Part 1b of the exam requires you to write a formal letter to the client explaining the impact of a design change.
The examiners make it clear in their reports that they are looking for you to identify any issues with the design and construction and propose solutions to the problem, not a letter saying that it can't be done or explaining that it will cost more and there will be programme implications. If the change makes your design non-viable then explain why and propose an alternative.
Remember to think about the effects of any constraint on the temporary works and construction as well as the permanent works design.
It's worth setting out your response as a formal letter; you can draw two boxes for the addresses and write "my address", "client's address" to show you know what the format is.
Don't sign your real name at the end of the exam paper, this is an instant fail. Practice signing off as "The Engineer".
The constraints introduced by part 1b (the letter) are not carried forwards to part 2 (calculations, drawings, method statement and programme).
Letter Topics in Previous Exams
The table below shows the frequency of different letter types in past exams:
| Year | Month | Change of foundation constraints | Change of headroom clearance | Level change | Change of loading | Change / introduce skew | Change / introduce curvature | Change of parapet / barrier | Notes |
| 1999 | April | x | Move access road closer to dock basin -> restricts support locations and affects span | ||||||
| 2000 | April | x | Raise deck level of walkway | ||||||
| 2001 | April | x | Move zone of no foundations | ||||||
| 2002 | April | x | Increase span by 10m to bridge over historic remains | ||||||
| 2003 | April | x | Increased headroom clearance to 6.5m | ||||||
| 2004 | April | x | Introduce 2m wide path either side of highway -> increased span | ||||||
| 2005 | April | x | Change horizontal alignment to 45° skew | ||||||
| 2006 | April | x | Change clearance envelope to match existing arch | ||||||
| 2007 | April | x | Increased headroom clearance | ||||||
| 2008 | April | x | Install 2m high noise barrier | ||||||
| 2009 | April | x | No columns at west end of footbridge | ||||||
| 2010 | April | x | Raise carriageway at one end by 5m (introduces longitudinal slope) | ||||||
| 2011 | April | x | Increased water level -> reduced structural depth | ||||||
| 2012 | April | x | Increased river width -> longer span. New supports may be adjacent to river -> impact | ||||||
| 2013 | April | x | Change of load limit on rocky outcrop | ||||||
| 2014 | April | x | Change of water level -> reduced structural depth | ||||||
| 2015 | January | x | Jetty load capacity reduced by 50% | ||||||
| 2015 | July | x | Impact load 3000kN | ||||||
| 2016 | January | x | New heavy wheel load on deck | ||||||
| 2016 | July | x | Change of water level -> reduced structural depth | ||||||
| 2017 | January | x | Increase headroom clearance to 5.7m | ||||||
| 2017 | July | x | Horizontal clearance to support increased by 5m | ||||||
| 2018 | January | x | Change of ground properties | ||||||
| 2018 | July | x | 20m HV cable exclusion zone adjacent to river | ||||||
| 2019 | January | x | Archaeological remains at north foundation | ||||||
| 2019 | July | x | Introduce 150m radius curved alignment | ||||||
| 2020 | January | x | No permanent structures on paths around the basin | ||||||
| 2020 | September | x | Architectural ruins increase exclusion zone 5m | ||||||
| 2021 | April | x | Highway below bridge widened from 25m to 40m | ||||||
| 2021 | September | x | Support exclusion zone 15m next to railway embankment |
In summary:
- 16no. or 53% change of foundation constraints
- 7no. or 23% change of headroom clearance
- 2no. or 7% for each of level change and loading change
- 1no. or 3% for each of skew, curvature, and change of parapet/barrier
Changing the foundation constraints is by far the most common topic, which should give you plenty to talk about - changing the support locations may affect the span and span to depth ratios, span proportions (main span to back span ratios) and may move supports into / out of impact zones etc. Changes to the headroom clearance often affect the available structural depth which may necessitate a different form of construction with smaller structural depth e.g. change to a half-through or through- girder/truss, tied arch or similar.
The cheat sheet below shows the format and has some items to think about during the design.
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