Grantville Gazette, Volume I Page 42

  The stones had to be broken so that they were angular; they had to be angular so that they would lock together when compacted. (Smiles, 430; Forbes, 534; 1911 EB). Pebbles rounded by the action of water would not create the desired surface. Likewise, the stones had to be small. If they were much larger than the effective area of contact between the wheel and the road surface—about one inch square—then the stones would not be consolidated by passing traffic. (Reader, 2, 32–3, 37–9).

  McAdam was very insistent that no "sand, earth or other matter" be used "on pretense of binding." (Reader, 39; Forbes, However, his road had an "intrinsic" binding agent—the traffic wore down the rocks and the resulting dust acted as a binder. That may explain the modern practice, described by Collier's Encyclopedia, of bonding the modern macadam road "into a solid mass by means of a finely crushed stone rolled into the surface."

  The up-timers' sources are not always consistent in the description of macadam roads. For example, the modern EB shows them as having 0.75–1 inch surface layer of gravel or broken stone. However, the 1911 EB says that while "Telford covered the broken stone of new roads with 1/2 in. of gravel to act as a binding material," his rival McAdam "absolutely interdicted the use of any binding material, leaving the broken stone to work in and unite by its own angles under the traffic."

  Another problem with the modern EB text is a sin of omission. McAdam cambered, not only the road surface, and the base course, but also the subgrade. While this is depicted in the figure, it is not commented upon. All the encyclopedia says is that the road was "elevated," which was true but not the whole story.

  Road Design: Plank Roads

  The plank road differs from the corduroy road discussed previously, in that it uses lumber (planks) instead of whole or split logs.

  In the period 1835–1855, many plank roads were constructed in New York, Pennsylvania, Ohio, Michigan, Illinois, and other timber-rich states. These roads were typically ten to fifteen miles of length, and fed into canals or railroads. Indeed, they were nicknamed "the Farmer's Railroad."

  According to the 1911 EB, "the plank road often used in American forests makes an excellent track for all kinds of traffic." The construction was straightforward. First the road bed was cleared and graded, and drainage ditches dug. Then two or more columns of longitudinal sleepers were put down, and transverse planks were laid (and sometimes nailed or spiked down) on top. The planks were two to four inches thick, eight to sixteen feet long, and made of oak, hemlock or pine. For drainage purposes, the outer sleepers may be set a few inches lower than the inner ones. (Majewki, 9; WHS, ISM, WiscHS, 1911 EB)

  These plank roads could be constructed at one-half to two-thirds the price of macadam roads. (Majewski) Naturally, they were cheapest to build on level terrain with forests nearby.

  In 1850, Charles E. Clarke told the Prairie State newspaper that the three plank roads near his Illinois farm were "the best roads imaginable—better by far than the best paved or 'macadamized' road—pleasanter for the person riding—easier for the animals, and far less destructive to the carriages that roll upon them." (Clarke) South Carolina manufacturer William Gregg even thought them superior to railroads (Majewski 9).

  From the section on "Friction," we know that wood is a "fast" road surface. On a new plank road, stage coaches traveled eight miles per hour (Luedtke; Clarke). Two horses could draw two tons forty miles per day (Clarke). The Watertown, Wisconsin Plank Road reduced the round trip from Milwaukee to Watertown from four to six days, to three, and allowed wagon loads to be increased from 1,500–2,000 pounds, to 3,000; freight rates were reduced by about 25%. (WHS). "Trips which took from four to six days on dirt roads were cut to from ten to fourteen hours over plank roads." (Mason) Unlike unsurfaced roads, plank roads could be used in any season (Majewski, 9).

  Not everyone liked plank roads quite so much as Clarke. Asa Stoddard critiqued the Kalamazoo-Grand Rapids highway in verse, asking the reader if he had ever "brave[d] the peril, dare[d] the danger, of a journey on the Plank?"

  The reason we hear such inconsistent views is that plank roads were excellent when new, but needed repairs or replacement more frequently than the plank road companies had expected. The boards decayed, warped, or were stolen. (Majewski 2 says that the expected life was 8–12 years, the true one 4–5. WiscHS states a life of 5–6 years, and Clarke says 7–8. Mason says that the roads were in good condition for 3–4 years, then needed constant attention, with maintenance costs running 30–40% of the original construction cost annually.) And toll revenues weren't sufficient to pay for the maintenance. The roads fell into disrepair and became hazardous.

  It does not appear that the wood used in the plank roads was treated in any way to make it more weatherproof. It is possible that such treatment, if it could be done economically, would substantially extend the working life of a plank road.

  A plank road one mile long, eight feet wide, with three inch thick planks would require 10,560 cubic feet of wood. Then for a mile's worth of two stringers, each three inches wide by three inches thick, add another 3,455 cubic feet. That is a total of about 14,000 cubic feet, or about 1,200 board feet.

  Unfortunately, the USE-controlled region of early seventeenth-century Germany is unlikely to be, in the near future, the site of a "plank road craze" comparable to the one in nineteenth-century America. That is because there is a relative shortage of wood. (Virginia DeMarce, Charles Prael, Manfred Gross, and Andrew Ramage, private communications.) Wood is the principal fuel, and, by "the early modern period," per capita consumption of wood was about 4–5 cubic meters per year. (Other uses of wood totaled another cubic meter, annually.) (Halstead)

  The Black Forest, nonetheless, was a wood exporting region, with pine, fir and spruce being shipped down the Rhine to Mainz, either as timber rafts, or as sawn lumber. (Id.)

  Unlike the American wilderness, the forests of Germany—which also include the nearby Thüringerwald —are owned by various nobles, but they are likely to allow plank roads to pass through their territory if it yields a net financial benefit to them. Whether that will prove to be the case is debatable; Virginia DeMarce informs me that the Thüringerwald covers low mountains, and that roads were customarily made simply by taking off the topsoil to expose the bare rock.

  Poland, Russia and Scandinavia also export wood (although there has been some question raised as to how heavily forested Sweden itself was in the 1630s). While it probably is not economical to import Baltic wood into Germany merely to construct plank roads, the Baltic countries may themselves find such roads to be advantageous, especially to connect one river to another.

  Road Design: City Pavements

  City pavements have to bear the heaviest traffic. In medieval times, the usual expedient was the familiar cobblestone street, with large stones embedded in soil, sand or gravel. Gregory (140) comments that cobbled roads were "largely used on the North German Plain, where there is no local supply of squared stone, but cobbles are plentiful in the glacial drifts."

  In nineteenth-century England, the noisy cobbled roads were gradually replaced by set stone pavements, which are described in the 1911 EB. The paving stones should be flat, square, and about three inches wide and nine inches deep.

  The stones are fitted closely together, and the joints sealed with a grout of lime or cement. This is adequate, says the 1911 EB, if the foundation is concrete or broken stone or hard core.

  It was not always possible to lay a proper foundation, as this required tearing up the original street. If so, then one could use a "bituminous grout," which was the result of adding a composition of "coal tar, pitch and creosote oil" to packed down gravel.

  The 1911 EB notes that brick, wood and asphalt can also be used in paving. (We will take up the issue of asphalt in the next section.)

  The use of brick dated back to about 1885, and brick roadways are said to have "stood well under hard wear for fourteen years." The 1911 EB provides particulars concerning the composition of the clay, the manufacturing me
thod used to minimize chipping, and tests for moisture and abrasion resistance.

  1911 EB adds that wood pavements were introduced in England in 1839, and improved in 1871. In essence, these streets feature wood blocks, fitted together. There is much debate in 1911 EB as to which is the best wood to use. The improved pavement was laid over an elastic foundation of tarred wood boards, which in turn rested on sand. The pavement joints were filled with tarred gravel.

  Gregory (140) is actually quite complimentary about wood block pavements, provided the wood is hard and heavy: "they form a smooth surface, which makes one of the quietest of road; the surface is easily cleaned and is durable. Wood pavement is well adapted for horse traffic and motors: it has the advantage over asphalt or macadam that it is not thrown into waves."

  Road Design: Modern Asphalt Roads

  Within the Ring of Fire, there are several modern asphalt roads. Such roads were completely unfamiliar to seventeenth-century Europeans. In K.D. Wentworth's "Here Comes Santa Claus" (Ring of Fire), General Pappenheim mused, "The unfamiliar substance was hard as rock, yet seemed to have been laid down in malleable form somehow, then smoothed like butter before it solidified."

  The nineteenth-century author-to-be Laura Ingalls Wilder was equally surprised by her first encounter with asphalt: "In the very midst of the city, the ground was covered by some dark stuff that silenced all the wheels and muffled the sound of hoofs. It was like tar, but Papa was sure it was not tar, and it was something like rubber, but it could not be rubber because rubber cost too much. We saw ladies all in silks and carrying ruffled parasols, walking with their escorts across the street. Their heels dented the street, and while we watched, these dents slowly filled up and smoothed themselves out. It was as if that stuff were alive. It was like magic." (NAPA)

  The usage of the terms "tar," "bitumen" and "asphalt" is somewhat quixotic. I will use "tar" to refer to coal tar, and "bitumen" to refer to solid or semisolid petroleum per se. "Asphalt" may mean the crude source (rock or lake asphalt), or the derivative road material.

  While Paris had its first asphalt footpath in 1810, it took time to develop the proper techniques for asphalt paving, and the modern EB says that the "first successful major application" was on the rue Saint-Honore in 1858.

  We have the expertise to lay it, we have the necessary equipment in the WVDOT garage . . . but where do we get the asphalt?

  There is, of course, asphalt in the Middle East. In fact, the first use of asphalt as a road surface was by the Babylonians. (NAPA) The asphalt came from Hit, in Turkey. (1911 EB, "Hit"). But the Ottoman Empire is hostile to the USE, and the trade route is in any event a long one.

  Fortunately, there are European sources (Earle, 28–33; 1911 EB). According to the 1911 EB "Asphalt" article, "the material chiefly used in the construction of asphalt roadways is an asphaltic or bituminous limestone found in the Val de Travers, Canton of Neuchattel; in the neighborhood of Seyssel, department of Am; at Limmer, near the city of Hanover; and elsewhere." Forbes (539) mentions Wietze, too, which would be a logical place to look since we are already drilling for oil there.

  The Val de Travers (Swiss) rock asphalt, a bituminous limestone with an oil content of about 10–12%, has been known since pre-Roman times, but in OTL, it was first described scientifically by Dr. d'Eyrinis (1712). The Limmer deposit was discovered around 1730 but not worked until 1840. The 1911 EB article fails to mention that there are also deposits at Vorwohle.

  Our access to French sources is uncertain, thanks to the war. However, their premiere asphalt mine can be found at Seyssel, near Annecy, in Haute-Savoire. In OTL, it was discovered in 1797. There is also asphalt at St. Jean de Maurejols and Arejans, both in the Department of Gard.

  Another European source I am aware of is in Sicily, near Ragusa. It is mentioned in 1911 EB, but only in the article on Ragusa (the town "is commercially of some importance, a stone impregnated with bitumen being quarried and prepared for use for paving slabs by being exposed to the action of fire"). If the up-timers have the 1911 EB on a searchable CD, they might well find it. Otherwise, its discovery will be fortuitous.

  Asphalt can also be found in Hungary, Romania, and, of special note, Osmundsberg in Sweden. (Forbes, 539) Unfortunately, the Swedish source is obscure even today.

  The modern encyclopedias do not mention any of the European sources. Rather, they tout the benefits of the lake asphalt of Trinidad. Trinidad is nominally under Spanish control, but Sir Walter Raleigh trounced the Spanish garrison in 1595, then used the asphalt to caulk his ships. Trinidad is indeed an incredibly rich source; it exported 23,000 tons in 1880; 86,000 in 1895; and almost twice that a few years later. (Borth 169). The 1911 EB also notes that asphalt can be mined in Cuba and Venezuela.

  A third source came into prominence once oil drilling became a big business. The crude oil was subjected to fractional distillation, and the heaviest fraction was suitable for use as a road asphalt.

  The sources on roadbuilding history are not always precise, or in agreement, as to whether the "asphalt" used was rock asphalt, lake asphalt, oil well asphalt, or even coal tar.

  * * *

  The modern asphalt road evolved in three stages. First, a thin coating of coal tar or asphalt was sprayed onto macadam roads. The tar acts as a binder, so that vehicular traffic does not raise clouds of dust. It also acted to waterproof the road. This early form can be termed a "seal coat tar macadam."

  According to Collier's Encyclopedia, the stones are best laid in several layers, each only slightly thicker than the largest stones used, so they can lock together. A typical thickness is 1.5–4 inches. The stones are spread and rolled. Then hot asphalt is sprayed onto them (one to three gallons per square yard). Stone chips can be spread and rolled in, to protect the asphalt.

  It later became possible to achieve a course in which broken stone and asphalt were mixed together throughout the entire thickness, resulting in a "penetration tar macadam," or "penny mac." This was not a trivial procedure; R.G. Taylor, in 1919, referred to the "many errors" made in the attempt to construct such surfaces. (R&P, I:53).

  The third stage was the "hot mix" or "hot rolled" sheet asphalt, also known as "black top."

  The 1911 EB describes two methods of preparing the asphalt for street use. The "European" method was to pulverize the European rock asphalt, heat it in revolving ovens to 220–250 deg. F., and then compress and smooth it. The heating reduces the moisture content without, hopefully, much loss of petroleum. The compression "reconstructs" the original rock, although with a more desirable composition.

  In contrast, the "American" method used the purer asphalt of Trinidad. It is similar to the methods described in the modern encyclopedias, and so I will turn to the latter for particulars.

  Rock "aggregate" and asphalt are mixed together at a high temperature (Collier's says about 350 deg. F., and EB, 300–400 deg. F.), and the mix is rolled while hot and therefore fluid. The aggregate may be graded sand and fine rock dust (Collier's), or broken stone less than 1.5 or even less than one inch in size (EB). It is perhaps worth mentioning that since it was already 88–94% limestone, there was no need to add rock aggregate to the European rock asphalt.

  In 1911, the asphalt was laid at a temperature of 150–200 deg. F., spread with rakes, compressed with light blows, and finally smoothed with a steam roller. Modern methods are similar. The asphalt is spread and compacted by specialized tamping or vibrating machines. Usually two to six inches will be laid at one time, and the total thickness ranges from two inches to a foot or more. (Encyclopedia Americana).

  Road Design: Modern Concrete Roads

  Instead of a flexible pavement made of asphalt, the road builder may lay a rigid pavement formed from concrete. The first successful post-classical use of concrete in road-building was, depending on who you ask, in Grenoble, France in 1876 (Collier's) or in Inverness, Scotland in 1865 (modern EB).

  Concrete can be thought of as a mixture of cement, sand and stone. The 1911 EB comments, "Rock
s like granite and syenite may be used in combination with Portland cement. The ingredients are mixed in about the proportion of four parts of broken stone that has first been well wetted, one and a quarter or two parts of clean sharp sand, and one of cement put on in two layers, the second being rolled by hand to the required shape and to a good surface. It should remain for two or three weeks to dry and set. Want of elasticity may be urged against concrete macadam, and it is productive of dust, but in some cases it has proved satisfactory."

  The modern formula provided in Collier's Encyclopedia (which is the source of the remainder of the information in this section) is similar: one part cement; two parts sand; and three to four parts gravel or stone. The concrete may be mixed at a central facility, en route (this requires a specialized vehicle), or at the construction site.

  The concrete may be of a uniform thickness (typically eight to ten inches), or it may be several inches thicker at the edges, relative to the center, to increase edge strength. Wire mesh reinforcement may be used, and, if so, is typically laid above the bottom two inches of the concrete.

  The concrete is usually laid in widths of 20–30 feet (equivalent to two lanes of traffic), with a "contraction joint" running down the center. Laying involves depositing the wet mix, spreading it out, compacting it, leveling it, and finally imparting a rough texture to it by dragging wet burlap over it. The concrete is kept moist for at least a week by spraying it with a protective compound or (a more likely expedient in the 1632 universe) covering it at all times with wet burlap.

  * * *

  Asphaltic concrete is a combination of the two roadbuilding materials, and is made by mixing crushed stone, sand, rock dust and asphalt at a temperature of 350 deg. F. The asphalt serves as a cementing agent.

  * * *

  Concrete may also be used as a base for asphalt or asphaltic concrete (resulting in a so-called "flexible over rigid" pavement). Base course concrete contains less cement than pavement concrete.