Q: Why would PennDOT replace both bridges on Tilghman Street over Chapmans Road and the railroad tracks in Upper Macungie and not repair the blatant problem of the low storm-sewer inlet on the right-hand westbound lane just west of the railroad bridge? During the project I was thinking, 'Thank God that will be fixed when the work is done,' but no. The inlet depression/pothole was the first thing I hit when the road reopened, and it seems I hit it every day. One would think it would have been the perfect time to raise the grate while there was no traffic on the road.
— Joan Zamper, Allentown
A: Dave Reiser of Upper Macungie Township raised the same question regarding the low storm grate on Tilghman Street, Joan, even before the construction work was completed. He noticed that even prior to the project, the low grate encouraged motorists to move slightly left to avoid the depression, crowding the lane line and possibly even drifting into the left-hand lane. That same tendency remains, at least on the part of some drivers, judging by the time I spent there observing the traffic patterns.
The shortcut answer, folks, is that the grate is a bit too far from the project area to have qualified for work related to the reconstruction and replacement, respectively, of the bridges, according to PennDOT construction engineer John Harmonosky.
Generally, bridge contracts such is this one specify that the bridge be repaired or replaced, and that any required "tie-in" road work required to reconnect the approaches be included, but generally no more than that, Harmonosky said. They have to stop somewhere, basically, in part because of cost constraints, and that's understandable.
Apart from the fact this particular grate was not addressed as part of the bridge project though, Harmonosky spoke generally about the conditions that help determine when these inlets should be raised by adding steel frames or "risers" beneath.
Before we get to that, when I looked at this grate closely in person, it didn't sit as far below the road surface as I had imagined when I hit it with both right tires (front and rear) as I passed. It was quite a jolt, especially in my small car, and you almost can't miss hitting the thing when properly remaining within the right-hand lane. But this particular grate doesn't appear to be all that far below the road surface, at least not compared to many others — or compared to many low utility-hole covers ("manholes") about which I receive even more complaints.
Still, the storm-sewer inlet on Tilghman just west of the westernmost of the two new bridges seems particularly jarring than most when you strike it. If not the depth alone, which appears to be about three inches, a recurring pothole seems to be plaguing this grate, as the photo shows.
PennDOT spokesman Sean Brown said it's possible the deterioration there can be addressed. I hope so; it sure seems like a patch-job might be in order.
Harmonosky cautioned, though, that not every sewer grate that seems too deeply recessed should be raised. There's conflicting traffic in the form of achieving the best possible water-intake efficiency.
The lower the inlet compared to the surface, the greater the intake capacity. To put it the other way, if the grate is too high, too much fast-running water will pass over it and continue on to the next grate, which might be overwhelmed by the excess even if it is properly designed.
The slope of the road both vertically and horizontally come into play, Harmonosky said. The center of the road is higher than the edges to promote runoff to the curbs, and the road is sloped vertically to direct the water in one direction or the other (and in some cases, the road is sloped simply because it's on a hill, which is the case in our example).
One problem here on Tilghman is the absence of any shoulder whatsoever — the guide rail extends to, and maybe even a bit past, the curb — which places the grate almost directly in the tire path. I think the continual wear of tire strikes at the left edge of the grate support, where it meets the road surface, has created the recurring pothole that seems attached to the grate.
Again, some even lower storm grates are out there. Back in 2007, a series of crater-like grates on Cedar Crest Boulevard between Minesite Road and Chestnut Street in Lower Macungie Township and Emmaus, respectively, averaged an astonishing 14 inches below the road surface; PennDOT raised those over the following few years. Other low grates dot the Valley, and recessed utility-hole covers, though generally not as deep, are far more abundant to my experience. (Some low covers are coated with a layer of asphalt all their own to match the road surface. The paving can be removed fairly easily from the cover for access when needed. I consider this an excellent solution, though it costs a few bucks and is not universally endorsed.)
From what I've been told by state and municipal officials over the years, many factors contribute to the problem of low utility covers. "Mill and pave" operations are intended to remove a specified depth of old asphalt, and then to add the identical thickness of new product (although slight but noticeable variations, maybe three quarters of an inch, are common). Risers are available only in specified sizes, so an absolutely perfect match might not be possible.
Some covers are not level with the road surface because of the slope of the road. Covers that are raised too much, to even a trace above the road surface, are subject to damaging snowplow strikes, so the tendency may be to err on the side of lower rather than higher adjustments.
Finally, engineers swear on a stack of owner's manuals that they don't intentionally design the access openings for utility lines beneath roadways to be located precisely in the path of most vehicles' tires.
It only seems that way.
Road Warrior appears Mondays and Fridays, and the Warrior blogs at mcall.com. Email questions about roadways, traffic and transportation, with your name and the municipality where you live, to hartzell@mcall.com, or write to Road Warrior, Box 1260, Allentown, PA 18105-1260.
