Harringworth Viaduct Case Study

Outline of the Survey

The viaduct was built in 1878, is owned by Network Rail and crosses the River Welland on the Rutland and
Northamptonshire border. It is the longest viaduct in the UK, is a grade II listed structure and it comprises 82 arches,
each with a 42ft span. 71 of the supporting piers are 6ft thick, with a further 10 being double thickness and spaced
evenly along its length.
Our Client, Donaldson Associates (now COWI) who we have worked with for many years asked us to carry out a 3D
topographical and Laser Scanning survey of the Viaduct and additionally to produce a 3D BIM model.

Why Scantech

We won this work on the basis of :

• Competitive price
• Previous Rail survey experience (15 years)
• Experience of producing 3D BIM Revit models from pointcloud data
• Time on site – 2 days at ground level and two trackside shifts and
• 15 days to produce the topographical drawings and 3D BIM model

Challenges

The viaduct is 57 feet high and the wind at track level created difficult working conditions for the laser scanning as the
targets used for the registration were prone to movement in the wind.

To overcome these issues we ensured that the targets were secured and also we utilised fixed control points as a
secondary check on the registration.

At the ground level the main obstacles to overcome were the horses in the field but we captured all of the data at this
level without the need for scaffolding or cherry pickers thus saving a considerable amount of time on site.
We also used our iStar camera again on the ground to take panoramic HDR photographs which were used to colourise
the pointcloud data. This had the added advantage over the built-in scanner camera that we could carry out the scanning and photography in half the time.

We set out control points around the site at both track and ground levels and coordinated these with the EDM and
subsequently orientated them to OS using GPS.

Deliverables

Detailed notes and photographs were taken to assist in the production of the 3D model in Revit.
Once all the scanning was completed the individual scans were registered together to produce an overall pointcloud of
the viaduct referenced to OS coordinates. From this overall pointcloud we produced the 3D BIM model in Revit.