The Cross Tay Link Road is Phase 2 of the Perth Transport Futures Project and is one with great strategic output for the whole region. It is going to connect the A9 over the River Tay to the A93 and A94 north of Scone. By early predictions it is planned to be finished in 2023.
AG Surveys were assigned the task to undertake a number of topographical surveys including road surveys, drainage section surveys and watercourse bed surveys for local watercourses to help infill data sets acquired from aerial photography, photogrammetry and Lidar data. Furthermore, once there, it was decided to establish a high accuracy control network along the whole project corridor, which can be used for the earthworks and construction phase of the project.
Instruments used for this purpose included Leica 1200 and GS15 GNSS and Leica Viva TS 16 Total Station. Leica Geo Office, Terramodel and CAD drafting applications have been used to process the project data.
The survey control has been surveyed forming a triangular network around the peripheral of the site. The points have been measured using several Leica GNSS receivers, recording static observations with baseline vectors forming a series of none overlapping triangles to provide a network of maximum redundancy. A single baseline on site, establishing Z control points, has been tied to the OS active network over several setups each taking between 8 and 10 hours to achieve a theoretical accuracy of below 2mm. The raw data was processed in Leica Geo Office with vector dependencies taken into account. In order to increase and check the height accuracy, high accuracy digital levelling has been carried out between the points.
The provided survey information was used for the following purposes:
- Specimen and Detailed Design Development
- Flood modelling and flow design
- Drainage design
- Earthworks design
- Landscape design