Changes in Roadway Design - Continued

Auto travel in the early years of the century was largely a seasonal activity, but by 1930 it was more of a year round affair – enough so, at least, that keeping roads clear of snow was a consideration.  Typically in a wet winter road ditches would fill with snow and ice and in the spring melt leave standing water that would penetrate the roadbed.  Travel over the road would create deeply rutted roads, and whatever gravel covering there might be would be lost in the muck. To combat the loss of gravel and the breakup of the roadway due to moisture, building roads higher than the surrounding land was initiated in the late 1920s and early 1930s.  The increased road elevation allowed winter winds opportunity to clear road surfaces of snow and, at the same time, created ditches deep and wide enough to hold the snow blown from the roadways.  The increased roadway elevation and wider, deeper ditches also served in more temperate seasons to keep the roadbed dry.  The increased roadway width coupled with constructing roads higher than the surrounding land resulted in increasing right-of-way widths (from 66 feet to 100 feet) in order to provide sufficient barrow for the wider, higher roads.

By the mid-1920s carnage on the nation’s highways due to motor vehicle accidents had already reached alarming proportions. In 1927 highway accidents accounted for 27,000 deaths in the United States, and 2,100 of them were at railroad grade crossings – the intersection of the highway with the railroad.  Eliminating grade crossings became a focus of effort for years to come.  U.S. Highway 10 at one time crossed the Northern Pacific’s tracks thirty-nine times in North Dakota.  By 1930, all but two of those crossings had been eliminated through road relocation – a substantially less expensive alternative than constructing grade separations (in Barnes County, for example, in 1922 earth roads were being constructed at a cost of approximately $3,100 per mile whereas construction of a grade separation in that county in the same year was approximately $37,500). 

Road relocation, often associated with eliminating railroad grade crossings, was done for a variety of other reasons – safety (such as straightening or eliminating curves), to shorten travel routes and, to limit highway maintenance costs.  Likely the most substantial route change in terms of deviation in miles from the original route in the road’s early history occurred sometime between 1920 and 1925  when a “loop” in Morton County that carried the Red Trail/National Parks Highway south to Almont and then northwest to Glen Ullin, closely paralleling the route of the Northern Pacific the entire way, was eliminated.  This saved six miles of travel.  Approximately a quarter of a century later, in 1947, the railroad would eliminate its service to Almont and realign its track between New Salem and Glen Ullin to parallel the highway route.  This stands as a rare, albeit perhaps insignificant, instance in which the highway pointed the way for a rerouting of the rail line that had effectively created the highway route.

Another important rerouting occurred in 1928, when the road, by then designated U.S. Highway 10, was rerouted between Belfield and Sentinel Butte.  This saved seven miles of travel.  More importantly, perhaps, it established the route followed today by I-94 between Fryburg and Medora.  Though lauded for its beauty when rerouted in 1928, it was not until the construction of the interstate that it would win any awards.  In 1967 the U.S. Department of Transportation would award the segment first place, out of 227 entries, in its Highway Beauty Awards competition for “’Excellence in blending the rural highway into its surroundings.”  In designing the project, the highway department worked closely with the National Park Service to achieve a result that would minimize damage to the fragile badlands environment.  Those efforts included: use of much wider right of way to preserve the Sheep Creek Channel and to allow for siting several miles of it in the median strip; carefully relocating the creek bed where construction could not avoid it; where back sloping was necessary, cutting long back slopes and cutting benches in the back slopes to conform to the contours of the surrounding slopes; modifying standard interchange designs so as to minimize alteration to the existing  landforms while still satisfying engineering requirements, and; obliterating all sections of the old U.S. Highway 10 that was being replaced and returning as nearly as possible the right-of-way to its original contours.

By the middle of the 1930s the state highway department was beginning to experiment with stabilized road surfaces to create dense surfaces that were easily maintained and resistant to traffic wear.  In some parts of the nation concrete was being used to mix with soils to create stabilized surfaces, but to keep costs down North Dakota’s approach was to use calcium chloride as the stabilizing agent.  First soil samples were conducted to determine how much clay or other binder was necessary to mix with the gravel and calcium chloride to create the stabilized road surface.  The calcium chloride was included in the mix in order to maintain the optimum moisture content to inhibit dust and loss of roadway material.  In the summer of 1936 contracts for the construction of stabilized gravel surfacing were awarded for construction of sections of Highway 10 in both Golden Valley and Stutsman counties.

The first concrete paving on U.S. Highway 10 began in the spring of 1931 when Fargo contractor, John L. McCormick (founder of Northern Improvement Construction Company), with a crew of one hundred began construction from Fargo to Mapleton.  It was an event that received banner headlines on the front page of The Fargo Forum – PAVING BEGINS ON HIGHWAY.  The project was part of a two-year construction effort that would straighten the highway and provide a paved surface from Fargo to Casselton.  As reported in The Fargo Forum, the paving was 20 feet in width laid atop a two-inch thick gravel base.  The paving was reinforced with 57 pounds of steel for every 100 square feet of paved surface.  Paving was laid in steel slip-forms, with a paving thickness of seven inches in the center of the roadway tapering to nine inches at the roadway edge.  Shoulders were eight feet wide.  The cement mix was hauled from a Fargo mixing plant in trucks holding four cubic yards of mix unloaded at the rate of one truck every three minutes.  On a good day estimates were that 1,100 feet of paving could be laid.

The Fargo Forum article provided an overview of the general state of U.S. Highway 10 through the rest of the state in the spring of 1931 and mentioned other work being done on the road:  oil mix surface to be laid between Jamestown and Cleveland and another section from between Bismarck and Driscoll, thus providing a total of sixty-one miles of oil-mix surfaced highway between Valley City and the state capitol.  West of Bismarck by the end of the 1931 construction season the road was completely graded and graveled.  By the end of 1938 the entire route was hard-surfaced road – the first across North Dakota, east to west or north to south.

By the time construction began on I-94 in North Dakota advances in construction techniques and machinery allowed construction of approximately two and a half times as much pavement as McCormick laid in 1931.  Philip Brua, an engineer with the highway department in 1956 captured some of the process of early I-94 construction between Buffalo and Tower City with an 8 mm movie camera.  Shown here is footage from that construction.

The process is detailed. Forms, locking at each joint, were laid atop the fine grade in ten foot sections.  The only steel used in the road were 30 inch long tie-bars to tie the centerline joint.  Concrete was mixed at a batch plant, for which the cement was supplied by rail.  At the batch plant trucks were loaded first with aggregate and sand and then with Portland Cement.  The trucks then transported their batches to the paver. The batch was dumped into the paver’s skip, the skip was raised and the batch then dumped into a mixing drum where it was mixed for one minute, then discharged into a bucket mounted on a horizontal boom.  The bucket full of concrete mix was then rolled along the boom and discharged on the sub-grade.  Inspectors took frequent concrete samples for curing, shipment, and subsequent testing in the state highway department’s materials and testing laboratory to assure the concrete met required compression standards.  Following the paver was a spreader which was followed by a twin screed finishing machine, which usually made two passes over the freshly spread concrete to level it.  The surface was then finished with a bull float and behind the float a man on either side of the paving to finish the edges of the freshly laid slab.  The final steps were dragging with a burlap drag and then covering the surface with sisle kraft paper for three days while the concrete cured.  At the end of that period the paper would be removed and reused.  Relief joints were sawed into the surface at 100 foot intervals.

The interstate was constructed with a design life of twenty years, but much of it outlasted that time span.  Indeed, it was not until 1983, twenty-seven years following the first interstate construction, that sections of I-94 in North Dakota were replaced.  Even before replacement began, efforts to extend the life of original pavements and restore their rideability were being made.  Those efforts included fairly standard treatments like joint repair, full or partial concrete slab replacement, pavement grinding, joint re-sawing and sealing.  They also included more experimental approaches.  In 1981, for example, a section of I-94 was covered with a layer of vulcanized rubber asphalt (the principal ingredients of which were asphalt cement and ground up old car tires) that was then topped with a hot bituminous overlay. It was hoped that the interlayer would reduce stress on the concrete caused by vehicular traffic as well as acting as a barrier to moisture build-up between the concrete and bituminous overlay, which causes deterioration of the bond between the two materials.  The experiment, however, proved ineffective. 

Two years later, however, a relatively new technique that has since become standard practice was introduced as part of the state’s first I-94 reconstruction project.  It began in the summer of 1983 and employed a concrete recycling technique – at that time relatively new.  A twelve-mile section of eastbound I-94 between the Streeter and Cleveland interchanges, constructed in 1958 and 1959, had begun to crack at the intersection of center and cross joints.  Left unchecked such cracks continue down the joint lines until ultimately only the center point of the slab is intact.

The pavement was broken by two machines – a “whiphammer” that first broke the 10 inch thick pavement into large pieces, followed by a pavement breaker with a 10” square metal shoe impacting the pavement at the rate of 44 times per second working in foot wide strips back and forth across the highway.  The breaking pulverized the concrete into approximately 1 inch pieces.

After being broken, the pavement was hauled to a crushing mill where it was further pulverized and the materials screened and divided into recycled rock and recycled sand.  The recycled material was then mixed with new rock and sand and mixed with cement to create new concrete.  The recyclled materials constituted eighty percent of the rock-sand mixture used in concrete production.

This recycling project was just one of several to follow in the years to come as sections of the interstate were reconstructed.  Today recycled concrete is used in almost all reconstructed segments of I-94.  That the technology of road building had changed was apparent in not only the recycling process.  Unlike the original construction, the fresh pavement was laid without the use of forms, the surface of the pavement was tined to decrease slipperiness of the road in wet conditions, construction joints were placed at closer intervals and askew to the road surface, concrete shoulders with rumble strips placed every 100 feet replaced the original asphalt shoulders.

Another innovation in North Dakota road building, introduced in the early 1970s, is the use of fly ash as a building material.  Fly ash is a by-product of energy production at the state’s coal-fired electrical generating plants.  When mixed with lime, gravel and water it forms an extremely hard surface when compacted.  Its early use in the state was in the creation of a base for asphalt-surfaced roadways. In I-94 reconstruction it is typically used as a substitute for cement (by up to 30%) in the creation of concrete.