HAVE YOU EVER stopped to question why many railway stations have a distinctive roof design?
In particular have you ever looked up when standing on the railway station platform and noticed the unique design of the canopy roof perimeter?
The crenullated design of railway station platform canopy borders are created with fascia boards and are often traditionally constructed in timber. The vertical slats of the fascia boards form a ‘valance’ to the station platforms’, often cantilevered, canopy roofs.
Known as daggerboards, these timber slats feature on many Victorian railway station buildings and form a distinctive design. Around a third of more than one thousand station canopy roofs are Grade II listed, according to the Railway Heritage Trust.
Often, the preserved daggerboards have an idiosyncratic design that is unique to that station or to the railway company that first built it. Isambard Kingdom Brunel is reputedly the first engineer to include daggerboards in his station designs.
Designs include ‘daggers’ that have a pointed end (shingled), a rounded end (scalloped), or a fleur-de-lys shaped ending.
Other daggerboards have a decoratively shaped cut-out, or a perforation cut into the board, or the vertical timber slats are cut to different sizes in a repetitive series which creates an attractive pattern.
Daggerboards have become a recognisable historical architectural feature of British railway stations constructed between 1850-1930s.
But daggerboards also serve a practical technical purpose: to carry rainwater run-off away from the canopy roof. Because they are usually pointed at the end, a drip-point is created to carry the rainwater away from the canopy roof, serving in effect as an alternative to gutters.
In an assessment of the case for replacing timber daggerboards with fibre reinforced polymer for the Railway Heritage Trust, Alan Baxter explains: “A straight-edged fascia does not control where water falls from the canopy, meaning that rainwater blows off randomly and may drip on passengers.
“Furthermore, water tends to cling to the underside of a flat edge, and thus be absorbed into the grain of the timber. To avoid this and the resultant rot, daggerboards are often painted and shaped at their end to create a pronounced drip-point for water runoff. Pointed or scalloped daggerboards, therefore, reduce the chances of rot developing.”
The daggerboards also help to reduce wind uplift to what is often a cantilevered canopy roof. Railway stations can sometimes suffer from something of a wind tunnel effect, with the sunken rail lines collecting wind and funnelling it along long the railway’s platforms. The punctuated and downward facing daggerboards at the canopy roof’s verge may help to break up this wind effect.
Additionally, when daggerboards were first incorporated into railway station roof designs, trains were of course steam powered. Profuse volumes of steam and smoke were generated in the station and the greater the valance on the platform canopy roof, the greater the screen for passengers standing below protecting them from these pollutants.
However, although daggerboards seem to perform several practical functions, it is their decorative aesthetic which is more noticeable today as an important contributor to the archetypal design of British railway stations.
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