Blog Entry 3: Design Concepts

Hi all! The past two weeks were quite eventful for our project team. Following a pre-established timeline, the team learned, to a better degree, of the project expectations and the site specifics. As mentioned in our second blog post, replacing the existing staircase with a safer and more accessible one is of prime importance. Furthermore, our clients, the good folks over at NorthShore Connexions hope to install a stairlift to facilitate the physically restricted and this would require the staircase to be a little wider than the initial estimate of 5′.

Learning of the above mentioned constraints, the team launched into the design stage with enthusiasm. Sam and Shanshui led the design-brainstorming meetings. Multiple designs were sieved through a series of discussions to two principal designs. Since, the staircase has to be of a much gentler slope compared to that of the existing, the first and the most popular of design ideas was to utilize much of the available space along the adjacent wall and build a staircase spanning 16.5′ horizontally in a single flight of stairs from the ground up to the 8′ high landing. As the second principal design concept, it was proposed to span the 8′ height in two flights of stairs, each flight covering 16.5′, thereby softening the slope to the half of the former design concept. To decide between the two concepts, the Multi-Criteria Decision Making technique was used.

Having taken CIVL 201, the predecessor of CIVL 202, all of the six team members were aware of and had experience working with the “Multi-Criteria Decision Making” technique. Multi-Criteria Decision Making (MCDM) is a technique originating from operations research and is used commonly to quantify the viability of the proposed options in all important design aspects of the project. MCDM very efficiently resolves conflicting criteria that require evaluation in the process of making a decision. In the case of this project, the safety factor was given paramount importance while using the MCDM. The net project cost and construction time were the next important factors.

The MCDM process revealed the first design to be better suited to the requirements of the project. Although the latter design was relatively safer given itsmuch gentler slope, it caused exorbitant bloating of the budget. The main cause of this over-budgeting was the spiking of the stairlift installation cost at the junction of the two flights of stairs. Furthermore, the first design seemed cheaper and easier to construct. The hand sketch below illustrates the first principal and also the design selected through MCDM.

Upon the selection of the design, the designers raised concerns about the achievable safety factor through the modest construction knowledge and experience of the team members. Having learnt the skills and the process of design in CIVL 201 and other second year civil engineering courses, we were able to successfully narrow down to a safe design. However, due to the lack of any construction help and knowledge the safe execution of the design seemed a stretch beyond our abilities. This concern was put forward the client representatives Ms. Wendy Padwick and Justine Taylor. During the meeting with the clients, it was mutually agreed that because the safety of the structure is prime, a reduction in the scope of the project was warranted. Subsequently, it was decided to conclude the project with industry level technical drawings of the structure, which may later be used by another team to execute the safe construction of the project.

The next step calls for a revision of the existing timeline and redistribution of tasks. We hope to submit a package of technical drawings, including CAD and SketchUp drawings, by the end of the project timeline.