Interstate_70_in

In the U.S. state of Colorado, Interstate 70 is an Interstate Highway traversing an east-west route across the center of the state. The highway connects the metropolitan areas of Denver and Grand Junction via a route through the Rocky Mountains. The Colorado portion of I-70 is noted for the Eisenhower Tunnel. With an elevation of 11,158 feet (3,401 m) this tunnel was, at the time of construction, the highest vehicular tunnel in the world, and is the highest point along the Interstate Highway System. The Glenwood Canyon portion of the freeway is also noted as an engineering marvel. Completed on 1992-10-14, this was one of the last pieces of the Interstate Highway system to open to traffic. The construction achievement earned 30 awards for the Colorado Department of Transportation, including the 1993 Outstanding Civil Engineering Achievement Award from the American Society of Civil Engineers.

The Colorado portion of I-70 was built parallel to U.S. Highway 40 east of Idaho Springs, Colorado. West of Idaho Springs I-70 was built along the corridor of a road that was numbered U.S. Highway 6 at the time of I-70's construction.

Route description

Major cities Bolded cities are officially-designated control cities for signs²
Green River, Utah Grand Junction Glenwood Springs Vail Denver Aurora Limon Goodland, Kansas

Grand Valley

I-70 enters Colorado from Utah following at first Rabbit Valley and then Grand Valley. Both valleys are just south of the Book Cliffs and formed by the Colorado River or its tributaries. The freeway then serves Grand Junction the largest city along the Western Slope and the economic capital of western Colorado and eastern Utah.³ The freeway passes to the north of downtown.

Western Slope

The highway exits the Grand Valley and continues to use the Colorado River as its path up the Western Slope of the Rocky Mountains. The first canyon of the Colorado the freeway traverses is De Beque Canyon. While traversing the canyon, the freeway passes through the Beavertail Mountain Tunnel, the first pair of several tunnels used to aid I-70 over the Rockies.⁴

Rocky Mountains

The highway departs the Colorado River near the railroad junction of Dotsero and follows the Eagle River for its path towards Vail and Vail Pass at an elevation of 10,666 feet (3,251 m).⁷ The highway then proceeds down to Dillon Reservoir and one final push up Straight Creek to the Continental Divide through Eisenhower Tunnel, the highest automotive tunnel in the world.⁸ At 11,158 feet (3,401 m) this is the highest point along the Interstate Highway System and the longest tunnel built under the Interstate Highway program.⁹

The freeway uses Clear Creek for its path down the eastern side of the Rockies. Along the way, the highway passes through the Twin Tunnel near Idaho Springs. The last portion of the Rocky Mountains traversed as the highway enters Denver is frequently called the Hogback.

Front Range

I-70 then enters the Denver metropolitan area, also frequently called the Front Range. The Front Range is also refers to the last portion of the Rocky Mountains, and the beginning of the Great Plains. The freeway is routed to the north of the LoDo district, the common name of the downtown area of Denver. Here it meets Interstate 25 in an intersection frequently called the Mousetrap. The highway then passes by the former site of Stapleton International Airport and then proceeds east out of Denver.

Great Plains

East of Aurora I-70 joins the alignment of Colfax Avenue. This street serves as the main street of Denver, and is still the alignment of U.S. Highway 40 through downtown Denver. From this point east the freeway, now joined with US 40 proceeds due east across the Great Plains. The freeway dips south to serve the city of Limon then continues due east. The highway enters Kansas due east of Burlington.

History

Earlier routes

The path of I-70 in Colorado is derived from two previous highways, U.S. Highway 6 and U.S. Highway 40. US 40 was an original piece of the U.S. Highway system commissioned in 1926. The portion now numbered U.S. Highway 6 came about in 1937 when the route over Vail Pass was paved. A portion of this route was also numbered U.S. Highway 24 at the time.¹⁰

Interstate Highway planning

As first proposed the western terminus of I-70 was Denver, using the corridor of US 40 as the base for the new freeway.¹¹ Colorado governor Edwin C. Johnson was a primary force in persuading the planners of the Interstate Highway System to extend the highway to traverse the entire state. He stated to the senate subcommittee:

He was able to convince officials in Utah that they would benefit by having a direct freeway link between Denver and Salt Lake City. Once officials in Utah were convinced to support the extension to I-70, the plans were changed to link Denver with Los Angeles, California instead of Salt Lake.¹¹ One of the bores of the Eisenhower Tunnel is named in his honor.

There was some debate on which corridor would be used to extend the freeway to Utah. The proposals were to use the routes of US 40, which crests the Continental Divide via Berthoud Pass, or US 6 which crests at Loveland Pass. US 24, which crests via Tennessee Pass, was also briefly considered. It was decided that the US 6 corridor was the most practical of the alternatives.¹¹

Eisenhower Tunnel

The decision was made to use the US 6 corridor. However US 6 traversed Loveland Pass at an elevation of 11,992 feet (3,655 m) and featured several hairpin turns to climb the summit.⁷ The decision was made to tunnel underneath the continental divide. The project was originally called the Straight Creek Tunnel, after the waterway that runs along the western approach, but was later renamed the Eisenhower-Johnson Memorial Tunnel, after U.S. President Dwight D. Eisenhower and Colorado Governor Edwin C. Johnson.⁹

Construction on the first bore of the tunnel was started on March 15, 1968.⁹ Construction efforts suffered many setbacks and the project went well over time and budget. The frustration prompted one engineer to comment, "We were going by the book, but the damned mountain couldn't read".⁹ 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.⁹ Though the project was supposed to take 3 years, the tunnel was not opened to traffic until March 8, 1973. Initially this tunnel (the Eisenhower bore) was used for 2 way traffic with one lane for each direction. The amount of traffic through the tunnel exceeded predictions and efforts soon begin to expedite construction on the second tube (the Johnson bore). Construction began on the eastbound tunnel on August 18, 1975 and finished on December 21, 1979.⁹

The tunnel construction became unintentionally involved in the Women's Liberation Movement when Janet Bonnema applied for work with the Colorado Department of Transportation. She was given a position in the construction of the Straight Creek tunnels project. However, after 18 months on the job she had still not entered the tunnel, instead doing support work from the office. There was opposition to a woman entering the construction site with one supervisor stating if she entered, "Those workers would flat walk out of that there tunnel and they'd never come back".¹¹ 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. She remained determined, and returned to work the next day. She even worked on the roof of the tunnel overlooking the men below.¹¹

Glenwood Canyon

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. A primitive dirt road was built through the canyon in the early 1900s.¹²

With the Eisenhower Tunnel's Edwin C. Johnson (eastbound) bore open for traffic, 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 but was stopped due to environmentalist protests that caused a 30-year controversy.¹¹ The final design attempted to minimize environmental impacts and involved 40 bridges and viaducts, three tunnels (not counting two that were built before construction was stopped in the 1960s) and 15 miles (24 km) of retaining wall.¹³⁸ The decision was made to build two runs for the highway, one elevated above the other.¹² The freeway was finally completed on October 14, 1992. With a cost of $490 million (1992, $737 million in 2007) to build 12 miles (19 km) this was one of the most expensive roads per mile to build in the Interstate System. The construction of I-70 through Glenwood Canyon earned 30 awards for the Colorado Department of Transportation, including the 1993 Outstanding Civil Engineering Achievement Award from the American Society of Civil Engineers.¹⁴ Many people consider I-70 through Glenwood Canyon to be the last piece of the Interstate Highway System to open,⁸¹² although gaps still exist on Interstate 95¹⁵ and at Breezewood, Pennsylvania.¹⁶

Modern impacts

I-70 through Colorado is regarded as one of the most technologically advanced highways in the U.S. To manage the numerous hazards in Glenwood Canyon the freeway features the first of its kind traffic monitoring system.¹² This includes a traffic monitoring system, control center, and variable message signs to warn of hazards. The center also has round the clock monitoring and officers on-call to remove stranded vehicles.¹²

Exit list

County	Location⁴	Mile¹	#	Destinations	Notes
Mesa		1.814	2	Rabbit Valley
	11.108	11	US 6 east / US 50 east – Mack	East end of US 6/US 50 overlap
	15.056	15	SH 139 north – Loma, Rangely
Fruita	19.426	19	SH 340 to US 6 – Fruita	Serves Colorado National Monument
Grand Junction	25.469	26	I-70 Bus. east / US 6 / US 50 / 22 Road – Grand Junction
27.451	28	24 Road; Redlands Parkway
31.191	31	Horizon Drive – Walker Field Airport
	36.471	37	I-70 Bus. west – Clifton, Delta, Grand Junction, Montrose
	41.413	42	To US 6 – Palisade
	43.527	44	US 6 west – Palisade	Westbound exit and eastbound entrance; west end of US 6 overlap; signed as I-70 Bus. west
	45.002	46	Cameo
	46.528	47	Colorado River State Park, Island Acres
	48.566	49	SH 65 south to SH 330 east – Grand Mesa, Collbran
	61.508	62	De Beque
Garfield	Parachute	74.441	15	Parachute, Battlement Mesa
	81.080	81	Rulison
	86.663	87	US 6 – Rifle	East end of US 6 overlap
Rifle	90.234	90	SH 13 north – Rifle, Meeker
	93.883	94	Garfield County Airport Road
	97.317	97	I-70 Bus. north – Silt
	105.136	105	New Castle
	108.866	109	US 6 west – Canyon Creek	West end of US 6 overlap
	111.184	111	South Canyon
Glenwood Springs	114.129	114	West Glenwood
116.184	116	SH 6 west / SH 82 east – Glenwood Springs, Aspen
	118.480	119	No Name
		121	Grizzly Creek – Hanging Lake
		123	Shoshone	Eastbound exit and westbound entrance
		125	Hanging Lake	Eastbound exit and westbound entrance
Hanging Lake Tunnel
		129	Bair Ranch
Eagle		134.126	133	Dotsero
	140.236	140	US 6 east – Gypsum	East end of US 6 overlap
Eagle	147.240	147	I-70 Bus. south – Eagle County Regional Airport
	157.139	157	SH 131 north – Wolcott, Steamboat Springs
	163.301	163	I-70 Bus. south – Edwards
	167.125	167	I-70 Bus. south – Avon
	168.702	168	William J. Post Boulevard
	169.249	169	US 6 – Eagle, Vail	Westbound exit and eastbound entrance
	171.720	171	US 6 west / US 24 east – Minturn, Leadville	West end of US 6 overlap
	173.787	173	Vail
Vail	176.469	176	Vail
	180.285	180	Vail
Summit		190.634	190	Shrine Pass Road
	195.870	195	SH 91 south – Copper Mountain, Leadville
	198.254	198	Officers Gulch
Frisco	201.370	201	Main Street – Frisco, Breckenridge
	202.730	203	SH 9 south – Frisco, Breckenridge	West end of SH 9 overlap
Silverthorne, Colorado	205.816	205	US 6 east / SH 9 north – Dillon, Silverthorne	East end of US 6/SH 9 overlap
Eisenhower Tunnel
Clear Creek		216.583	216	US 6 west – Loveland Pass	West end of US 6 overlap
	218.737	218	Herman Gulch Road
	221.676	221	Bakerville
Silver Plume	226.012	226	Silver Plume
Georgetown	228.347	228	Georgetown
	232.287	232	US 40 west – Empire, Granby	West end of US 40 overlap
	233.419	233	Lawson	Eastbound exit only
	234.589	234	Downieville, Lawson, Dumont
	235.378	235	Dumont	Westbound exit and eastbound entrance
	238.015	238	Fall River Road
Idaho Springs	239.237	239	I-70 Bus. east – Idaho Springs
240.003	240	SH 103 – Mount Evans
241.455	241A	I-70 Bus. west – Idaho Springs
241B	County Road 314	Eastbound access is via exit 241A
	243.315	243	Hidden Valley, Central City
	244.595	244	US 6 east to US 40 east / SH 119 – Golden, Black Hawk	East end of US 6/US 40 overlap; left exit eastbound; no eastbound entrance
	246.855	247	Beaver Brook, Floyd Hill	Eastbound exit and westbound entrance
Jefferson		248.048	248	Beaver Brook, Floyd Hill	Westbound exit and eastbound entrance
	251.213	251	US 40 west (Evergreen Parkway) / SH 74 south – El Rancho	Eastbound exit and westbound entrance
	251.762	252	US 40 west (Evergreen Parkway) / SH 74 south	West end of US 40 overlap; westbound exit and eastbound entrance
	252.688	253	Chief Holsa
	253.972	254	US 40 east – Genesee Park	East end of US 40 overlap
	256.404	256	Lookout Mountain
	259.113	259	To US 40 east – Golden, Morrison
Golden	260.237		SH 470 east – Colorado Springs	Signed as exit 260 westbound
260.277		SH 470 west – Colorado Springs	Eastbound exit and westbound entrance
261.443	261	US 6 east (West Sixth Avenue)	Eastbound exit and westbound entrance
Lakewood	262.039	262	I-70 Bus. east (Colfax Avenue) / US 40 west to US 6
262.923	263	Colorado Mills Parkway – Denver West
Wheat Ridge	264.724	264	Youngfield Street; West 32nd Avenue
265.692	265	SH 58 west – Golden, Central City	Westbound exit and eastbound entrance
266.076	266	Ward Road, West 44th Avenue (SH 72)
267.644	267	Kipling Street (SH 391)
Arvada	267.270	269A	Wadsworth Boulevard (SH 121)
269.505	269B	I-76 east – Fort Morgan	Eastbound left exit and westbound entrance
Wheat Ridge	270.312	270	Harlan Street, Sheridan Boulevard (SH 95)
Denver	270.807	271A	Sheridan Boulevard (SH 95)	Westbound exit and eastbound entrance
271.855	271B	Lowell Boulevard, Tennyson Street	Westbound exit and eastbound entrance
272.364	272	Federal Boulevard (US 287)
273.348	273	Pecos Street
274.337	274	I-25 / US 6 west / US 85 south / US 87 – Fort Collins, Colorado Springs	West end of US 6/US 85 overlap
274.826	275A	Washington Street	Eastbound exit is part of exit 274
275.320	275B	Brighton Boulevard (SH 265)
275.704	275C	York Street, Josephine Street	Eastbound exit and westbound entrance
	276A	Vazquez Boulevard, Steele Street (US 6 east / US 85 north)	East end of US 6/US 85 overlap
276.525	276B	SH 2 east to US 6 north / US 85 / Colorado Boulevard
277.033 278.050	277	Dahlia Street, Holly Street, Monaco Street
278.560	278	Quebec Street (SH 35)
279.292	279	I-270 west / US 36 west – Fort Collins	West end of US 36 overlap; westbound exit and eastbound entrance
280.566	280	Havana Street
281.538	281	Peoria Street	Westbound exit splits from exit 282
Adams	Aurora	282.591	282	I-225 south – Aurora, Colorado Springs
283.561	283	Chambers Road
283.76	284	Peña Boulevard – Denver International Airport	Eastbound exit and westbound entrance
284.664	285	Airport Boulevard
285.765	286	Tower Road
288.346	288	I-70 Bus. west / US 40 west / US 287 north / Colfax Avenue	West end of US 40/US 287 overlap; no westbound entrance; left exit westbound
289.141	289	E-470 – Fort Collins, Colorado Springs, Denver International Airport
292.062	292	Airpark Road (SH 36 east)
Watkins	295.332	295	I-70 Bus. north – Watkins
	299.459	299	Manila Road
	304.453	304	SH 79 north – Bennett
	305.456	305	Kiowa	Eastbound exit only
Arapahoe		305.869	306	SH 36 – Kiowa
	310.224	310	I-70 Bus. north – Strasburg
	315.930	316	US 36 east / SH 36 west – Byers	East end of US 36 overlap
	322.078	322	Peoria
	328.292	328	I-70 Bus. south – Deer Trail
Elbert		336.700	336	Lowland
	340.248	340	I-70 Bus. south – Agate
	348.675	348	Cedar Point
	352.436	352	SH 86 west – Kiowa
	354.627	354	River Bend
Lincoln	Limon	359.609	359	I-70 Bus. east to US 24 west / US 24 Spur east / US 40 south (SH 71) – Limon	East end of US 40/US 287 overlap
361.848	361	US 24 / US 40 / US 287 to - SH 71 - Limon
	363.112	363	I-70 Bus. west / US 24 west / US 40 / US 287 – Hugo, Kit Carson, Limon	West end of US 24 overlap
	371.513	371	SH 71 - Genoa, Hugo
	376.563	376	Bovina
	383.543	383	Arriba
Kit Carson		394.597	395	Flagler
	404.946	405	US 24 east / SH 59 north – Seibert	East end of US 24 overlap
	411.957	412	I-70 Bus. north – Vona
	419.378	419	SH 57 – Stratton
	428.899	429	Bethune
Burlington	436.881	437	I-70 Bus. east (Lincoln Street) / US 385
438.312	438	I-70 Bus. west (Rose Avenue) / US 24	West end of US 24 overlap