@Judd 211190 wrote:
Took a peek at this yesterday. It appears that the decking is reinforced concrete with a layer of asphalt. The hole appears to be the result of the rebar rusting out. It doesn’t look like it’s going to be an easy fix. [emoji853]
Rebar rusting out, perhaps aggravated by recreation and police staff driving over that bridge repeatedly? Recreation seems to use full-size trash compaction trucks to collect the bags from the few trash cans between the baseball and soccer fields, and for the past year or more it has been very common for one or more police SUVs to be parked by the elementary school and baseball fields — I expect these are the same officers chasing folks off the trail after 10pm.**
Initially the damage was just a 6″ hole; see this Alex311 case from May for a photo; I think it’s subsequently been enlarged by staff investigating the problem. The initial hole lined up pretty well with where you’d expect automotive tire tracks. I’m no civil engineer, but the design does not look sufficient for motor vehicles — the internal I beams are very beefy but there’s very little material on top of them. I’m surprised to hear there was rebar, since from my recollection I don’t think the concrete could have been much thicker than rebar. The visible cupping on the bridge suggests that it’s been used (and degraded!) by autos for years; having looked in the hole I’m suprised that it held out as long as it did, considering the deck thickness. There seems virtually no support between the I beams so I imagine the old concrete provided virtually no strength, and merely served as a substrate to hold new asphalt in place while it cooled and hardened — only because of the rebar was that decking able to support autos.
ISTM the City should just replace the decking with pressure treated lumber and perhaps not cross it with those big trash trucks (not that I’ve ever actually seen that happen). The I beams are close enough together that load shouldn’t be a problem (the sagulator suggests even with I-beams 18″ apart –and I think they’re spaced closer than that– the police should be able to cross safely even if the decking were made of generic 2x6s). A wooden deck would be less expensive to build than asphalt etc, easier to inspect, and might discourage parks staff from using the bridge as a shortcut when picking up 4MR park trash. Traction shouldn’t be a concern since this is straight, short, in the middle of a > 90 degree turn, and with so many pedestrians that nobody should be racing across it.
** It seems some APD and RPCA staff consider these trails to be subject to the City ordinance that sets default “park” hours, which would mean use would be forbidden between 10pm and 5am.
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