Tuesday
Concept Sketches (by Smita & Damian)
After a morning of sketching ideas inspired by my precedent studies the night it was time to meet Smita. We spent the morning discussing our research and putting our ideas together. It was safe to say we both agreed on the idea of a cantilevered design as it gave us the freedom to design over the road with minimal construction in the road.
After our discussion Smita and I had a conceptual idea of what we wanted to create now it was time to go through the Design Development stage. Luckily as well as putting together sketches Smita had done some researching into Building Regulations Part A, H, K, M, N and the Design Manual for Road and Bridges Part 8 – Design Criteria for Footbridges. These two documents were vital in determining if our bridge design could be built.
We had 3 main issues with our design after researching through the Design Development Stage they were…
- Design Manual for Road and Bridges Part 8 – Design Criteria for Footbridges Section 6.14-16 states a gradient ramp higher than 1 in 20 will require landings at every 650mm. Any gradient ramps at 1 in 20 will only require landings at 2.5m.
This is something we did not allow for, these standards meant that our ramps now needed to change in gradient effecting their placement and location that they were to be installed so that we only required one landing.
- The Design Manual for Road and Bridges Part 8 – Design Criteria for Footbridges Chapter 12.4 states that for a cycle track to also be incorporated into the bridge footpath it needs to be segregated by at least 1.5m for pedestrians and 1.5 for cyclist.
This requirement was minor as all it required was for the bridge to be increased in width slightly to accommodate both paths.
- The Design Manual for Road and Bridges Part 8 – Design Criteria for Footbridges Chapter 7.1 (e) states that if glass is used it shall be laminated and toughened to reduce risk of glass being smashed onto the roads below.
This effects the specification of our glazing to the bridge which is not much of an issue but may become more expensive.
We were easily able to design these all out but the biggest issue was the ramps and landings. The issue with tramps and landings were now determine where our bridge and ramps could go.
Sketch of Proposed Location
Originally we wanted our bridge to go diagonally across the cross road and have ramps go either side across the two smaller roads as this would mean that pedestrians could get to the 4 different parts of the path. But we needed a clearance of 4.8m from the road to the underside of our bridge which meant we would no longer be able to proceed with our idea. This ultimately determined the final location of our bridge.
We had now determined the location and the requirements for our bridge it was time to work out the details and finishes of our bridge. We spend the afternoon sketching and developing our ideas into scaled sketches playing around with ideas and bouncing ideas and information of each other.
Sketches of Finish’s/Detail
We had finalised our ideas by the end of the afternoon with a few main points of our design…
- Prefabricated steel design
- Laminated glazing
- Slim design
- Two 23m cantilever spans meeting in the middle to create a 46m span
- Supported from cables either side
It was now time to prepare for the model making, the Hazlewick students would be back tomorrow and we needed to utilise their time to make maximise production of our bridge. We had agreed what materials we needed to get and would gather them together for the morning. It was agreed I would work on the detailed model at a scale of 1:10 with Joe and Smita would work on the main model with Katie and Taylor.
Today has been a very important day for me in my learning on this project, working with Smita has been very beneficial for me as she has opened my eyes to what is required and the process in how it is done. I like the way she values the importance of Regulations to insure the bridge can be built as this is how it would be done in industry.