(4) bidding section of the Shanghai-Nanjing freeway interchange in Eastern Nanjingis of many styuctures and complex alignment. The PC-E500 portable computer is used to ensure the accurate orientation of 9 overpass bridges, 1 river-spanning bridge and 8 small bridges and the exact connection between 15 routes. It is applied to the compunction of center-line shake coordinates of differentforms of curves, the coordinate computation of bridge axes and reference stakes, and the staking-outdata processing in constuction lay-out and measurement with total stations by pole coordinate method.With the use of computers, the computation work is greatly reduced. This practice helds the engineering construction, a breakthough from the conventional method of detail lay-out of curves from mainpoints of curves.