175d. Buxton Road, Bridgemont, Whaley Bridge, High Peak. Situated at the northern end of this town are a small number of tapering 8 m sheet steel columns supporting integral gear Thorn Alpha 9 90 Watt SOX lanterns, with the two most notable examples featuring deep bowls. These columns all date from the mid-late 1980s; having been installed as part of the adjacent bypass that opened in 1987, which makes the deep-bowled lanterns seem all the more unusual, as lamp control gear had shrunk sufficiently by then for the deeper bowls to be rendered obsolete. The two lanterns have not had the deeper bowls fitted as casual replacements, however, as these do incorporate the larger ballasts that warranted the use of the deeper bowls.
The first of the deep-bowled examples is installed almost opposite the old Bridgemont road, which ceased to be used by through traffic with the opening of the bypass.
The chunky Thorn G53365.4 ballast is the reason for the deep bowl - as a consequence of its use, the lamp is situated at a lower position in the bowl. A Royce Thompson Oasis 1000 photocell dating from the mid-2000s provides the automatic switching for this lantern.
Little optical control is offered with the Alpha 9's bowl - a couple of refractor panels being the sole means of diffusing the lamp's output from the long sides of the lantern.
The second deep-bowled installation follows immediately after this one.
The G53365.4 ballast is the replacement for the similarly-sized G53232.4 unit. Along with 90 Watt SOX lamps, both ballasts were able to run 140 Watt SLI/H lamps too.
The same column, viewed from the other side.
Apart from the bowl requiring cleaning, the lantern is in good, complete, condition.
The other Alpha 9s feature shallower bowls.
Judging by how low the lamp is set in this lantern, I can't help wondering whether it would have had a deep bowl originally, with the current bowl being a replacement - notice that the refractor panels are situated above the lamp, serving little purpose except to obscure the control gear from this angle!
The style of the Thorn logo on the ballast dates the lantern to no later than about 1984; the logo changing after then, when Thorn EMI branding began to appear until the late 1980s, when the EMI suffix was dropped.
The Alpha 9s were changed to Thorn Isaro Pro-S 47 Watt LED lanterns in 2021; however, the columns themselves were re-used for supporting the replacement lanterns.
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