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Interstate 70 in Colorado

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Title: Interstate 70 in Colorado  
Author: World Heritage Encyclopedia
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Subject: Timeline of Colorado history, Interstate 70, Colorado State Highway 35, List of U.S. Highways in Colorado, Colorado State Highway 74
Collection: Colorado River, Interstate 70, Interstate Highways in Colorado
Publisher: World Heritage Encyclopedia

Interstate 70 in Colorado

Interstate 70 marker

Interstate 70
Route information
Maintained by Colorado Department of Transportation
Length: 449.589 mi[1] (723.543 km)
History: Designated in 1956
Completed in 1992
Major junctions
West end: I‑70 / US‑6 / US‑50 at Utah state line
  US 50 in Grand Junction
US 24 near Vail
US 40 near Empire
I‑76 in Arvada
I‑25 / US 87 in Denver
I‑270 / US 36 in Denver
I‑225 in Aurora
US 40 / US 287 in Aurora
E-470 in Aurora
US 24 in Limon
East end: I‑70 / US-24 at Kansas state line
Highway system
Colorado State Highways
SH 69 SH 71

Interstate 70 (I-70) is a transcontinental Interstate Highway in the United States, stretching from Cove Fort, Utah to Baltimore, Maryland. In Colorado, the highway traverses an east–west route across the center of the state. In western Colorado, the highway connects the metropolitan areas of Grand Junction and Denver via a route through the Rocky Mountains. In eastern Colorado, the highway crosses the Great Plains, connecting Denver with metropolitan areas in Kansas and Missouri. Bicycles and other non-motorized vehicles, normally prohibited on Interstate Highways, are allowed on those stretches of I-70 in the Rockies where no other through route exists.

The U.S. Department of Transportation (USDOT) lists the construction of I-70 among the engineering marvels undertaken in the Interstate Highway system, and cites four major accomplishments: the section through the Dakota Hogback, Eisenhower Tunnel, Vail Pass and Glenwood Canyon. The Eisenhower Tunnel, with a maximum elevation of 11,158 feet (3,401 m) and length of 1.7 miles (2.7 km), is the longest mountain tunnel and highest point along the Interstate Highway System. The portion through Glenwood Canyon was completed on October 14, 1992. This was one of the final pieces of the Interstate Highway System to open to traffic, and is one of the most expensive rural highways per mile built in the United States. The Colorado Department of Transportation (CDOT) earned the 1993 Outstanding Civil Engineering Achievement Award from the American Society of Civil Engineers for the completion of I-70 through the canyon.

When the Interstate Highway system was in the planning stages, the western terminus of I-70 was proposed to be at Denver. The portion west of Denver was included into the plans after lobbying by Governor Edwin C. Johnson, for whom one of the tunnels along I-70 is named. East of Idaho Springs, I-70 was built along the corridor of U.S. Highway 40, one of the original transcontinental U.S. Highways. West of Idaho Springs, I-70 was built along the route of U.S. Highway 6, which was extended into Colorado during the 1930s.


  • Route description 1
    • Colorado River 1.1
    • Glenwood Canyon 1.2
    • Rocky Mountains 1.3
    • Clear Creek 1.4
    • Great Plains 1.5
  • History 2
    • Earlier routes 2.1
    • Interstate Highway planning 2.2
    • Construction 2.3
      • Eisenhower Tunnel 2.3.1
      • Vail Pass 2.3.2
      • Glenwood Canyon 2.3.3
    • Legacy 2.4
  • Exit list 3
  • See also 4
  • References 5
  • External links 6

Route description

A railroad, river and two-tiered highway following a narrow canyon
Westbound I-70 on a viaduct inside Glenwood Canyon paralleling the Colorado River and former Denver and Rio Grande Western Railroad (now Union Pacific) main line

Colorado River

I-70 enters Colorado from Utah, concurrent with US 6 and US 50, on a plateau between the north rim of Ruby Canyon of the Colorado River and the south rim of the Book Cliffs. The plateau ends just past the state line and the highway descends into the Grand Valley, formed by the Colorado River and its tributaries.[2] The Grand Valley is home to several towns and small cities that form the Grand Junction Metropolitan Statistical Area, locally known as the Western Slope. The highway directly serves the communities of Fruita, Grand Junction and Palisade. Grand Junction is the largest city between Denver and Salt Lake City and serves as the economic hub of the area.[3] The freeway passes to the north of downtown, while US 6 and 50 retain their original routes through downtown. US 6 rejoins I-70 east of Grand Junction; US 50 departs on a course toward Pueblo.[2]

I-70 exits the valley through De Beque Canyon, a path carved by the Colorado River that separates the Book Cliffs from Battlement Mesa. The river and its tributaries provide the course for the ascent up the Rocky Mountains. In the canyon, I-70 enters the Beavertail Mountain Tunnel, the first of several tunnels built to route the freeway across the Rockies. This tunnel design features a curved sidewall, unusual for tunnels in the United States, where most tunnels feature a curved roof and flat side-walls. Engineers borrowed a European design to give the tunnel added strength.[4] After the canyon winds past the Book Cliffs, the highway follows the Colorado River through a valley containing the communities of Parachute and Rifle.[2]

Glenwood Canyon

Approaching the city of

Interstate 70
Previous state:
Colorado Next state:
  • I-70 Road conditions, construction updates, traffic cameras, and traveler alerts by Colorado Department of Transportation
  • I-70 Guide by AARoads
  • Glenwood Canyon: An I-70 Odyssey - History of the Canyon and Construction of I-70 by Matthew E. Salek
  • Truckers, You Are Not Down Yet - Unnerving highway signs on eastbound I-70 approaching Denver by Dale Sanderson

External links

  1. ^ a b c d "Highway Data".  
  2. ^ a b c d e f g h i j DeLorme (2002). Colorado Atlas & Gazetteer (Map). 1 in:2.5 mi. Cartography by DeLorme (2002 ed.). ISBN . OCLC 52156345.
  3. ^ "Grand Junction Colorado: Trip Planning". Grand Junction Visitor & Convention Bureau. Retrieved 2009-02-22. 
  4. ^ a b c d e f g h "The History of I-70 in Colorado <1--(Construction Timeline, EJMT and GC I-70 Final Link subpages)-->". Colorado Department of Transportation. Retrieved 2008-04-01. 
  5. ^ a b Weingroff, Richard F. (Summer 1996). "Dwight D. Eisenhower System of Interstate and Defense Highways Engineering Marvels". Public Roads (Washington, DC:  
  6. ^ a b c d "CDOT Fun Facts". Colorado Department of Transportation. Retrieved 2008-02-15. 
  7. ^ "Glenwood Canyon Corridor". Flat Iron Construction Company. Retrieved 2009-04-20. 
  8. ^ a b c d e f g Stufflebeam Row, Karen; LaDow, Eva; Moler, Steve (March–April 2004). "Glenwood Canyon 12 Years Later". Public Roads (Washington, DC: Federal Highway Administration) 67 (5). Retrieved 2009-08-09. 
  9. ^ "Bicycle and pedestrian guidance". Federal Highway Administration. October 22, 2008. Retrieved 2008-04-30. 
  10. ^ Zimmermann, Karl (2004). Burlington's Zephyrs. Saint Paul, MN: MBI. pp. 38–40.  
  11. ^ "Collegiate Peaks Scenic Byway/ Highway of the Fourteeners". Buena Vista Chamber of Commerce. April 29, 2009. Retrieved 2009-06-13. 
  12. ^ a b c d e f g h i Weingroff, Richard (December 29, 2008). "Why Does I-70 End in Cove Fort, Utah?". Ask the Rambler. Federal Highway Administration. Retrieved 2009-06-07. 
  13. ^ a b c d e f "Eisenhower Tunnel". Colorado Department of Transportation. Retrieved 2009-06-15. 
  14. ^ "China Completes World's Highest Railroad". Railway Track and Structures. December 1, 2002. Retrieved 2009-06-13. 
  15. ^ "Structure List for Highway 070". Colorado Department of Transportation. Retrieved 2011-07-01. 
  16. ^ "Rocky Mountain National Park: The Dakota Hogback".  
  17. ^ "Straight Line Diagram (for I-70)". Colorado Department of Transportation. Retrieved 2009-09-21. 
  18. ^ "A need for speed(ways): Colorado's Long and Winding Road Before joining Eisenhower's Interstate Plan".  
  19. ^ "Lets Talk Colorado: Limon". Colorado Tourism Office. Retrieved 2009-07-23. 
  20. ^ "Lets Talk Colorado: Driving to Colorado From the Kansas State Line: I-70 and Hwy. 50 West". Colorado Tourism Office. Retrieved 2009-07-23. 
  21. ^ a b c d e f g h i j k l m n o p q Associated Cultural Resource Experts (2002). Highways to the Sky: A Context and History to Colorado's Highway System. Colorado Department of Transportation. Retrieved 2009-05-22. 
  22. ^ Noeth, Louise Ann (2002). Bonneville: The Fastest Place on Earth. St. Paul, MN: MotorBooks/MBI Publishing Company. p. 18.  
  23. ^ Weingroff, Richard F. (January 1, 2009). "U.S. 6: The Grand Army of the Republic Highway". Highway History. Federal Highway Administration. Retrieved 2009-05-24. 
  24. ^ Rand McNally (1946). Road Atlas (Map). p. 24. Retrieved 2008-05-05.
  25. ^ a b c "Eisenhower Memorial Bore". Colorado Department of Transportation. Retrieved 2009-07-25. 
  26. ^ "Edwin C Johnson Bore". Colorado Department of Transportation. Retrieved 2009-07-25. 
  27. ^ a b Garner, Joe (August 31, 1999). "Freeway Opened the State to the Rest of the U.S.". Rocky Mountain News. 
  28. ^ Scotese, Thomas; Ackerman, John (1992). "Engineering Considerations for the Hanging Lake Tunnel Project, Glenwood Springs, Colorado" (PDF). International Society of Explosives Engineers. Retrieved 2009-04-30. 
  29. ^ McGregor, Heather (May 22, 1994). "Old Tires To Heal Glenwood Scar: Highway Eyesore Dates to 1930s".  
  30. ^ "Travel Advisory; New I-70 Stretch Helps Skiers".  
  31. ^ "Nation Briefings".  
  32. ^ Williams, Leroy (1993-06-08). "Glenwood Canyon Traffic Can Savor Delay-Free Season". Rocky Mountain News. 
  33. ^ "Costliest Rural Freeway: $100 An Inch".  
  34. ^ "Outstanding Civil Engineering Achievement Award". American Society of Civil Engineers. Retrieved 2008-02-24. 
  35. ^ Edwards & Kelsey. "I-95/I-276 Interchange Project Meeting Design Management Summary—Draft: Design Advisory Committee Meeting #2" (PDF). Pennsylvania Turnpike Commission. Retrieved 2009-08-03. 
  36. ^ Weingroff, Richard. "Why Does The Interstate System Include Toll Facilities?". Ask The Rambler. Federal Highway Administration. 
  37. ^ Geary, Edward A. "Utah History to Go: Interstate 70". State of Utah. Retrieved 2008-02-16. 
  38. ^ a b "Army Rights Tipped Truck Carrying Navy Torpedoes". The Spokesman-Review (Spokane, WA). August 2, 1984. Retrieved 2009-09-24. 
  39. ^ Getlin, Josh (September 20, 1987). "Record of Risk-Free Transportation Torpedoed by Denver's Experience".  
  40. ^ "Errors Many in Torpedo Incident". Eugene Register-Guard. August 10, 1984. 
  41. ^ Kowalski, Robert (February 26, 1990). "Hazardous Cargo at Heart of Controversy". The Denver Post. 
  42. ^ Flynn, Kevin (December 16, 2003). "This Mousetrap Wasn't a Snap". The Denver Post. 
  43. ^ Lott, Renelle (October 31, 2012). "Ribbon Cutting Marks Upcoming November Opening of new I-70 West Parachute Interchange" (Press release). Garfield County, Colorado. Retrieved February 27, 2013. 
  44. ^ Cabrera, Ana (December 11, 2010). "Neighbors Concerned Over Deadly Intersection". Denver:  


See also

County Location Mile[1] km Exit Destinations Notes
Mesa   0.000 0.000 I‑70 west / US‑6 west / US‑50 west Continuation into Utah
  1.814 2.919 2 Rabbit Valley
  11.106 17.873 11 US 6 east – Mack East end of US 6 overlap
  15.081 24.271 15 SH 139 north – Loma, Rangely
Fruita 19.444 31.292 19 SH 340 – Fruita, Colorado National Monument
Grand Junction 25.563 41.140 26 I‑70 Bus. east / US 6 / US 50 – Grand Junction East end of US 50 overlap
27.570 44.370 28 24 Road, Redlands Parkway
31.351 50.455 31 Horizon Drive – Grand Junction Regional Airport
Clifton 36.644 58.973 37 To US 6 / I-70 Bus. west – Clifton, Grand Junction, Delta
Palisade 41.578 66.913 42 To US 6 – Palisade
  43.682 70.299 44 I‑70 Bus. west – Palisade
  45.332 72.955 46 Cameo
  46.867 75.425 47 James M. Robb – Colorado River State Park, Island Acres Former port of entry
  49.015 78.882 49 SH 65 south to SH 330 – Grand Mesa, Collbran
  Beavertail Tunnel
  61.648 99.213 62 De Beque
Garfield   72.319 116.386 72 West Parachute Opened October 31, 2012[43]
Parachute 75.152 120.945 75 Parachute, Battlement Mesa
  81.236 130.737 81 Rulison
  86.850 139.772 87 US 6 east – Rifle East end of US 6 overlap
Rifle 90.422 145.520 90 SH 13 north – Rifle, Meeker
  93.991 151.264 94 Garfield County Regional Airport
  97.427 156.794 97 I‑70 Bus. north – Silt
  105.260 169.400 105 New Castle
  109.000 175.418 109 Canyon Creek
  111.328 179.165 111 South Canyon Creek Road
Glenwood Springs 114.295 183.940 114 West Glenwood
116.380 187.295 116 SH 82 – Glenwood Springs, Aspen
  118.640 190.933 119 No Name
  120.954 194.657 121 Grizzly Creek – Hanging Lake
  122.588 197.286 123 Shoshone Access Road Eastbound exit and westbound entrance
  124.970 201.120 125 Hanging Lake Eastbound exit and westbound entrance
  Hanging Lake Tunnel
  128.314 206.501 129 Bair Ranch Road
Eagle   133.384 214.661 133 Dotsero
  139.533 224.557 140 US 6 east – Gypsum East end of US 6 overlap
Eagle 146.648 236.007 147 Eagle
  156.547 251.938 157 SH 131 north – Wolcott, Steamboat Springs
  162.782 261.972 163 I‑70 Bus. south – Edwards
  166.635 268.173 167 Avon
Avon 168.157 270.622 168 William J. Post Boulevard
  168.758 271.590 169 US 6 – Eagle-Vail Westbound exit and eastbound entrance
  171.105 275.367 171 US 6 west / US 24 east – Minturn, Leadville West end of US 6 overlap
Vail 173.319 278.930 173 West Vail
175.872 283.039 176 Vail Ski Area – Vail Museum
179.866 289.466 180 East Vail
Summit   190.095 305.928 190 Vail Pass, Shrine Pass Road
  195.298 314.302 195 SH 91 south – Copper Mountain, Leadville
  198.254 319.059 198 Officers Gulch
Frisco 200.995 323.470 201 Main Street
202.352 325.654 203 SH 9 south – Frisco, Breckenridge West end of SH 9 overlap
Silverthorne 205.423 330.596 205 US 6 east / SH 9 north – Dillon, Silverthorne East end of US 6/SH 9 overlap
SummitClear Creek
county line
  Eisenhower Tunnel
Clear Creek   216.583 348.557 216 US 6 west – Loveland Pass West end of US 6 overlap
  218.346 351.394 218 (no name)
  221.297 356.143 221 Bakerville
Silver Plume 225.719 363.260 226 Silver Plume
Georgetown 227.910 366.786 228 Georgetown
  231.889 373.189 232 US 40 west – Empire, Granby West end of US 40 overlap
  233.047 375.053 233 Lawson Eastbound exit only
  234.209 376.923 234 Downieville, Lawson
  235.005 378.204 235 Dumont Westbound exit and eastbound entrance
  237.660 382.477 238 Fall River Road
Idaho Springs 238.885 384.448 239 I‑70 Bus. east – Idaho Springs
239.652 385.683 240 SH 103 south – Mount Evans
241.125 388.053 241 I‑70 Bus. west – Idaho Springs Signed as exit 241A (I-70 Bus.) and exit 241B (County Road 314) eastbound
  Twin Tunnel
  242.980 391.038 243 Hidden Valley, Central City
  244.260 393.098 244 US 6 east (US 40) – Golden East end of US 6 overlap; unsigned east end of US 40 overlap; no eastbound entrance
  246.602 396.867 247 Beaver Brook, Floyd Hill Eastbound exit
Jefferson   247.604 398.480 248 Beaver Brook, Floyd Hill Westbound exit
  250.769 403.574 251 SH 74 (Evergreen Parkway, US 40) – El Rancho Eastbound exit and westbound entrance
  251.318 404.457 252 SH 74 (Evergreen Parkway, US 40) Unsigned west end of US 40 overlap; westbound exit and eastbound entrance
  252.244 405.947 253 Chief Hosa
  253.528 408.014 254 US 40 east – Genesee Park East end of US 40 overlap
  255.974 411.950 256 Lookout Mountain
  258.722 416.373 259 US 40 / CR 93 – Golden, Morrison
Golden 259.803 418.112 260 SH 470 south – Colorado Springs
261.060 420.135 261 US 6 east (6th Avenue) Eastbound exit and westbound entrance
Lakewood 261.630 421.053 262 I‑70 Bus. (Colfax Avenue) / US 40 east Westbound also signed to US 6
262.571 422.567 263 Colorado Mills Parkway
Wheat Ridge 264.341 425.416 264 Youngfield Street, 32nd Avenue
265.343 427.028 265 SH 58 west – Golden, Central City Westbound exit and eastbound entrance
265.726 427.645 266 SH 72 (Ward Road)
267.402 430.342 267 SH 391 (Kipling Street)
Arvada 269.002 432.917 269A SH 121 (Wadsworth Boulevard)
269.242 433.303 269B Fort Morgan Eastbound left exit and westbound entrance
Wheat Ridge 270.000 434.523 270 Harlan Street Eastbound also signed as SH 95 (Sheridan Boulevard)
  270.496 435.321 271A SH 95 (Sheridan Boulevard) Westbound exit and eastbound entrance
City and County of Denver 271.549 437.016 271B Lowell Boulevard, Tennyson Street Westbound exit and eastbound entrance
272.005 437.750 272 US 287 (Federal Boulevard)
273.015 439.375 273 Pecos Street
274.062 441.060 274 I‑25 – Fort Collins, Colorado Springs West end of US 6 overlap, informally known as The Mousetrap
274.607 441.937 275A Washington Street Eastbound signed exit 274
275.200 442.891 275B SH 265 north (Brighton Boulevard)
275.550 443.455 275C York Street, Josephine Street Eastbound exit and westbound entrance
276.080 444.308 276A US 6 east / US 85 north (Vazquez Boulevard) East end of US 6/US 85 overlap
276.572 445.099 276B SH 2 (Colorado Boulevard)
277.024 445.827 277 Dahlia Street, Monaco Street, Holly Street
278.548 448.280 278 SH 35 (Quebec Street)
278.920 448.878 279A I‑270 / US 36 west – Boulder West end of US 36 overlap; eastbound entrance via SH 35
279.321 449.524 279B Central Park Boulevard New interchange in progress, will open in 2011[44]
280.567 451.529 280 Havana Street
281.560 453.127 281 Peoria Street Westbound exit splits from exit 282
282.550 454.720 282 I‑225 south – Aurora, Colorado Springs
Adams Aurora 283.532 456.301 283 Chambers Road
284.300 457.536 284 / Peña Boulevard – Denver International Airport Westbound exit via exit 285
284.627 458.063 285 Airport Boulevard
285.727 459.833 286 Tower Road
288.219 463.844 288 I‑70 Bus. west / US 40 west / US 287 north / Colfax Avenue West end of US 40/US 287 overlap
  289.028 465.145 289 E-470 – Fort Collins, Colorado Springs
  292.128 470.134 292 SH 36 east (Airpark Road)
Watkins 295.256 475.168 295 I‑70 Bus. north – Watkins
  299.328 481.722 299 Manila Road
  304.360 489.820 304 SH 79 north – Bennett
  305.370 491.445 305 Kiowa Eastbound exit only
Arapahoe   305.784 492.112 306 Kiowa, Bennett
  310.160 499.154 310 I‑70 Bus. north – Strasburg
  316.000 508.553 316 US 36 east – Byers East end of US 36 overlap
  322.086 518.347 322 Peoria
Deer Trail 328.329 528.394 328 I‑70 Bus. south – Deer Trail
Elbert   336.787 542.006 336 Lowland
  340.354 547.747 340 I‑70 Bus. west – Agate
  348.798 561.336 348 Cedar Point
  352.340 567.036 352 SH 86 west – Kiowa
  354.537 570.572 354 (no name)
Lincoln Limon 359.499 578.558 359 I‑70 Bus. east / US 24 west / SH 71 south – Limon, Colorado Springs
361.150 581.215 361 Limon
  363.025 584.232 363 US 40 / US 287 – Hugo, Kit Carson West end of US 24 overlap; east end of US 40/US 287 overlap
  371.482 597.842 371 Genoa, Hugo
  376.520 605.950 376 Bovina
  383.496 617.177 383 Arriba
Kit Carson   394.564 634.989 395 Flagler
  404.065 650.280 405 US 24 east / SH 59 north – Seibert East end of US 24 overlap
  411.961 662.987 412 Vona
  419.311 674.816 419 SH 57 – Stratton
  428.824 690.125 429 Bethune
Burlington 436.788 702.942 437 US 385 (Lincoln Street)
438.225 705.255 438 US 24 (Rose Avenue) West end of US 24 overlap
  449.589 723.543 I‑70 east / US-24 east Continuation into Kansas
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

Exit list

One accident at the Mousetrap, a complex interchange, had national ramifications. On August 1, 1984, a truck carrying six torpedoes for the U.S. Navy overturned. The situation was made worse as no one answered at the phone number provided with the cargo, and an unknown liquid was leaking from one of the torpedoes. It took more than three hours before any military personnel arrived on the scene, U.S. Army personnel from a nearby base. The incident left thousands of cars stranded and Denver's transportation network paralyzed for about eight hours. Approximately 50 residents in the area were evacuated.[38][39] Investigations later revealed that the truck driver did not follow a recommended route provided by officers, and was specifically warned to avoid the Mousetrap.[38] The Navy promised reforms after being criticized for providing an unstaffed phone number with a hazardous cargo shipment, a violation of federal law, and failing to notify Denver officials about the shipment.[40][41] The Mousetrap was grandfathered into the Interstate Highway system, with some structures built in 1951.[4] The incident provided momentum to rebuild the interchange with a more modern and safer design. Construction begin in several phases in 1987 and the last bridge was dedicated in 2003.[42]

The freeway is credited with enhancing Colorado's ski industry. The ski resort town of Vail did not exist until I-70 began construction, with developers working in close partnership with the Department of Transportation.[21] By 1984, the I-70 corridor between Denver and Grand Junction contained the largest concentration of ski resorts in the United States. The towns and cities along the corridor have experienced significant growth, luring recreational visitors from the Denver area. As one conservationist lamented, I-70 "changed rural Colorado into non-rural Colorado".[21]

Interstate 70 through the Colorado Plateau

When first approved, the extension of I-70 from Denver to Cove Fort was criticized in some area newspapers as a road to nowhere;[37] an information liaison specialist with the U.S. Department of Transportation in Baltimore, Maryland—the eastern terminus of I-70—claims people have asked "did we think Baltimoreans were so desperate to get to Cove Fort that we were willing to pay $4 billion to get them there?"[12] However, a resident engineer with the USDOT has called the extension one of the "crown jewels" of the Interstate Highway System.[8] In Colorado, the freeway helped unite the state, despite the two halves being separated by the formidable Rocky Mountains. The Eisenhower Tunnel alone is credited with saving up to an hour from the drive across the state.[21] Prior to I-70's construction, the highway through Glenwood Canyon was one of the most dangerous in the state. With the improvements, the accident rate has dropped 40% even though traffic through the canyon has substantially increased.[8] The Colorado Department of Transportation is considering the nomination of various portions of I-70 as a National Historic Landmark, even though the freeway will not qualify as historical for several decades.[21]


[36].Breezewood, Pennsylvania and a section of I-70 in [35],central New Jersey in Interstate 95 of a section However, as of 2009, at least two sections of the original Interstate Highway System have not been constructed: [8][6] At the dedication it was claimed that I-70 through Glenwood Canyon was the final piece of the Interstate Highway System to open to traffic. For this reason, the system was proclaimed to be complete.[34].American Society of Civil Engineers including the 1993 Outstanding Civil Engineering Achievement Award from the [8],Colorado Department of Transportation The construction of I-70 through Glenwood Canyon earned 30 awards for the [33] This figure exceeded that of [21] The cost was $490 million (equivalent to $800 million today) to build 12 miles (19 km), 40 times the average cost per mile predicted by the planners of the Interstate Highway system.

The freeway was finally completed on October 14, 1992, in a ceremony covered nationwide.[30][31] Most coverage celebrated the engineering achievement or noted this was the last major piece of the Interstate Highway System to open to traffic. However, newspapers in western Colorado celebrated the end of the frustrating traffic delays. For most of the final 10 years of construction, only a single lane of traffic that reversed direction every 30 minutes remained open in the canyon. One newspaper proudly proclaimed "You heard right. For the first time in more than 10 years, construction delays along that 12-mile (19 km) stretch of Interstate 70 will be non-existent."[32]

Diagram showing the former profile of a canyon wall with a new profile showing re-graded slopes, re-graded riverbank, medians and a two-tiered highway. The tops of the highway cantilever over the retaining wall, to hide the infrastructure below.
Department of Transportation drawing showing how re-using the existing footprint of US 6 combined with elevating two lanes helped minimize the environmental impact of the freeway on Glenwood Canyon

With the Eisenhower Tunnel finished, the last remaining obstacle for I-70 to be an interstate commercial artery was the two lane, non-freeway portion in Glenwood Canyon. Construction had started on this section in the 1960s with a small section opening to traffic in 1966.[4] The remainder was stopped due to environmentalist protests that caused a 30-year controversy.[12] The original design was criticized as "the epitome of environmental insensitivity". Engineers scrapped the original plans and started work on a new design that would minimize additional environmental impacts.[27] A new design was underway by 1971, which was approved in 1975; however, environmental groups filed lawsuits to stop construction, and the controversy continued even when construction finally resumed in 1981.[21] The final design included 40 bridges and viaducts, three additional tunnel bores (two were completed before construction was stopped in the 1960s) and 15 miles (24 km) of retaining walls for a stretch of freeway 12 miles (19 km) long.[6] The project was further complicated by the need to build the four-lane freeway without disturbing the operations of the railroad. This required using special and coordinated blasting techniques.[28] Engineers designed two separate tracks for the highway, one elevated above the other, to minimize the footprint in the canyon.[8] The final design was praised for its environmental sensitivity. A Denver architect who helped design the freeway proclaimed, "Most of the people in western Colorado see it as having preserved the canyon." He further stated, "I think pieces of the highway elevate to the standard of public art."[27] A portion of the project included shoring up the banks of the Colorado River to repair damage and remove flow restrictions created in the initial construction of US 6 in the 1930s.[29]

Glenwood Canyon has served as the primary transportation artery through the Rocky Mountains, even before the creation of U.S. highways. Railroads have used the canyon since 1887 and a dirt road was built through the canyon in the early 20th century.[8] The first paved road was built from 1936 to 1938 at a cost of $1.5 million (equivalent to $25 million today).[21]

A two tiered highway snaking around bends in a canyon, with some fall foliage visible
I-70 in Glenwood Canyon as seen from the California Zephyr

Glenwood Canyon

While designing the Eisenhower Tunnel, controversies erupted over how to build the portions over Vail Pass and Glenwood Canyon. The route of US 6 over Vail Pass has a distinctive "V" shape. Initially engineers thought they could shorten the route of I-70 by about 10 miles (16 km) by tunneling from Gore Creek to South Willow Creek, an alternative known as the Red Buffalo Tunnel.[21] This alternative sparked a nationwide controversy as it would require an easement across federally protected lands, through what is now called the Eagles Nest Wilderness. After the U.S. Secretary of Agriculture refused to grant the easement, the engineers agreed to follow the existing route across Vail Pass. The engineers added infrastructure to accommodate wildlife, and had significant portions of the viaducts constructed offsite and lifted in place to minimize the environmental footprint.[21]

Vail Pass

The tunnel construction became unintentionally involved in the women's rights movement when Janet Bonnema was given a position in the construction of the Straight Creek Tunnel project. After 18 months on the job, however, she had still not entered the tunnel. There was opposition to a woman entering the construction site; one supervisor stated that if she entered, "Those workers would flat walk out of that there tunnel and they'd never come back". Emboldened by the passage of an equal rights law in Colorado, she finally entered the tunnel on November 9, 1972. Several workers did walk off the job, but most returned the next day.[12]

A parking lot with a view of several snow-capped mountains
Rest Area along Interstate 70 at the top of Vail Pass

Construction on the first bore of the tunnel was started on March 15, 1968.[13] Construction efforts suffered many setbacks and the project went well over time and budget. One of the biggest setbacks was the discovery of fault lines in the path of the tunnel that were not discovered during the pilot bores.[25] These faults began to slip during construction and emergency measures had to be taken to protect the tunnels and workers from cave-ins and collapses.[21] A total of nine workers were killed during the construction of both bores. Further complicating construction was that the boring machines could not work as fast as expected at such high altitudes, and the productivity was significantly less than planned. The frustration prompted one engineer to comment, "We were going by the book, but the damned mountain couldn't read".[25] The first bore was dedicated March 8, 1973. Initially this tunnel was used for two-way traffic, with one lane for each direction. The amount of traffic through the tunnel exceeded predictions, and efforts soon began to expedite construction on the second tube (the Johnson bore), which was finished on December 21, 1979.[13] The initial engineering cost estimate for the Eisenhower bore was $42 million; the actual cost was $108 million (equivalent to $574 million today). Approximately 90% of the funds were paid by the federal government, with the state of Colorado paying the rest. At the time, this figure set a record for the most expensive federally aided project. The excavation cost for the Johnson bore was $102.8 million (equivalent to $334 million today).[25][26]

Planning on how to route the freeway over the Rocky Mountains began in the early 1960s. The US 6 corridor crosses two passes: Loveland Pass, at an elevation of 11,992 feet (3,655 m) and Vail Pass, at 10,666 feet (3,251 m).[2] Engineers recommended tunneling under Loveland Pass to bypass the steep grades and hairpin curves required to navigate US 6. The project was originally called the Straight Creek Tunnel, after the waterway that runs along the western approach. The tunnel was later renamed the Eisenhower–Johnson Memorial Tunnel, after U.S. President Dwight D. Eisenhower and Colorado Governor Edwin C. Johnson.[13]

Eisenhower Tunnel

The first Colorado portion of I-70 opened to traffic in 1961. This section bypassed and linked Idaho Springs to the junction where US 6 currently separates from I-70 west of the city. The majority of the alignment through Denver was completed by 1964. The Mousetrap reused some structures that were built in 1951, before the formation of the Interstate Highway system. The last piece east of Denver opened to traffic in 1977.[4]

Several mountains with scars from roads visible at the base and up the sides
View from Loveland Pass, showing a hairpin turn along the US 6 alignment on top right, and the straighter I-70 emerging from the Eisenhower Tunnel on the left


Congress approved the extension of I-70; however, the route still had to be approved by the representatives of the U.S. military on the planning committee. Military representatives were concerned that plans for this new highway network did not have a direct connection from the central U.S. to southern California; and further felt Salt Lake City was adequately connected. Military planners approved the extension, but moved the western terminus south to Cove Fort, using I-70 as part of a link between Denver with Los Angeles instead of Salt Lake City. Utah officials objected to the modification, complaining they were being asked to build a long and expensive freeway that would serve no populated areas of the state. After being told this was the only way the military would approve the extension, Utah officials agreed to build the freeway along the approved route.[12]

Beavertail Mountain tunnel as seen from the Amtrak California Zephyr

Colorado held several meetings to convince reluctant Utah officials they would benefit from a freeway link between Denver and Salt Lake City. Utah officials expressed concerns that, given the terrain between these cities, this link would be difficult to build. They later expressed concerns that the construction would drain resources from completing Interstate Highways they deemed to have a higher priority. Colorado officials persisted, presenting three alternatives to route I-70 west of Denver, using the corridors of US 40, US 6 and a route starting at Pueblo, proceeding west along US 50/US 285/US 24. In March 1955, Colorado officials succeeded in convincing Utah officials with the state legislature passing a resolution supporting a link with Denver. The two states jointly issued a proposal to the U.S. Congress that would extend the plans for I-70 along the US 6 corridor. Under this proposal the freeway would terminate at I-15 near Spanish Fork, Utah, linking the Front Range and Wasatch Front metropolitan areas.[12]

You are going to have a four-lane highway through Wyoming. You are going to build two four-lane highways through New Mexico and Arizona. Colorado needs to be able to compete with our neighboring states. We do not want to take anything away from them. We do not want them to get way out ahead of us, either, because these interstate highways are going to be very attractive highways for the East and West to travel on.[12]

Governor Edwin C. Johnson, for whom one of the tunnels along I-70 was later named, was a primary force in persuading the planners of the Interstate Highway System to extend the highway across the state. He stated to the Senate subcommittee:

A sharp curve with a cut in the mountain visible to support the highway
Interstate 70 descending into Clear Creek Canyon

Interstate Highway planning

While US 6 was also one of the original 1926 U.S. Highways, the road originally served the portion of the United States east of the Rocky Mountains. The highway was not extended to the Pacific coast until 1937, mostly following the Midland Trail.[23] Around the time the U.S. Highway system was formed, the portion of the Midland Trail through Glenwood Canyon, known as the Taylor State Road, was destroyed by a flood.[21] When US 6 was extended, the Works Progress Administration was rebuilding the road through the canyon and the Public Works Administration was nearing completion of a new highway over Vail Pass.[12][21] In western Colorado, US 6 was routed concurrent with US 50 from the Utah state line to Grand Junction and eventually replaced US 24 from Grand Junction to near Vail.[24] To keep these routes over the Rockies competitive with alternatives in other states, the Colorado Department of Highways relied on ingenuity to keep the roads safe. The department pioneered new machines to clear snow and various bridge and culvert designs to protect the roads from flooding.[21]

After losing the connection to the Lincoln Highway, officials convinced planners of the Victory Highway to traverse the state. The highway entered Colorado from Kansas along what was previously called the Smoky Hill Trail. The highway crossed the mountains along a trail blazed by a railroad surveyor and captain in the American Civil War, cresting at Berthoud Pass.[21] After a round of political infighting between Utah and Nevada, the Victory Highway would become the Lincoln Highway's main rival for San Francisco-bound traffic.[22] When the U.S. Highway system was unveiled in 1926, the Victory Highway was numbered U.S. Highway 40.[21]

A highway about to curve to the right while descending down a canyon
I-70 crossing the Rocky Mountains

Before the formation of the auto trail system. The surveyors of most trails chose either South Pass in Wyoming or a southern route through New Mexico to traverse the Rocky Mountains. Both options were less formidable than the higher mountain passes in Colorado, but left the state without a transcontinental artery. When the planners of the Lincoln Highway also decided to cross the Rockies in Wyoming, officials pressed for a loop to branch from the main route in Nebraska, enter Colorado, and return to the main route in Wyoming. While the Lincoln Highway was briefly routed this way, the loop proved impractical and was soon removed.[21]

Earlier routes

As first proposed in 1944, the western terminus of I-70 was Denver, along the corridor of US 40. The portion across the Rocky Mountains was added to the plans, after lobbying by Colorado officials, following the US 6 corridor.[12] The origins of both the US 40 and US 6 pre-date the U.S. System of numbered highways, using established transcontinental trails.[21]


Leaving Denver, the highway serves the redevelopment areas on the former site of Stapleton International Airport; runway 17R/35L crossed over the Interstate at the runway's midsection.[2] East of Aurora, I-70 rejoins the alignment of U.S. Highway 40 at Colfax Avenue. The freeway proceeds east across the Great Plains, briefly dipping south to serve the city of Limon, which bills itself as Hub City because of the many rail and road arteries that intersect there.[19] I-70 enters Kansas near Burlington, a small community known for having one of the oldest carousels in the United States.[20]

I-70 has one official branch in Colorado, Interstate 270, which connects the interstate with the Denver–Boulder Turnpike. Where these two freeways merge is the busiest portion of I-70 in the state, with an annual average daily traffic of 183,000 vehicles per day.[17] While State Highway 470 and E-470 are not officially branches of I-70, they are remnants of plans for an Interstate 470 beltway around Denver that were cancelled when the allocated funds were spent elsewhere.[18]

A city view with a pair of steel arch bridges in the foreground and various skyscrapers in the background.
Downtown Denver

As the freeway passes from the Rocky Mountains to the Great Plains, I-70 enters the Denver metropolitan area, part of a larger urban area called the Front Range Urban Corridor. The freeway arcs around the northern edge of the LoDo district, the common name of the lower downtown area of Denver. Through the downtown area, US 40 is routed along Colfax Avenue, which served as the primary east–west artery through the Denver area before the construction of I-70. Through downtown, US 6 is routed along 6th Avenue before departing the I-70 corridor to join Interstate 76 on a northeast course toward Nebraska.[2] The freeway meets Interstate 25 in an interchange frequently called the Mousetrap.[4]

Great Plains

The last geographic feature of the Rocky Mountains traversed before the highway reaches the Great Plains is the Dakota Hogback. The path through the hogback features a massive cut that exposes various layers of rock millions of years old. The site includes a nature study area for visitors.[4][16]

A highway near the top of a ridge. On either side of the highway are big yellow signs reading,
Warning sign stating, "Trucks, Don't be Fooled—4 more miles of steep grades and sharp curves."

The freeway follows Genesee Park to descend into Mount Vernon Canyon to exit the Rocky Mountains.[2] This portion features grade-warning signs with unusual phrasings, such as "Trucks: Don't be fooled," "Truckers, you are not down yet," and "Are your brakes adjusted and cool?"[15] Runaway truck ramps are a prominent feature along this portion of I-70,[4] with a total of seven used along the descent of either side the Continental Divide to stop trucks with failed brakes.[1]

Clear Creek

The highway descends to Dillon Reservoir, near the town of Frisco, and begins one final ascent to the Eisenhower Tunnel, where the freeway crosses the Continental Divide. At the time of dedication, this tunnel was the highest vehicular tunnel in the world, at 11,158 feet (3,401 m).[13] As of 2010, it is still the highest vehicular tunnel in the United States;[6] but there are now higher tunnels elsewhere, such as the Fenghuoshan Tunnel in China.[14] The Eisenhower Tunnel is noted as both the longest mountain tunnel and highest point on the Interstate Highway System.[13] The tunnel has a command center, staffed with 52 full-time employees, to monitor traffic, remove stranded vehicles, and maintain generators to keep the tunnel's lighting and ventilation systems running in the event of a power failure. Signals are placed at each entrance and at various points inside the tunnel to close lanes or stop traffic in an emergency.[13] There are several active and former ski resorts in the vicinity of the tunnel, including Breckenridge Ski Resort, Keystone Resort, Arapahoe Basin, Loveland Ski Area, Berthoud Pass Ski Area and Winter Park Resort.[2]

The construction of the freeway over Vail Pass is also listed as an engineering marvel. One of the challenges of this portion is the management of the wildlife that roams this area. Several parts of the approach to the pass feature large fences that prevent wildlife from crossing the freeway and direct the animals to one of several underpasses. At least one underpass is located along a natural migratory path and has been landscaped to encourage deer to cross.[1][12]

Automobiles are driving on a road leading to one of two openings in a building against a mountain. Letters above each opening read
Entrance to the Eisenhower Tunnel

The highway departs the Colorado River near Moffat Tunnel route.[10] I-70 uses a separate route between the two rail corridors. From this junction I-70 follows the Eagle River toward Vail Pass, at an elevation of 10,666 feet (3,251 m). In this canyon I-70 reaches the western terminus of U.S. Highway 24, which meanders through the Rockies before rejoining I-70. US 24 is known as the Highway of the Fourteeners, from the concentration of mountains exceeding 14,000 feet (4,300 m) along the highway corridor.[11] Along the ascent, I-70 serves the ski resort town of Vail and the ski areas of Beaver Creek Resort, Vail Ski Resort and Copper Mountain.[2]

Rocky Mountains

To minimize the hazards along this portion, a command center staffed with emergency response vehicles and tow trucks on standby monitors cameras along the tunnels and viaducts in the canyon. Traffic signals have been placed at strategic locations to stop traffic in the event of an accident, and variable message signs equipped with radar guns will automatically warn motorists exceeding the design speed of one of the curves.[8] The USDOT makes provision for bicycles, which are usually prohibited along Interstate Highways, along the freeway corridor in Glenwood Canyon.[9]

A pair of bridges leading to a pair of tunnels at the canyon wall
The western portal of the Hanging Lake Tunnel; at this point in the canyon both the river and railroad are directly below the freeway viaducts

[2]) occupies the south bank.Union Pacific (now part of Denver and Rio Grande Western Railroad Along this run, the freeway hugs the north bank of the Colorado River, while the main line of the former [7][5] over the Colorado River and the westbound lanes are suspended on a viaduct several feet above the canyon floor.cantilevered Through a significant portion of the canyon, the eastbound lanes extend [6], and miles of retaining walls.viaducts A 12-mile (19 km) section of roadway features the No Name Tunnel, Hanging Lake Tunnel, Reverse Curve Tunnel, 40 bridges and [5][4]

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