FROM
Clifton Boulevard Trunk Ring Road Flyover at
Abbey Street Junction was opened to traffic on
the 29th July 1969.
The scheme was designed by Mr. F. N. Little,
the Nottingham City Engineer, on behalf of the
Ministry of Transport, utilising a flyover of the
Braithwaite ‘Fliway’ design which was awarded
a prize in the competition sponsored by the
Ministry of Transport in 1964. Its design is
such that it can be dismantled for re-erection
elsewhere when traffic conditions on an existing
site necessitate works of greater magnitude.
In the present case, the existing roundabout
was designed as two levels so that a flyover
could be added. The flyover carries Clifton
Boulevard (Trunk Outer Ring Road) traffic
across the A453 route to Birmingham. By
removing the ‘through’ group of traffic from the
ground level roundabout its traffic capacity has
been increased, and conditions for pedestrians
crossing near the junction have also been made
safer and more convenient.
Clifton Boulevard has 24ft wide twin
carriageways and an 18ft central reservation.
Near and alongside the flyover the outer kerb
lines are set back to give 23ft. Lighting is
by three 80ft high-mast columns carried on
foundations at ground level.
To reduce interference with traffic during
construction and for convenience on site, a
storage and casting yard was established
about 600 yards away from the job. During
erection, units were transferred from here to
the site by mobile crane and low loader. The
location of the foundations was governed by
the presence of two large sewers beneath the
roundabout. It was necessary to use 45ft spans
over the roundabout with 36ft spans for both
approaches. The flyover has open guardrailing
on either side, the running surface being
concrete. The portal trestles are protected by
‘Armco’ type crash barriers.
The flyover carries a two lane carriageway
designed to take the loadings in the Construction
30 NSC
Nov/Dec 19
and Use regulations of the Ministry of Transport.
It comprises 10 spans of 36ft, 6 spans of 45ft
and 4 spans of 18ft. Total spanned length is
702ft plus the approach ramps on solid, giving a
total flyover length of 833ft. The width is 25ft 4in
overall and between kerbs 22ft. The headroom
to the ground level roundabout is 16ft 9in and
the gradient is 1 in 15 for the approach spans
and 1 in 83 for the centre spans. The foundations
are 18in nominal bored piles approximately 25ft
long, established in dense sand, with reinforced
concrete pile caps and tie beams.
The deck spans of the Braithwaite ‘Fliway’,
which are simply supported on portal frame steel
trestles, are prefabricated to single traffic lane
width and are of steel and concrete construction
acting compositely. Each unit comprises two
longitudinal universal beams joined by a series
of transverse members. Welded studs provide
the composite shear connection with the 7in
thick reinforced concrete deck slab.
The flyover is anchored to each abutment and
also has two intermediate portal braced bays to
cater for longitudinal forces. These forces are
transmitted through the composite deck units
via the cast ‘Meehanite’ bearings, which allow
for expansion and rotation movements, and
rubber compression pads between the ends
of the units, which are pre-compressed during
erection.
The parapets are fabricated from rectangular
hollow sections and act as crash barriers. The
uprights are bolted to the slabs and to the
main longitudinal steel beams. Special joints
are incorporated in the longitudinals to cater
for expansion and to maintain continuity of
strength from end-to-end of the ‘Fliway’. PVC
coated steel splash panels and flashings are
provided.
225 tons of steelwork were used in the
superstructure and protection was by grit
blasting followed by a four coat paint system.
Erection of the deck units was completed in
ten days, without interference to traffic at peak
period, using a 50 ton capacity lorry-mounted
mobile crane.
Two main contracts were placed, one
for the foundations and the other for the
steel superstructure, approach ramps and
decking and other miscellaneous work above
foundation level. Two main contractors were
GKN Foundations Ltd for the foundations
and the Butterley Engineering Co Ltd for the
superstructure and associated work. Site
investigation was by Le Grand Adsco.
Street lighting was designed by the City
Lighting Engineer. Roadworks, direction
and other signs were carried out by the City
Engineer’s Department. The total cost of all the
work, including foundations, superstructure,
site investigation and alterations to statutory
undertaker’s services, was £160,000. Of this
total, the superstructure approach ramps and
other miscellaneous work above foundation
level came to £79,000 and this cost, divided by
the total area of flyover (833ft long by 25ft 4in
wide), represents 75/- 0d per sq ft. Similarly the
foundations represent a cost of 19/- 0d per sq ft.
Temporary flyovers often provide the only
solution to the problems caused by our everincreasing
traffic density. Since the first
temporary flyover was built in Birmingham
some nine years ago several cities and large
towns have found that this type of structure
has been the only feasible method of achieving
traffic flow without massive reconstruction
and high expense. Similar structures have
been built for instance at Bristol, Kingston and
Barking and in each of these the main framing
has been made from steel which lends itself
particularly well to the reduction of dead load
and simplicity of fabrication both on and off site.
It is certain that many more temporary flyovers
will be erected in the years ahead and although
planned for only a limited life it is reasonable to
suppose that many will be giving good service
years after their original time span has been
reached.
50 Years Ago
Building
with Steel
NOVEMBER 1969
Nottingham
Flyover
Roads are getting more congested, junctions are becoming bottlenecks
– often the only solution is to build a temporary flyover. Mr F. I. Lees,
Director and Contracts Manager, The Butterley Engineering Co. Ltd.,
describes a recently completed structure at Nottingham