Construction begun The Central Pacific broke ground on January 8, 1863. Because of insufficient transportation alternatives from the manufacturing centers on the east coast, virtually all of their tools and machinery including rails,
railroad switches,
railroad turntables,
freight and passenger cars, and
steam locomotives were transported first by train to east coast ports. They were then loaded on ships which either sailed around South America's
Cape Horn, or offloaded the cargo at the
Isthmus of Panama, where it was sent across via
paddle steamer and the
Panama Railroad. The Panama Railroad gauge was , which was incompatible with the gauge used by the CPRR equipment. The latter route was about twice as expensive per pound. Once the machinery and tools reached the
San Francisco Bay area, they were put aboard river paddle steamers which transported them up the final of the
Sacramento River to the new state capital in
Sacramento. Many of these steam engines, railroad cars, and other machinery were shipped dismantled and had to be reassembled. Wooden timbers for railroad ties, trestles, bridges, firewood, and telegraph poles were harvested in California and transported to the project site. The Union Pacific Railroad did not start construction for another 18 months until July 1865. They were delayed by difficulties obtaining financial backing and the unavailability of workers and materials due to the Civil War. Their start point in the new city of
Omaha, Nebraska, was not yet connected via railroad to
Council Bluffs, Iowa. Equipment needed to begin work was initially delivered to Omaha and Council Bluffs by paddle steamers on the
Missouri River. After the
American Civil War ended in 1865, the Union Pacific still competed for railroad supplies with companies who were building or repairing railroads in the south, and prices rose.
Rail standards At that time in the United States, there were two primary standards for track gauge, as defined by the distance between the two rails. In Britain, the gauge was , and this had been adopted by the majority of northern railways. However, much of the south had adopted a gauge. Transferring railway cars across a
break of gauge required
changing out the
trucks. Alternatively, cargo was
offloaded and reloaded, a time-consuming effort that delayed cargo shipments. For the transcontinental railroad, the builders adopted what is now known as the
standard gauge. The
Bessemer process and
open hearth furnace steel-making were in use by 1865, but the advantages of steel rails which lasted much longer than iron rails had not yet been demonstrated. The
rails used initially in building the railway were nearly all made of an
iron flat-bottomed modified
I-beam profile weighing . The railroad companies were intent on completing the project as rapidly as possible at a minimum cost. Within a few years, nearly all railroads converted to
steel rails.
Time zones and telegraph usage Time was not standardized across the United States and Canada until November 18, 1883. In 1865, each railroad set its own time to minimize scheduling errors. To communicate easily up and down the line, the railroads built telegraph lines alongside the tracks. These lines eventually superseded the original
First Transcontinental Telegraph which followed much of the
Mormon Trail up the
North Platte River and across the very thinly populated
Central Nevada Route through central Utah and Nevada. The telegraph lines along the railroad were easier to protect and maintain. Many of the original telegraph lines were abandoned as the telegraph business was consolidated with the railroad telegraph lines.
Union Pacific route The Union Pacific's of track started at MP 0.0 in
Council Bluffs, Iowa, At the end of 1865, Peter A. Dey, Chief Engineer of the Union Pacific, resigned over a routing dispute with
Thomas C. Durant, one of the chief financiers of the Union Pacific. With the end of the Civil War and increased government supervision in the offing, Durant hired his former M&M engineer
Grenville M. Dodge to build the railroad, and the Union Pacific began a mad dash west. Former Union General
John "Jack" Casement was hired as the new Chief Engineer of the Union Pacific. He equipped several railroad cars to serve as portable bunkhouses for the workers and gathered men and supplies to push the railroad rapidly west. Among the bunkhouses, Casement added a galley car to prepare meals, and he even provided for a herd of cows to be moved with the railhead and bunk cars to provide fresh meat. Hunters were hired to provide
buffalo meat from the large herds of American bison. The small survey parties who scouted ahead to locate the roadbed were sometimes attacked and killed by raiding Native Americans. In response, the U.S. Army instituted active cavalry patrols that grew larger as the Native Americans grew more aggressive. Temporary, "
Hell on wheels" towns, made mostly of canvas tents, accompanied the railroad as construction headed west. The
Platte River was too shallow and meandering to provide river transport, but the Platte river valley headed west and sloped up gradually at about , often allowing to lay a mile (1.6 km) of track a day or more in 1866 as the Union Pacific finally started moving rapidly west. Building bridges to cross creeks and rivers was the main source of delays. Near where the
Platte River splits into the
North Platte River and
South Platte River, the railroad bridged the North Platte River over a bridge (nicknamed ½ mile bridge). It was built across the shallow but wide North Platte resting on piles driven by steam
pile drivers. Here they built the "railroad" town of
North Platte, Nebraska, in December 1866 after completing about of track that year. In late 1866, former
Major General Grenville M. Dodge was appointed Chief Engineer on the Union Pacific, but hard-working General "Jack" Casement continued to work as chief construction "boss" and his brother Daniel Casement continued as a financial officer. The original emigrant route across Wyoming of the Oregon, Mormon and California Trails, after progressing up the
Platte River valley, went up the
North Platte River valley through
Casper, Wyoming, along the
Sweetwater River and over the
Continental Divide at the
South Pass. The original westward travelers in their ox and mule pulled wagons tried to stick to river valleys to avoid as much road building as possible—gradients and sharp corners were usually of little or no concern to them. The ox and mule pulled wagons were the original off-road vehicles in their day since nearly all of the
Emigrant Trails went cross country over rough, unimproved trails. The route over South Pass's main advantage for wagons pulled by oxen or mules was a shorter elevation over an "easy" pass to cross and its "easy" connection to nearby river valleys on both sides of the continental divide for water and grass. The emigrant trails were closed in winter. The North Platte–South Pass route was far less beneficial for a railroad, as it was about longer and much more expensive to construct up the narrow, steep and rocky canyons of the North Platte. The route along the North Platte was also further from
Denver, Colorado, and went across difficult terrain, while a railroad connection to that City was already being planned for and surveyed. Efforts to survey a new, shorter, "better" route had been underway since 1864. By 1867, a new route was found and surveyed that went along part of the
South Platte River in western Nebraska and after entering what is now the state of
Wyoming, ascended a gradual sloping ridge between
Lodgepole Creek and
Crow Creek to the
Evans Pass (also called Sherman's Pass) which was discovered by the Union Pacific employed English surveyor and engineer, James Evans, in the
Great Divide Basin in about 1864. This pass is now marked by the
Ames Monument (), commemorating two of the main backers of the Union Pacific Railroad, and the ghost town of Sherman. From North Platte, Nebraska (elevation ), the railroad proceeded westward and upward along a new path across the
Nebraska Territory and
Wyoming Territory (then part of the
Dakota Territory) along the north bank of the
South Platte River and into what would become the state of Wyoming at Lone Pine, Wyoming. Evans Pass was located between what would become the new "railroad" towns of
Cheyenne and
Laramie. Connecting to this pass, about west of Cheyenne, was the one place across the
Laramie Mountains that had a narrow "guitar neck" of land that crossed the mountains without serious erosion at the so-called "gangplank" () discovered by
Major General Grenville Dodge in 1865 when he was in the U.S. Army. The new route surveyed across Wyoming was over shorter, had a flatter profile, allowing for cheaper and easier railroad construction, and also went closer by Denver and the known coalfields in the
Wasatch and
Laramie Ranges. The railroad gained about in the climb to Cheyenne from North Platte, Nebraska—about —a very gentle slope of less than one degree average. This "new" route had never become an emigrant route because it lacked the water and grass to feed the emigrants' oxen and mules. Steam locomotives did not need grass, and the railroad companies could drill wells for water if necessary. Coal had been discovered in Wyoming and reported on by
John C. Frémont in his 1843 expedition across Wyoming, and was already being exploited by Utah residents from towns like
Coalville, Utah, and later
Kemmerer, Wyoming, by the time the Transcontinental railroad was built. Union Pacific needed coal to fuel its
steam locomotives on the almost treeless plains across Nebraska and Wyoming. Coal shipments by rail were also looked on as a potentially major source of income—this potential is still being realized. The Union Pacific reached the new railroad town of Cheyenne in December 1867, having laid about that year. They paused over the winter, preparing to push the track over Evans (Sherman's) Pass. At , Evans Pass was the highest point reached on the transcontinental railroad. About beyond Evans pass, the railroad had to build an extensive bridge over the Dale Creek canyon (). The
Dale Creek Crossing was one of their more difficult railroad engineering challenges. Dale Creek Bridge was long and above Dale Creek. The bridge components were pre-built of timber in
Chicago, Illinois, and then shipped on rail cars to Dale Creek for assembly. The eastern and western approaches to the bridge site, near the highest
elevation on the transcontinental railroad, required cutting through granite for nearly a mile on each side. The initial Dale Creek bridge had a train speed limit of per hour across the bridge. Beyond Dale Creek, railroad construction paused at what became the town of
Laramie, Wyoming, to build a bridge across the
Laramie River. Located from Evans pass, Union Pacific connected the new "railroad" town of Cheyenne to Denver and its
Denver Pacific Railway and Telegraph Company railroad line in 1870. Elevated above sea level, and sitting on the new Union Pacific route with a connection to Denver, Cheyenne was chosen to become a major railroad center and was equipped with extensive railroad yards, maintenance facilities, and a Union Pacific presence. Its location made it a good base for
helper locomotives to couple to trains with
snowplows to help clear the tracks of snow or help haul heavy freight over Evans pass. The Union Pacific's junction with the Denver Railroad with its connection to
Kansas City, Kansas,
Kansas City, Missouri, and the railroads east of the Missouri River again increased Cheyenne's importance as the junction of two major railroads. Cheyenne later became Wyoming's largest city and the capital of the new state of Wyoming. The railroad established many townships along the way:
Fremont,
Elkhorn,
Grand Island,
North Platte,
Ogallala and
Sidney as the railroad followed the Platte River across Nebraska territory. The railroad even dipped into what would become the new state of
Colorado after crossing the North Platte River as it followed the
South Platte River west into what would become
Julesburg before turning northwest along Lodgepole Creek into Wyoming. In the
Dakota Territory (Wyoming) the new towns of
Cheyenne,
Laramie,
Rawlins (named for
Union General
John Aaron Rawlins, who camped in the locality in 1867),
Green River and
Evanston (named after James Evans) were established, as well as many more fuel and water stops. The Continental Divide was crossed west of Rawlins, at what would become the site of a town named Creston. The
Green River was crossed with a new bridge, and the new "railroad" town of Green River constructed there after the tracks reached the Green River on October 1, 1868—the last big river to cross. On December 4, 1868, the Union Pacific reached Evanston, having laid almost of track over the Green River and the
Laramie Plains that year. By 1871, Evanston became a significant maintenance shop town equipped to carry out extensive repairs on the cars and steam locomotives. In the
Utah Territory, the railroad once again diverted from the main emigrant trails to cross the
Wasatch Mountains and went down the rugged Echo Canyon (Summit County, Utah) and
Weber River canyon. To speed up construction as much as possible, Union Pacific contracted several thousand Mormon workers to cut, fill, trestle, bridge, blast and tunnel its way down the rugged Weber River Canyon to
Ogden, Utah, ahead of the railroad construction. The Mormon and Union Pacific rail work was joined in the area of the present-day border between Utah and Wyoming. The longest of four tunnels built in Weber Canyon was Tunnel 2. Work on this tunnel started in October 1868 and was completed six months later. Temporary tracks were laid around it and Tunnels 3 (), 4 () and 5 () to continue work on the tracks west of the tunnels. The tunnels were all made with the new dangerous
nitroglycerine explosive, which expedited work but caused some fatal accidents. While building the railroad along the rugged Weber River Canyon, Mormon workers signed the
Thousand Mile Tree which was a lone tree alongside the track from Omaha. A historic marker has been placed there. The tracks reached
Ogden, Utah, on March 8, 1869, although finishing work would continue on the tracks, tunnels and bridges in Weber Canyon for over a year. From Ogden, the railroad went north of the
Great Salt Lake to
Brigham City and
Corinne using Mormon workers, before finally connecting with the
Central Pacific Railroad at Promontory Summit in Utah territory on May 10, 1869. Some Union Pacific officers declined to pay the Mormons all of the agreed upon construction costs of the work through Weber Canyon, and beyond, claiming Union Pacific poverty despite the millions they had extracted through the
Crédit Mobilier of America scandal. Only partial payment was secured through court actions against Union Pacific. where the railroad grade slightly exceeded two percent. In June 1864, the Central Pacific railroad entrepreneurs opened Dutch Flat and Donner Lake Wagon Road (DFDLWR). Costing about $300,000 and a years worth of work, this toll road wagon route was opened over much of the route the Central Pacific railroad (CPRR) would use over Donner Summit to carry freight and passengers needed by the CPRR and to carry other cargo over their toll road to and from the ever-advancing railhead and over the Sierra to the gold and silver mining towns of Nevada. As the railroad advanced, their freight rates with the combined rail and wagon shipments would become much more competitive. The volume of the toll road freight traffic to Nevada was estimated to be about $13,000,000 a year as the
Comstock Lode boomed, and getting even part of this freight traffic would help pay for the railroad construction. When the railroad reached Reno, it had the majority of all Nevada freight shipments, and the price of goods in Nevada dropped significantly as the freight charges to Nevada dropped significantly. The rail route over the Sierras followed the general route of the Truckee branch of the
California Trail, going east over Donner Pass and down the rugged
Truckee River valley. The route over the Sierra had been plotted out by Judah in preliminary surveys before his death in 1863. Judah's deputy,
Samuel S. Montague was appointed as Central Pacific's new Chief Engineer, with Lewis M. Clement as Assistant Chief Engineer and Charles Cadwalader as second assistant. To build the new railroad, detailed surveys had to be run that showed where the cuts, fills, trestles, bridges and tunnels would have to be built. Work that was identified as taking a long time was started as soon as its projected track location could be ascertained and work crews, supplies and road work equipment found to be sent ahead. Tunnels, trestles and bridges were nearly all built this way. The spread-out nature of the work resulted in the work being split into two divisions, with L. M. Clement taking the upper division from Blue Cañon to Truckee and Cadwalader taking the lower division from Truckee to the Nevada border. Other assistant engineers were assigned to specific tasks such as building a bridge, tunnel or trestle which was done by the workers under experienced supervisors. The summit tunnel (Number 6), , was started in late 1865, well ahead of the railhead. Through solid granite, the summit tunnel progressed at a rate of only about per day per face as it was being worked by three eight-hour shifts of workers, hand drilling holes with a rock drill and hammer, filling them with black powder and trying to blast the granite loose. One crew worked drilling holes on the faces and another crew collected and removed the loosened rock after each explosion. The workers were pulled off the summit tunnel and the track grading east of Donner Pass in the winter of 1865–1866 as there was no way to supply them, nor quarters they could have lived in. The crews were transferred to work on bridges and track grading on the Truckee River canyon. In 1866, they put in a vertical shaft in the center of the summit tunnel and started work towards the east and west tunnel faces, giving four working faces on the summit tunnel to speed up progress. A steam engine off an old locomotive was brought up with much effort over the wagon road and used as a winch driver to help remove loosened rock from the vertical shaft and two working faces. By the winter of 1866–67, work had progressed sufficiently and a camp had been built for workers on the summit tunnel which allowed work to continue. The cross section of a tunnel face was a , oval with an vertical wall. Progress on the tunnel sped up to over per day per face when they started using the newly invented
nitroglycerin—manufactured near the tunnel. They used nitroglycerin to deepen the summit tunnel to the required height after the four tunnel faces met, and made even faster progress. Nearly all other tunnels were worked on both tunnel faces and met in the middle. Depending on the material the tunnels penetrated, they were left unlined or lined with brick, rock walls or timber and post. Some tunnels were designed to bend in the middle to align with the track bed curvature. Despite this potential complication, nearly all the different tunnel center lines met within or so. The detailed survey work that made these tunnel digs as precise as required was nearly all done by the Canadian-born and -trained Lewis Clement, the CPRR's Chief Assistant Engineer and Superintendent of Track, and his assistants. Hills or ridges in front of the railroad road bed would have to have a flat-bottomed, V-shaped "cut" made to get the railroad through the ridge or hill. The type of material determined the slope of the V and how much material would have to be removed. Ideally, these cuts would be matched with valley fills that could use the dug out material to bring the road bed up to grade—
cut and fill construction. In the 1860s there was no heavy equipment that could be used to make these cuts or haul it away to make the fills. The options were to dig it out by pick and shovel, haul the hillside material by
wheelbarrow and/or horse or mule cart or blast it loose. To blast a V-shaped cut out, they had to drill several holes up to deep in the material, fill them with black powder, and blast the material away. Since the Central Pacific was in a hurry, they were profligate users of black powder to blast their way through the hills. The only disadvantage came when a nearby valley needed fill to get across it. The explosive technique often blew most of the potential fill material down the hillside, making it unavailable for fill. Initially, many valleys were bridged by "temporary" trestles that could be rapidly built and were later replaced by much lower maintenance and permanent solid fill. The existing railroad made transporting and putting material in valleys much easier—load it on railway dump cars, haul where needed and dump it over the side of the trestle. The route down the eastern Sierras was done on the south side of
Donner Lake with a series of switchbacks carved into the mountain. The Truckee River, which drains
Lake Tahoe, had already found and scoured out the best route across the
Carson Range of mountains east of the Sierras. The route down the rugged Truckee River Canyon, including required bridges, was done ahead of the main summit tunnel completion. To expedite the building of the railroad through the Truckee River canyon, the Central Pacific hauled two small locomotives,
railcars, rails and other material on wagons and sleighs to what is now
Truckee, California, and worked the winter of 1867–68 on their way down Truckee canyon ahead of the tracks being completed to Truckee. This feat was dramatized in John Ford's film
The Iron Horse with one of Central Pacific's actual locomotives,
C.P. Huntington. In Truckee canyon, five
Howe truss bridges had to be built. This gave them a head start on getting to the "easy" miles across Nevada. In order to keep the higher portions of the Sierra grade open in the winter, of timber
snow sheds were built between Blue Cañon and Truckee in addition to utilizing
snowplows pushed by locomotives, as well as manual shovelling. With the advent of more efficient oil fired steam and later diesel electric power to drive plows, flangers, spreaders, and rotary snow plows, most of the wooden snowsheds have long since been removed as obsolete. Tunnels 1–5 and Tunnel 13 of the original 1860s tunnels on Track 1 of the Sierra grade remain in use today, while additional new tunnels were later driven when the grade was double tracked over the first quarter of the twentieth century. In 1993, the
Southern Pacific Railroad (which operated the CPRR-built
Oakland–
Ogden line until its 1996 merger with the
Union Pacific) closed and pulled up the section of Track #1 over the summit running between the Norden complex (Shed 26, MP 192.1) and the covered crossovers in Shed #47 (MP 198.8) about a mile east of the old
flyover at Eder, bypassing and abandoning the tunnel 6–8 complex, the concrete snowsheds just beyond them, and tunnels 9–12 ending at MP 195.7, all of which had been located on Track 1 within two miles of the summit. Since then all east- and westbound traffic has been run over the Track #2 grade crossing the summit about south of Donner Pass through the Tunnel #41 ("The Big Hole") running under Mt. Judah between Soda Springs and Eder, which was opened in 1925 when the summit section of the grade was double tracked. This routing change was made because the Track 2 and Tunnel 41 Summit crossing is far easier and less expensive to maintain and keep open in the harsh Sierra winters. On June 18, 1868, the Central Pacific reached
Reno, Nevada, after completing of railroad up and over the Sierras from
Sacramento, California. By then the railroad had already been prebuilt down the Truckee River on the much flatter land from Reno to
Wadsworth, Nevada, where they bridged the Truckee for the last time. From there, they struggled across a
forty mile desert to the end of the Humboldt river at the
Humboldt Sink. From the end of the Humboldt, they continued east over the
Great Basin Desert bordering the
Humboldt River to
Wells, Nevada. One of the most troublesome problems found on this route along the Humboldt was at
Palisade Canyon (near
Carlin, Nevada), where for the line had to be built between the river and basalt cliffs. From Wells, Nevada, to
Promontory Summit, the Railroad left the Humboldt and proceeded across the Nevada and Utah desert. Water for the
steam locomotives was provided by wells, springs, or pipelines to nearby water sources. Water was often pumped into the water tanks with
windmills. Train fuel and
water cranes for the early trains with steam locomotives may have been as often as every . On one memorable occasion, not far from Promontory, the Central Pacific crews organized an army of workers and five train loads of construction material, and
laid of track on a prepared rail bed in one day—a record that still stands today. The Central Pacific and Union Pacific raced to get as much track laid as possible, and the Central Pacific laid about of track from Reno to Promontory Summit in the one year before the Last Spike was driven on May 10, 1869. Central Pacific had 1,694 freight cars available by May 1869, with more under construction in their Sacramento yard. Major repairs and maintenance on the Central Pacific rolling stock was done in their Sacramento maintenance yard. Near the end of 1869, Central Pacific had 162 locomotives, of which 2 had two drivers (drive wheels), 110 had four drivers, and 50 had six drivers. The
steam locomotives had been purchased in the eastern states and shipped to California by sea. Thirty-six additional locomotives were built and coming west, and twenty-eight more were under construction. There was a shortage of passenger cars and more had to be ordered. The first Central Pacific sleeper, the "Silver Palace Sleeping Car", arrived at Sacramento on June 8, 1868. The CPRR route passed through
Newcastle and
Truckee in California, Reno, Wadsworth,
Winnemucca,
Battle Mountain,
Elko and Wells in Nevada (with many more fuel and water stops), before connecting with the Union Pacific line at Promontory Summit in the Utah Territory. When the eastern end of the CPRR was extended to Ogden by purchasing the
Union Pacific Railroad line from Promontory for about $2.8 million in 1870, it ended the short period of a boom town for
Promontory, extended the Central Pacific tracks about and made Ogden a major terminus on the transcontinental railroad, as passengers and freight switched railroads there. Subsequent to the railhead's meeting at Promontory Summit, Utah Territory, the San Joaquin River Bridge at Mossdale Crossing (near present-day
Lathrop, California) was completed on September 8, 1869, with the first through freight train carrying freight from the East Coast leaving Sacramento and crossing the bridge to arrive that evening at the Alameda Wharf on San Francisco Bay. As a result, the western part of the route was extended from Sacramento to the
Alameda Terminal in
Alameda, California, and shortly thereafter, to the
Oakland Long Wharf at
Oakland Point in
Oakland, California, and on to
San Jose, California. Train ferries transferred some railroad cars to and from the Oakland wharves and tracks to wharves and tracks in
San Francisco. Before the CPRR was completed, developers were building other feeder railroads like the
Virginia and Truckee Railroad to the
Comstock Lode diggings in
Virginia City, Nevada, and several different extensions in California and Nevada to reach other cities there. Some of their main cargo was the thousands of
cords ( each) of firewood needed for the many steam engines and pumps, cooking stoves, heating stoves etc. in Comstock Lode towns and the tons of ice needed by the miners as they worked ever deeper into the "hot" Comstock Lode ore body. In the mines, temperatures could get above at the work face and a miner often used over of ice per shift. This new railroad connected to the Central Pacific near Reno, and went through
Carson City, the new capital of Nevada. After the transcontinental railroads were completed, many other railroads were built to connect up to other population centers in Utah, Wyoming, Kansas, Colorado, Oregon, Washington territories, etc. In 1869, the
Kansas Pacific Railway started building the
Hannibal Bridge, a
swing bridge across the
Missouri River between
Kansas City, Missouri, and
Kansas City, Kansas, which connected railroads on both sides of the Missouri while still allowing passage of
paddle steamers on the river. After completion, this became another major east–west railroad. To speed completion of the
Kansas Pacific Railroad to Denver, construction started east from Denver in March 1870 to meet the railroad coming west from Kansas city. The two crews met at a point called Comanche Crossing, Kansas, on August 15, 1870. Denver was now firmly on track to becoming the largest city and the future capital of
Colorado. The
Kansas Pacific Railroad linked with the
Denver Pacific Railway via Denver to Cheyenne in 1870. The original transcontinental railroad route did not pass through the two biggest cities in the so-called
Great American Desert—
Denver, Colorado, and
Salt Lake City, Utah. Feeder railroad lines were soon built to service these two and other cities and states along the route. Modern-day
Interstate 80 roughly follows the path of the railroad from Sacramento across modern day California, Nevada, Wyoming and Nebraska, with a few exceptions. Most significantly, the two routes are different between Wells, Nevada, and
Echo, Utah. In this area the freeway passes along the south shore of the
Great Salt Lake and passes through
Salt Lake City, cresting the
Wasatch Mountains at
Parley's Summit. The railroad was originally routed along the north shore, and later with the
Lucin Cutoff directly across the center of the Great Salt Lake, passing through the city of
Ogden instead of Salt Lake City. The railroad crosses the Wasatch Mountains via a much gentler grade through
Weber Canyon. Most of the other deviations are in mountainous areas where
interstate highways allow for grades up to six-percent grades, which allows them to go many places the railroads had to go around, since their goal was to hold their grades to less than two percent. ==Construction==