Sent: Tuesday, October 27, 2009 10:37 AM
Subject: Evergreen 3 Project : Aristotle Lane Level Crossing

Tony,



Thank you once again for taking the time last week to meet with us.  During
our discussions, I promised to supply further information on a number of
issues:



1.  Reasoning behind location and length of the proposed additional ramp from
the footbridge to the allotments



I have discussed this matter with the design team that produced the plans
that I shared with you.  In coming up with the proposed arrangement, the
design team took into account a variety of factors including:

    * Overall length of walking route from the proposed parking area to the allotments
    * Visual impact of the new structure
    * Effects on local flood storage capacity and flows
    * Structural considerations including the effects on the existing bridge structure and ramps
    * Potential loss of “Public Open Space”
    * The environmental designations applicable to Port Meadow
    * Quantity of land within the allotment site that would be required



The design team considered numerous options for providing the additional
section of ramp including options that incorporate a ramp that starts at
bridge deck level (i.e. at the top of the existing ramp).  There were two
main reasons why these options were rejected.  The first is that any such
option would require a greater amount of land within the allotment site as a
longer section of ramp would need to be accommodated.  The second, and
perhaps more problematic, reason is the difficulty in establishing a stable
foundation for the new section of ramp where it meets the existing structure.
The designers advise me that in order to provide adequate support at the
higher level there would be a need to either locally widen the existing
embankment that supports the ramps or construct a large and visually
intrusive steel supporting structure with piled foundations.  The widening of
the ramp would impact on flood storage capacity.  As it would not be possible
to compensate for the lost capacity this option would be unacceptable to the
Environment Agency.  (The usual means of compensating for lost capacity is to
construct a flood storage pond but given the status of Port Meadow this would
not be possible).  In contrast, the shorter, lower ramp requires a
significantly smaller foundation arrangement and therefore has no impact on
flood storage capacity.  The design team judged that the lower, shorter ramp
had a lower magnitude of adverse impacts and was therefore least likely to
meet with objections from the various statutory bodies.



2. Ramp gradients



The existing ramps on each side the footbridge have an average gradient of 1
in 17.  The gradient varies slightly over the length of each ramp and the
steepest gradient recorded by our surveyors is 1 in 15.  The ramps are
currently continuous with no intermediate landings.  As part of the package
of improvements that we propose to undertake to the bridge we would seek to
re-profile the footway surface to provide a series of shorter rises
interspersed with short, level landing areas.  In order to provide the
landings, it will be necessary to increase the gradient of the ramps
slightly.  It is envisaged that the resulting ramp gradients would be no
steeper than 1 in 12.



The new section of ramp will have a relatively shallow section of ramp
(approximately 1 in 38) crossing the drainage ditch.  The final section
within the allotment site will be 1 in 15.



3. Network Rail stance on new level crossings



As I explained, the new infrastructure that we are providing will, on
completion, pass into Network Rail ownership.  Network Rail is responsible
for the maintenance and safe operation of the railway infrastructure that
forms the national network.  We have to obtain approval from Network Rail for
all aspects of our scheme.  Network Rail have stated that creating a new
level crossing to provide access the existing crossing over our proposed
additional track would be unacceptable.  Additionally, Network Rail seeks to
eliminate existing level crossing when the opportunity arises by virtue of
other changes in the vicinity of a crossing.  Network Rail has provided us
with a copy of their Level Crossings Policy document, which I attach for your
reference.  Although large parts of the document are not relevant to the
situation at Aristotle Lane (because they refer to vehicular level
crossings), you will note that the document clearly states the point
regarding new crossings.





I trust that this information adequately addresses your queries.  However, if
you require any further information, please do not hesitate to get in touch.



Regards,



Steve Barker

Infrastructure Interface Manager

Evergreen 3 Project