Texas State Highway Loop 1

State Highway Loop 1
MoPac Expressway
Loop 1 highlighted in red
Route information
Length	25.698 mi[1] (41.357 km)
Existed	1967–present
Major junctions
South end	SH 45
Major intersections	US 290 SH 71 US 183
North end	SH 45 Toll
Location
Country	United States
State	Texas
Counties	Travis, Williamson
Highway system
Highways in Texas Interstate US State Toll Loops Spurs FM/RM Park Rec
← SH 1 → FM 1

Loop 1 is a freeway which provides access to the west side of Austin in the U.S. state of Texas. It is named Mopac Expressway (or, according to some highway signs, Mopac Boulevard) after the Missouri Pacific Railroad (or "MoPac"). Local residents almost always use the name "MoPac" rather than calling the road by its number,^[2][3] which can cause much confusion, for few signs along the road use this name.^[4][5]

The original section of the highway was built in the 1970s along the right-of-way of the Missouri Pacific Railroad (now owned by Union Pacific), with the railroad tracks running in the highway median between West 8th Street and Northland Drive. To the north, the tracks run along the east side of newer sections of the highway from Northland Drive to Braker Lane.

The first mention of Loop 1 in public record was in 1929. In 1944, the City of Austin Planning Commission (CMAC) proposed that the highway be built in parts of the under-utilized right of way owned by the MoPac Railroad. Thus, the highway was eventually given the nickname "MoPac" for its proximity to the railroad. The current Loop 1 was designated on October 27, 1967, from US 290 northward to Farm to Market Road 1325 (FM 1325).^[6] On October 24, 1985, the designation was extended southward from US 290 to SH 45.^[1]

This table contains the dates of the construction of segments of the road.^[7][8][9]

From	To	Length (mi)	Length (km)	Project start	Project completion	Notes
RM 2244 (Bee Cave Road)	RM 2222 (Northland Road)	5.4	8.7	February 1969	November 1975	Loop 1 project started with construction of the 45th Street Interchange in February 1969.
RM 2222	US 183	4.6	7.4	September 1977	June 1981	Northern terminus of Loop 1 completed, until July 1989 - with construction of the freeway extension to FM 734.
RM 2244	Loop 360	1.9	3.1	January 1979	March 1982	Southern terminus of Loop 1 completed, until October 1989 - with construction of the freeway extension to US 290.
Loop 360	US 290	1.6	2.6	October 1983	October 1989	Southern terminus of Loop 1 completed, until November 1990 - with construction of the roadway extension to Slaughter Lane.
US 183	FM 1325 (Burnet Road) and FM 734 (Parmer Lane)	3.7	6.0	January 1986	July 1989	Northern terminus of Loop 1 completed, until October 2006 - with construction of the SH 45 North/ Loop 1 Connector toll road. Stack interchange at US 183 is constructed - involved major freeway improvements between Steck Avenue and US 183, from March 1987 to June 1992.
US 290	Slaughter Lane	3.6	5.8	January 1988	November 1990	Southern terminus of Loop 1 completed, until July 1991 - with construction of the roadway extension to La Crosse Avenue.
Slaughter Lane	La Crosse Avenue	1.0	1.6	July 1989	July 1991	Southern terminus of Loop 1 completed, until May 1994 - with construction of the roadway extension to State Highway 45 .
La Crosse Avenue	SH 45	2.5	4.0	November 1989	May 1994	Southern terminus of Loop 1 completed.
FM 734	SH 45 North/ Loop 1 Interchange	4.0	6.4	February 2003	October 2006	Construction on the SH 45 North Interchange began in September 2003. Northern terminus of Loop 1 completed.

Loop 1's southern terminus is at the beginning of the State Highway 45 stub south of Austin. It passes through the Circle C Ranch housing development and the Edwards Aquifer and intersects SH 71/US 290 (Ben White Boulevard) and Loop 360 (Capital of Texas Highway). It crosses the Colorado River near downtown Austin; the view of the Texas State Capitol from the bridge became one of the Capitol View Corridors protected under state and local law from obstruction by tall buildings in 1983.^[10] North of the river, the highway runs parallel to the Balcones Fault and the Missouri-Pacific Railroad (Union Pacific) before it intersects US 183 (Research Boulevard) northwest of downtown. Loop 1 travels concurrently with Farm to Market Road 1325 for several miles before the non-tolled freeway ends at Parmer Lane, spanning a distance of 22.061 miles (35.504 km).

Loop 1 is designated a scenic roadway by the City of Austin.^[11]

North of Parmer Lane, Loop 1 continues as a limited-access toll road to the SH 45 North/Loop 1 interchange, spanning 3 miles (4.8 km). Frontage roads flank either side of the toll road to Merrilltown Drive.

The Texas Department of Transportation completed construction of the tollway as part of the 2002 Central Texas Turnpike Project (CTTP). SH 45 North, also part of the project, provides freeway access to Interstate 35 from Loop 1. The 2002 CTTP was scheduled to be completed in September 2007. However, certain sections of the project, including Loop 1 opened early and more than $100 million under budget.

If and when SH 45 is completed to the south of Austin between FM 1626 and I-35, Loop 1 will effectively serve as a full western loop to the city, being directly connected to SH 45 (and indirectly to I-35) at both ends.

Loop 1 Express
Mopac Improvement Project
Location	Austin
Existed	2017–present

Since 1994, TxDOT has proposed the addition of managed lanes to portions of Loop 1. The MoPac Improvement Project^[12] was relaunched in July 2010 by the Central Texas Regional Mobility Authority (CTRMA). In December 2010, four alternative proposals were presented to the public, each of which would add one or more lanes; the "no-build" alternative was also presented. The additions would not increase the right-of-way of the highway, but would be created by reducing the width of existing lanes and reducing and/or eliminating shoulders. An environmental study was completed in August 2012 with a Finding Of No Significant Impact and a recommendation of one new travel lane in each direction, operated as express lanes.^[13] Construction began in 2013, and was originally scheduled for completion in September 2015, but by August 2016, the Central Texas Regional Mobility Authority announced further delays.^[14] The first of four tolled sections, specifically the northbound toll lane from RM 2222 to Parmer Lane, opened on October 17, 2016. The remainder of the northbound express lane, from Cesar Chavez Street to Parmer Lane, opened on October 7, 2017, and the entire southbound express lane opened on October 28, 2017.

In 2013, CTRMA and TxDOT initiated an environmental study to analyze the best options to improve the MoPac intersections at Slaughter Lane and La Crosse Avenue. In December 2015, the study was completed with a Finding Of No Significant Impact for the project, which allowed it to move forward.^[15] The selected design included replacing the at-grade intersection at Slaughter Lane with a diverging diamond interchange (DDI)^[16] and the at-grade intersection at La Crosse Avenue with a diamond interchange. The project broke ground in January 2018 with Webber, LLC as the general contractor.

On August 10, 2018, the at-grade Slaughter Lane intersection was rerouted to the south as construction began on an overpass bridge on the original alignment.^[17] The completed DDI opened to traffic on November 11, 2018, with final completion occurring in Spring 2019. The La Crosse Avenue intersection began construction in Fall 2018. On March 29, 2019, the La Crosse Avenue at-grade intersection was closed for reconstruction as a bridge.^[18] The La Crosse Avenue bridge and intersection opened to traffic on April 16, 2020. The full project, including surrounding sound walls and retention ponds, was officially completed on December 16, 2020.^[19][20]

In 2013, CTRMA and TxDOT initiated an environmental study of the MoPac corridor from Cesar Chavez Street to Slaughter Lane.^[21] The environmental study identified the Express Lane(s) Alternative as the Recommended Build Alternative.^[22] In October 2015, six proposals were presented to the public, each of which would add one of more express lanes; the "no-build" alternative was also presented.^[23] In February 2016, the project was put on hold by a Save Our Springs lawsuit claiming the project had not complied with the National Environmental Policy Act's requirements for environmental studies.^[24] The lawsuit was settled on July 18, 2018 with a ruling in favor of CTRMA by the 5th Circuit U.S. Court of Appeals.^[25] However, the project was further delayed by a state moratorium on toll projects receiving funding from State Propositions 1 and 7. TxDOT gave CTRMA preliminary approval to resume planning for MoPac South in August 2019.^[26] In November 2021, the project was officially revitalized with a virtual open house, and it is currently in public planning phases.

All exits are unnumbered.

County	Location	mi	km	Destinations	Notes
Travis	Austin	0.0	0.0	SH 45 west / SH 45 Toll east
		0.7	1.1	South Bay Lane	At-grade intersection; dead end both directions, turnaround only
		1.5	2.4	La Crosse Avenue
		2.3	3.7	Slaughter Lane	Diverging Diamond Interchange
		2.9	4.7	Davis Lane	Southbound exit and northbound entrance
		4.7	7.6	William Cannon Drive
		6.0	9.7	US 290 / SH 71 / Southwest Parkway – Johnson City, Llano, Sunset Valley	Access to Baylor Scott & White Medical Center – Austin
		6.6	10.6	Frontage Road	Southbound exit only
		7.5	12.1	Loop 360 (Capital of Texas Highway)	Only one exit ramp travels from southbound Loop 1 to southbound Loop 360; all others are at-grade
		8.9	14.3	Barton Skyway
		9.8	15.8	RM 2244 (Bee Caves Road) / Wallingwood Drive – Rollingwood, West Lake Hills
				Roberta Crenshaw Bridge over the Colorado River
				Loop 1 Express begins	South end of variable toll lanes
		10.5	16.9	Cesar Chavez Street / 5th Street / Lake Austin Boulevard
		11.2	18.0	Enfield Road
		11.7	18.8	Windsor Road
		12.3	19.8	Westover Road / Northwood Road
		12.9	20.8	35th Street – Camp Mabry	Access to Seton Shoal Creek Hospital
		13.8	22.2	45th Street
		14.8	23.8	RM 2222 (Northland Drive)
				Loop 1 Express	Access point for variable toll lanes
		15.9	25.6	Far West Boulevard
		16.6	26.7	Anderson Lane / Spicewood Springs Road	Direct northbound exit and southbound entrance (southbound exit signed at Steck Avenue)
		17.1	27.5	Steck Avenue	No direct northbound entrance
		17.3	27.8	(no name)	Northbound exit only; replaced by northbound collector distributor road underneath Steck Avenue[27]
		18.0	29.0	US 183 (Research Boulevard)	No direct southbound exit to US 183 north (signed at Capital of Texas Highway), access to Seton Northwest Hospital
		18.7	30.1	Capital of Texas Highway
		19.1	30.7	Braker Lane – Q2 Stadium	Direct southbound exit and northbound entrance (northbound exit signed at Capital of Texas Highway)
		20.5	33.0	FM 1325 south (Burnet Road) / Duval Road	South end of FM 1325 overlap, access to North Austin Medical Center
				Loop 1 Express ends	North end of variable toll lanes; despite being signed as such, no direct access to FM 734 (Parmer Lane) exists
		21.7	34.9	FM 734 (Parmer Lane)
		22.4	36.0	Scofield Ridge Parkway	Last free northbound exit before toll road begins; no direct southbound exit
		22.4	36.0	Loop 1 ends Loop 1 Toll begins	Northern terminus of Loop 1 (Mopac Expressway); southern terminus of Loop 1 Toll
		23.1	37.2	FM 1325 / Wells Branch Parkway / Howard Lane, Merrilltown Drive	Howard station
	​	24.0	38.6	Merrilltown Toll Plaza
Travis–Williamson county line	​	24.5	39.4	Shoreline Drive	No southbound exit
Williamson	​	25.6	41.2	SH 45 Toll
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Closed/former       Concurrency terminus       Incomplete access        Tolled       Route transition

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