OR/16/034 Modelled volume, purpose and scale

Barron, A J M. 2016. Metadata report for GSI3D cross sections along the HS2 route in Area 9 (Birmingham spur). British Geological Survey Open Report, OR/16/034.

The Area 9 cross-section based model depicts the bedrock, natural superficial deposits and artificially modified ground geology along the western part of the HS2 Birmingham Spur of the proposed route of the High Speed Rail link between London and Birmingham. This is one of an initial group of nine models along the proposed route. These models and cross-sections are suitable for use at scales between 1:100 000 and 1:10 000 to a depth of 30 m below OD. Whereas the models for Areas 1–8 are full 3D models (with geological units represented by surfaces and volumes), the Area 9 model is represented by a network of cross-sections from which no attempt has been made to create geological surfaces.

To constrain the geology along the entire Birmingham Spur between Castle Bromwich and the Birmingham Terminus, nineteen cross-sections were constructed. For the eastern part of the Birmingham Spur, corresponding cross-sections were added to the existing Area 7 geological model. This report describes the cross-sections along the western part of the Birmingham Spur between Castle Bromwich and the Birmingham terminus (Figure 1), with the ‘online section’ following the proposed HS2 route. Construction of the online section was aided by the compilation of cross sections that intersect it, which enable the integration of borehole data in the vicinity and held by BGS in 2013 to inform the nature and depth/thickness of geological units.

File:OR16034fig1.jpg

Figure 1    Location of the Birmingham Spur cross section.

Prior to the cross section construction an assessment of the quality and availability of digital geological linework and existing 3D models of the entire HS2 route between London and Birmingham was undertaken (Barron et al., 2012). Following this review, the geological mapping of this sector was deemed to be adequate, dating from the 1960s to the 1990s. Thus these cross sections are based on geological linework from existing 1:10 000 and 1:50 000 scale DiGMapGB data. The cross sections lie entirely within BGS 1:50 000 Sheet 168 (Birmingham), surveyed between 1978 and 1992, published in 1996 and accompanied by a memoir (Powell et al., 2000).

The cross sections following the proposed route of HS2 Birmingham Spur are shown as black lines; cross sections constructed to inform the geology of the route are coloured red (numbered NS1 to 17 from east to west); Birmingham 1:50 000 sheet cross-section 1 shown in green; Area 7 model area outlined in purple, with Area 7 cross-sections shown in blue. This report describes the cross-sections in Area 9, to the west of Area 7. Contains Ordnance Survey data © Crown Copyright and database rights 2016. ==References==