My plans for a weekend hike met an unexpected obstacle when the parking lot shown on a rough map for some town conservation land turned out to be somebody’s driveway. Unable to find the actual parking area, and already running quite late in the day, I had to give up. But it put me in the area to capture a distinctive image of something I’ve long wanted to photograph, the Canton Viaduct. I’ve tried to do this previously, and haven’t been happy with the results. The east side is largely obscured by houses and trees, and the slightly more open west by commercial buildings and power lines. And the sun’s angle on it is usually poor, as it orients to the southwest. The best photo I’ve seen is an aerial government image from decades ago, in black and white (available via Wikipedia).
The viaduct is one of the oldest railroad structures in the U.S., built in 1834 for the Boston and Providence Railroad, connecting its two namesake cities. Overall length is 615′ (187 m) and height above the river is 60′ (18 m). The 180-year old structure today carries America’s most modern railroad line, Amtrak’s Northeast Corridor, home to 150 mph (240 kph) passenger trains (and just south of here is a long straight where they hit that speed). That’s hardly high speed by current international standards, with the fastest trains now exceeding 200 mph, but it’s still an accomplishment, particularly for a structure of this age. And it is essentially the original structure. There is a new cast concrete deck atop the viaduct to provide added room for two high-speed tracks; the older tracks were too close to each other. In a sense that’s actually the third deck, as the original was modified substantially in 1860 to add a second track. But the original (well, nineteenth-century) cast-iron fencing is attached to the new deck, and the original stone structure is still the load-bearing component, not just a pretty shell over a modern concrete bridge.
Well, okay, the arch tops were reinforced with concrete in 1910 (and that was re-done in 1995) so it’s not completely a stone structure. You can clearly see that in the photo. Still, that’s reinforcement of the original structure, not a replacement of it. And it’s possible that the structural problems (cracking stones) were due to water getting inside and freezing, rather than to a load issue (see the history on the Wikipedia page for more on that).
Speed over the bridge is somewhat limited, as it’s just a short distance south of the suburban Route 128 station where most trains (including the Acela Express) stop, as well as a closer commuter station. In addition, despite looking straight in this photo, it’s actually a curved structure, as the railway line makes a sharp (for railroads), one degree curve to the southwest here. Regardless, the rated speed is reportedly 125 mph (200 kph) across the viaduct, although I haven’t been able to verify that from an authoritative source. And as a passenger, unless you look out the window, you won’t feel any difference (I always try to spot the viaduct when I travel on the Acela, and I often miss it).
Despite appearances, it’s not actually an arch bridge, and those big arches don’t extend all the way through. Instead it’s a hollow shell with two outer walls, structurally more similar to a castle wall than a bridge, although walls are usually filled with rubble and this is just empty. When it was inspected for the upgrading of the line nineteen years ago, engineers had to rappel down inside it to examine the stonework.
The railway is located here, across this awkward valley, for a number of reasons, but one is that just behind the viaduct is the now-abandoned site of the original Revere copper works (yes, that Revere, who moved on from silversmithing to industrial copper sheeting production for naval vessels), whose owners in the early nineteenth century saw the railroad as vital to bringing in supplies and taking out products, and were backers of the railroad corporation.
The road seen on the right passes through two of the arches, with minimal clearance. And this is a subject of some local annoyance, as there is no separate sidewalk passage (and, apparently, big trucks routinely get stuck). The railroad has repeatedly denied town requests to open an additional archway for pedestrians, although they did open a second arch for cars in 1953 (and did a rather ugly job of it, not even trying to mimic the stonework of the original and using concrete of a much lighter color).
I like this photo, because as I noted I’ve long wanted to take a good picture of the viaduct, and this one was worth the wait. The strong lighting brings out the detail of the stonework very dramatically. The still air leaves the millpond smooth, except on the right where the water is funneling over the dam, providing a mirror for bridge and sky. And the stark branches of the leafless trees go well with the sunset light.
This image is, as usual, an HDR from a bracket of five photos at 1 EV offsets. The bracket was centered at 1/125th-second exposure, with ISO 800, f/11 and the lens at 24 mm. It was taken with a circular polarizing filter, which helped bring out the detail in the clouds and cut glare off the millpond. It was cropped to place the focus more firmly on the viaduct, and to remove some shadowed scenery on the far right, and had a touch of chromatic aberration fix applied due to the strong lighting against the tree branches. In the HDR software, I took the Deep 2 preset, but changed the Depth setting back to “normal”, and boosted contrast (which the preset had dropped) while also reducing the Exposure setting to get more of the feel of the sharply-shadowed late afternoon sun. Back in Aperture, the usual Edge Sharpening was performed before export.