Thursday, August 09, 2018

Trees Take a Hit for Pedestrians: the New Thoroughfare Along Walnut Lane

Back in early July, when local media were focused on four Norway maples threatened by construction on Hawthorn Avenue, there was considerable carnage going on just blocks away along Walnut Lane. About twelve mature London plane trees (or sycamores) met their demise.

The rings could be counted to tell the age.

Further down, across from JW Middle School, the roots of a row of hackberry trees next to the ballfield were dealt a considerable hacking when the old, uneven sidewalk was removed.

Soon, the only evidence that shade trees once stood near the highschool were neat mounds of woodchips left by the root grinder.

The reason for the logging and root disruption became clear in the weeks that followed, as workers removed the old curb and sidewalks and began installing new, along with upscale Belgian block curbs.

Judging from the double-wide sidewalks being installed on both sides of Walnut Lane, the trees were sacrificed as part of a vision for a broad pedestrian thoroughfare that, it can be hoped, will encourage walking and biking to school.

The new sidewalk construction includes the area where the highschool has been inundated by stormwater runoff twice in the past.

This is what the same spot looked like two years ago, after a flash flood sent runoff cascading into the school basement and onto the performing arts stage, requiring once again a replacement of the wooden stage. The recurrent damage is due to the school and its detention basin being lower than Walnut Lane. When the street's drain pipes become overwhelmed, there's no place for the water to go other than into the school.

A few of us had proposed a solution so that the high school would not be flooded the next time Princeton gets hit by another of those thick, heavy rains that all our earth-warming is making thicker and heavier. It's an approach influenced more by landscape thinking than engineering, and focuses on surface flow rather than putting faith in pipes that can clog and overflow. The solution would take advantage of a wonderful open field on Westminster property that Westminster's own consultant had declared unbuildable because of its wetland status. It might seem that Westminster would not be excited about having runoff directed onto its own property, but Westminster has a vested interest in preserving the high school performing arts center. I heard that they provided some of the funding for the construction of the facility, in exchange for access for periodic use. The idea, then, was to create a means--essentially a swale--for excess water from the street and the school to more easily flow into the adjacent Westminster property's field, thereby preventing the water from rising high enough to enter the school's basement and music facilities.

That idea seems not to have made much headway with the powers that be, and yet the sidewalk construction is still being used to make some positive changes.

Here you can see that the new curb is lower than the current street level. The street will actually be lowered,  knawed down by a giant asphalt-eating machine, so that the street can hold more floodwater. In addition, the town engineer informed me via email, "We are installing upsized pipes across Walnut Lane and adding an inlet to assist in getting overflow into the storm sewer system. All this increased capacity still runs into a smaller pipe that goes under the Westminster property.

The most positive change is that they lowered the sidewalk and driveway on the Westminster side of the street two inches. This is not as much as we suggested, but two inches could conceivably be the difference between inundation and preservation of the high school's basement and performing arts wing. As any beaver will tell you, when backing up water, an inch here and there can make a big difference.

A view down Walnut Lane, with hackberries on the left and Norway Maples on the right, in front of the middle school.

Though trees have been sacrificed or traumatized, the new double-wide sidewalks represent another of Princeton's improvements to the pedestrian experience near schools. It's a contrast with what many of us have to deal with in neighborhoods, ducking around shrubs left to grow by inattentive homeowners.

Some of the shade trees were saved along Walnut Lane, but it will take a lot of thoughtfully chosen and strategically placed new trees to eventually shade this new pedestrian-friendly corridor.

Update: With the passing of Aretha Franklin, the thought occurs: Why not name the walkway after her. "Aretha Way," perhaps. The sidewalk intersects with Franklin Avenue, and runs between two great centers of music.

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