Guidance for the Design of Road Pavement Foundations

For the layout of the street pavement basis, the dressmaker ought to discuss with
CD225 (layout for brand spanking new Pavement Foundations, Rev 0, layout guide for Roads
And Bridges, March 2020), or the cutting-edge revision thereof, and the modern-day revision
Of West Sussex County Council standard detail S278/38/21.
A geotechnical investigation should be undertaken alongside the line of the proposed
Roads as a way to set up the design California Bearing Ratio (CBR) and frost
Susceptibility of every subgrade type present alongside the street hall. The
Sampling/checking out must be undertaken at frequencies to suit the expected
Ground and location conditions however the spacing should not be more than 30m to
50m, staggered across the width of the motorway corridor. On small websites, a
Minimum of 3 samples/tests is needed.
The ground investigation document, consisting of exploratory hollow logs, in-situ and
Laboratory test effects, together with the interpretation of the facts used to
Establish the layout CBR cost, have to be submitted to West Sussex County
Council for evaluation and approval. cbr testing
The layout CBR value need to be mounted in general accordance with the
Guidance given in CD225 (layout guide for Roads and Bridges, March 2020),
And TRRL LR1132 (The Structural layout of Bituminous Roads – Powell, Potter,
Mayhew, and Nunn, 1984) using either of the subsequent strategies, depending on
The website conditions, ground and groundwater situations, proposed drainage
Measures, and the time of year of construction, etc.
 Laboratory CBR trying out in accordance with BS1377: element four: 1990. In line
With CD225 the tests have to be achieved over a number conditions to
Reproduce, as a long way as feasible, the conditions of moisture content and
Density that are probable to be skilled at some point of production and inside the
Finished pavement. If relevant, soaked CBR tests may additionally want to be
 The Suction Index technique, as noted in TRRL LR1132.
It have to be noted that in-situ CBR readings can vary considerably relying on
A variety of of factors, together with the moisture content of the soil and this will in
Turn vary relying on the weather situations leading up to and for the duration of trying out.
For these motives it’s miles deemed that the effects of in-situ CBR checking out constitute
The CBR cost handiest at the day of the test and are not taken into consideration as being
Equal to the layout CBR cost. The thickness of capping should be primarily based on
The agreed design CBR cost on my own.
All materials used within 450mm of finished floor level shall be non‐frost
Prone as defined in Clause 602.19 of the manual of contract files for
Highway Works (MCHW) extent 1 Specification for highway Works (SHW),
Series six hundred Earthworks, February 2016, (or modern revisions thereof).
Any earthworks shall be undertaken in wellknown accordance with the steerage in
The guide of contract files for motorway Works (MCHW) volume 1
Specification for motorway Works (SHW), collection six hundred Earthworks, February 2016,
(or state-of-the-art revisions thereof).
Steering for the design of avenue Pavement Foundations
2 remaining updated: may also 2020
Creation phase
During creation the Developer ought to demonstrate that the CBR price of the
Subgrade is equal to or extra than the design CBR value. It should be mentioned
That the construction thickness can also need to be increased if in-situ CBR values at
The time of production are less than the design CBR price. However, a
Discount in the creation thickness will no longer be considered if the in-situ CBR
Values at the time of production are greater than the design CBR value.
In-situ CBR checking out shall be finished at now not greater than 30m centres,
Staggered throughout the width of the street corridor. Acceptable in-situ CBR test
Methods encompass TRL Dynamic Cone Penetrometer checking out, California Bearing
Ratio (BS1377, component 9), or rather the CBR price may be derived from Plate
Bearing test data

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