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Texas Highways Primer

This page last updated May 5, 2015

Texas is a big place.  It's nearly 880 miles from the Louisiana border near Orange to the New Mexico border near El Paso, and nearly 500 miles from the Oklahoma border north of Dallas to the Mexican border in Laredo.  That size gives the state a tremendous amount of diversity.  A hot, humid sub-tropical climate in the Valley yields to a varying Midwest climate, complete with snow, in Amarillo.  There are Piney Woods in East Texas, desert in West Texas, and plains, prairies, and the Hill Country in between.  The state has some of the nation's biggest metropolitan areas and some of its most desolate ranges.  With this size and diversity, a large and rapidly growing population, a booming economy, an increasing role in international trade, and its overwhelming dependence on the automobile, Texas cannot help but have the nation's biggest, most well-developed highway system with nearly 80,000 miles of state-maintained roads.

This primer is designed to give you an overview of the state's highway system and its idiosyncrasies.  If you're looking for a route log, check out Texas Highway Routes by David Stanek, a complete listing of all highways in Texas.  Both Ron Jackson's TexasFreeway.com  and Andy Field's LoneStarRoads sites have lots of in-depth information on freeways and other highways statewide.

On this page:

Some Texas highway facts

Highways in Texas are managed by the Texas Department of Transportation (TxDOT).  TxDOT was created in 1991 from the former State Department of Highways and Public Transportation (SDHPT).  Here are some facts about the highway system in Texas:

Interstates 3,233
US Highways 12,105
State Highways 16,336
Farm-to-Market roads 40,939
Park roads 340
Frontage Roads 7,041
  • REST AREAS: 92
  • FIRST HIGHWAY: Started in 1918 and finished in 1920, between Falfurrias and Encino in Brooks County, along present day US 281.
  • FIRST INTERSTATE: 1956, I-45 (then US 75) near Corsicana in Navarro County
  • SHORTEST HIGHWAY: Loop 168 in Tenaha, Shelby County, is 391 feet (.074 miles)
  • LONGEST HIGHWAY: US 83 stretches 899 miles from the Oklahoma state line near Perryton to the Mexican border near Brownsville
  • HIGHEST HIGHWAY: A spur from Texas 118 at the McDonald Observatory on Mt. Locke in West Texas is 6,791 feet above sea level.
  • BUSIEST HIGHWAY: I-10/Katy Freeway in Houston just west of Beltway 8 carries 328,000 vehicles daily.
  • LONGEST BRIDGE: The Queen Isabella Causeway between Port Isabel and South Padre Island is 2.37 miles long.

State-maintained highways comprise about 26% of the total roadway mileage in Texas but carry about 73% of all traffic.


In addition to having the nation's largest highway system overall, Texas also has more Interstate mileage than any other state.  There are now 17 different Interstates in the state:

I-2 I-10 I-20 I-27 I-30 I-35 I-37 I-40 I-44 I-45 I-69
I-110 I-345 I-410 I-610 I-635 I-820

Texas has two of the three "forked" Interstates in the nation.  The first, I-35, is split into I-35E through Dallas and I-35W through Ft. Worth.  I-69 is split three ways: first, I-69 splits into I-69E and I69W at Victoria with I-69E running south to Brownsville along US 77 and I-69W continuing south to Laredo along US 59.  Then I-69C branches from I-69W at George West and runs along US 281 south to I-2 at Pharr

Texas also has two "hidden" or unsigned Interstates: I-345, which is a short extension of I-45 in downtown Dallas, and I-110, which connects I-10 to the Mexico border in El Paso.

Interstates in Texas were generally developed along existing US and State highways.  I-45 replaced US 75, I-35 replaced US 81, and I-40 replaced the famed US 66, to name a few.  In urban areas, many existing expressways were simply re-signed as Interstates.  The first Interstate contract let in Texas was for a segment of I-45 in Navarro County near Corsicana in 1956.   The latest addition to Texas' Interstate inventory is I-69.  (See the I-69 section below.)  Prior to that, the last Interstate to be completed was I-27 between Lubbock and Amarillo in 1992.

Of the inter-urban Interstates in Texas, I-35 between San Antonio and Dallas-Ft. Worth is the busiest.  Most of I-35 operates at or above its capacity.  Every traffic counter location between San Antonio and Hillsboro reported more than 50,000 vehicles per day in 2008.  As a result, traffic delays, especially during holiday periods, are common.  Besides increases in passenger vehicles, truck traffic on I-35 and other Interstates is growing rapidly, mainly as a result of the North American Free Trade Agreement (NAFTA) and the General Agreement on Tariffs and Trade (GATT).  TxDOT reports that Interstate traffic has increased every year since 1987.  Between 1996 and 1999, passenger vehicle traffic statewide increased 12% while truck traffic increased 19%, and between 1999 and 2011 truck traffic is predicted to grow 50-70%.  In fact, Texas has the highest volume of truck traffic in the nation. 

All of I-35 between San Antonio and Georgetown is now six lanes or more, and a bypass tollway (SH 130) from Georgetown to I-10 at Seguin was completed in 2012.  Work continues to upgrade I-35 to six lanes all the way north to Hillsboro.  TxDOT is also participating a $1.5 million federal study of I-35 from Laredo to Duluth, Minnesota, which aims to provide comprehensive improvements to the corridor.  (More information on the I-35 corridor between San Antonio and Austin is available as part my San Antonio roads pages.)

In addition to I-35, TxDOT has plans to widen the other two legs of the "Texas Triangle" (I-10 between Houston and San Antonio and I-45 between Houston and Dallas) to six lanes.

Exits, entrances, and the ubiquitous frontage roads
As you drive through Texas, you may notice that exits and entrances on many of our Interstates tend to be at more frequent intervals than in other states.  This is the result of the wishes of Dewitt Greer, a former long-time director of the state highway department.  It was his belief that, given the vastness of the state, Interstates should not just serve "interstate" traffic, but also "interregional" traffic within Texas, and more frequent exits would help facilitate that.

Another byproduct of this philosophy is perhaps the most unique feature of the state's highway system: frontage roads.  There are over 7,000 miles of these along freeways in Texas, which is more-- much more-- than any other state.  The reason for the widespread use of frontage roads in Texas again can be traced to Dewitt Greer.  He decided that it was cheaper to build frontage roads to keep access to adjacent properties than it was to purchase those access rights, which is required under state law.  This quickly became standard operating procedure at the Highway Department (and subsequently TxDOT) and nearly all of the state's freeways were built under this policy.  In June 2001, the Texas Transportation Commission considered a major policy change that would've rocked TxDOT and Texans in general to the core-- frontage roads would not be included in any new freeways unless absolutely necessary.  This was a fundamental change and caused quite a stir around the state-- enough of one that the Commission decided, after statewide hearings, to scrap the idea.

There are several ramp configurations used with frontage roads.  The "diamond" interchange is pretty standard, with the on- and off-ramps connecting to the frontage roads in the general shape of a diamond relative to the cross street (see illustration below).  Sometimes, especially in urban areas, the ramps are reversed in an "X"-interchange with the exit ramp for the next cross street preceding the entrance ramp from the previous cross street.  This provides better access to and from frontage properties between the intersecting roads and helps reduce through traffic loads on the frontage roads at intersections.  Occasionally, if space is limited, both the on and off ramps are built at the same location in a "braided" arrangement (i.e. one ramp passes-over the other).

Diamond interchange
Frontage roads with diamond interchanges
  "X" interchange
Frontage roads with "X" interchanges

Speed limits on frontage roads generally range from 50-60 mph in rural areas to 40-50 mph in urban areas.  In urban areas, access roads are one-way in the same direction as the adjacent freeway lanes.  In rural areas they are generally two-way.  On the frontage road, traffic leaving or entering the freeway has the right-of-way.  

Our ubiquitous frontage roads are an oddity unique to Texas.  However, within Texas, frontage roads have their own oddity.  If you travel through the state, you may notice that people in each of the major cities call their frontage roads something different: in Houston, they're "feeder" roads; in Dallas-Ft. Worth, they're "service" roads; in San Antonio, they're "access" roads; and in El Paso, they're called "gateways".  The term generally used in Austin and the state's official term is "frontage" road, which is how you'll see them marked on guide signs statewide, even in the aforementioned areas where the popular vernacular differs.  You can often tell what part of the state someone hails from just by asking them what they call that road next to the freeway.

It should be noted that frontage roads (or whatever you call them) are not just found on Interstates-- US and state highways that are freeways also commonly have frontage roads.

Native Texans are frequently surprised when they go to other places and find no frontage roads.  A comment many make after their trip to another state is, "They don't have frontage roads on their highways!"  But many native Texans don't realize how much of an oddity our extensive frontage roads are.  Conversely, many out-of-state visitors immediately notice and comment on our frontage roads with no clear majority between thumbs-up and thumbs-down.

Going hand-in-hand with frontage roads are "turnarounds".  These are separate U-turn ramps that allow traffic heading in one direction on a one-way frontage road to turn around and head the other way on the opposite frontage road without having to traverse the two frontage road/cross street intersections (see diagram below).  This helps ease congestion in those intersections.  Turnarounds can run underneath the freeway using the same underpass as the cross street, or they can cross over the freeway on the same overpass as the intersecting street or on separate overpasses.  Turnarounds are only used on one-way frontage roads and therefore are generally found only in urban areas.  Like frontage roads, these may have different names in different parts of the state.  "Turnaround" is the term in San Antonio, and it's the only place that actually uses "Turnaround" signs, although the "U-turn ONLY" sign found in most of the rest of the state is starting to make an appearance there.  Other terms used for turnarounds are "U-turn lane" and "crossover", although the later more correctly describes an opening in the median on a divided highway.

Turnaround diagram

Turnaround diagram

Typical San Antonio turnaround

Typical turnaround in San Antonio

Another semantic idiosyncrasy is how TxDOT abbreviates "Interstate".  In most other states, it's I-35, I-10, etc.  Here, TxDOT's official term is "IH", as in IH-35 or IH-10, with "IH" being short for "Interstate Highway".  Furthermore, depending which part of the state you're in, you may locals using that term as well.  (As you can tell by my pages, I prefer "I" myself.)  I believe TxDOT uses "IH" because all of their other highway abbreviations are two letters as well.

Interstate 69
With the growth of NAFTA traffic, Texas began making plans in the late '90s for a new Interstate, I-69, from Texarkana through Houston and on to Laredo and the lower Rio Grande Valley. 
During the first decade of this century, planning for this route was rolled-into the Trans-Texas Corridor as "TTC-69" (more details on the TTC below) and "Future I-69" signs began appearing on US 59 in the Houston area in 2000.  However, after the demise of the TTC, the I-69 project was continued as a standalone effort.

I-69 will upgrade the existing US 59 corridor, one of several corridors being strained by burgeoning NAFTA traffic.  South of Victoria, I-69 forks into two routes: I-69E along US 77 south to Brownsville and I-69W, which continues south along US 59 to Laredo.  Near George West, another spur, numbered I-69C, branches off of I-69W and follows US 281 south to Pharr.  

In August 2011, the Federal Highway Administration approved Texas' request to sign the first section of I-69 in the state.  In December 2011, signs went up on a 6.2 mile section of the US 77 expressway between I-37 and Robstown just west of Corpus Christi.  In September 2012, 35 miles of US 59 stretching from Loop 610 in northeast Houston to the Montgomery/Liberty county line was also signed as I-69.  Since then, numerous additional sections have been signed as they have been upgraded to Interstate standards and, as of May 2015, there were 194 miles of I-69 signed in Texas.

As part of the I-69 project, the federal government approved signing US 83 through the Rio Grande Valley as I-2, connecting I-69C at Pharr with I-69E at Harlingen.

More information on I-69 in Texas is available at the Alliance for I-69 Texas website.

Interstate 27 extension
TxDOT commissioned a study during the early '90s to investigate extending I-27 south from Lubbock.  Three corridors were considered: US 87/SH 349 to Midland, a Sweetwater-San Angelo-Junction corridor connecting to I-10, and another corridor through Big Spring to I-10 at Ozona with the I-20 to I-10 segments of these corridors studied separately from the Lubbock to I-20 corridors.  The study concluded that there was not enough traffic, present or projected, to warrant an extension of I-27 for the foreseeable future.  Instead, a package of upgrades to US 385, SH 349, US 87, and US 84 was recommended.

With the passage of NAFTA, additional studies have been done on this "Ports-to-Plains" corridor.  You can read more about it at Andy Field's AARoads website and at the Ports-to-Plains coalition website.  Once again, projected traffic volumes were determined to not be sufficient for an Interstate in this corridor.  Instead, various options including bypasses, intersection improvements, additional lanes on existing roads, and ITS measures were recommended.

Exit numbers
Texas, like most states, switched from a sequential exit numbering system to a milepost numbering system in the mid to late '70s and early '80s.  The exit number was typically posted on a tab above the exit board, but starting in 2012, signs with the exit number incorporated in the exit sign became the standard and began appearing.

State highways

The State Highway system includes State Highways (SH), Loops (LP), and Spurs (SP).  There are also Park Roads and Business Routes.  There are a few "special" state highway designations as well: OSR (Old San Antonio Road) near Bryan, NASA Road 1 leading to the Johnson Space Center, and Beltway 8 around Houston.

A term you are sure to hear across the state is "Loop".  Even when they're Interstates, you'll usually hear beltways and other bypasses referred to as "Loop" such-and-such.  For example,
I-410 around San Antonio is usually called "Loop 410" and I-610 in Houston is known simply as "The Loop" (usually with the cardinal location inserted, e.g. "the West Loop.")  However, there is an official state highway designation of "Loop (LP)".  This category includes many routes that are not circular or even a bypass!  Short state highways whose main purpose is to connect two or more highways are usually designated as a Loop.  A good example is Loop 1 (MoPac Expressway) in Austin: it is basically straight and runs pretty much through the heart of the city, but it connects several US, SH, and FM routes along the way.

Business Routes
US 90 (A) Business
Prior to 1991, all business routes carried an internal or "hidden" arbitrary State Highway Spur or Loop designation, although in most cases they were actually marked with the business route sign for the parent route from which they branched.  In 1991, those internal designations were dropped and the business route designations were made official.

How Texas marks business routes is unique.  Firstly, TxDOT often puts a small letter at the bottom of most business route shields (see example to the right.)  This letter indicates which branch in the series for the parent highway that particular segment is.  For example, US 90 passes through several towns.  The business route through the first town would be labeled "A", the one through the next town labeled "B", and so on, although this practice isn't followed consistently throughout the state.  Secondly, on US business routes, TxDOT often does not use the "BUS" or "BUSINESS" auxiliary plate mounted above the US route marker.  Rather, the word "BUSINESS" is included within the US shield above the number, as shown to the right.

Interstate Business Loops were fairly rare in Texas until the state decommissioned all US highways that were completely coexistent with Interstates in 1991.  Along those Interstates, the US route had previously provided the parent route for the business routes.  Those have since been replaced with Interstate Business Loops.

Park roads
The state also has 88 or so Park Roads and Recreation Roads, which provide access to state and national parks and other designated recreational areas.  TxDOT also maintains all roads within state parks, although most are not marked state routes.

Farm-to-market roads

More than half of the state's highway system is comprised of the Farm-to-Market (FM) road system, which also includes Ranch-to-Market (RM) roads.  Although the first FM road opened in 1937, the system really grew after the 1949 Legislature set aside $15 million annually from the state's General Fund for their construction.  General Fund money is no longer used, but the FM system is still paid for entirely by the state.  The FM system is the most extensively developed rural highway system in the nation.  Its nearly 41,000 miles is more than double the entire state highway mileage of the six New England states combined.

Although the FM/RM route sign reads "Farm Road" or "Ranch Road", the routes are officially designated as "Farm-to-market" or "Ranch-to-market".  Larger guide signs do mark the routes as "FM" and "RM" (see the "signs" topic below.)  There is only one route officially designated as "Ranch Road", that being Ranch Road 1 leading up to the LBJ Ranch east of Fredericksburg.  There is no difference between FM and RM roads; just another Texas highway semantic idiosyncrasy.  Routes east of US 281 are generally labeled as FM roads; those west of US 281 are generally marked as RM roads. 

Proposed Urban Route signWith the explosive growth of metropolitan areas in Texas over the years, many FM routes are now in metropolitan areas.  Houston and San Antonio in particular have a large number of FM roads within their urban areas.  One could drive many of these routes and never see a farm or ranch, much less anything being transported to market.  Still, only about 4% of the total FM mileage is within urban areas.  Since the FM system is entirely state-funded, an effort was made in 1995 to create a new classification for FM routes in urban areas called "Urban Roads" to enable them to receive federal funding.  The proposed sign would be the simple state highway square with the word "urban" and the route number.  An outcry from the public about the changing the familiar Texas-shaped sign stopped the plan to re-sign the roads, but TxDOT's internal highway designation logs were changed to re-classify FM roads in metro areas as Urban Roads.  In 2012, there were 252 roadway segments classified as UR.

Prior to the Urban Road system, TxDOT created a classification of roadway in 1988 called the Principle Arterial Street System, or PASS (designated as PA routes.)  This classification allowed for existing and new major urban arterials that provide access to or relief for major state corridors (typically freeways) to receive matching state and federal funding without being officially signed as state roadways.  Due to financial constraints, the PASS program was essentially discontinued in 1992 and is slowly being sunsetted with the 190 roadway segments included in the PASS system being funded as resources become available or transitioned to other funding categories.


Texas has always been on the leading edge of highway technology.  The Texas Transportation Institute (TTI) at Texas A&M University has spearheaded much of this highway research.  Here are some of the many innovations to come from Texas:

  • The "Texas Twist" guardrail end was developed in the 1970s to deflect vehicles by burying the ends of the guardrails.  As cars got smaller, though, many overturned when hitting this.  So in the late '80s and early '90s, TTI developed a new guardrail end treatment called the ET2000.  This new guardrail end absorbs the impact of a vehicle by extruding the rail and breaking the wooden posts.
  • Texas initiated the concept of roadside parks.  The first picnic area opened in 1933 along Texas 71 between Smithville and La Grange.  In recent years, though, funding issues, as well as the proliferation of fast-food restaurants, has resulted in Texas closing an increasing number of picnic and rest areas, especially near urban areas.
  • The "adopt-a-highway" project was developed in Texas and it was the first state to implement it statewide.  More than 45 other states have since emulated this program.  There are currently about 3,800 groups collecting litter along 8,000 miles of highway.  It is estimated that this program saves the state $2.5 million a year in litter clean-up costs.  (Also see the "Don't Mess With Texas" section below.)
  • Breakaway sign posts and streetlights were developed in a two-year program in the 1970s to reduce the seriousness of roadside object impact accidents.  Heavy-duty barrier stops tankerAfter 125 crashes resulted in not one single injury, the federal government mandated their use on all federally-funded roads.  Texas also developed the breakaway "coat hanger" rural mailbox support, which was recently redesigned.
  • A modified version of the standard Jersey-barrier designed to reduce the likelihood of smaller vehicles flipping over on impact was developed in the 1980s by TTI.  TTI also designed a special heavy-duty extra-tall guardrail for a downtown San Antonio freeway ramp to prevent heavy trucks from crashing down onto a high school football field below the ramp.  To test it, they crashed a fully-loaded tanker truck into it!  This rail design has since been used in many other locales where extra strength crash-barriers are needed.

Don't Mess With Texas™

During the mid '80s, the forerunner of TxDOT introduced what would become an incredibly popular anti-litter campaign: "Don't Mess With Texas".  Signs went up around the state and the slogan took off.  Today, you can get "Don't Mess With Texas" T-shirts, mugs, stickers, keychains, hats... you get the idea.  There have also been numerous "Don't Mess With Texas" commercials featuring various celebrities.  TxDOT owns the trademark on the slogan and logo and zealously pursues unauthorized uses. 


With freeways in many areas reaching their maximum width, the Texas Transportation Commission in 1989 committed to building Intelligent Transportation Systems (ITS) in the state's largest metro areas.  The first system to go online was TransGuide in San Antonio, which at the time was the first advanced metro freeway ITS system in the nation.  TransStar in Houston followed shortly thereafter.  Most of the state's largest metro areas now have ITS systems, and it has been expanded to several busy rural corridors as well.  These systems use a various technologies to monitor traffic conditions and warn drivers of incidents and congestion.  ITS also plays a major role in hurricane evacuations and other emergency situations.


Texas has more road signs than any other state. There are over 500,000 signs on state maintained highways.

Texas is probably the only state that has two different versions of our highway markers.  One version is the freestanding sign and the other is for use on freeway guide signs.  Here are some examples:

After World War II, the route marker for state highways was changed to today's boring square. Prior to then, the shield featured the much more unique circle and five-point star design shown at the left.

Toll roads

Until the early 2000s, Texas law prevented the state from building or operating toll highways.  Instead, they could be built and operated by subsidiaries of TxDOT or independent agencies created specifically for that purpose.  For instance, the Texas Turnpike Authority built and operated tollways in the Dallas area, including the Dallas-Ft. Worth Turnpike, which was the state's first toll road.  North Texas tollways are now operated by North Texas Tollway Authority while the Harris County Toll Authority built and operates several tollways in the Houston area (see sidebar below).  In the late '90s, a private toll road, the Camino Columbia, was built to connect the Columbia Solidarity Bridge northwest of Laredo to I-35.  Due to a lack of traffic caused by federal delays to implementing the North American Free Trade Agreement (NAFTA), that road eventually was sold to the state and is now operated by TxDOT.  In the early 2000s, with worsening congestion and declining revenue from the state gas tax, the state promoted toll roads as a major mechanism to fund new or expanded roads.  To facilitate this, the legislature authorized the creation of so-called Regional Mobility Authorities around the state.  Perhaps the most controversial toll road proposal was the statewide Trans-Texas Corridor project (see below).

Toll roads in Texas are marked with special signage such as that shown to the right above.

The Sam Houston Tollway around Houston is also signed as Beltway 8, a state highway.  However, because of the previous restriction of not allowing state highways to be toll roads, only the frontage roads along the toll route are actually Beltway 8.  The tolled mainlanes are just the "Sam Houston Tollway", operated by the Harris County Toll Road Authority. 

Trans-Texas Corridor

Trans-Texas Corridor logo (TM)In 2002, Texas Governor Rick Perry announced a concept for a massive new transportation system in Texas.  The plan, called the "Trans-Texas Corridor" (TTC), was subsequently approved by the legislature and called for 4,000 miles of superhighway/rail/utility corridors crisscrossing the state.  As envisioned, each corridor would have been 1,200 feet wide and included separate roadways for passenger vehicles and trucks, separate tracks for freight and passenger rail, and a right-of-way for utilities such as gas, oil, and water pipelines and electrical transmission and telecommunications lines.  Specifically, here's how a typical corridor would have been divvied up:

  • Four truck lanes, four each way (A on the diagram below)
  • Six passenger vehicle lanes, three each way (B)
  • Two sets of tracks for high-speed passenger rail, with stations (C)
  • Two sets of tracks for freight rail (D)
  • Two sets of tracks for commuter rail, with stations (E)
  • A utility corridor about 200 feet wide (F)
  • Maintenance, safety, and expansion zones as necessary

Trans-Texas Corridor

Trans-Texas Corridor typical cross-section
(Letters correspond to descriptions above)

The roadways would have had limited interchanges with exits only at intersections with other TTC routes, Interstates, US highways, and major state highways.  It was planned that the passenger roadways would have speed limits of 80mph.  The corridors would have been developed and operated by private companies under a state franchise.  These companies would charge tolls and fees for users. 

There were four priority corridors:

  • TTC-35, to parallel or overlap I-35 from Denison to Laredo
  • TTC-69/future I-69, from Texarkana to Laredo via Houston, with branches to the Lower Rio Grande Valley
  • I-45 from Dallas to Houston
  • I-10 from El Paso to Orange

The project, however, met with fierce opposition across the state.  Opposition was especially pronounced in rural areas as the wide corridors would have taken many acres of farming and ranch lands.  Furthermore, there was a general discontent with the concept of having the roads operated by private companies, especially ones with foreign ties.  As a result, the project was killed by the Legislature in 2009.  The TTC-35 and TTC-69 projects, which were in advanced planning at the time, continued but not under the TTC brand.  The TTC-35 project was also eventually canceled.  However, the segment from Georgetown to Seguin, which had originally been conceived as a traditional toll project, was allowed to be completed as a regional project and today is SH 130.   Planning for TTC-69 (the I-69 extension) continued as a traditional Interstate project (see I-69 above.)

TTC map

Map of proposed Trans-Texas Corridor
(Priority routes are in gold)

Speed limits

Texas is the only state that does not have statutory speed limits for different types of highways in the state system.  Instead, a general limit of 70 mph applies on any rural numbered highway regardless of classification or number of lanes and 60 mph on any other rural roadway.  A 30 mph general limit applies in urban areas.  These limits can be raised or lowered based on an engineering study.  Speed limits can be raised to 75 mph on numbered highways and up to 85 mph on select roadways.  This means Texas is the only state that has 75 mph speed limits on two-lane roads. 

85 mph speed limit signAs speed limits have been increased across most of the US in recent years, Texas has lead the way.  Today, Texas has an 80 mph speed limit on about 520 miles of I-10 and I-20 in west Texas.  Several tollways in the Austin area also have an 80 mph speed limit, and SH 130 from SH 45 south of Austin to I-10 near Seguin has an 85 mph speed limit-- the fastest in the United States.

Prior to 2011, Texas posted separate speed limits for trucks and for nighttime.  The truck limits were usually 60 mph when the general speed limit was 65 mph or higher and 70 mph when the general speed limit was 75 mph or higher.  Nighttime speed limits were 65 mph when the daytime limit was 70 mph or higher with nighttime limits for trucks generally 55 mph.  All truck and nighttime speed limits were repealed in 2011. 

To help reduce air pollution, Texas experimented with so-called "environmental speed limits" in the Houston and Dallas-Ft. Worth areas starting in 2000.  This scheme lowered the speed limit by 5 mph on roads with an existing 65 or 70 mph limit.  In 2002, speed limits in the Houston area were arbitrarily lowered to 55 mph regionwide, but opposition, poor compliance, and a finding that the lowered limit did not significantly improve air quality scuttled that plan within a couple of years and speed limits returned to the original 5 mph reduction scheme.  However, the uproar caused the state legislature in 2003 to ban any new environmental speed limits.  Environmental speed limits in the DFW region were completely repealed in 2015.

In late 2014, TxDOT conducted a pilot project for variable speed limits at three locations around the state.  Variable speed limits are those that can be adjusted in real-time to address congestion, inclement weather, construction, or other issues that could affect traffic safety.  The results of the program will be analyzed by the legislature to determine if it should be approved for statewide implementation.

Tunnels & ferries

TxDOT operates two ferry services.  The longest is on SH 87 from northern Galveston to Port Bolivar.  Another short ferry connects Port Aransas and Aransas Pass on SH 361.  The Harris County Toll Road Authority studied a possible bridge to replace the Galveston-Bolivar ferry, but determined it to not be feasible.  Harris County also operates the Lynchburg Ferry east of Houston near San Jacinto State Park.

There are currently no tunnels on the state highway system.  At one time, TxDOT did operate a tunnel under the Houston Ship Channel on SH 146 between La Porte and Baytown.  It was replaced in the early '90s by the impressive cable-stayed Hartman Bridge. There are, however, three road tunnels in Texas that are not part of the state highway system: the Washburn Tunnel, which is also under the Houston Ship Channel on Federal Road; the Addison Airport Toll Tunnel in Addison north of Dallas (operated by NTTA); and one in Big Bend National Park.

Other sites of interest

Texas Department of Transportation
TxDOT - Keep Texas Moving
Don't Mess With Texas campaign
Texas Highway Routes (by David Stanek)
TexasFreeway.com (by Ron Jackson)
LoneStarRoads.com (by Andy Field)
Port-to-Plains Coalition
Alliance for I-69 Texas
San Antonio Freeway System
Houston Freeways
Dallas-Ft. Worth Freeways

This page and all its contents are Copyright © 2015 by Brian Purcell

The information provided on this website is provided on an "as-is" basis without warranties of any kind either express or implied.  The author and his agents make no warranties or representations of any kind concerning any information contained in this website.  This website is provided only as general information.  The author expressly disclaims all liability with respect to actions taken or not taken based upon the information contained herein or with respect to any errors or omissions in such information.  All opinions expressed are strictly those of the author.  This site is not affiliated in any way with any official agency.