River Crossings and Migratory Fish: Design Guidance

River Crossings and Migratory Fish: Design
Sarah Boyack MSP
John Home Robertson MSP
Migratory fish such as salmon and sea trout are an important recreational and
commercial resource in Scotland, as well as being integral components of Scottish
biodiversity. The associated tourism and angling industries are also important
contributors to the Scottish economy, particularly in rural areas. However, salmonid
populations in Scottish waters are currently under pressure. The decline has been
attributed mainly to a reduction in the numbers of fish surviving to return after the
marine part of their life cycle. The causes for this reduced survival are not clear but
changes in the marine environment are undoubtedly involved. There is little we can
do directly to reverse any changes there have been in the ocean, so we are left to
exercise control where we can, particularly by ensuring that the freshwater
environment is as productive as it can be.
River-crossing structures such as culverts can, if not properly designed, form a
barrier to the movement of migratory fish. That is why two Scottish Executive
Departments, in consultation with fishery interests and practitioners involved in the
road design process, have developed this guidance. It is our aim to implement the
approach detailed in this document on all trunk road new-build and maintenance
The approach adopted in 'River Crossings and Migratory Fish' ensures that the free
passage of migratory fish is not impeded by new river-crossing structures associated
with the trunk road network. This will assist in the sustainable management of fish
stocks by maximising the area of habitat available to spawning fish, which will in turn
enable the populations to better withstand the many stresses to which they are
currently exposed. The approach also prevents habitat fragmentation, which is a
principle detailed in the Scottish Executive publication 'Trunk Road Biodiversity
Action Plan'. But the guidance contained in this document should not be limited to
the trunk road network. We hope that all those involved in designing river-crossing
structures will adopt the guidance offered.
While practitioners will find 'River Crossings and Migratory Fish' of immediate use,
only through application, feedback and development can the document's robustness
be established. We have therefore initiated a twelve-month consultation period,
during which you are formally invited to apply the document's contents and provide
comments and suggestions for its improvement. Arrangements are also being made
towards taking 'River Crossings and Migratory Fish' forward for inclusion in the UK
Design Manual for Roads and Bridges.
We commend 'River Crossings and Migratory Fish' to you and look forward to
feedback on its use and application.
Sarah Boyack MSP
Minister for Transport and the
John Home Robertson MSP
Deputy Minister for Rural Affairs
Fish passage at stream crossings is an important consideration in the planning,
design, installation and upgrading of river-crossing structures. The purpose of this
publication is to give design guidance to the engineer and others with an interest in
river crossings that will ensure free fish passage can be achieved.
For many fish, migration is essential to the survival of the species. Salmon, for
example, travel from the sea up river to spawn, and both juveniles and spawned
adults migrate downstream to the sea. Other fish such as trout migrate upstream and
downstream during their life cycle seeking a variety of aquatic habitats for spawning,
rearing young and hiding. Although these migrations may only be over a few
kilometres, they can be important for the long-term survival of the species and
maintenance of fish production in a watercourse.
Improperly planned and designed culverts and other river-crossing structures can be
barriers to such migration. Common problems at river crossings are mainly
associated with culverts, but can also be present at bridges, fords and weirs, and
inadequate water depth during periods of migration;
excessive water velocities; and
vertical barriers to fish passage (e.g. perching).
The Road Planning Process
Avoiding or minimising obstruction to fish passage requires consultation by the
engineer with SEPA, SNH, SERAD and DSFBs throughout the design process to
ensure that all relevant requirements are identified (see Figure 1). The resolution of
engineering, biological, hydraulic and cost factors requires a balanced and
interactive approach across these disciplines so that structures do not present a
barrier to fish migration. The first three steps indicated can be equated to the three
stage DMRB assessment process used in the development of a road project. The
process is also relevant to minor improvement and major maintenance projects
although these are not subject to the three stage process.
Design Requirements for Fish Passage
In general, fish will be able to travel through a river crossing structure provided that
the conditions in the structure are not substantially different from those in the existing
watercourse. The design parameters detailed in Table 1 have been developed to
ensure the free passage of most migratory fish species through river-crossing
structures (specific advice relating to individual fish species is given in Table 5.1 of
this document). These parameters must be incorporated into the design of new or
altered structures to ensure that they do not present a barrier to migrations.
It is not necessary to design for fish passage at all flow conditions. A suggested
"passage design flow range" for checking for excessive velocity at high flows and
inadequate water depth at low flows is the 10 percentile and 90 percentile of normal
flows respectively (the flows which are exceeded for 10% and 90% of the time).
The preferred form of structure is one in which the characteristics and dimensions of
the original watercourse are maintained. This may be achieved by using a bridge or
a culvert. If using a culvert, the following alternatives should be considered in turn
until a successful solution for fish passage is determined:
Case 1 :
Culvert barrel with dimensions derived for flood flow conditions;
Case 2 :
Culvert with depressed invert to allow for inclusion of stream bed material
within the barrel;
Case 3 :
Provision of a bottomless arch culvert to retain the natural stream bed;
Case 4 :
Provision of a low flow channel within the culvert invert; and
Case 5 :
Provision of baffles within the culvert.
Table 1 Design Criteria for Salmonids
Design Factor
Maximum water velocity at 10
percentile flow (mean over crosssection) (1)
Target Criteria
Up to 20m
culvert length
20 - 30m
culvert length
over 30m
culvert length
Minimum pipe diameter
Minimum water depth at 90
percentile flow (1)
Maximum water level drop (1)
Minimum gap on trash screen (if
also relevant in bridge design
Existing Problem Sites
There are two approaches to retro-fitting existing culverts and bridge aprons to allow
for fish passage:
(a) raising the tailwater level by installing a weir which backs up water; and
(b) installing baffles.
Design details of these measures are contained in Chapter 7 of this document. Both
are effective in deepening water levels and reducing excessive velocities. However,
they result in a reduction of the structure's flow capacity which may have significant
effects on upstream flooding during storm flow conditions.
1.1 Historically there has been little consideration given to fish passage in the design
of in-river road structures. As a result fish which migrate in Scottish rivers and
streams may be obstructed and unable to use habitat upstream or downstream of a
culvert or bridge crossing.
1.2 A variety of interrelated factors affect the design of any in-river road structure
including hydrology, topography, engineering and costs. Environmental issues
including the requirements of fish must also be taken into account.
1.3 The purpose of this guidance is to identify good practice which will ensure that
the free passage of fish in watercourses is not compromised by the construction,
operation or maintenance of any public road. The potential to improve existing
structures is covered as well as the design of new structures.
1.4 The guidance adopts an integrated approach to engineering, hydraulic and fish
passage design. Wider environmental issues, such as aesthetic considerations and
requirements of other fauna, are not covered. Appropriate guidance on these issues
should be used in parallel with this guide.
1.5 The guidance concentrates on the requirements of species such as salmon and
trout but also considers the implications of in-river structures for other migratory and
non-migratory species.
1.6 The design of a variety of road structures including culverts, bridge aprons, fords
and weirs is considered in this document. River diversion works are not included.
1.7 The guidance is intended for all those with interests in the design of in-river road
structures including engineers, hydrologists and environmental consultants as well
as local authorities and agencies such as SEPA and SNH, and other organisations
including District Salmon Fishery Boards (DSFBs).
1.8 It is intended that this document should be used in conjunction with other
relevant guidance including the recent CIRIA Culvert Design Guide (1997). The stepby-step approach which is adopted can be loosely related to the three stage process
advocated in the Design Manual for Roads and Bridges (DMRB), Volume 5 and it is
intended that the guidance should be used in the assessment and design processes.
The guidance should also be used when existing in-river road structures are
upgraded, for example during major maintenance or to accept heavier loads.
1.9 The guidance provides background information, as well as guidance on the
assessment of requirements and design. The remainder of the document is set out
as follows:
Chapter 2 discusses Life Cycles and Migrations of relevant fish species;
Chapter 3 reviews Common Problems for Fish Passage at River Crossings;
Part 2 - Assessment
Chapter 4 introduces the Assessment Process which should be followed in
the evolution of the road proposals to ensure that the requirements for fish
passage are adequately addressed.
Part 3 - Design
Chapter 5 introduces Design Requirements for Fish Passage.
Chapter 6 provides Design Considerations.
Chapter 7 describes options for Improvement at Existing Problem Sites.
1.10 The document is supported by the following:
A Glossary of technical terms.
Appendix A which provides details of District Salmon Fishery Boards.
A Technical Report which is available from the Scottish Executive.
2.1 Several species of fish living in Scottish rivers migrate between the sea and the
upper reaches of rivers during their life cycle. Others make significant migrations
within fresh water. River-crossing structures have potential to disrupt the life cycles
of such species by interfering with both upstream and downstream movement. The
overall production of fish stocks is limited by the area available for spawning and
rearing. Optimum yield will depend upon access to as much of the catchment as
possible. Often the best spawning and rearing areas are in small upland tributaries.
In the case of salmon and sea trout, the fish return to spawn in the tributary and even
the same part of the tributary where they themselves were spawned and reared. This
has led to the formation of genetically distinct sub-stocks in larger catchments, which
are likely to be adapted to conditions in that part of the catchment. It is therefore
important that all spawning areas are accessible on a regular basis for the
maintenance of the genetic integrity of the sub-stocks.
Atlantic Salmon
2.2 The Atlantic salmon (Salmo salar) is widespread throughout Scotland. The adult
fish (typically 55 to 100 cm or more in length) may spawn in quite small headwater
streams as well as in suitable areas in larger watercourses. The adult fish enter
rivers from the sea at almost any time of year, but they migrate into smaller
spawning streams on elevated flows following rainfall in the autumn (September November). After spawning in October to December the adult fish return seawards
over a period of up to several months.
2.3 The eggs are laid in areas of gravel where there is an adequate flow of water.
After hatching, the young fish remain within the gravel for several weeks, eventually
emerging in March to May. The fry disperse for distances of up to several hundred
metres downstream. As the fish grow (known as parr at this stage) they redistribute
themselves, generally downstream in direction. After 2 to 4 years the parr develop a
silver colour and migrate seawards, usually in April to June. At this stage they are
termed smolts. The survivors return to spawn after 1 to 3 years of feeding and
growing in the sea.
2.4 There are two forms of trout (Salmo trutta) in Scottish waters: the sea trout,
which migrates to the sea and the brown trout, which migrates only within the river
Sea Trout
2.5 The migratory sea trout has a life history very similar to that of the salmon. The
main differences are that the fish may return to fresh water after only a few months
at sea, and the adults are generally smaller than salmon (typically 25 to 60 cm). The
adults may also enter smaller spawning tributaries earlier than salmon, often
penetrating to the upper headwaters during the summer. A higher proportion survive
to spawn again than is the case for salmon.
Brown Trout
2.6 Brown trout spend their whole life cycle in fresh water, but may nonetheless
make extensive migrations between upper headwaters and the main river and lochs.
The timing of these movements is similar to that of salmon, but the adult fish may be
very much smaller, typically 15 to 50 cm in length.
2.7 Sea lamprey (Petromyzon marinus) and river lamprey (Lampetra fluviatilis) have
similar life cycles. Eggs are laid in the gravel in streams and the young fish spend
several years living in silt banks in fresh water before migrating to sea to feed and
grow, returning to the river to spawn. Lamprey do not enter such small and rocky
headwaters as salmonids, but nevertheless where they occur they can be affected
by structures which do not permit access to their breeding grounds. Their swimming
ability is limited, but they are able to ascend fairly rapid rocky reaches using their oral
sucker to hold on between bursts of activity.
2.8 Eels (Anguilla anguilla) are also migratory but have quite a different life history,
breeding in the sea and ascending the river as juveniles to feed and grow. They may
migrate to the highest headwaters, but may take up to two years to do so. Eels may
spend up to 40 years or more in fresh water before returning to sea to spawn. They
are small when migrating upstream (typically 6 to 30 cm) with only limited swimming
ability but are adept at exploiting slower moving water among rocks and in-stream
2.9 The European grayling (Thymallus thymallus) is a river dwelling fish which has
been introduced to several river systems in south and east Scotland. They make
limited migrations within the river systems and spawn in spring close to where they
live the remainder of the year.
2.10 Some details of upstream and downstream migrant fish in small streams are
summarised in Tables 2.1 and 2.2.
Table 2.1 Details of Upstream Migrant Fish in Small Streams
Typical Size
Main Migratory
55-100 cm
elevated flows
Sea trout
25-60 cm
all but the
lowest flows
Brown trout
15-50 cm
elevated flows
Eel (elvers)
6-10 cm
all flows
Eel (older fish)
10-30 cm
all flows
Sea lamprey
40-100 cm
all flows
River lamprey
25-40 cm
all flows
20-40 cm
March - May
all flows
Temperature and flow conditions are relevant to the upstream migration because of their impact
upon swimming performance and current speeds within culverts. These factors are not relevant to
downstream migration.
Table 2.2 Details of Downstream Migrant Fish in Small Streams
Stage Range
Typical Size
Migratory Period
Salmon and trout
Spawned adults
15-100 cm
November - May
Salmon and trout
4-6 cm
April - July
Salmon and trout
7-12 cm
September - March
Salmon and trout
12-22 cm
April - June
25-60 cm
June - November
Burst / Cruise Speed
2.11 The capacity of fish of various species and sizes to swim against fast currents
and to leap at obstacles is clearly fundamental to consideration of the design criteria
for in-river structures. Fish have two basic swimming modes: burst speed swimming
and cruising speed swimming. Burst speed can be maintained for only a matter of
seconds, and quickly leads to fatigue. The maximum velocity and the time for which
it can be maintained are strongly influenced by water temperature. Fish can swim
faster at higher temperatures but are unable to maintain swimming activity for as
long as they can at lower temperatures. Cruising speed can be maintained for
extended periods or even indefinitely. In Chapter 5 these observations are used to
provide water velocity criteria for various sizes of fish for culverts of different lengths
based upon the swimming ability of the fish. These involve minimising the
requirement for fish to use burst speeds to attain passage.
2.12 Although salmonid fish in particular are renowned for their leaping behaviour,
successful leaps to overcome obstacles are dependent upon certain conditions of
water flow at the take-off point and depth and velocity at the landing point. At culvert
outlets and inlets in particular these conditions may not occur. Further, salmon and
trout only leap at obstructions when they have to, their preferred method of ascent
being fast swimming wherever possible. The other species of interest do not leap at
obstructions at all. Good design criteria for culverts should minimise the requirement
for fish to leap and to use burst speeds.
3.1 Some river crossings may pose a problem for fish passage because some or all
of the fish that attempt to pass the structure cannot do so, or can do so only with
difficulty, under the environmental conditions prevailing at the time. This may be due
to some hydraulic feature of the structure, such as high water velocity, inadequate
water depth or extreme turbulence or due to very large level changes in the
watercourse (falls) or as a result of the physical nature of the structure obstructing
passage, such
as small pipes or narrow grids. While some river-crossing structures are effectively
impassable to upstream migrants at all times, many others are passable only by
certain species or sizes of fish under only part of the annual range of environmental
conditions. Delay caused by this can be an important factor not only in terms of
reaching spawning grounds in time but in making fish more vulnerable to predation
and poaching.
3.2 Success of passage through such structures will be affected by many factors
the species of fish: some fish are stronger swimmers or more adept "leapers"
than others;
the size of the fish: generally large fish can swim faster than smaller fish but
larger fish require a greater depth of water to swim in;
the condition of the fish: fish heavy with spawn are likely to be less agile than
immature fish, and fish may be tired by their migration up to the crossing
(particularly if migrating salmon and sea trout are a long way from the sea and
have not fed since then);
the stream discharge: the hydraulic conditions within and around the structure
(e.g. velocity, depth and turbulence) may vary substantially with changes in
discharge -which may vary 1000 fold or more between dry-weather flow and
peak flow at some sites; and
water temperature: generally speaking fish can swim faster at higher water
3.3 Bridges generally result in fewer problems for fish passage than culverts
because the original channel dimensions, gradient and stream bed tend to be
retained. Bridge aprons or associated weirs can, however, cause problems.
3.4 Common problems at river crossings which have been encountered are
described in the remainder of this chapter.
Inadequate Water Depth
3.5 Inadequate water depth for fish swimming can occur at low flows and/or in wide
shallow culverts. This is also linked with the gradient and water velocity in a culvert
where faster currents will result in shallower depths in a given culvert cross-section.
3.6 Bridge aprons which are flat in cross section may result in inadequate water
depth for fish to swim effectively and safely. Similarly, fords may result in flows
spread too thinly for fish passage.
Perched Structures
3.7 Perching is a term applied to a culvert outlet (the downstream end) which is set
above the stream bed immediately downstream, so that there is a fall. This can occur
when the culvert is installed too high, resulting in erosion of the downstream channel.
While salmon and trout are capable of leaping at falls to surmount them, conditions
at culvert outlets are frequently not conducive to successful jumps. The stream
below the fall may be shallow and the water turbulent, representing poor conditions
for "take off" for a leap. Water shooting from the culvert, rather than falling vertically,
may confuse fish which may jump at the wrong point. Shallow, fast flowing water
inside the culvert barrel presents difficult conditions for fish landing after a leap and
the fish may be washed downstream out of the culvert.
3.8 Bridge aprons and weirs can also become perched in a similar way to culverts
and can then cause difficulties for fish passage.
Culvert Inlets
3.9 Changes in the stream hydraulics at the culvert inlet resulting from the
constriction of the flow into the culvert barrel may cause problems to fish passing
upstream even though they have successfully negotiated the culvert itself.
Steep Culvert Gradient and Smooth Barrels
3.10 Excessive water velocity that impedes fish passage may occur when the
gradient of a culvert is too great. The problem becomes more severe in periods of
high flow and in installations with smooth walls, particularly if there are no resting
places (e.g. behind baffles) for fish within the barrel.
Inadequate Culvert Diameter
3.11 Inadequate culvert diameter for fish to swim through can occur where a number
of small pipes are provided rather than one large barrel. Even a pipe which is
physically large enough for fish passage may deter the passage of fish if the fish is
reluctant to enter a confined space.
Lack of Rest Places and Pools
3.12 If fish have to attempt passage through a culvert without the opportunity to rest
immediately downstream, or have to continue strenuous swimming having just
ascended a challenging culvert, they may become exhausted and be washed back
downstream. A lack of rest areas and pools immediately upstream and downstream
can thus render a difficult but theoretically passable culvert effectively impassable.
Debris Accumulation
3.13 Blockage by debris and the downstream movement of river bed material can
occur in small-diameter culverts and where trash screens or farm animal barriers are
installed. While total blockage is unlikely, collection of debris can effectively prevent
passage of large upstream migrants. Any blockage may cause local increases in
current speed which may defeat fish of all sizes. Downstream migrating fish may
also become trapped in debris blockages.
Percolating Flow
3.14 Percolating flow through gabion mattresses and rip-rap can deplete the main
flow or even cause the whole flow to pass through the gaps. This can prevent
upstream passage but can be particularly harmful to downstream migrants, which
may become stranded or trapped.
Impassable Weirs
3.15 Weirs are sometimes installed immediately downstream of bridges, either at the
same time as the bridge was constructed or at a later date, to prevent or reduce
erosion of the bridge footings. While this is likely to make fish passage through the
bridge area straightforward, the weir itself can be an impediment to migration.
Construction Activities
3.16 Construction work and river diversions can cause temporary disruption of
migration even if the permanent works are designed to allow fish passage.
4.1 The requirements for fish passage should be considered throughout the
development of the road project. A step-by-step approach is provided in Figure 4.1
which shows the progression of proposals through a staged process leading to the
conceptual design of the in-river structure. The procedure for integrating fish
passage requirements within the development of the conceptual design is described
in Chapter 6.
Stage 1
4.2 As part of the initial assessment of the overall road improvement strategy the
location of river and burn crossings should be considered and included in the review
of options for positioning the road alignment to achieve a balance between broad
engineering, cost and environmental considerations. The need for crossings should
be confirmed through examination of broad alternatives for the route of the road. If
possible, crossings of important watercourses should be avoided. This step should
be considered as part of the constraints analysis in the Stage 1 environmental
assessment process outlined in the DMRB.
4.3 Early consultation with SEPA, SNH and SERAD(1) is essential. Information
obtained from consultation and initial site visits should be taken into account in
considering the siting and justification for a stream crossing as part of the Stage 1
assessment. In assessing the requirement for fish passage facilities at a river
crossing, it is important to consider any existing obstructions to fish passage nearby.
There is little point in providing good conditions for migrating fish passage if the
stream is impassable downstream or a short distance upstream due to a natural
Stage 2
4.4 In this stage further relevant data on the watercourse should be collated in order
to identify the future requirements for the design of the structure. The hydrological
data for the catchment are collated for later use in calculation purposes in Stage 3
and also to identify any significant flooding risks. Other considerations at this stage
include identification of potential ground conditions for foundation design,
investigating the potential to temporarily divert the watercourse so that the structure
can be built "in the dry" and any specific access and maintenance requirements (e.g.
for cattle, farm traffic etc). Consultations with relevant bodies (including the relevant
DSFB (see Appendix A)) and, if appropriate, site surveys, should be undertaken to
establish the need to accommodate particular fish species, in conjunction with other
wildlife needs (for example, allowance for otter passage).
4.5 This step concludes with the comparison of options which have been identified
and consideration of their relative costs in relation to the overall costs of the road
improvement. These options could, for example, include a short culvert with a
realigned watercourse, a long culvert on original line, a bridge, etc (see Figure 4.2).
This review of options should contribute to the Stage 2 DMRB route option
environmental assessment.
Stage 3
4.6 The development of the conceptual design should be undertaken as part of the
Stage 3 environmental assessment of the preferred option. For culverts this stage
closely relates to that presented in the CIRIA Culvert Design Guide (1997) and firms
up on the type and size of the in-river structure. The sizing is derived from the
hydrological parameters gathered in Stage 2 by calculating the acceptable maximum
headwater depth for flood flows. In terms of fish passage, the flow velocity and depth
under typical conditions when the fish are running needs to be identified (see Section
5.5). Consultations should continue with relevant organisations to ensure the
developing design takes adequate account of the requirements for fish passage.
Scheme Procurement
4.7 With Design and Construct schemes it is necessary to complete sufficient
development of the conceptual design to ensure that robust requirements can be
included in the contract documentation. Development of the detailed design will be
the responsibility of the appointed contractor.
4.8 For road projects which are not formally assessed using the 3-stage DMRB
process, such as maintenance and minor improvement schemes, the principles of
the staged process described above should be followed to ensure early
consideration of fish passage requirements.
(1) Contact the Inspector of Salmon and Freshwater Fisheries (ISFF) and The Freshwater Fisheries
Laboratory, Pitlochry.
5.1 Consideration of the life history, migratory behaviour and swimming ability of
various types and sizes of fish, together with a review of where fish passage
problems have arisen, indicates that the following factors must be acceptable for
successful fish passage:
adequate depth of water at the time of passage;
appropriate water velocity;
adequate resting places above and below the structure; and
no physical obstructions to passage.
5.2 Attention to the above design factors is only required where a culvert installation
modifies the stream profile. If the preferred option is for a bridge or a large culvert
with effective retention or re-creation of the stream channel features these
considerations need not apply (see Chapter 6).
5.3 It is not necessary for installations to be passable to fish at all times. Most
upstream migrations take place at flows well above the dry-weather (Q95) flow, and
well below the peak discharges. Peaks of discharge are generally short-lived events
in smaller watercourses and a short delay in passage periods need not be critical.
5.4 In planning fish passage facilities it is important to consider the range of flows
over which conditions for fish passage are to be optimised - the "passage design
flow range". Good passage conditions should be provided during the period when
fish are migrating in a particular area.
5.5 The appropriate DSFB (2) or other fisheries experts can provide advice on the
passage design flow range, as it will vary between sites and fish species. Generally,
there will be a shorter window of time over which fish passage can occur in small
streams than in larger ones. A suggested "passage design flow range" for checking
for excessive velocity at high flows and inadequate water depth at low flows is that
lying between the 10 percentile and 90 percentile of normal flows respectively (the
flows which are exceeded 10% and 90% of the time).
Design Criteria
5.6 The design criteria listed in Table 5.1 for river-crossing structures to enable
successful salmonid passage have been determined from a combination of biological
data and other guideline publications. Key references are included in a Technical
Report which is available to accompany this guidance document.
5.7 Small fish are able to exploit boundary layers close to culvert walls, where the
water velocity is significantly lower than that in the central section of the water flow.
For this reason the criteria presented in Table 5.1 for brown trout are likely to allow
passage for much of the time of smaller fish and weaker swimmers such as eel and
lamprey. In most situations no special consideration of other species is necessary.
However, where other species, especially smaller fish and weaker swimmers, are of
specific conservation interest, more stringent design criteria may be justified. Such
cases are beyond the scope of this document, and specialist advice should be
(2) Contact addresses for each DSFB are provided in Appendix A and a summary of the role of the
DSFBs is included.
Table 5.1 Design Criteria for Salmonids
Brown Trout
Sea Trout
25cm to
Salmon >
Culvert Length <20m
Culvert Length 20-30m
Culvert Length >30m
Maximum Water Velocity:
Minimum Diameter of Pipes
Minimum Depth of Water
Maximum Water Level Drop
Trash Screen (minimum
a) Mean velocity of cross-section (there will be areas of lower and higher velocity).
b) The velocities for the shorter culverts approximate to the burst speed achievable by each species at 5ºC, and the velocities
for culverts > 30m approximate to the cruising speed.
c) These velocities should not be exceeded at any flow within the passage design flow range.
d) Minimum depth acceptable at the lower end of the passage design flow range.
e) Maximum drop at either intake or outlet.
f) The minimum gap a fish can pass through will depend upon the size of the fish - these gaps are for
typical large adults. Trash screens should be avoided whenever possible but if this is not possible
a grid of sufficient size to allow fish passage should be used.
5.8 Resting areas immediately downstream of and upstream of the culvert are
desirable with the requirements being:
an area of water of adequate depth (at least 30cm for trout, 45cm for salmon);
an area of deeper water with adequate cover for resting;
rocks or overhanging vegetation; and
moderate flow conditions (well within the cruising speed of the fish (3)).
5.9 Resting pools within the culvert are not recommended as they are likely to collect
silt and debris and would be difficult to maintain.
(3) See Table 5.1 (Note b).
6.1 This chapter introduces the steps for ensuring that fish passage considerations
are integrated into the design process for in-river structures.
Culvert Conceptual Design
6.2 It is recommended that the conceptual design of a culvert is carried out using the
process described in the Culvert Design Guide (CIRIA, 1997). The guide identifies
that the conceptual design takes into account the relevant importance of hydraulic,
environmental, operational and economic performance criteria. If the Culvert Design
Guide is used with the guidance set out below it will be possible to ensure that
issues of fish passage are adequately addressed in the culvert design process.
6.3 During the earlier stages of the road project design, initial data will have been
collated such as the fish species which may be affected, the passage design flow
range, the design flood return period etc (see Chapter 4). At the initial stage of the
conceptual design, calculations of trial sizes for the culvert barrel size will have been
undertaken and various data collated including the design flow rate, gradient, barrel
roughness and culvert length.
6.4 This is the stage when the designer must check that the predicted hydraulic
conditions in the structure at critical times are appropriate for any fish species which
will migrate through it (see Section 5.5).
6.5 The main parameters to be considered in the calculation of flow velocity and
water depth are culvert slope, length and the Manning n value (roughness) for the
culvert invert material being considered. These parameters together with the culvert
size can be adjusted through iteration to develop an economical solution which
allows both for fish passage and flood flow conditions.
6.6 The criteria which will allow the successful passage of fish are provided in
Chapter 5.
6.7 The suggested approach is to review a number of alternative culvert designs and
check which will ensure the free passage of fish.
6.8 The alternatives should be considered in the order listed below. If the basic
culvert in Case 1 is found to be unsatisfactory for fish passage then the designer
considers Case 2, etc until a satisfactory design is achieved.
(i) Case 1: Culvert barrel with dimensions derived for the passage of flood flows.
(ii) Case 2: Culvert with a depressed invert to allow the inclusion of stream bed
material within the barrel. For circular and pipe arch culverts this will result in the
specification of an increased diameter for the barrel. Similarly for rectangular shaped
culverts the height of the box section will need to be increased to accommodate both
flood flows and the bed material.
(iii) Case 3: Provision of a bottomless arch culvert to retain the natural stream bed.
(iv) Case 4: Provision of a low flow channel within the culvert invert, resulting in
increased structural dimensions as identified in Case 2.
(v) Case 5: Provision of baffles within the culvert (particularly appropriate for steeply
sloping culverts), resulting in increased structural dimensions as identified in Case 2.
6.9 In Chapter 3 common problems which affect the passage of fish have been
described. Other factors which will help avoid these problems and should be
considered during conceptual culvert design include the following:
(i) Matching culvert gradient with the stream gradient where possible to minimise
changes in stream hydraulics which may affect fish passage.
(ii) The provision of outlet pools as a means of raising tailwater levels and avoiding
extensive erosion protection works at the outlet. These pools provide resting places
for migratory fish prior to negotiating the culvert. Inlet resting pools may also be
required in certain situations.
(iii) When a multi-pipe structure is used ensure at least one barrel is set at sufficiently
low level to ensure an adequate depth of water for fish passage under low flow
(iv) Designing inverts to allow for both the free passage of fish and the passage of
other animals (otters etc).
(v) Maintaining appropriate conditions for fish passage through long culverts. (Long
culverts do not in themselves represent an increased obstruction to fish as long as
appropriate conditions for fish passage are maintained throughout.) Lack of light in a
culvert does not appear to influence fish passage.
(vi) The design of a trash screen (if this cannot be avoided) should ensure fish
passage is not impeded.
(vii) Approach conditions should be within the cruising ability of the fish in the
6.10 The design of river bridges and their foundations should accord with BA 59/94
in Volume 2 of the DMRB. This gives advice in the consideration of scour protection
of in-river piers and abutments. If the foundations are designed at an adequate depth
to avoid scouring then it is unlikely that bridge aprons and weirs will be required and
issues of fish passage will not be of concern. Where a bridge apron is unavoidable it
should be designed to ensure an adequate depth of water to ensure fish passage is
facilitated through the passage design flow range and to avoid the need for a control
structure such as a weir downstream. In situations where a weir is unavoidable it is
important to ensure that there is an adequate depth of water to facilitate fish passage
in low flow conditions over at least part of it. Baffles may be necessary to reduce
water velocity through any fish passage measure.
General Design Principles to Minimise Construction Impacts to Fish
6.11 The following principles should be followed in the design process and contract
preparation to ensure that construction impacts on fish are minimised.
(i) Avoid in-river structures where possible to prevent scour and reduce the impacts
of temporary works during construction which could affect fish passage.
(ii) Where appropriate use a bridge in preference to a culvert to minimise impacts to
free fish passage.
(iii) Design all new in-river structures to avoid the necessity for retrofit measures.
(iv) Wherever possible, schedule in-river works to minimise impacts to fish.
(v) Ensure the detailed design is complete and construction process adequately
planned before starting construction to reduce impacts on fish and other wildlife.
(vi) Inspect culverts regularly during construction to ensure inlets and outlets are kept
free from debris which could prevent fish passage.
(vii) Explore the potential to restore the natural river banks at the end of construction
and avoid the use of gabions and rip rap where possible to ensure that shelter at the
bankside is retained for fish.
(viii) Use of rip rap or boulders for erosion protection is preferred to gabion baskets
which may harm fish if they become damaged (and also results in lower
maintenance liabilities).
(ix) Remove all redundant in-stream works where these affect fish passage unless
such action would cause other significant environmental damage or where cost
would be prohibitive.
(ix) If a stream requires realignment as part of the works, consideration should be
given to provision of straight lengths upstream and downstream of the structure to
reduce the need for extensive erosion protection works which may be detrimental to
fish passage.
Other Issues
6.12 As well as guidance contained in this report other general best practice
guidance, such as SEPA Best Management Practices, should also be implemented
during construction.
6.13 The risk of disturbance to and pollution of watercourses should be minimised
during the construction process by careful control of site run-off, chemicals and fuels.
6.14 Maintenance issues should be considered at an early stage in collating contract
requirements. Requirements for timing and form of maintenance should be
discussed with SNH and DSFBs during consultations. For example, it may be
necessary to include a maintenance requirement to clean trash screens prior to fish
runs to that ensure that these do not obstruct fish passage.
7.1 Many existing river crossings present significant or even total obstacles to fish
migration, restricting the overall productivity of the river system. This chapter
examines the process of evaluating, planning and executing improvements.
Assessment of the Extent of the Existing Problem
7.2 A complete bar to migration is more serious than an obstruction that lets some
fish through on occasions. Visual inspection by an appropriate expert will
immediately indicate that some crossings are probably a complete barrier while
others are likely to represent no hindrance to all. It is important that the level of
barrier represented by those that fall between these two extremes is carefully
evaluated. Obstructions which appear severe, and indeed may represent a major
delay or hindrance to migration under some conditions, may not warrant remedial
action if surveys show that stocks of juvenile salmon and trout are routinely present
Assessment of Responsibilities
7.3 The approval of the Roads Authority is required for proposed works to any ditch,
watercourse, bridge, culvert, tunnel or pipe constructed, laid or erected by the Roads
Authority for the purpose of draining a road.
Options for Amelioration
7.4 Options for introducing measures to assist fish passage should be identified
based on local topographical constraints, hydraulic considerations and cost
effectiveness. Relatively low cost measures can be effective in many cases.
Complete rebuild, using sound design principles to ensure that the new installation
provides good fish passage conditions (see Chapters 5 and 6) may be the only
viable option for extreme problems.
7.5 There are two approaches to tackling the problem of excessive water velocity
and both can help ameliorate the problem of water being too shallow for effective fish
(i) reduce the velocity throughout the section of the flow by increasing the depth of
water through the installation of one or more additional structures;
(ii) introduce some roughness to the bed of the culvert causing local lowering of
current speed and thus leading to some increase in water depth.
7.6 In evaluating these options consideration should be given to the effective
reduction in flow capacity of the culvert and the significance of increased water levels
Weirs at Culvert Outlets
7.7 An effective approach to deepening the water and slowing the flow is to raise the
tailwater level by installing a weir downstream of the culvert outlet, backing up the
water through the culvert itself. Installation and maintenance are easier in the open,
and there is no requirement to attach any structure to the fabric of the culvert. This
approach can also ameliorate any perching problem.
7.8 Several North American reports present guidelines for the design of low stone
weir installations intended to raise tailwater height. It is recommended that weirs
should be a minimum of 6m apart and have a maximum fall of 30 cm between
successive weir crests, and that the most downstream structure should have its crest
level with the stream bed to act as an erosion control mechanism (see Figure 7.1).
7.9 The shape and orientation of baffles depends on the culvert barrel shape and its
gradient. The recommended solutions, based on recent research are shown in
Figures 7.2 and 7.3.
Increasing Bed Roughness
7.10 A simple low-cost approach to increasing bed roughness has been applied in a
number of streams in Montana, USA. This involves installation of a pre-fabricated
steel frame rather like a ladder which lies along the bed of the culvert. It can be
constructed in 6 metre long sections for transport to site, and the cross-bars or
"rungs" are fixed at 1200mm intervals (see Figure 7.4).
7.11 After installation an average of three "large" rocks are placed against, and are
therefore anchored by each cross-member. The rocks thus provide the turbulence
and depth to allow fish to migrate.
7.12 Bridges generally represent much more benign conditions for fish passage than
culverts. The main potential for problems is with bridge aprons or sills, installed
either when the bridge was constructed or retro-fitted to correct erosion that
potentially threatens the bridge structure. These can be perched in the same manner
as culverts, making it difficult or impossible for fish to ascend at certain flows. Flat
bridge aprons can also present problems for fish passage at low flows as the
available water is spread very thinly over the width of the channel.
7.13 The most straightforward solution to perching at bridge aprons is the installation
of low stone weirs as described in Sections 7.8 and 7.9. This approach may also be
appropriate to overcome inadequate water depth problems on the apron itself. An
alternative approach would be to re-cast the apron into a v-shaped channel so that
the flow is concentrated in the centre. This creates shallow slow-moving water at the
edges which will ease the passage of smaller fish, while providing a deeper zone for
larger fish in the centre. Alternatively the lip of aprons can be broken down or baffles
or boulders used on the apron to channel low flows.
7.14 The simplest solution to the inadequate water depth problem at fords is to install
a pipe or culvert to carry low flows beneath the roadway, allowing the high flows to
pass over the roadway. The culvert can be much smaller than would be required if
flood flows had to be conveyed, but it should not be below 30 cm diameter for trout
passage or 45 cm diameter for salmon passage. Such small diameter pipes are
vulnerable to blockage by debris so regular inspection and maintenance may be
required. Pipes installed beneath natural bed level will also be subject to blockage
through siltation.
7.15 Weirs have often been installed immediately downstream of road bridges to
prevent erosion of the bridge foundations. Whilst making the bridge itself readily
passable to fish the weir may represent a major or even total obstruction. There are
two approaches to alleviating this problem. The first is to raise the tailwater level of
the weir using a series of further stone weirs (as described in Sections 7.8 and 7.9).
The second is to install a fish pass in the weir. Design of fish passes should be made
with reference to the guidelines published by SOAFD (1995).
CIRIA (Construction Industry Research and Information). 1997. Culvert Design
Guide. Report 168. CIRIA, London.
Department of Transport/Scottish Office Industry Department/Welsh
Office/Department of the Environment for Northern Ireland. 1993. Design Manual for
Roads and Bridges. HMSO, London.
SEPA (Scottish Environment Protection Agency). 1996. A Guide to Surface Water
Best Management Practices.
SOAFD (Scottish Office Agriculture and Fisheries Department). 1995. Notes for
Guidance on the Provision of Fish Passes and Screens for the Safe Passage of
Erosion protection replacing or reinforcing stream bed in an area of
high velocity flow such as downstream of a culvert.
Obstruction, usually wood, concrete, or metal placed inside a culvert to
deflect and check the flow of water.
The highest rate of speed a fish can generate for a short period of time
(such as several seconds).
The speed at which a fish can swim indefinitely.
See trash.
A quantity (rate) of flow that is expected at a certain point as a result of
a design storm or a specific low flow condition. Usually expressed as a
rate of flow in metres3 per second.
The movement of individual fish and/or fish populations for any
purpose, including feeding, spawning, etc.
A road crossing a stream where a hard causeway is provided in the
bed of the stream.
Juvenile salmon and trout in their first few months of life.
A patented woven or welded wire basket filled with rocks of such a size
that they do not pass through the openings in the basket. Individual
baskets are stacked in place like building blocks and filled with rock to
form erosion resistant structures.
The rate of rise or fall of a slope - expressed as a percentage or ratio
as determined by a change in elevation to the length.
Entry point to a culvert.
The lowest internal point of any cross section in a culvert.
An equation for determining the quantity of flow whose factors are the
Formula or hydraulic radius, cross section area of flow, and a coefficient of
roughness, Manning's n.
Exit point from a culvert.
Juvenile salmonids between the fry and smolt stages.
The flow range used in assessing fish passage parameters.
Flow Range
Peak Flow
The maximum instantaneous rate of flow during a flood.
The development of a fall or cascade at a culvert outlet due to the
erosion of the stream channel downstream from a culvert barrel, bridge
apron or ford.
Pipe Arch
Multi-plate or structural plate culverts assembled on a treated timber or
concrete foundation. Because of their size (normally in excess of 2 m
in diameter) and the fact they are placed on a foundation, they are
normally assembled on site. A series of interlocking steel plates are
bolted together to make the required shape and length. Many older
pipe arches have been formed using brick.
A statistical term defining the probability of occurrence of an (in years)
event. Thus a 1-in-50 year return period flood (also referred to as the
50 year flood) is one likely to be equalled or exceeded only once on
average in a 50-year period.
Any of the fish belonging to the family Salmonidae such as salmon and
Term used to describe soil erosion when it occurs underwater as in the
case of a stream bottom or bank.
The juvenile downstream migrant stage of salmon and sea trout.
Any buoyant or semi-buoyant material carried by the flow of water in a
channel but which could form a blockage in a culvert. Also referred to
as debris.
Small dam in a stream that causes water to back up behind it, and flow
over or through it.
In Scotland, the day to day responsibility for enforcing salmon fisheries regulations
rests with District Salmon Fishery Boards. Where a District Salmon Fishery Board is
formed it must be in accordance with the terms of the Salmon Act 1986. Members of
the board comprise proprietors of fishing rights in the district, or their mandatories,
and co-opted representatives of anglers and tenant netsmen where appropriate.
Proprietors are designated as upper or lower proprietors according to the location of
their fisheries and the members of the board who are proprietors are elected from
these two constituencies. The chairman, who must be a proprietor, is elected by the
whole board, i.e. proprietors and co-optees. In many cases, boards invite
representatives from SNH and SEPA to attend their meetings.
Where District Salmon Fishery Boards are formed they have statutory duties and
powers under the Salmon Act 1986. Although they are not statutory consultees they
should always be consulted regarding works that may affect watercourses or
fisheries. A Board has duties to appoint a Clerk, maintain a roll of upper and lower
proprietors, prepare an annual report, hold an annual meeting, and call triennial
elections. Boards have powers to do such acts, execute such works and incur such
expenses as seem to them expedient for the protection or improvement of salmon
within their districts, for the increase of salmon, and for the stocking of waters of their
districts with salmon.
Each Board also has powers to appoint water bailiffs, sue in the name of the clerk,
impose an assessment on each salmon fishery in its district, charge interest on
arrears of assessments, borrow money, and exempt persons from certain provisions
of the law for scientific and other purposes.
Ms C A K Rafferty
Per Messrs McJerrow & Stevenson
55 High Street
Dumfriesshire DG11 2JJ
(01576 202123-4)
2. AWE
T C MacNair Esq
Per Messrs MacArthur Stewart & Co
Boswell House
Argyll Square
Oban PA34 4BD
(01631 562215)
3. AYR
F M Watson Esq
D W Shaw & Company Solicitors
34a Sandgate
Ayr KA7 1BG
(01292) 265033
J Wotherspoon Esq
MacAndrew & Jenkins WS
Solicitors & Estate Agents
5 Drummond Street
(01463 233001)
Peter M Murray Esq
Per Messrs A B & A Matthews
Bank of Scotland Buildings
Newton Stewart DG8 6EG
(01671 404100)
Mr G C Muirden
Per Messrs Middleton Ross & Arnot
PO Box No 8
Mansefield House
Ross-shire IV15 9HJ
(01349 862214)
(Fax 863819)
C J Whealing Esq
Sutherland Estates Office
Duke Street
Sutherland KW10 6RR
(01408 633268)
P J W Blackwood Esq Estate Office
Thurso East
KW14 8HW
(01847 63134)
E M B Larby Esq
Finlayson Hughes
45 Church Street
(01463 224343)
10. CREE
Peter Murray Esq
Per Messrs AB & A Matthews Solicitors
Bank of Scotland Buildings
Newton Stewart
(01671 3013)
Lady Stewart
PA38 4BJ
12. DEE
George Alpine Esq
per Messrs Paull & Williamsons
Investment House
6 Union Row
(01224 621621)
13. DEE
G S Scott Esq
Messrs Gillespie, Gifford & Brown
27 St Cuthbert Street
(01557 330539)
John A Christie Esq
Murdoch, McMath & Mitchell
27/29 Duke Street
Aberdeenshire AB54 5DP
(01466 792291)
15. DON
George Alpine Esq
Per Messrs Paull & Williamsons
Investment House
6 Union Row
Aberdeen AB9 8DQ
(01224 621621)
16. DOON
A M Thomson Esq
23 Wellington Square
Ayr KA7 1HG
(01292 266900)
Robert C G Teasdale Quarry Cottage
By Dunoon
Argyll PA23 8QT
(01369 84510)
18. EAST
George H MacDonald Estate Office
North Uist Estate
North Uist
(01876 500329)
19. ESK
John Scott Esq
Scott Alexander
46 High Street
Montrose DD10 8JF
(01674 671477)
20. EWE
G C Muirden Esq
Per Messrs Middleton, Ross & Arnot
PO Box No 8
Mansefield House
Ross-shire IV15 9HJ
(01349 862214)
(Fax 863819)
Sir William Gordon Cumming
Altyre House
Altyre By Forres
C R Graves Esq
Carse of Trostrie
(01557 860618)
Mr T McKenzie
12 Charles Street
FK15 9BY
(01786 825544)
S B Sheddon Esq
Messrs James Smith & Valentine
Solicitors & Estate Agents
16 Hamilton Street
KA26 9EY
(01465 713476)
G D Robertson
Young Robertson & Co
29 Traill Street
KW14 8EQ
(01847 893247)
G A Macdonald
The Estate Office
North Uist
(01876 500428)
Mr N Wright
Arthur & Carmichael
Cathedral Square
(01862 810202)
J W Perkins
Isle of Arran
KA27 8JD
(01770 810671)
T Dixon Esq
Carter Jonas CS
22 Broad Street
A Sykes Esq
Per Messrs Brodies WS
15 Atholl Crescent
Edinburgh EH3 8HA
(0131 228 4111)
J Mason Esq
Bell Ingram Ltd
Estates Office
Bonar Bridge
IV24 3EA
32. LAGGAN &
R I G Ferguson Esq
Per Messrs Stewart, Balfour &
2 Castlehill
PA28 6AW
(01586 553737)
33. THE
Malcolm Spence QC
2 Gray's Inn
Gray's Inn
P M Fairweather Esq Cherry Park
PA32 8XE
(01499 302203)
Mr A McCartan
Messrs Andrew McCartan & Co
145 High Street
(01309 675259)
36. LUCE
E A Fleming-Smith
Stair Estates
Estate Office
Wigtownshire DG9 8BX
(01776 2024)
Mr George MacDonald
Estate Office
North Uist
(01876 3324)
E M B Larby Esq
Finlayson Hughes
45 Church Street
Norman Wright
Messrs Arthur & Carmichael
Cathedral Square
IV25 3SW
40. NESS
F Kelly Esq
Per Messrs Anderson Shaw & Gilbert
York House
20 Church Street
Inverness IV1 1ED
(01463 236123)
41. NITH
R Styles Esq
Walker and Sharp Solicitors
37 George Street
Dumfries DG1 1EB
(01387 267222)
A R Whitfield
The Estate Office
IV27 4BQ
43. RUEL
J Ferguson Esq
6 The Strand
East Sussex
TN31 7DB
(01797 222601)
44. SKYE
P Butler Esq
Mile End House
Glen Hinnisdal
Isle of Skye
IV51 9UX
(01470 542331)
45. SPEY
C D R Whittle Esq
Per Messrs R & R Urquhart
121 High Street
Morayshire IV36 0AB
(013096 72216)
Mrs A McGinnis
6 The Avenue
Nr Girvan
KA26 9TX
47. TAY
R P J Blake Esq
Per Messrs Condies Solicitors
2 Tay Street
Perth PH1 5LJ
(01738 440088)
Mrs J Nicol
River Tweed Commissioners
The North Court
Drygrange Steading
By Melrose
(01896 848294)
(Fax 01896 848277)
49. UGIE
B Milton Esq
50. URR
Masson & Glennie Solicitors
Broad House
Broad Street
AB42 6JA
(01779 74271)
Primrose & Gordon Solicitors & Estate
92 Irish Street
(01387 267316)
M H T Andrew Esq
Estate Office
Mains of Haddo
Tarves, Ellon
Aberdeenshire AB41 0LD
(01651 851664)
Steering Group:
Phil Gilmour, Amanda Chisholm, James Ellaway (Scottish Executive Development
David Dunkley, Ross Gardiner, Ian Phillips (Scottish Executive Rural Affairs
Lt Col Dougie Keelan, Judith Nicol (Association of District Salmon Fishery Boards)
Steve Wallace (Carl Bro Group)
Annie Say (ERM)
David Solomon (Consultant, Salmon and Freshwater Fisheries)
District Salmon Fishery Boards (DSFB)
Annan DSFB
Bladnoch DSFB
Brora DSFB
Conon & Nairn DSFB
Dee DSFB (Aberdeen)
Dee DSFB (Kirkcudbright)
Eachaig DSFB
Forth DSFB
Grudie & Dionard DSFB
Helmsdale DSFB
Kyle of Sutherland DSFB
Laxford DSFB
Loch Fyne DSFB
Loch Inchard DSFB
Loch Shiel DSFB
Lochy DSFB
Morar DSFB
Naver and Borgie DSFB
Ythan DSFB
Local Authorities:
Aberdeenshire Council
Angus Council
Argyll and Bute Council
City of Glasgow Council
Clackmannanshire Council
East Ayrshire Council
East Renfrewshire Council
Inverclyde Council
Midlothian Council
Moray Council
North Ayrshire Council
North Lanarkshire Council
Perth and Kinross Council
Renfrewshire Council
Scottish Borders Council
South Ayrshire Council
South Lanarkshire Council
Stirling Council
West Lothian Council
Atlantic Salmon Trust Ltd
Babtie Group
Colin Carnie
Countryside Commission
Countryside Commission for Wales
English Nature
Environment Agency
Fairhurst and Partners
Forest Enterprise _ Forest Civil Engineering
Game Conservancy Council
Highways Agency
Institution of Freshwater Ecology
Institution of Highways and Transportation
Institution of Structural Engineers
Ironside Farrar
Joint Nature Conservation Committee
Kincardine Estate
M6 Joint Venture
Powys Engineering Consultancy Services
Rivers Agency
Scottish Anglers National Association
Scottish Hydro Electric
Scottish Natural Heritage
Scottish Wildlife Trust
The Game Conservancy Trust
Turnbull Jeffrey Partnership
Tweed Foundation
This document is being circulated as a Consultation Paper subject to a twelve-month
consultation period. Feedback on the application of the approach detailed in the
document, together with suggestions for improvements, should be made by 31st
March 2001 to:
Amanda Chisholm - Environmental Advisor
Trunk Roads - Design and Construction Division
Scottish Executive Development Department
Victoria Quay, Edinburgh EH6 6QQ
Tel: 0131 244 7225
Fax: 0131 244 7228
Email: amanda.chisholm@scotland.gov.uk