The Lambeth Road site is located near Vauxhall Station to the south (51.495°N, 0.116°W). It is adjacent to the main railway line between Waterloo and Vauxhall Station with varying express services running to Salisbury, Weymouth and Portsmouth along with high intensity local services to numerous locations. In the peak hours approximately 60 trains per hour pass the site.
A signal gantry is located to the south of Lambeth Road. However, the signals appear only to be visible from the southern approach.
We approached this complex problem by using a software based methodology we adopted for the rail industry and improving this to include the risk of the nearby signals at a height . This modelling also required inserting each component of facade and it’s movement capability from the 3D model into the analysis.
challenge
There was uncertainty if the Radiance Software would successfully provide the effect of glazing within the bridge and also to the sides and their effect on the driver approach. Without enhancing the techniques for glare analysis and how the technique can be effectively used on a glass bridge structure directly above the railway was a great risk and challenge.
solution
For the purposes of sunlight simulation, various elements of the 3D model were applied with reflection properties approximated by images of materials Q Sustain received via the client.
The methodology for this stage of simulation is described below:
- Create routes for the trains passing the development that travel eastbound and westbound through the significant reflections.
- The model reflection properties were approximated based on images provided by
Window reflection properties are assumed 70% transmittance - Simulations were completed at ten frames/second along the railway lines at driver eye height (2.75m above track) The frames were then combined into a real-time animation at 30mph to simulate the speed of the passing train.
A mathematical algorithm was also applied to each frame to predict the magnitude of any disability glare using the Hassall method. Using this data, graphs were created which identify the veiling luminance (disability glare) over time and the difference between the static façade and reference façade.
The creation of an improved Radiance software 3D sunlight simulation model for the bridge based on the Architect’s 3D model was created and tested successfully, but further refined and improved with various viewpoints across the track approaching the bridge and including signal graphical data.
Using the software, we ran the 3D animations including further improved view of the nearby signals to more accurately represent the train drivers view. This study also calculated the intensity of reflection onto any signal that may create signal lamp ‘Wash Out’ where there is the possibility of a reflection illuminating the signal directly which could possibly cause a ‘phantom aspect’.