BCF2/BOF6: June 2002
Printable version of these minutes:
|Ian Leigh||BRB||Charles Cocksedge||FaberMaunsell|
|Geoff Medd||BRB||Stuart Withycombe||Halcrow|
|John Powell||British Waterways||Vardy Jones||Highpoint Rendell|
|Rod Howe||British Waterways||Mike Chubb||WS Atkins|
|Gordon Reid||County Surveyors Society||Tony Small||Pell Frischmann|
|Graham Cole||County Surveyors Society||Steve Denton||Parsons Brinkerhoff|
|Andrew Cook||Dept. for Transport||Simon Collins||Mouchell|
|Ronnie Wilson||DoRD (Nth Ireland)||Angus Low||Arup|
|Gerry Hayter||Highways Agency||Gareth Hughes||WSP|
|Victoria Hogg||Highways Agency||Nigel Beavor||Babtie|
|Jim Moriarty||London Underground Ltd||Javad Akhtar||Mott MacDonald|
|Brian Bell||Railtrack||David MacKenzie||Flint & Neill|
|Raymund Johnstone||Scottish Executive||Peter Sparkes||Bullen|
|Richard Morgan||Welsh Assembly||Peter Chong||Peter Brett|
|John Vincent||Tony Gee & Partners|
|John Menzies||Technical Secretary|
|BOF members unavailable for meeting||Cambridge University|
|John Collins||Welsh Assembly||Cam Middleton||Chairman|
|Barry Mawson||WATO (Welsh Tech. Officers)||Paul Fidler|
|Brian Swan||SCOTS||Rebecca Lock|
|Graham Bessant||London Underground Ltd||Hai-Yun Lu|
Campbell Middleton (CRM) welcomed those present to this first joint meeting of the Bridge Owners Forum (BOF) and Bridge Consultants Forum (BCF). He hoped the meeting would be a positive interaction between bridge owners and consultants. He outlined the main goals for the meeting:
- To identify research needs
- To present key topics and debate the issues
- To prepare recommendations for priorities for research
Prior to the meeting, the consultants had worked together in five small Subgroups to discuss issues and research needs in five theme areas:
- Procurement methods
- New materials
- New design/analysis methods
- Assessment of existing bridges
- Bridge management
Presentations of the Subgroup's findings and views were then made.
Procurement Methods - Subgroup: CC, SC, VJ and TN.
Clients' objectives were identified relating to:
- Speed of delivery
- Whole life cost
- Confidence in outturn cost and time
Attention was drawn particularly to the importance of quality and the perception that, nevertheless, lowest price still wins in most/many cases. Associated Client's difficulties were discussed. Whilst different methods of procurement are available to the Client (D&B, DBFO, PPP/PFI etc) it was emphasised that efficient implementation is the key concern whatever procurement method is used. The procurement method needs to be matched to the size and complexity of the project. Difficulties were seen to arise from the separation of technical engineering expertise from the procurement process which is often in the hands of procurement managers/administrators.
The main principles of good procurement were identified as:
- Clarity of objectives
- Clarity of award criteria
- Short short lists
- Communication (briefing, feedback, interviews)
The presentation concluded that successful procurement requires active client involvement in the process and positive relationships throughout. The prime need is to focus on the project and good communications. Early contractor involvement was believed to be very beneficial.
In discussion, it was agreed there are many questions to consider. Points and suggestions made were:
- Outturn cost is an imperative across the whole industry.
- Tenderers often face difficulty in obtaining information from 'neighbours' at the project location. It was suggested that it is the Client's responsibility to get necessary information from 'neighbours' and then to pass it to all tenderers.
- DBFO is likely to lead to real problems with the bridge stock at the end of the operating period.
- It is important to have strong and capable Clients.
- Prequalification: A lot of time and energy is expended in this process. Organisation memberships required are too many. There was a suggestion that perhaps the Institution of Civil Engineers (ICE) might be asked to take the lead in simplifying this process.
- Procurement is now a large part of Highways Agency work - effort is being made to make the process transparent through, for example, a strategy document now available; whole life costing is being used.
- Procurement is becoming more difficult to control because more and more aspects have to meet European Union requirements.
- D & B: good Client involvement is essential to gain benefits of the method. How a contractor procures his consultant for the detailed design was thought to be an issue.
- Procurement should be on a quality basis only, with fees subject to subsequent negotiation.
- Short short lists were strongly advocated as that enables tenderers to focus more on specifics and to take the task more seriously. The Forum was reminded that in the 1970s, consultants were selected from lists of 5 or 6, and this became a recipe for lack of quality and innovation. A process is needed that maintains vibrancy and encourages innovation.
The marking of quality was seen as an area of particular difficulty often resulting in quality being relatively unimportant compared to costs. Wide marking ranges for quality were advocated: guidelines are needed. It was also suggested benefits would accrue if engineers were in control of procurement.
The relative success of different procurement methods is not known. It is not clear how the Client can/should measure success. Work to gain a measure of the relative success of methods would be worthwhile.
New Materials - Subgroup: RB, SD, DM.
Attention was first drawn to the general difficulties in introducing new materials into bridge construction:
- The direct substitution 'mindset' - direct substitution of a 'new' material can be an irresistible temptation but is unlikely to produce a satisfactory solution.
- The lack of performance data for a 'new' material, especially monitoring data on its use in practice.
- Development costs.
Demonstration projects were suggested as essential to overcome/minimise these difficulties.
The development of concrete was considered. Two areas of development were identified:
- Reduction of defects and increase in the reliability of existing concrete technology
- New concretes: ultra-high strength concretes and fibre concretes.
To improve existing technology , three streams of research/development are needed:
- Pure research, eg relating to heat of hydration, long-term deterioration and repair costs.
- Encouragement of more rapid introduction of improved technology, eg use of flowing concrete to produce thinner decks and box sections in one pour, through demonstration projects.
- Evolution and promulgation of ideas through developments in design practice and codes, eg guidance on provision of ductility to reduce progressive collapse risks.
Project funded research for field research relevant to the project was advocated, based on a levy of x% on each project over £Xm cost.
It was suggested that mistakes had been made in the introduction of 'new' materials resulting in particular from lack of full understanding of the new material, its characteristics and limitations. Hence demonstration projects are valuable as they 'test' all the issues at once. The strengthening of concrete beams with FRP composites was given as an example. Issues mentioned were thermal effects, use on curved beams, ductility, robustness, material characteristics/specification and installation management. Conclusions were that the introduction of 'new' materials is often rather the development of existing materials and needs to be derived from a wide research base. The use of a peer review panel to improve the chance of success was advocated in addition to demonstration projects. Peer review in advance was thought to be especially valuable in order to prevent the reputation of a 'new' material being lost through a bad application.
In discussion of the three proposals (demonstration projects, levy and peer review) the following points were made:
- Some progress has been made by the Highways Agency in using demonstration projects - the difficulty is being even-handed - a levy might help with that.
- Demonstration projects carry greater risk - peer review can help with that.
- Clients/consultants/researchers do not 'get together' enough.
- Operative qualifications are very important but industry is reluctant to give this the attention needed.
- Potential economic benefits for UK and UKplc are considerable but builders prefer not to innovate (for good reasons) - low-risk applications should be tried first.
- Lack of demonstration projects has prevented some new materials from 'taking off', eg lightweight concrete.
- Monitoring performance of new materials over time is essential but very difficult to maintain over the long term.
- Adverse performance must not be 'swept under the carpet'
New Design/Analysis Methods - Subgroup: AL,JA,SW,JV,VJ.
In introduction, two 'overarching' points were made:
- The Structural Eurocodes contain lots of good material and their use should be encouraged more (so that UKplc is well positioned in Europe).
- Development studies (procured by Clients) are needed to underpin the use of new design/analysis methods.
Development studies should examine, for example, the effect of the proposed new method of bridge design, implications, opportunities for significant savings, suggested design solutions, examples of justification calculations, design development conditional on other research to be done, and proposed prescriptive rules for D & B.
It was suggested Clients should step back from prescribing solutions and instead give higher level project objectives, eg relating to risk/safety level, durability and loading. Much saving can be obtained at the design concept stage if alternative structural systems can be considered.
Issues relating to the dynamics of lightweight structures were presented:
- There is a need to pull together existing knowledge.
- Clear rules are needed for pedestrian loading on footbridges together with acceptance criteria - existing rules are based on single pedestrians and short span solutions whilst new designs are much more slender and daring.
- The stock of cable supported bridges is growing.
- Cable supported bridge systems are continually evolving - DMRB is silent on specifications and durability provisions.
- Cable supported bridges are largely prefabricated and modular - testing requirements for fatigue are not defined and dynamic excitation (wind, rain) is not well formulated.
- Dependability of suppliers is an issue.
- Inspection requirements are not established nor are 'cable-out' criteria.
Actions needed to deal with these issues were proposed:
- For pedestrian bridges, develop rules for loading and acceptance criteria.
- For cable supported bridges, develop a model specification for cables.
- Prepare guidance on fatigue testing.
- Seek national/international agreement on cable removal criteria.
- Develop guidance on inspection regimes.
Areas for research to assist consideration of alternative structural systems were suggested:
- Integral bridges: Soil-structure interaction (run-on slabs, soil reinforcing elements, back-fill materials - need to reduce demand for imported fills - and joints)
- Restraint systems: Static forces/energy/dynamics approaches to design for impact (parapets, barriers, impact loads, highway layout)
- Selection of structural form: Trade-off between alternatives, opportunities for new/recycled materials.
In addition some specific reseach topics were suggested:
- Concrete: time dependent/maturity/durability performance.
- Stitches between concrete slabs/panels.
- Weld on weld.
- Use of bolts in tension (review needed).
The following points were included in the discussion of the presentation:
- The introduction of proprietary products in civil engineering D & B projects raises problems of even-handedness.
- Codes do not cover 'new' materials.
- There are no standards for timber, masonry or moveable bridges [TO note - see Eurocodes]
- Consultants rarely ask for 'departure from standards' to use other codes.
- Clients may try to encourage innovation but contractor’s very competitive position make them very reluctant to innovate.
- The TAA is under more pressure in D & B projects.
- Most academic research is EPSRC funded but rarely are consultants involved with the industrial advisory panels. Too often research findings are published only in 'research' journals.
- The concept of the 'standard bridge' is not useful but 'standard details' - if they are regularly updated - are useful and more time should be spent developing them.
Areas where research is needed were suggested:
- Structural forms where no analysis method is available.
- Actual structural strength as assessment calculations often indicate substantial reserves of strength.
- U-frame action (parametric study).
- Masonry arches - transverse load distribution, influence on capacity of brick pattern, 3D shape, abutment restraint and condition.
- Detailing rules - beams without shear reinforcement (TRL tests in progress for Railtrack), curtailment rules, outstands, shear in slabs.
- Parapets - unreinforced masonry, short parapets, plinth height, transitions, parapet/safety fence connections.
In discussion, points made included:
- There are benefits for Clients in pooling research information but it was noted there is reluctance/difficulty in doing this.
- A masonry arch 'network' is being launched by Clive Melbourne.
- Railtrack is now using less onerous rules for assessing rivets. There was a suggestion that, whilst these new (shear) rules are more realistic, more relaxation may be possible.
- Safety fences: A European standard is about to replace BS6779.
- A huge amount of research has been/is being done and there is a heavy cost to consultants in keeping track of it. The biggest problem is the collection of available data. An issue for Clients to consider? How can it be done?
Bridge Management - Subgroup: MC, NB, GH, TS.
Elements of the process were outlined [Assessment, Strengthening, Maintenance (Routine/Preventative), Improvements and Monitoring] and the objectives summarised:
- To minimise disruption.
- To ensure safety.
- To obtain value for money.
Areas suggested for research were:
- Since the largest effects on disruption are generally due to traffic management and statutory undertakers works, review of case histories was suggested as a basis for improving guidelines.
- Standardisation of reports to owners.
- Value of monitoring techniques.
- Deterioration rates - The situation relating to a typical
reinforced concrete bridge and a post-tensioned viaduct was
[R/C viaduct: History - leaks through joints, crossheads in a bad state, much testing and monitoring done, wide scatter in results, corrosion 'hot spots' move around. On assessment passes 40T now but for how long?]
[P/T viaduct: History - leaks through segmental joints, 27% strands lost in worst case, monitoring in progress. On assessment passes 40T now but for how long?]
Collection of (existing) data was proposed as a basis for review of design/assessment standards to re-jig partial factors so there is as explicit factor for deterioration that is a function of usage and difficulty of repair.
- Verge loading - The design requirement for the 40T accidental vehicle was questioned. Review is needed to evaluate risks with a view to reducing this load.
- Parapets - Work for Transport for London was outlined.
- Repair Techniques - the appropriateness of rules in whole life cost models was questioned.
- Peer review - It was suggested that in order to learn from mistakes a system of peer review of assessment/strengthening work should be set up.
The following points were raised in discussion:
- The reluctance of an incoming consultant to accept the work of an outgoing consultant was seen as an issue.
- There is insufficient research on performance in service, eg silanes, cathodic protection.
- The Highways Agency is preparing guidance on NDE techniques.
- Peer review of assessments is valuable - error and scope for adjustment can often be found.
CRM summarised the main issues that had emerged:
- Technical quality
- Preference for engineers to be in control of procurement
- New Materials
- Demonstration projects
- Project-based levy
- Peer review
- New design/analysis methods
- Development studies
- High level project objectives
- Standard details
- Assessment of existing bridges
- Pooling of research
- Keeping track of latest research
- Bridge management
- Acceptance of previous consultant's work
- Need for research on performance in service
Since there is no other national bridges group, CRM suggested it is important that the BOF/BCF tackles such issues.
3 July 2002