Chapter 9: Road drainage and the water environment

1 Introduction
1.1 Overview
Jacobs UK Limited has been appointed by Skanska Construction UK/Highways
Agency to undertake a Flood Risk Assessments (FRA) for a proposed road
improvements scheme.
Junction 19 of the M1 forms the intersection between three major parts of the
motorway and trunk road network - the M1 and M6 motorways and A14 Trunk
Road. The A14/M6 corridor also forms part of the Ireland/UK/Benelux Trans
European Network or TEN. It is therefore a key node for both north/south and
east/west movements. The Location Plan, Figure A (Appendix A), shows the
current layout.
The existing junction 19 on the M1 gives rise to the following problems:
• congestion, delays and long queues
• accidents sometimes resulting in serious injuries and fatalities
• conflicts between local and longer distance traffic
• presents a barrier to pedestrian, cyclist and horse rider movements
The proposed improvement, illustrated by Figure B (Appendix B) aims to relieve
congestion at the junction, making the roads safer and decreasing journey times,
whilst minimising the environmental impacts of the scheme.
According to Planning Policy Statement 25: Development and Flood Risk, a FRA
is required to support the planning application because:
• There will be new areas of development within an area identified as being
at risk of flooding (from the River Avon).
• The area of the development is greater than 1 hectare.
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1.2 Proposed Development Details
The proposed junction would be constructed on three levels and would be similar
in height to the existing junction. It would involve the construction of new free flow
links, A14 to M1 northbound, M1 southbound to A14 and M6 to A14 in both
directions. The existing link between M6 to M1 southbound would be
reconstructed, and that from M1 northbound to M6 modified. The M1 motorway
through the junction would be retained on its current alignment.
The improvement would require several new structures, including viaducts on the
higher level links. There would also be changes to existing lighting and gantry
provision. The above works would all be constructed to motorway standard, dual
two lane carriageways for the M6 to A14 link and single two lane carriageways for
the remainder, all with hardshoulders.
Facilities would be provided for vulnerable users, pedestrians, cyclists and horse
riders, both as part of the local road network to provide direct utility links, and in
the form of new and diverted field paths to provide recreational links, including a
new bridleway. The proposed bridleway would require two crossings of the
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