Moved from the North Carolina thread in Southeast forum.
Some old ideas never die -- the eastern route for I-77 from Princeton via U.S. 460 surfaced as a route for I-73 from Princeton to I-81, although it was an all-U.S. 460 routing instead of jogging over to VA 100 (the better to hit closer to Roanoke, then the turn south).
Bruce in Blacksburg
Wasn't the original plan for I-73 to take the planned routing of I-781 out of Blacksburg and down Ellett Valley to connect with I-81 at/near the Ironto exit? A short section of this route has already been constructed and is being used by Virginia Tech Transportation Institute as the Smart Road.
There is a long history here. U.S. 460 from the Blacksburg bypass to I-81 (except for the Christiansburg bypass) was the original two-lane road between the two towns, dual-ized by the VDH to create a four-lane road. Due to growth, the addition of more traffic lights, and an unsignalized left turn on to the Christiansburg bypass, the road was horribly congested, especially on Fridays, Virginia Tech football weekends, and the start of VT holiday breaks. VDOT finally deemed a study was needed to find a solution. There were 15 (I seem to remember) alternatives, from "do nothing" to a variety of improvements to the existing roads to a number of different routings between Blacksburg and I-81. The winner was the "connect the bypasses" plan with several new interchanges, both at the Blacksburg end and at I-81. There were at least two versions of the routing that would have gone from Blacksburg to I-81 at Ironto but they were rejected due to high cost and environmental issues. Another direct route was picked up by some local politicians and others, who (with no study or details) started to promote what is now the Smart Road. Part of the push to get a portion of the road built was that it would be available in the future when the planned "connect the bypasses" highway became inadequate (which will probably never happen).
The initial section of the road was constructed (including several unused ramps that complicate the Blacksburg interchange) and put into use as a research project, with the idea that in a few years it would be extended to I-81 and a new interchange about where the Norfolk Southern tracks pass under the interstate (about a mile from the present Christiansburg interchange). The money and need never materialized but the research highway and expansion of the Virginia Tech Transportation Institute has been quite successful. VTTI has attracted a number of research projects that have had a direct impact on highway and vehicle safety; it just opened an adjacent area to test vehicles on rural roads (
https://vtnews.vt.edu/articles/2020/11/111920-vtti-ruralroadway.html).
When the I-73 reroute through Roanoke (instead of just using I-77 between W. Va. and North Carolina) was pushed by politicians, the U.S. 460 corridor between the Virginia state line and I-81 at Christiansburg was put into play (the highway in West Virginia is almost adequate for an interstate once at-grade connections are eliminated). "We can finish the Smart Road" was the thought as an additional enticement to build the interstate. But the same problems of route around the Narrows of the New River and a lack of any funding for the project put it way off any back burner. The idea resurfaced recently when a Montgomery County supervisor thought the Smart Road should be extended, with a goofy plan to only use the road at certain times of day and in certain directions so it would still be viable as a research platform. Again, lack of concrete plans or money killed that idea.
IF a big pot of money were to fall into VDOT's lap that would fund construction of I-73 from end to end, the chances of the work actually being done are pretty slim. At most, it could be laid on top of I-77 and I-81 to reach Roanoke and extend down I-581 to its end -- but not go any further. There is too much opposition to building a new interstate between Roanoke and Martinsville; there is opposition to the new section of road being built now from Martinsville to North Carolina (see
https://www.virginiamercury.com/2020/11/24/in-a-shrinking-part-of-southside-virginia-vdot-presses-forward-with-highway-expansion-plans/). The Smart Road would also be somewhat compromised if it were actually completed to I-81 so there probably won't be major support from that camp. For now, VDOT needs to concentrate on fixing I-81, then turning its eyes to I-77 improvements (at the least, some truck-climbing lanes in several sections).
Bruce in Blacksburg