Derby's Street Lighting PFI Contract

Kedleston Road, Allestree - Part Three

The use of 8 m columns and 90 Watt SOX lanterns continued for the rest of Kedleston Road. The following photographs were taken on Sunday, 10th October 2010.

As with the lanterns pictured on the previous page, most of the lanterns on this section of road were Thorn Alpha 1s, and once again, just such a lantern commences this gallery:

This column was situated within a recess in a stone wall. For ease at this location, the new column would be also be installed within this recess, hence the "In/Out" marking on the footway.

A close-up of the lantern reveals that the Opticell was in rather poor condition - there are signs of water ingress, and the baffle plate that is meant to be positioned above the lamp, so as to reduce upward light spill, and increase downward useful light, has fallen onto the lamp.

The next column doubled up as a bus stop. Fortunately, the replacement column was installed alongside; meaning that the bus stop 'flag' was simply transferred over to the new column, in preparation for the removal of the old column.

This Opticell was in better condition than that of the previous lantern was, but it was still not perfect - the underside of the plastic was cracked, for example.

The replacement Iridium was still awaiting a power supply connection at the time.

An overhead telecommunications cable passed through the gap between the old and new columns at the following location:

This Opticell was still in good condition - there were few signs of water ingress or damage.

A Thorn Alpha 4 was attached to the next bracket; an Alpha 1 would have existed here in the past, but for whatever reason, it must have required replacement at some point.

A Royce Thompson SC1000 photocell was fitted to the Alpha 4 - this is the type of cell that was fitted to all new lanterns installed under the PFI, prior to September 2010.

After Memorial Road is passed, Kedleston Road quickly takes on an altogether more rural feel - the houses here all look out on to open fields.

Despite the new column being installed to the left of the old column, the Alpha 1's bracket creates the illusion that it is actually to the left of the Iridium. The right-hand photograph provides a good comparison of two generations of optical control in street lighting lanterns.

Even from ground level, a fault with the following Alpha 1's Opticell can be seen:

The toggle clamp that secures the lantern assembly must have become 'unsprung'; meaning that a length of insulation tape was required, in order to keep the lantern intact in its final weeks of operation.

The next few columns were installed opposite the houses, in order to highlight the upcoming bend in the road.

Several of the Alpha 1s at this location were dayburning when these photographs were taken - the reason is detailed a little further down this page.

The difference in height between the old and new columns is very apparent here:

The lanterns had been dayburning for many months when these photographs were taken; although not visible here, the electrode ends of the lamps were glowing red as a result of their continuous operation. Incidentally, this photograph is a personal favourite of mine.

Although not yet powered up at this stage, there would never again be a group-dayburn along this road, as each Iridium is individually switched by its own photocell.

Another two dayburning lanterns are visible in this photograph:

Some stunning views could be glimpsed at this location...and the view in the background isn't bad, either!

The explanation behind the dayburning lanterns is explained below: the control point was removed long before this scheme commenced, causing the 'slave' lanterns to be unlit at night. A few weeks later, a new 10 m column was erected in the same location that the control point column had been installed. A lantern wasn't fitted to the new column at the time; instead, a temporary overhead supply was installed, with a length of twin-and-earth cable linking the new control column with the first slave lantern on the circuit. This must then have travelled down the column shaft and into the cut-out in the base, before connecting to the existing underground supply cable to the other columns on the circuit.

The catenary support wire for the cable can just be seen in this photograph:

A small hole had been drilled a short distance down the column shaft - this allowed the temporary supply cable to connect with the existing underground cable in the column base.

Two temporary supplies emerge from the feed column, although, now that a lantern is fitted to the column spigot, I can't quite help wondering whether the cables would be crushed up against the inside of the lantern. This Iridium must think that it's an Alpha 1 - notice the dirt in the supposedly IP66-rated optic!

This column was also fed from the control point, although this was not dayburning when photographed.

Again, the overhead supply enters the column near the bracket joint.

The lamp doesn't look particularly worn, so the lantern probably did work at night; perhaps it was switched from the Iridium's photocell.

I took this photograph to try to convey how the Opticell's refractors were diffusing the autumn sunlight:

Looking back along the road, with three of the four dayburning lanterns visible.

After that random section of group-switching, we now return to individually-switched lanterns.

This lantern's Opticell was in a terrible condition - part of the plastic on the side was broken, allowing dirt to gather beneath the lamp.

PART TWO | CONTINUE TO PART FOUR

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