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April Technical Meeting – Unique Design Solutions for a Mountain Highway


Presentation Topic: Unique Design Solutions for a Mountain Highway – Powell Valley, Route 23 in Wise County

Registration: Registration for this event is now closed.

Abstract: For 10 years a primary highway across Little Stone Mountain between Big Stone Gap and Norton in southwest Virginia remained unfinished because, during construction, massive landslides wiped out the fill on which the roadway was to be built. In 1984, VDOT selected Wiley│Wilson to design 2.5 miles of roadway, including landslide remedies.

Initial investigations revealed that the mountain was composed of soft shale, which disintegrated when exposed to water. Highly acidic groundwater compounded the disintegration creating an unstable base for the roadway. In a partnership with geotechnical engineering subconsultant TAMS, a palate of solutions were developed. Highlighted solutions include zoned earth fills similar to dam construction, mechanically stabilized earth (MSE) walls, rockfill buttresses, horizontal drains, and flattening of slopes.

A 580-foot bridge was designed to span the chasm created by the largest landslide. Built on a horizontal curve, the five-span bridge is supported by concrete piers socketed into rock. Reaching a height of 135 feet, the bridge is fixed to two piers which, together, sustain lateral forces.

Unique drainage systems were essential to the highway’s stability and ultimate completion. Wiley│Wilson engineers designed a unique storm culvert preservation system with twin culverts at six locations. Acidic groundwater flowing in dry weather is carried by polyethylene pipe, while a larger parallel concrete culvert carries stormwater.

The Federal Highway Administration recognized the project in 1995 with the National Quality Initiative Achievement Award, the first of its kind and one of five granted in the US. This presentation will cover the multiple design solutions utilized to complete this project’s construction.

Presenter: W.M. (Bill) Davidge, PE, has been involved in the design and evaluation of hundreds of structures throughout his 46 years of professional experience. Projects included highway and railway bridges (short, medium, and long span), dams, towers, tunnels, underground structures, and a multitude of different building types. During his career with Wiley│Wilson, the firm he retired from, he served as Transportation Market Manger, Dean of Structural Engineering, Department Manager, Office Manager, and Vice President.

Bill received his Civil Engineering undergraduate degree from the University of Virginia and a graduate degree in Structural Engineering from George Washington University. He has been an active member, including holding offices, in many professional and technical organizations, including ASCE.


When: Thursday, April 2oth, 2023
11:45 AM -12 PM – Sign in and Networking
12 PM -1PM – Presentation

Where: 2810: a community gathering place, 2810 W Cary St, Richmond, VA 23221
(Reserved parking spaces on both sides of building and in gravel lot located through gate)

Registration Price: $30 members and $35 non-members, price increases after January 25th, 2023.

Members may bring a non-member guest for free; please identify the guest in registration.
(Non-member guests should be civil engineers who may be interested in joining our local branch)

Lunch is included: Will be “Don’t Look Back Taco” this month.

PDH: 1.0 HR