The following is an extract from Next Navigation West, 2013 Revision, by Dr Geraint Coles. It describes the historical context, constraints, options and development plans for getting underneath the mineral railway at Lowgates.

© Chesterfield Canal Partnership.


10.4    Options Appraisal:  Staveley Mineral Railway

10.4.1    At present the Chesterfield Canal is blocked by the Staveley Mineral Railway at Staveley Lowgates. The line runs over the top of the canal line on the site of a former bridge now dropped and infilled.

Historical Background
10.4.2    The Chesterfield Canal at Staveley Lowgates was first crossed by a mineral railway at this point in the 1850’s when the Lowgates branch canal to Speedwell Colliery was infilled and converted to a railway.   In the 1870’s, much of the extensive industrial railway system belonging to the Staveley Ironworks was sold to the Midland Railway.  The Midland improved and extended the system –  eventually making parts of it suitable for passenger traffic with a new branch to Creswell (1888) and another to Bolsover (1890).  As part of this rebuilding, a new bridge on a more gently curving alignment was built to the west of the first crossing. 
10.4.3    The crossing was subsequently further rebuilt on the same site.  By the 1970’s the bridge was a double track iron bow girder bridge.  Continued mining subsidence gave constant problems with clearance and, with the abandonment of the canal, led to the removal of the bridge and the infilling of the canal line between the abutments.  The track was then re-laid on a deep ballast base.  The line is in-situ but currently mothballed (as of March 2013).  There are plans to re-open the line to load coal from opencast coal extraction and, long term, to serve a rail-freight depot on the Markham Vale development site.  To that end, the line has recently undergone upgrading to make it suitable for the heaviest traffic.  This places a restriction on the type of structure which can be used to secure a passage under the line – in particular it will not be possible to reinstate the type of thin decked bridge originally present.

10.4.4    Site survey and consultation with Network Rail generated a crossing specification which has been used to constrain the possible options for the bridge.  Two issues are critical:
10.4.5    (1) Mining subsidence has lowered the ground surface (and with it the railway) by circa 0.5 m at this point.  The level of the waterway is determined by the pound level set outside the area of subsidence.  This reduces the available headroom under the railway.
10.4.6    (2) Network Rail requires that the replacement structure carry a deep ballast bed.  This enables the track to be carried continuously over the bridge without the need for special arrangements at the bridge.  This means that the required distance from rail top to bottom of bridge bearers has increased from around 0.8 m on the original bridge to in excess of 2 m on the new bridge.  This again reduces the available headroom between water level and the underside of the bridge.
10.4.7    Taken together the mining subsidence and the requirements of the modern railway reduce headroom by 2.25 m – effectively eliminating the original clearance between canal and railway.

Options Explored
10.4.8    Given the continued existence of the railway, it is necessary for the canal to pass under the railway at some point.  Given the topography and constraints placed by houses in Hartington and Lowgates, the original location is the most favourable.
10.4.9    Given mining subsidence and the requirements of Network Rail it is obvious that the level of the canal has to be lowered to secure a passage under the line.  Two main options were explored: – a “drop lock” or a “dropped pound”.
10.4.10    A Drop Lock:  A lock immediately before the railway and a lock immediately after linked by a concrete culvert under the railway.  Water is discharged by an integral side weir.  This would be an integrated structure enabling the passage of a single boat in any direction at a time.  To that end some form of electrical interlocking is required to prevent both gates being operated at the same time.  This would also prevent a boat in passage being lifted and possibly jammed under the bridge.  Water continuity is maintained by a siphon pipe running from the entrance to the down lock to the exit of the up lock. 
10.4.11    A Dropped Pound:  A lock some distance from the railway to create a lowered “short-pound” with its own side weir.  A further lock on the other side lifts the canal back to its original level.   Water continuity is maintained by a siphon pipe running from the entrance to the down lock to the exit of the up lock.  There is no need for an electrical interlocking between locks as (a) the short pound can absorb any excess waterflow and safely discharge it and (b) two or more boats can pass on the short pound removing the need for “traffic control”.

10.4.12    Both drop lock and dropped pound solutions were worked up as part of the part of the Next Navigation Project (2006).  In deciding which option to pursue issues considered were:
* Reliability – Drop locks have not proved entirely reliable on other waterways due to the mixing of water and electrical systems with public operation.  Simple locks are far more resilient and user friendly.
* Operation & Simplicity – The system has to be operated unaided by the untrained boating public; drop locks elsewhere require staffed operation with consequent costs.
* Operation & Safety – The ability of boats to pass each other and the greater difficulty of “flooding out” a dropped pound (by either accident or intent) and jamming a boat against the bridge deck supported the dropped pound over the drop lock.
* Maintenance – The dropped pound requires two conventional locks without the need for electro-mechanical interlocking and has obvious benefits over the drop lock in terms of reducing long term maintenance and renewal costs.  On the other hand the dropped pound requires a much longer siphon pipe with consequent maintenance costs.
10.4.13    On balance, it was concluded that a dropped pound would provide a better solution in this context than a drop lock.

Development of the Dropped Pound and Current Situation
10.4.14    The dropped pound solution was further developed in parallel with the construction of the Staveley Northern Loop Road in 2007-2010.  Working with Derbyshire County Council Engineers and the Contractors, the design of both the Northern Loop Road Bridge and Eckington Road Bridge were modified to accommodate the dropped pound levels and the earthworks for the canal channel to the west of the railway were completed.
10.4.15    In 2009 structural engineers Scot Wilson’s were engaged to provide detailed advice on the design of the railway structures and to conduct negotiations with the Network Rail.  In July 2010 the detailed structural requirements were agreed with Network Rail.  These included confirmation of the required foundation and invert levels for any new structure (given the upgrading of the Staveley Mineral Railway Branch).
10.4.16    In parallel, ground investigations were carried out on either side of the railway in late 2009 and a final report produced in 2010. 
10.4.17    The route has been protected in the Chesterfield Borough Council Local Plan and will be carried forward into the new Local Development Framework.

Staveley Town Lock is at the bottom left, just above the basin. Railway Lock is at the top right.
Plan courtesy Derbyshire County Council.

The mineral railway bridge in the 1970s.
The bridge in the background is the old Great Central Railway line, now the Trans-Pennine Trail.

The same view in 2012.

A view under the bridge taken in 1973 by L.B.Cooper.

The bridge in 1979 by John Marsden.

This view shows the old Eckington Road Bridge in 1979, again by John Marsden.
The canal went under the main arch. The bridge extension on the left goes over the mineral railway.
The mineral railway bridge is in the background.

The same view in 2011. The bridge on the right goes over the new Loop Road.
The canal goes under the bridge on the left to the right of the central pillar, the mineral railways is to its left.