Ken Larsen's web site - DOLRT proponents advocate for density along the route


Durham-Orange County Light Rail (DOLRT) proponents claim that one benefit of DOLRT is that it will motivate developers to build dense development along the route.  This is certainly true, because DOLRT will be a permanent transit corridor.  Developers can confidently build along it, because they know their investment can be rewarded.  This would not be true if they built along a bus route, because a bus route can easily be removed or changed. 


DOLRT proponent Tom Farmer cites St. Louis and Minneapolis-St. Paul cites as shining examples of light rail success stories.  In reviewing those areas, I learned that each has over 20 skyscrapers.  I conclude that we should likewise build skyscrapers as it makes no sense to build picayune developments.  Build massive ones instead.


St. Louis has over 30 skyscrapers.  These are buildings where the height is at least 250 feet.  By comparison, the Alexan apartment building on Elliott Road in Chapel Hill is only 90 feet high.  It was completed in 2016.  People have complained about it being too tall.


Minneapolis has 36 skyscrapers (height is at least 300 feet tall).  St. Paul has 21 tall buildings.


Unfortunately, the soil on the eastern side of Chapel Hill [where the DOLRT route intends to go] is ill suited for skyscrapers.  Here's what geologist Diane Willis has to say: 

"The geology in eastern Chapel Hill and into Durham is Triassic mudstones and sandstones weathered to thick clays that are subject to a lot of shrinking and swelling depending on moisture content. For our homes in these areas that means foundation problems, diagonal cracks above doorways, cracking of chimneys and porches, and difficulty finding solid rock as a base for a foundation. Riddled through those Triassic rocks/sediments are intrusive diabase dikes and sills which came in later as deep molten magmatic flows either in vertical fissures or in horizontal tabulate form. Diabase is hard rock which is often present near the surface as boulders or as small hills. Rounded orangey-brownish rocks you sometimes see around people's landscapes can be boulders of diabase.

Tall buildings can be built anywhere, though cost can drive the decisions. Tall buildings can be built on fill (as in San Francisco) but unless the engineering is appropriate, those buildings won't stay up. So tall buildings can be built in Triassic areas underlain by clays with no solid rock, but special engineering conditions pertain, driving up the cost.

As you mentioned, downtown Chapel Hill (note the word "hill") sits on a granitic pluton, i.e. a big dome of granite that intruded the metavolcanic rocks around it approximately 633 million years ago. (Hillsborough was basically a huge volcano!) That granitic intrusion is what causes the hill in Chapel Hill, and indeed would provide a solid rock foundation for tall buildings, depending on some other factors as well."




Ken Larsen's home page