桥上的大门
松山国家级自然保护区的入口设在两山之间面南的一条小溪之上，一座东西走向的公路桥北侧。
基地夹在东西两侧的山峰之间，山上流下的溪水在基地北侧汇聚成了一个水潭。这一潭水宁静中包容着四季的变化，山，水，桥，瀑及植被这些自然的元素，共同构成了松山入口处的自然环境特征。
我们把松山大门作为一个集散和疏导人流的重要场所来设计。大门东西两端分别设置了售票办公空间和纪念品服务商店。中置的弧型墙将大门分割成了内外两个区域，这些区域都分别设置了休息座椅。游客在大门的区域内可以随性停留。
动线，大门结合北侧的水塘形成一个小环线，进出人流不交叉。
视线，游客从外部看到是两山之间一道比桥面略高的屋顶脊线。从景区内看，廊桥隐藏于环境之中。弧形墙的中间开设的景窗，让景区内的流水和潭边的景物扑面而来。
曲线，大门的两侧是高起的山峰。大门起到续接自然的图景，以屋顶的一条下弦弧线完成两边山势的连接，同时又与下面的桥洞形成了倒影般的映射关系。
Gates on the bridge
-- Entrance of Beijing Songshan National Nature Reserve
The entrance of the Songshan National Nature Reserve is located on a small stream facing south between the two mountains, and on the north side of an east-west highway bridge.
The base is sandwiched between the peaks on the east and west sides, and the streams flowing down the mountain converge into a water pond on the north side of the base. The pond contains the changes of the four seasons. The natural elements of mountains, water, bridges, waterfalls and vegetation together form the natural environmental characteristics.
The gate is an important place for visitor’s gathering and leaving. Ticket office and souvenir shop are set at the east and west ends while the central curved wall divides the gate into two areas, the inside and the outside, each of which have many seats. Visitors can have a rest at these areas.
Circulation, a small loop combines with the north pond.
Sight, from outside there is a roof ridge line slightly higher than the bridge deck. inside, the covered bridge is hidden in the environment. The hole in the middle of the curved wall lets the flowing water and the scenery come out.
Curve, the gate serves as a continuation of the natural landscape. A lower chord arc on the roof completes the connection between the two sides of the mountain, and at the same time forms a reflective view with the bridge.
