Main Tech Questions Flashcards
How is a road or pavement constructed?
- First removal of topsoil, scraping and grading an area called the formation level.
- Lowest level is the subgrade or ‘soil’ CBR testing
- Drainage and services should be laid along gully
- Layer of sand or gravel on top of subgrade (sublayer)
- Base layers above this then;
- Flexible (asphalt) or rigid (concrete) paving can be layered on top to form the base layers.
- On top of the base layers the surface layer is laid
What are the sustainable environmental assessments to certify a project?
- Building Research Establishment Environmental Assessment Method. (BREAM)
- Leadership in energy and Environmental design (LEED)
- Both - Assessing, rating, and certifying the sustainability of buildings.
What is the difference between rigid and flexible paving?
- Flexible paving has multiple base layers whereas rigid usually has a concrete slab.
- Rigid layer costs more but more durable, flexible layer isn’t as strong but reacts better to temp changes.
Difference between green roof and blue roof?
- Green roof – absorbs rain water, insulation, habitats wildlife, aesthetics, helps lower urban air
- Blue roof – collects water and releases it slowly when rain has stopped – e.g attenuation tank
What is the difference between artificial stone paving and York stone paving?
- ASP: Pros Convenient to source, lots of choice, widely available, cost effective
- ASP: Cons: Quicker to fade, easily damaged, very large carbon footprint.
- York stone: Pros: Lasts a long time, lots of choice, easy to install.
- York stone: Cons: Expensive Natural so can be varied or inconsistent between batches
How did you estimate the cost of the HVM’s?
I spoke to a specialist supplier who provided the associated costs of the different mitigation methods, this included installation costs.
How do you install palisade fencing?
Dig a hole for each fence post, add gravel and pour concrete in the hole, insert the post and ensure level and let it set at least a day.
How do you install Heras fencing?
Poles are fitted securely into concrete bracing blocks and connected using anti-tamper couplers.
What was the design and cost of the proprietary mat system?
- Heavy Duty Ground Protection mat is manufactured from 100% recycled high density polyethylene (HDPE)
- Weight tested to maximum load of 80* tons on both flat and somewhat uneven grounds. Connected together with couplers
- £60 per matt, £5 connector - £70k About 1000 mats
What things does a contractor need to consider when excavating?
- Nature of soil
- Moisture Content
- Method of excavation
- How Deep you are going
- Proximity of other buildings
What is a retaining wall?
A retaining wall is a structure designed and constructed to resist the lateral pressure of soil, when there is a desired change in ground elevation that exceeds the angle of repose of the soil.
Name some types of foundation?
- Strip
- Raft
- Pad
- Piled
What are the different types of construction methods for bridges?
- Balanced Cantilever Method of Bridge Construction - this method is used for constructing bridges with span 50 to 250m.
- Cast insitu – construct from ground – complex shapes
- Suspension Bridge
- Arch Method for Bridge Construction – economical- concrete or pre cast
What are the different types of construction methods for tunnels?
- Cut and cover tunnel – constructed in a shallow and covered over
- Bored Tunnel – constructed in situ without removing the ground above
- Immersed tube tunnel – sunk in water and buried.
What sort of temp drainage solutions are there?
- Surface water drainage – Sustainable urban drainage systems (SUDS), permeable pavements Soak ways (disperses water gradually).
- Foul water drainage – Connection to mains drainage or collection in a sceptic tank.
What types of fencing are there? Why did you advise heras?
- Mesh palisade - more labour intensive, more expensive
- Chain-link – more labour intensive, need excavation
- Wooden hoarding - used more in construction rather, longer to install
- Heras – Lightweight, anti-climb, secure interlocking, weather resistant, can be altered easily
What are typical surveys that would be required for a construction project?
Services
- Services
- Topography
- Asbestos - what has the land been used for previously?
- Ground investigation - ground bearing suitability for requirements
- Ecology - are there protected species preventing works
- Transport - are there restrictions on access.
- UXO discovery - is it an area where explosives might be present
What are the main suites of construction contract?
- JCT 2016 Standard, Mnior works, design and build, framework
- NEC3 (New Engineering Contact)
- NEC3 (New Engineering Short Contract)
- NEC3 Professional Services Contract)
- FIDIC - Lump Sum, Cost plus, Turnkey
- ICE (Institution of Civil Engineers)
Advantages of FIDIC contract?
Internationally recognized
4 main options, Lump sum, design and build, short form and turnkey which NEC3 doesn’t offer
Please talk me through an example from your experience of a situation where you have prepared a report which recommends the appropriate form of contract to be adopted?
- On Beckton Depot Enabling works package 2:
- TfL standard form of Contract is NEC3 ECC
- Considered option A & C
- Client being risk averse
- Looking for a set price
- Detailed scope of works
- Work was not complex in nature
• Option A – Fixed price with activity schedule
Lowest risk
more price certainty
pay a premium for risk
• Option B – Fixed price with Bill of quantities –
Weren’t defined quantities in scope
defined scope but not defined quantities
Design and build so incentivize over design
- Option C – Target Price with activity schedule – Scope wasn’t likely to change, weren’t expecting many changes.
- Option D – Target Contract with bill of quantities – quantities might be difficult to define
• Option E – Cost Reimbursable
low cost certainty - usually used when scope isn’t clear
Explain how you have advised on the appropriateness and implications of proposed contractual mechanisms?
Whilst on Beckton depot enabling works package 2 I advised the use of the additional clauses
• X4 - Parent company guarantee
• X7 - Delay damages
• X16 - Retention
i also considered inflation but project not long enough
I was aware that the contractor was a subsidiary of a larger company so I advised that a parent company guarantee would offer insurance against insolvency of the contractor we were in contract with.
What is a Parent Company Guarantee?
An arrangement where the contractual performance of one company in a corporate group is underwritten by the other members of that corporate group.
What are the contractual benefits of a Framework over other procurement options?
- Pre agreed rates for suppliers
- Terms and conditions already set
- Supplier relationship already exists
- Simpler to run a call off contract to make individual contract amendments for the specified works.
Explain how you have managed a compensation event in a project you worked on?
Beckton depot enabling works:
Early Warning Notification – protected species
Risk reduction meeting – discuss mitigation
NCE raised – assessed for entitlement – Within 8 weeks
Detailed as employers’ risk in contract data 2
Gained necessary internal approvals
Accepted NCE – Employer reply’s in 1 week
No reply Contractor notifies after 1 week
If no decision is made 2 weeks after reminder then treated as accepted
Awaited quotation - 3 weeks to submit a quotation
Assessed Quotation - 2 weeks to reply to quotation
If no reply contractor notifies, if PM does not reply then after 2 weeks after reminder quote accepted