SLIDE 1
Scrutiny of Highway Maintenance 17 th June 2011 www.hertsdirect.org - - PowerPoint PPT Presentation
Scrutiny of Highway Maintenance 17 th June 2011 www.hertsdirect.org - - PowerPoint PPT Presentation
Scrutiny of Highway Maintenance 17 th June 2011 www.hertsdirect.org Introduction to the Topic Chris Allen-Smith Service Manager (Asset Management & Maintenance) www.hertsdirect.org Agenda What are the pressures and challenges?
SLIDE 2
SLIDE 3
www.hertsdirect.org
Agenda
- What are the pressures and challenges?
- How are roads made?
- Why do they need maintenance?
- What types of maintenance are there?
- What treatments are available?
- What is our strategy?
- What do we mean by ‘Whole Life Cost’?
SLIDE 4
www.hertsdirect.org
What are the challenges?
- Road condition has
improved slightly in the last ten years but may now be slipping back due to recent harsh winters.
SLIDE 5
www.hertsdirect.org
What are the challenges?
- Road maintenance
spending has not increased in real terms in the last ten years, only keeping pace with inflation.
SLIDE 6
www.hertsdirect.org
What are the challenges?
- Resources will reduce in
the future due to spending cuts
SLIDE 7
www.hertsdirect.org
What are the challenges?
- At the same time councils
face challenges from increasing traffic, high public expectations, bad weather and substantial cost inflation.
SLIDE 8
www.hertsdirect.org
SLIDE 9
www.hertsdirect.org
SLIDE 10
www.hertsdirect.org
SLIDE 11
www.hertsdirect.org
SLIDE 12
www.hertsdirect.org
- Multiple small-medium towns
- One million residents
- 277,000 cross-boundary commuters
- 362,000 live & work in Herts
- Poor East-West rail links
- 5,000 km of roads
SLIDE 13
www.hertsdirect.org
How are roads made?
- Roads are built in layers
- Surface layers - usually asphalt
– Surface for traffic – Provides grip – Waterproofs the road – Gives some strength
- Structural layers – usually
stone – Provides shape and strength
SLIDE 14
www.hertsdirect.org
How are roads made?
- Construction Varies
- Designed Roads
– Thick construction – Strong
- Evolved Roads
– Most of the network – Thin/uneven construction
SLIDE 15
www.hertsdirect.org
Why do roads need maintenance?
Asphalt surfaces:
- Lots of different types/names – similar job
- Mix of different sizes of stone
- Bound together with bitumen
– Bitumen is oil-based – Oxidises over time – Becomes brittle & cracks – Water can get in
SLIDE 16
www.hertsdirect.org
Why do roads need maintenance?
Asphalt surfaces:
- Water freezes in winter widening the cracks
- Water can penetrate to lower layers, causing
damage
- Keep the surface sealed!
SLIDE 17
www.hertsdirect.org
Why do roads need maintenance?
Structural layers can develop problems due to:
- High numbers of very heavy vehicles
- Poor ground conditions
- Utility reinstatements
- Need expensive repairs
- Fortunately rare
SLIDE 18
www.hertsdirect.org
What types of maintenance are there?
- Reactive repairs
– Reactive fix to immediate problem (e.g. fill a pothole)
- Planned repairs
– Planned work to restore condition/service (e.g. patching works)
- Planned maintenance
– Planned work to maintain condition (e.g. surface sealing)
SLIDE 19
www.hertsdirect.org
What types of maintenance are there?
20 40 60 80 100 120 140 160 180 Typical Cost P
- t
h
- l
e P a t c h R e s u r f a c e D r e s s
Cost to treat 1 sq m
- More planning and less reactive = lower cost
SLIDE 20
www.hertsdirect.org
What treatments are available?
- Many different options:
– Short term repairs – Longer term repairs – Surface treatments – Resurfacing – Reconstruction
SLIDE 21
www.hertsdirect.org
Short term repairs
- Temporary, cold pothole fills
– Used to keep the road safe – Expensive – Not very durable – Often seen as poor value
SLIDE 22
www.hertsdirect.org
Longer term repairs
- Patching with hot material
- Jet patching
– Can be repairs on their own – Or preparation for further works
SLIDE 23
www.hertsdirect.org
Surface treatments
Surface dressing:
- Hot liquid binder & stone chips
laid on existing road surface
- Seals the surface
- Restores texture & grip
- Quick to apply
- Low cost (£5 - £8 per m2)
SLIDE 24
www.hertsdirect.org
Surface treatments
Micro asphalt:
- Cold emulsion of binder &
stone laid on road
- Seals the surface
- Regulates minor dips
- Restores texture & grip
- Quick to apply
- Low cost (£8 - £13 per m2)
SLIDE 25
www.hertsdirect.org
Resurfacing
- Existing surface removed & replaced, possible
lower layers too
- Restores texture & grip
- Restores ride quality
- Reasonably fast
- Costs vary (£15 - £50 per m2)
SLIDE 26
www.hertsdirect.org
Recycling
- Replaces the surface
- Restores texture and grip
- Extends road life
- Restores ride quality
- Creates/restores structural
layers of quieter roads
- Quite expensive (~£35 per m2)
SLIDE 27
www.hertsdirect.org
Reconstruction
- Replaces the surface
- Restores texture and grip
- Extends road life
- Restores ride quality
- Creates/restores structural
layers of the road
- Expensive (£40 to £100 per m2)
SLIDE 28
www.hertsdirect.org
What is our strategy?
Category (Cat) 1 works: – Entirely reactive – Fix immediate hazards – Focused on safety – Expensive – Poor value (but necessary)
SLIDE 29
www.hertsdirect.org
What is our strategy?
Category (Cat) 2 works: – Mostly planned repairs – Reduce Cat 1 defects – Maintain serviceability by fixing non-hazardous defects – Delay need for more extensive works
SLIDE 30
www.hertsdirect.org
What is our strategy?
Category (Cat) 4 works: – Mix of planned repairs and preventative maintenance – Maintain asset for the future – Optimise long-term condition – Deliver value for money – Focus available money where it gives greatest benefit
SLIDE 31
www.hertsdirect.org
What do we mean by ‘whole life cost’?
- Audit Commission: ‘minimise whole life costs’
- Core principle of asset management – look at
long term, not just immediate implications
- More of the detail later - introduce the concept
SLIDE 32
www.hertsdirect.org
Consider alternative strategies…
SLIDE 33
www.hertsdirect.org
Put ‘whole life costs’ against each…
e.g.:
- 6 x £5 = £30
- 3 x £25 = £75
- 2 x £50 = £100
SLIDE 34
www.hertsdirect.org
Consider other factors…
What implications might each option have for:
- Reactive costs (like potholes)
- Impact on traffic on the network
Often this means a cheaper, preventative treatment is best value for money but that is not always the case, for example…
SLIDE 35
www.hertsdirect.org
Applying WLC to case studies
A414 London Colney Roundabout:
- Accident problem
- Poor lane definition a cause
- Initial proposal – define East to West route
using anti-skid surfacing
- But anti-skid is
– Expensive – Not very durable
SLIDE 36
www.hertsdirect.org
Applying WLC to case studies
A414 London Colney Roundabout: – Same solution, different material – Coloured conventional asphalt – Marginally higher initial cost – Four times the life – Much lower WLC
SLIDE 37
www.hertsdirect.org
thank you
SLIDE 38