NewUrbanStreets

Sharring experiences in urban infrastructure delivery.
Subscribe

Paver Crosswalks–Loading Considerations

By: Tom Davis Category: Sidewalk Features

You need to seriously consider the type of traffic the concrete unit pavers in crosswalks must support.Traffic moves from the left to the right. Note space between pavers is excessive due to shift to the left due to vehicle thrust. Keep in mind that in many urban streeets the right-side curb lane is used by buses and face a much greater range and frequency of heavy loads than do the other lanes. In addition, I believe, the crosswalk on the approach side of the intersection experiences a greater load from the buses–and to some extent cars–because when the signal changes to green the vehicles are accelerating harder as they cross over those pavers than when they cross the paver crosswalk on the other side of the intersection.

Within s0me crosswalks there is  evidence that the acceleration force of the vehicles causes  more rapid deterioration.  The force of the tires as the vehicle accelerates pushes the pavers forcefully together and I believe causes crushing and expulsion of the sand particles thereby allowing the pavers to be move closer together. The pavers move into that reduced gap and creates wider gaps between the pavers on the other side of that crosswalk.  The wider gaps on the opposite side can be seen at some crosswalks but not all.  Note sand washing to surface and spalding of corners.

Some, admittedly not all, of the intersections show a greater breaking and spalling of pavers on the approach side. But that effect not does occur at all locations.  At some  crosswalks we are seeing lateral cracking in a pattern that appears to be due to the shifting of the pavers unequally due to the wheel thrust always  occurring in  the wheel tracks.

There are surely other factors at play that contribute to these conditions.Note that  manhole ring is slightly lower than pavers and gap at ring is wide and random allowing sand to wash from gaps.

What can be done to prevent this from occurring?  Regular re-sanding. Re-sanding is sweeping sand back into the gaps often enough that the pavers do not begin to shift vertically or horizontally. Also whenever a manhole or valve box falls within the paver area avoid the wide gaps by pouring  a reinforced concrete skirt such that the concrete edges align with the paver pattern. this prevents the wide gap where the saw-cut pavers try to match the circular manhole or valve cover.

What must be done after the cracking and spalding begins? Remove the pavers, refill and relevel that sand bed and replace the  pavers using new pavers in place of  the  cracked ones.

print

Leave a Reply