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Highway construction question

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The OP asked about converting shoulders to traveling lanes.  I don't see how this doesn't happen with any project that adds an additional lane.


--- Quote from: XamotCGC on November 28, 2021, 11:13:42 PM ---Can the existing shoulders on a two lane highway be converted to or widen enough for use as another driving lane?

--- End quote ---

Yes, though the road bed and the surface of the shoulder would need to be reconstructed to handle highway traffic. But could be done within the same physical space.

Doing so however will of course remove the shoulder, which can have negative consequences regarding things like roadside safety (removes the margin of safety a shoulder provides), guiderail or barrier placement, space for ped/bikes, room for oversize vehicles (like farm equipment), snow removal. Also through curves, especially on the outside of a superelevated (banked) curve, the reconstruction would be more substantial and may not be able to be done within the existing space.

I-95 between Baltimore and Wilmington, the John F. Kennedy Memorial Highway, was two lanes in each direction upon opening in 1963. The shoulders of the Tydings Bridge over the Susquehanna River were made wide enough to be turned into a third lane in each direction, which eventually did happen along the entire highway.

I think most of us have driven on shoulders as temporary lane during highway construction somewhere. I remember some instances where signs directed trucks to stay in the left lane and only cars were allowed to drive on the shoulder, though this wasn't the usual. When I lived in Tidewater, I-264 just east of the I-64 interchange allowed rush hour traffic to drive on the shoulder east to at least Witch Duck (this was about 15 years ago).

Examples of shoulders being converted to temporary travel lanes I've seen in recent years include I-66 in the DC area of NoVA, I-70 west of Denver, and US 23 north of Ann Arbor.

The reason that the Brent Spence Bridge is considered functionally obsolete is that it was originally built for three lanes with shoulders, but because of increasing traffic, was restriped to be four lanes with no shoulders.

--- Quote from: Scott5114 on November 29, 2021, 12:06:02 AM ---I think in some states, a shoulder may not be built to the same thickness or durability level as the travel lanes, due to the expectation of lower wear. I seem to recall there being a discussion on here of afreeway work zone where the travel lanes were realigned outward so that the right lane partially rode on the shoulder, and trucks were directed to use the left lane because, unlike the mainlines, the shoulder wasn't built to withstand heavy truck traffic.

--- End quote ---

You are correct. In areas where the shoulders are pressed into service as travel lanes during long-term construction projects, it's common to see "Trucks Use Left Lane" signage.


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