000301_Ms3_Gantry_Foundations_Javad_Akhtar

abcInnovation for Cantilever Sign Foundations
Innovation For Cantilever Sign
Foundations
At Highways Agency 1 March 2000
A Cavendish-Tribe Manufacture/Inspection
A O’Brien Foundations/Geotechnics
J Akhtar General Design
1 9 9 6 1 9 9 8

MS3 Components
 Enclosure
 Arm/Upper Post
 Main Post
 HD Arrangement

MS 3 Documentation - Foundations
 TRH 1642 - Infrastructure Design Guide
 TRH 1239 NMCS Installation Drawings:
 MCX Drgs 0583 - Structure
 MCX Drgs 0584 - Site Layout

MS 3 Maximum Dimensions [m]
MS 3 (3x18) MS 3 (2x16)
Structure Outreach 8.664 7.960
Signal width 9.360 8.190
Signal depth 0.500 0.500
Signal height 3.315 2.535

Enclosure
 Aluminium Box
 3x18 or 2x16 character message
 Requires cabling for power and
communication
 Requires walkway access to rear
 Bolted connection to arm
 Tilt adjustment 0 to 6°

 800mm wide walkway
 Handrail & infil for safety
 Upper Bolted connection to Main
Post allows tilt adjustment
MS Support Arm
Anticlimb mesh to ladder

MS 3 Post
 Painted Steel CHS
 820 x 20 mm
 Internal Cableduct
 Ladder
 Flanged connection for arm
support
 Flanged Connection for HD
bolts -
 Slotted Holes for Rotational
Adjustment

HD Arrangement
 Studs
 levelling nuts
 Grout
 Coupler
 Bearing Ring -
cast into plinth

Plinth
 Contains HD Bolts
 Connects to Foundation
 Provides Headroom
Adjustment
 Takes Lower Impact load
 Cable duct & Drain

 Cabinets
 Ducts
 Safety Fence
 Retaining Walls
 Paving
 Vehicle Hardstanding?
Site Infrastructure

Sign Siting Considerations
 Logistical
 Visibility
 Ground conditions
 Services
 Access
 Orientation - to point 200m away in middle of lane 2

Foundation Design Procedure
Geotechnical
desktop Study
Trial Location For
Design + 5m
[determined by
client]
Drainage &
Services
Information
Design Of Standard
Foundations for
generalised ground
conditions
Notification of Standard
Structures & Foundation
Loads
Topographic
Survey
OS 1:1250 or
1:2500 mapping
As Built Highway
Drawings
Soil "Window"
Sample to 5m
depth
AIP for site &
Foundations
submitted to TAA
Environmental
Impact assessment
Specific Site
Layout Plan
Submission To
Planning Authority
Detail Design of
Foundation & Site
Detail Design of
Special
Foundation
Deep borehole Site
Investigation
Is
standard foundation
suitable?
Yes
Drainage &
Services
Information
No
AIP
Approved?
Planning
Authority
Comments
Amend EIA to
incorporate minor
comments
(see note 1)
Amend AIP to
incorporate minor
comments
(see note 1)
No
Yes
Complete Checks,
Certification & For
Construction Issues
Notes
1. In the event of externa l
no n- ap pr ova l d u e to
reasons beyond control of
fo un d ati o n de si g n er ,
restart as new site.
START
Objectives
•Allow tasks to be
undertaken in parallel
•Selection of most
suitable Standard design
•Verified or modified to
suit individual sites
•Use of spreadsheets or
standard analysis models

Possible Design Objectives 1
 Provision to upgrade to future standard
 Provision for motorway widening
 Provision for Re-cabling
 Minimise land take
 Minimise visual intrusion
 Collision Behaviour:
 Safety of vehicle occupants - protection strategy
 Minimise damage to installation

Possible Design Objectives 2
 Speed of construction
 Safety during construction
 Simplicity of Technical Approval & Design
 Ability to adopt in a variety of ground conditions
 Minimise environmental impact
 Maximise use of recycled materials
 Stability and stiffness
 Long term settlement & tilt limits

Provision For Future Motorway Widening
Some Options:
 Construct gantry leg at future position.
 Extended Cantilever, or
 Portal Gantry
 Provide second set of couplers on wide foundation
 Relocatable steel pile foundation

Some ideas
 Incorporate cabinets into plinth
 Reduces land take
 Simplifies construction
 More direct cable connections
 Innovations in comms design mean comms cabinet may no
longer be necessary
 Extend post to ground level
 eliminates separate plinth (less site work, easier to widen
motorway?)
 May require several standard post lengths

Some Concrete Foundation Types
 Mass Concrete
 4 - Pile
 2 - Pile
 1 - pile

Some Steel Foundation Types (1)
 Dawsons
 Single large diameter circular casing
 H-piles connected by conventional pilecap

Some Steel Foundation Types (2)
 Cable stays to
structure with
ground anchors or
tension piles
 Works better if
structure cantilevers
backwords
 Large landtake
 May be configured to
avoid obstructions

Design Parameters
 Loading - Load Table From TRH 1642
 Wind Speed - 51 [m/s] standard
 Soil Properties - From Site Investigation
 Geometric/layout Constraints:
Landtake, Cutting proximity, Services
 Site Stability - embankment, poor ground
 Groundwater - level, aggressiveness

000301_Ms3_Gantry_Foundations_Javad_Akhtar

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