VIBRATION FROM LIVE TRAINS. Tuesday, 10 June 2014

Transcription

1 VIBRATION FROM LIVE TRAINS Tuesday, 10 June

2 QUALITY CONTROL PROCESS 2

3 TWAO VIBRATION OBLIGATIONS QUALITY CONTROL PROCESS Network Rail Local Planning Authority Network Rail appoint specialist designer Atkins to support discharge of vibration requirements under Transport & Works Act Order Atkins establish a specialist team to review obligations and identify vibration mitigations. Team included a number of subject matter experts and suppliers, including: Acoustic consultants Geotechnical engineers Structural engineers Track engineers Edilon Sedra (track systems specialist) DB Schenker Rail (stone train input) Vibration Report reviewed and assessed by Network Rail s appointed Independent specialist ERM Ltd (planning/consent prospective) Final report reviewed by all parties to confirm report meets requirements prior to submission to Local Planning Authority Vibration Report reviewed and assessed by Local Authority and Independent Expert appointed under the Transport & Works Act Order. Any queries or comments raised are fed back to Network Rail through the Local Planning Authority Any responses from Network Rail are fed directly to the Local Planning Authority Decision made against Order obligations Vibration Report Issued to Network Rail NR Competency Check Atkins Quality Check NR Quality Check LPA Quality Check Comments fed back to Atkins for report update 3

4 CURRENT PROJECT STAGE Public inquiry (complete) TWA Order made (complete) Discharge of Conditions (current) 4

5 SUBMISSION AND REVIEW PROCESS NR review SoA NR expert review Alec Glendinning Submission made to OCC and CDC Independent expert advises OCC and CDC not NR (Condition 19 requirement) Dr Chris Jones OCC and CDC to confirm that Conditions are discharged when satisfied 5

6 DISCHARGING PLANNING CONDITIONS Condition 19 (noise and vibration) Schemes of Assessment or SoA Noise (ERM) Vibration (Atkins) 6

7 WHAT IS THE SOA FOR VIBRATION? Atkins, Plain Line Vibration Assessment and Mitigation ( ATK-VIB-RPT Revisions P07) Atkins, Vibration from Switches & Crossings Assessment and Mitigation ( ATK-VIB-RPT Revisions A01) Cover letter dated 28 November 2013 sets out the monitoring scheme Independent Expert s report (forwarded by LPA officers) 7

8 GROUND CONDITIONS 8

9 WOLVERCOTE GEOLOGICAL PLAN EXTRACT Railway Oxford Clay Sands and gravels over Oxford Clay Vibration monitoring points Alluvium over Oxford Clay 9

10 SCHEMATIC GEOLOGICAL SECTION THROUGH WOLVERCOTE CUTTING Glacial sands and gravels Approx. 2m thick Weathered firm Oxford Clay Increasing shear stiffness Railway ballast/trackbed Oxford Clay 10

11 SCHEMATIC GEOLOGICAL SECTION AT SITE OF MONITORING POINTS Railway ballast/trackbed Earthworks embankment Alluvium soft clays, sand and gravels Weathered Oxford Clay becoming unweathered with increasing depth 11

12 GEOLOGICAL INFLUENCE Effect of shear stiffness of the soil the stiffer the soil, the lower the vibration Effect of soil at the immediate surface shallow top soil will follow the motion of the lower soil layers Effect of material damping of soil for a conservative estimate of low frequency vibration near the railway, damping attenuation is small 12

13 COSMETIC DAMAGE TO BUILDINGS 13

14 VIBRATION: COSMETIC DAMAGE TO BUILDINGS Risk of building damage is often a primary concern of residents who experience perceptible vibration in their homes Assessed using peak particle velocity (mm/s) with criteria for cosmetic damage set out in BS 7385 Part 2 Threshold is frequency dependant, increasing from15mm/s at 4Hz to 20mm/s at 15Hz, and then to 50mm/s at 40Hz (for transient vibration) In comparison the threshold of perceptible vibration is circa 0.14 mm/s (Z axis) 14

15 HUMAN RESPONSE TO VIBRATION IN BUILDINGS BS 6472 Measured using acceleration based index of vibration dose value (vdv) ms VDV= ( 0T a 4 (t)dt) 0.25 Response is expressed in terms of probability of adverse comment Day time: adverse comment possible 0.4 ms Night time: adverse comment possible 0.2 ms Hence these levels chosen as design levels 15

16 Q&A 16

17