Speed limits in the United States

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Main article: Speed limit

Speed limits in the United States are set by each state. Speed limits are usually:

25–30 mph (40–50 km/h) on residential streets
35–45 mph (55–70 km/h) on urban arterial roads
50–65 mph (80–105 km/h) on major highways inside cities
45–65 mph (70–105 km/h) on rural two-lane roads
55–70 mph (90–110 km/h) on rural expressways
65–75 mph (105–120 km/h) on rural Interstate highways

Western states generally have higher limits than eastern states, and some limits fall outside these ranges. For example, some two-lane rural roads in Texas have 75 mph (120 km/h) speed limits, and there are two stretches of Interstate in West Texas with a daytime 80 mph (130 km/h) speed limit for passenger vehicles (see below). In contrast, the highest speed limit posted on Interstates in Hawaii is 60 mph (95 km/h).

A standard sign indicating a speed limit of 80 miles per hour (mph), a night-time speed limit of 65 mph, and a truck speed limit of 55 mph

[edit] Charts

[edit] Speed limits

This table contains the usual speed limit, in miles per hour, on typical roads in each category. This is usually, but not always, the statutory speed limit.

Some states have lower truck speed limits applicable to heavy trucks.

State	Interstate (rural)	Interstate (urban)	4 lane (rural)	2 lane (rural)	County (rural)	Residential (urban)
Alabama	70, 55^hazmat	55	65	55	45^paved, 35^gravel
Alaska	65	65	65	65	50
Arizona	75	65	65	65	55
Arkansas	70	65	65	55
California	70	65	65	65^desert, 55	65	25
Colorado	75, 65^mtn	55	65	65
Connecticut	65	55, 50	65	55
Delaware	65	55	55	55
District of Columbia	N/A	55	N/A	N/A	N/A	25
Florida	70	65	65	60	55
Georgia	70	55	65	55	45	30
Hawaii	60	50	45	45	45
Idaho	75	65	65	65
Illinois	65	55	65	55	55
Indiana	70	55	60	55	55
Iowa	70	55	65	55
Kansas	70	65	65	65
Kentucky^[1]	70^ky, 65	55	55	55	55
Louisiana	70	60	65	55
Maine	65	55	55	55	50
Maryland	65	55	55	55
Massachusetts	65	55	55	55		30
Michigan	70	70^[2]	70, 55	55	55	25
Minnesota^[3]	70	55, 60	65	60^[4]	55	30
Mississippi	70	70	65	55
Missouri	70	60	65, 70^us	65, 60, 55 ^mohwys
State	Interstate (rural)	Interstate (urban)	4 lane (rural)	2 lane (rural)	County (rural)	Residential (urban)
Montana	75	65	70	70
Nebraska^[5]	75	65^lin, 60	65	65^west, 60	55^paved, 50^gravel	25
Nevada	75	65	70	70	70	30
New Hampshire	65	55	55	45	35	30
New Jersey	65	65, 55	65, 55	50		25
New Mexico	75	65	75, 70	65, 60, 55
New Mexico	US70 between Las Cruces and Alamogordo is posted at 75 mph on a section between the WSMR and White Sands National Monument entrances. It is the only non-Interstate road to be posted at 75 mph. 2 lane 65 mph speed limits are posted on roads with wide paved shoulders. Roads with a narrow paved shoulders are posted at 60 mph. 2 lane roads with no paved shoulders are posted at 55 mph. left lane minimum speed limit on roads posted at 75 mph is 65 mph.
New York	65	55, 50^nyc	55	55	55	30
North Carolina	70	65	70, 55 (if road has at grade intersections)	55		25
North Dakota^[6] ^[7]	75	65, 60, 55	70	65 Most St. Hwys., 55 (ND 57, ND 43)	55 Unmarked or Other wise posted.	25
Ohio ^[8]	65	65, 60, or 55	65, 60, or 55	55	55	25
Oklahoma	75^t, 70	65	70	65	45	25
Oregon	65	60, 55	55	55	55	25
Pennsylvania	65	55	55	55
Rhode Island	65	55	55	55
South Carolina	70	60	60	55	45	30
South Dakota	75	65	70, 65	65	55	35, 25
Tennessee	70	55	65	55
Texas	80, 75, 70, 65^night	60	75, 70, 65^night	75, 70, 65^night	70^hctra, 60, 55^night	30
Utah	75	65	65	65
Vermont	65	55	55	50	50
Virginia	70 (I-85), 65	60, 55	60 (US 29, US 301, US 58), 55	55	55	25
Washington	70	60	60	60	50	25
West Virginia	70	55	65	55
Wisconsin	65	55	65	55	55	25
Wyoming	75	60	65	65
State	Interstate (rural)	Interstate (urban)	4 lane (rural)	2 lane (rural)	County (rural)	Residential (urban)

[edit] Legend

Interstate: Interstate highway or other state- or federally numbered road built to Interstate standards.
4 lane: State- or federally numbered 4 lane road not built to Interstate standards.
2 lane: State- or federally numbered 2 lane road.
County: County-owned roads that are generally not numbered by the state.
Residential: Residential roads within an urban area.

[edit] Footnotes

gravel: Gravel roads.
hazmat: Trucks hauling hazardous materials. Only applies to four-lane and Interstate roads in Alabama. ^[9]
hctra: Harris County, Texas's toll road authority may post up to 70 mph limits on its tollway system.^[10]
ky: 70 MPH limits have been approved, although studies must be done before it is implemented. As of 2007, no roads are currently signed at this limit.
lin: Interstate 80 through Lincoln.
mtn: Speed limit in mountainous areas.
night: Night speed limit.
nyc: New York City freeway speed limit.
paved: Paved roads.
t: Turnpike.
west: West side of state.
us: Selected 4-lane US highways with few crossover points.
mohwys: 60 or 65 MPH on most 2-lane US Highways, 60 or 65 on a few NHS-class primary state highways, and very few lettered state roads. 55 MPH on all other 2 highways.
desert: CalTrans can post limits of 65 on 2 lane roads. This occurs mostly in rural desert areas. ^[11]

[edit] Other speed-related laws

State	Typical Fine	Recklessness threshold or enhanced penalty	Absolute/Prima Facie	Ticket Dismissal Options	Point System
Texas	$1-$200^[12] plus court fees. Doubled in active school zone or construction zone when workers are present^[13].	None^[14]	Prima facie^[15]	Defensive driving^[16] (once per year) or deferred disposition^[17] (restrictions vary, but generally at least 4 per year), but only valid if: Texas resident, speed < 25 under limit, and not in active school zone or construction zone where workers are present.	Point system is annual surcharge only. No provision for license suspension.^[18]
Virginia	*Up to $250^[19] School zone: up to $250 additional^[20] Work zone: up to $500^[21] $100 civil penalty in certain towns^[22]	20 mph over limit or over 80 mph^[23] or "exceeds reasonable speed"^[24].	Absolute^[25]		Point system^[26] leading to fines, suspension, and mandatory driver education^[27].

[edit] Definition of speeding

Speeding is defined by the US Federal Government as either exceeding posted limits or driving too fast for conditions^[28]. Speeds in excess of posted maximum speed limits account for most speed-related traffic citations. However, most speed-related crashes involve speed too fast for conditions^[29] such as limited visibility or reduced road traction. Variable speed limits offer some potential to reduce speed-related crashes, but due to the high cost of implementation exist primarily on motorways, while most speed-related crashes occur on local and collector roads ^[30] Speed-related crashes can also occur at speeds below 30 miles per hour; for example, truck rollovers on exit ramps.^[31]

[edit] Prima facie

Most states have absolute speed limits, meaning that a speed in excess of the limit is illegal per se. However, some states have prima facie speed limits. This offers motorists a valid defense to a speeding charge if it can be proven that the speed was in fact reasonable and prudent.

A successful prima facie defense is rare. Not only does the burden of proof rest upon the accused, a successful defense may involve expert witnesses or other expenses well in excess of the cost of a ticket. Furthermore, since prima facie defenses must be presented in a court, such a defense is difficult for out of town motorists.

Speed limits in Texas, Utah, and Rhode Island are prima facie. Some other states have a hybrid system: speed limits may be prima facie up to a certain speed or only on certain roads.

[edit] Federal speed limit controls (55 mph)

For more details on this topic, see National Maximum Speed Law.

In response to the 1973 oil crisis, Congress enacted a National Maximum Speed Law that federally mandated that no speed limit may be higher than 55 mph. The law was widely disregarded, even after the national maximum was increased to 65 mph in 1987 on certain roads. In 1995, the law was repealed, returning the choice of speed limit to each state.

[edit] Noteworthy state distinctions

[edit] Alabama

Alabama recently set the speed limit for HAZMAT trucks to 55 mph, being the only state to have done so as of the present time. Also, in Birmingham, a 50-mph limit is being proposed for flatbed trucks carrying coils due to recent occurrences of coils falling off the trucks on the interstates there.

[edit] California

In California, many speed limit signs are identified as "Maximum Speed," usually when the limit is 55 mph (90 km/h) or more. Rural Speed Limit on Interstate Highways such as: I-5, I-8, I-10, I-15, I-40, I-80 and even CA-99 south of Madera, and Fresno, and U.S. 101 on the central coast carry the Maximum Speed of 70 mph (110 km/h), with supplementary signage stating "AUTOS WITH TRAILERS/TRUCKS 55 MAXIMUM." This is an accident of legal history. California's Basic Speed Law, ^[32] of the California Vehicle Code, defines the maximum speed at which a car may travel as a reasonable and prudent speed, given road conditions. The numerical limit set by CalTrans engineers for "Speed Limit" signs, generally found on all non-controlled-access routes, is considered a presumptive maximum "reasonable and prudent" speed. However, it is technically allowable for a driver ticketed for exceeding this "Speed Limit" to present the argument that his or her speed was "reasonable and prudent" at the time the ticket was issued. While rare, some speeding tickets have been thrown out based on this provision. When the National Maximum Speed Limit was enacted, California was forced to create a new legal signage category, Maximum Speed, to indicate to drivers that the Basic Speed Law did not apply on these federally funded highways; rather, it would be a violation to exceed the fixed maximum speed indicated on the sign, regardless of whether the driver's speed could be considered "reasonable and prudent."

[edit] Delaware

In Delaware, only two roads are posted with a 65 mph (100 km/h) speed limit: I-495 and Delaware Route 1. The remaining two Interstates, Interstate 95 and Interstate 295, along with all rural four-lane non-Interstate highways, have 55 mph (90 km/h) speed limits. All rural two-lane state-owned roads have 50 mph (80 km/h) speed limits, while all urban speed limits, regardless of location, is held at 25 mph (40 km/h) for two-lane roads and up to 35 mph (55 km/h) for four-lane roads. School zones are posted at 20 mph (30 km/h).

[edit] Hawaii

Hawaii was the last state to raise its maximum speed limit after the National Maximum Speed Limit was repealed in 1995. In 2002, after public outcry after a controversial experiment with speed enforcement using road safety cameras, the state Department of Transportation raised the speed limit to 60 mph on two stretches of road:

Interstate H-1 between Kapolei and Waipahu, and
Interstate H-3 between the Tetsuo Harano Tunnels and the junction with H-1.^[33]

All other Interstates have a maximum speed limit of 55 mph, with the limit dropping to 50 mph in central Honolulu. Non-interstates generally have speed limits of 55 mph and in many cases much less.^[34]

[edit] Indiana

In Indiana speed limits on Interstate highways are usually 70 mph (110 km/h) for cars and 65 mph (105 km/h) for trucks, except in urban areas, where it is generally 55 mph (90 km/h) in city centers and 65 mph (105 km/h) cars/60 mph (95 km/h) trucks in suburban areas. Prior to July 5, 2005, all Interstate highways were 65 mph and below.

Most non-Interstate highways are 55 mph, but some rural four-lane divided highways are set at 60 mph. These limits often decrease to 30-45 mph (50-70 km/h) approaching urban areas, and within cities a speed limit of 20–30 mph (30–50 km/h) is not uncommon, though larger arterial roads within cities may reach as high as 45 mph (70 km/h).

[edit] Iowa

According to The Des Moines Register, the Iowa House may take up a measure that would increase the speed limit on two-lane roads to 60 MPH.

[edit] Montana

For a brief period (December 1995 - June 1999) Montana had no rural highway speed limit. However, even so a law prohibiting reckless driving, applicable to extreme speeds but less stringent than the previous "reasonable and prudent" standard, still applied.

In the years before 1974's 55 mph National Maximum Speed Limit and for three years after its 1995 repeal, Montana had a non-numeric "reasonable and prudent" speed limit during the daytime on most rural roads. Montana Code Annotated (MCA) Section 61-8-303 said "A person . . . shall drive the vehicle . . . at a rate of speed no greater than is reasonable and proper under the conditions existing at the point of operation . . . so as not to unduly or unreasonably endanger the life, limb, property, or other rights of a person entitled to the use of the street or highway."

Typical speed limit sign that one would see at the Montana state line from December 1995 to June 1999.

Montana law also specified a few numeric limits: a night speed limit, usually 55 or 65 mph (90–100 km/h), depending on road type; 25 mph (40 km/h) in urban districts and 35 mph (60 km/h) in construction zones.

The phrase "reasonable and prudent" is found in the language of most state speed laws. This allows prosecution under non-ideal conditions such as rain or snow when the posted speed limit would be imprudently fast.

On March 10, 1996 ^[35], a Montana Patrolman issued a speed ticket to a driver traveling at 85 mph (140 km/h) on a stretch of State Highway 200. The 50 year-old male driver (Rudy Stanko) was operating a 1996 Camaro with less than 10,000 miles (16,000 km) on the odometer. Although the officer gave no opinion as to what would have been a reasonable speed, the driver was convicted. The driver appealed all the way to the Montana Supreme Court. The Court reversed the conviction in case No. 97-486 on December 23, 1998; it held that a law requiring drivers to drive at a non-numerical "reasonable and proper" speed "is so vague that it violates the Due Process Clause ... of the Montana Constitution".

Due to this reversal, Montana scrambled to vote in a numerical limit as it technically had no speed limit whatsoever in the meantime. In June 1999, a new Montana speed limit law went into effect. The law's practical effect was to require posted limits on all roads and disallow any speed limit higher than 75 mph (120 km/h).

Montana law still contains a section that says "a person shall operate a vehicle in a careful and prudent manner and at a reduced rate of speed no greater than is reasonable and prudent under the conditions existing at the point of operation, taking into account the amount and character of traffic, visibility, weather, and roadway conditions." However, this is a standard clause that appears in other state traffic codes and has the practical effect of requiring a speed lower than the posted limit where a lower speed is necessary to maintain a reasonable and prudent road manner.

[edit] New Hampshire

The highest limit is a maximum lawful speed limit of 65 mph (100 km/h), which can be found on the Interstate System, the Everett Turnpike, the New Hampshire Turnpike and the Spaulding Turnpike, in locations in which the highways are divided and have four or more lanes.

Provided that no hazard exists that requires lower speed, the speed of any vehicle not in excess of the limit is deemed to be prima facie lawful. The limit for "rural residential districts" and Class V highways outside the city or town compact is 35 mph. The limit for any "business or urban residence district" is 30 mph. School zones receive a 10 mph reduction in the limit 45 minutes before and after the beginning and end of a school day. The speed limit for a road work or construction area is 10 mph lower, but no more than 45 mph, than the posted limit when work is in progress. The speed limit for all other locations is 55 mph. The minimum limit that a speed can be set in a rural or urban district is 25 mph.

[edit] New York

A standard-style New York State speed sign indicating the 'State Speed Limit'.

The highest speed limit is 65 mph (100 km/h), which is found on most of the Thruway and other rural Interstate highways. The State Speed Limit (a blanket speed limit for rural roads) is 55 mph (90 km/h), which is also the highest a non-freeway highway may have. Signs in New York thus read "State Speed Limit" when the speed limit is 55. The theme is followed, and many signs read "Area Speed Limit", "Town Speed Limit", "City Speed Limit" or "Village Speed Limit" with varying speeds shown below. New York City (and some other urbanized areas) has a blanket speed limit of 30 mph (50 km/h) except where otherwise posted. The highest speed limit on freeways in New York City is 50 mph (80 km/h) speed limit.

Governor George Pataki signed legislation in September 2003 that enables NYSDOT and NYSTA to raise speed limits to 65 mph on its roads that meet established design and safety standards. This legislation became active in March 2004, and has been used on over 100 miles worth of highway. Prior to the new law, consent of the State Legislature was necessary to enact a 65 mph speed limit, a process that could take months or years.

[edit] Ohio

Truck maximum speed applied to all vehicles with an empty vehicle weight greater than 8,000 pounds and all non-commercial buses.^[36]

[edit] Oregon

A standard-style Oregon speed sign omitting the word 'limit'.

Up until 2002, Oregon state law required that all speed limit signs omit the word 'limit' from their display. The reasoning behind this is unknown but the practice has been known to produce some unusual number fonts. The spacing between and appearance of the numbers on the signs vary greatly depending on which jurisdiction made the sign. In 2002, the Oregon Department of Transportation permitted the inclusion of the word 'limit' on speed signs and left it up to local government agencies to decide on whether 'limit'-branded signs would be installed. Most have chosen not to change over with a few exceptions to the rule. Speed Limit 60 signs can be found on Interstate 5 through Salem and on Interstate 84 through east Portland. The City of Beaverton has been the most liberal in retrofitting the standard-form Speed Limit sign, presumably because the 'SPEED' signs do not use a standard number font and are likely more expensive to make. Whenever a 'Speed' sign is damaged or vandalized in Beaverton city limits, a 'Speed Limit' sign takes its place.

Throughout the late 1990s the Oregon State Legislature passed multiple bills that would have raised the speed limit to 75 miles per hour on rural Interstate highways and up to 70 mph on certain rural two lane highways in the eastern portions of the state. Each year Governor John Kitzhaber vetoed the bill. In 2003, the Oregon State Legislature passed a bill that would have raised the maximum permissible speed limit on Interstate highways to 70 mph for cars with a 5 mph differential for trucks, up from the previous 65 mph limit for cars with a 10 mph differential, this bill was signed into law by then newly elected Governor Ted Kulongoski. In 2004 the Oregon Department of Transportation decided to not implement the increase out of concerns that it would not be safe to have trucks traveling at 65 mph. Prior to the National Maximum Speed Law, the speed limit on Oregon interstates could be as high as 75 mph.

In 2004, a law was passed revising Oregon's school speed limit laws. On roads with speed limits of 30 mph or below, drivers were required to slow to the school speed limit of 20 mph 24 hours a day, 365 days a year, regardless of whether or not children were present. This replaced most 'when children are present' placards. If the speed limit was 35 mph or higher, the school zone limit would be imposed either by flashing yellow lights or a placard denoting times and days of the week when the limit was in effect. The at-all times rule was highly unpopular with motorists and was widely ignored. In fact, it is likely that this law has lead to a reduced acceptance of school speed limits, regardless of how and when they are in effect. In 2006, the law was revised again, taking away the 'at all times' requirement and replacing it with a time-of-day system (usually school days, 7 a.m. to 5 p.m.). School crossings with flashing yellow lights remain.

[edit] Pennsylvania

In 1940, when the Pennsylvania Turnpike was opened between Irwin and Carlisle, the entire 110 mile highway did not have a posted speed limit, similar to that of the German Autobahns. In 1941, a speed limit of 70 mph (110 km/h) was established, only to be reduced to 35 mph (55 km/h) during the war years (1942–45). After WWII, the limit was raised to 70 mph on the four-lane sections, with the two-lane tunnels having 50 mph (80 km/h) for cars and 40 mph (65 km/h) for trucks. Prior to the 1974 federal speed limit law, all Interstates and the Turnpike had a 65 mph (105 km/h) speed limit on rural stretches and 60 mph (100 km/h) speed limit in urban areas.

In 1995, the state raised the speed limit on rural stretches of Interstate Highways and the Pennsylvania Turnpike system to 65 mph (105 km/h), with urban area having a 55 mph (90 km/h) limit. In 1997, PennDOT raised the speed limit to some rural non-Interstate highway bypasses to 65 mph (105 km/h). In 2005, with the change in the designation of "urban zones" in the state, the entire lengths of both the Pennsylvania Turnpike's east-west mainline and Northeast Extension were given 65 mph (105 km/h) limits, except at the tunnels and through the very winding 5.5 mile (9 km) eastern approach to the Allegheny Mountain Tunnel.

On non-freeway roads, speed limits are generally held at 55 mph (90 km/h) for rural two and four-lane roads, 45 mph (70 km/h) for urban four lane and state-owned two lane roads, 35 mph (55 km/h) for major roadways in residential areas, 25 mph (40 km/h) for most municipal residential streets, including main north–south and east–west roads in county seats, and 15 mph (25 km/h) for school zones.

[edit] South Dakota

Shortly after the December 1995 repeal of the 65/55 mph National Maximum Speed Limit, South Dakota raised its general rural speed limits to 75 mph on freeways and 65 mph on other roads. Almost a decade after posting the 75 mph limit, average speeds on South Dakotan rural freeways remain at or below the posted speed limit^[37]. South Dakota also has the distinction of being the only state that does not assign points to one's driving record for speeding convictions.

[edit] Texas

Typical Texas rural speed limit sign. Note the black backgrounded 65 mph night speed limit sign, common on Texas roads. (Few other states have widespread night speed limits.) This sign is on southbound U.S. 69/96/287 just north of Beaumont.

Texas is the only state that does not prescribe a speed limit for each road type. Any rural road—two lane, four lane, Interstate, or otherwise—that is numbered by the state or federal government has a 70 mph (110 km/h) statutory limit^[38]. The law generally allows changing the 70 mph limit only if a study recommends a different limit^[39].

[edit] 75 mph and 80 mph limits

Texas statutorily allows the Texas Department of Transportation to post 75 mph (120 km/h) speed limits in counties with average populations of fewer than 15 people per square mile.^[40] The same statute also allows 80 mph (130 km/h) speed limits on I-10 and I-20 in certain rural west Texas counties with low population density. Daytime truck limits are capped at 70 mph, and nighttime speed limits remain 65 mph for all vehicles. (Nothing prohibits nighttime speed limits from being raised to 70 mph, but the Department has not elected to do so.)

In 2001, the Texas Legislature allowed the Texas Department of Transportation to post 75 mph (120 km/h) speed limits in counties with fewer than 10 people per square mile^[41]. This has the practical effect of only allowing 75 mph speed limits in the most sparsely populated counties, all of which are generally well west of a line stretching from San Antonio to Odessa. In 2005, the Texas Legislature revised this law, allowing 80 mph (130 km/h) limits on I-10 and I-20 in certain rural counties in west Texas^[42]. This bill also revised the eligibility for 75 mph speed limits: now eligible counties can have up to 15 persons per square mile. This did not substantially increase the miles of roadway eligible for higher limits, however.^[43]

Texas Legislator Pete Gallego unveiling a new 80 mph speed limit sign on Interstate 10 near Fort Stockton, Texas.

On May 25, 2006, the Texas Transportation Commission has approved 80 mph speed limits^[44], and signs are posted.

In a widely printed Associated Press story about the 80 mph speed limit^[45], Texas is incorrectly reported as having legalized 75 mph limits in 1999. In fact, the bill that would have done this, HB 3328^[46] by Pete Gallego, died in conference committee just before the Texas Legislature's session ended. This bill would have, in effect, set 75 mph as the statutory speed limit on any rural road numbered by the state or federal government, and it would have enacted—not simply allowed—an 80 mph speed limit on I-10 and I-20 in any county with fewer than 25,000 residents.

While Texas's 80 mph limit is higher than any limit authorized by another state, it is equivalent to the 130 km/h recommended speed on the Autobahn and the actual 130 km/h rural expressway speed limit in thirteen other European countries^[47].

Since Texas law allows 75 mph speed limits on any road numbered by the state or federal government, it is the only state with 75 mph limits on two-lane roads. Several west Texas two-lane roads carry 75 mph limits, including portions of US 90^[48]. No other state has a limit higher than 70 mph on any two-lane road.

[edit] 85 mph limits

The legislation creating the Trans-Texas Corridor allows speed limits of up to 85 mph (140 km/h)^[49] on roads built under the program. However, no such roads have been built as of September 2006. The language of the statute does not prohibit the Texas Transportation Commission from raising the truck speed limit or the night speed limit on these roads.

[edit] Night speed limits

While the "basic rule," which requires drivers to drive a "reasonable and prudent" speed at all times, is usually relied upon to regulate proper night speed reductions, night speed limits generally may be established on roads where safety problems require a speed lower than what is self-selected by drivers.

[edit] Texas

Texas is the only state with a broadly-applicable legislatively-specified night speed limit. Texas statutorily prescribes:

a blanket 65 mph (100 km/h) night speed limit on roads with a speed limit of at least 70 mph (110 km/h)^[50]. While the Texas Department of Transportation has the power to lower this night speed limit or raise it to 70 mph, it in fact rarely does, so nearly every 70 mph or higher speed limit sign has an accompanying 65 mph night speed limit sign.
a 55 mph night speed limit for trucks on farm to market roads, complementing the statutory 60 mph truck day limit on these roads. (This is a holdover from Texas's truck speed limits.)
a 55 mph night speed limit on county roads (except for Harris County Toll Road Authority-owned toll freeways).

[edit] Other states

North Dakota, Montana^[51], and Oklahoma also have night speed limits, but they are only generally applicable to rural, non-Interstate-class roads.

Minnesota once had a night speed limit on sections of MN 61, between Duluth and Two Harbors, due to the danger of rocks falling off the cliffs alongside the road. Tunnels have since been constructed, bypassing the dangerous areas under the cliffs and making the night speed limit unnecessary.

[edit] Environmental speed limits

[edit] Texas

55 mph speed limit signs photographed on August 20, 2002. These signs were on southbound I-45 at the north border of Montgomery County. Immediately before this point, the speed limit was 70 mph. These were part of an unpopular 55 mph speed limit cap in the Houston–Galveston area.

Same location as prior picture with the more recent 65 mph speed limit, photographed on August 4, 2005.

Texas is the first state to lower speed limits for air quality reasons. In roughly a 50 mile (80 km) radius of the Houston–Galveston and Dallas–Ft. Worth regions, the Texas Commission on Environmental Quality co-opted the Texas Department of Transportation to reduce the speed limit on all roads with 70 mph (110 km/h) or 65 mph (100 km/h) speed limits by 5 mph^[52]. This was instituted as part of a plan to reduce smog-forming emissions in areas out of compliance with the federal Clean Air Act.^[53]

Initial studies found that lower speed limits could bring the areas roughly 1.5% closer to compliance^[54]. However, follow up studies found that the actual reduction is far less:

The emissions modeling software initially used, MOBILE 5a, overestimated the emissions contribution of speed limit reductions. Rerunning the models with the next generation software, MOBILE 6, produced dramatically lower emissions reductions.
Speed checks in the Dallas area performed 1 year after implementation of speed limit reductions show that actual speed reductions are only about 1.6 mph, a fraction of the anticipated 10% (5.5 mph) speed reduction.

With both of these facts combined, it is possible that the speed limit reductions only provide a thousandth of the total emissions reductions necessary for Clean Air Act compliance.^[55]

In mid-2002, all speed limits in the Houston–Galveston area were capped at 55 mph (90 km/h)^[56]. Facing immense opposition^[57]^[58], poor compliance^[59], and the finding that lowered speed limits produced only a fraction of the originally estimated emissions reductions^[60], the TCEQ relented and reverted to the 5 mph reduction scheme^[61].

In 2003, the Texas Legislature prospectively banned environmental speed limits effective September 1, 2003. The wording of the bill allows environmental speed limits already in place to remain indefinitely; no new miles of roadway may be subjected to environmental speed limits, however^[62].

This law has allowed interesting inconsistencies. Generally, all primary arterial roadways within the inner loops of Texas cities have speed limits of 60 mph (95 km/h) or lower, so they were not subjected to environmental speed limits. Arterial roads between the inner loop and the outer loop generally have 65 mph (100 km/h) limits, and arterial roads outside the outer loop generally have 70 mph (110 km/h) limits. (Note that this is only the typical pattern and is not prescribed by law.) In at least one case—TX 121 between I-35W and I-820 in Ft. Worth—the speed limit rises from 60 mph to 65 mph as one crosses IH-820 approaching downtown^[63], contravening the standard.

[edit] Tennessee

Following the example of Texas, Tennessee has used environmental speed limits as part of pollution control efforts in Shelby, Hamilton, Sullivan, Knox, Jefferson, Roane, Loudon, Anderson, and Sevier counties, lowering the maximum truck speed limit to 55 mph (90 km/h) and the maximum car speed limit to 65 mph (100 km/h) within these counties.^[64]^[65]

[edit] Minimum speed limits

In addition to the legally defined maximum speed, minimum speeds may be posted. There is little evidence to suggest they are enforced.^{[citation needed]}

Connecticut limited access divided highways have minimum speed of 40 mph (65 km/h),^[66] but they are not always posted.

Florida interstate highways have minimum speeds of 40 to 50 mph.^{[citation needed]}

Hawaii has a minimum speed posted along much of Interstate H-1 of only 10 mph below the speed limit. The minimum speed is usually 45 mph when the speed limit is 55, and 40 mph when the speed limit is 50.

Illinois interstate highways are posted with both minimum and maximum speeds in many cases. The minimum speed is 45 mph.^{[citation needed]}

Iowa rural interstates have a maximum speed limit of 70 mph and a minimum speed limit of 40 mph, and U.S. Highway 20 between Interstate 35 and Dubuque also has a 40 mph minimum speed, even though its interstate-quality road is signed at a 65 mph maximum. Other four-lane divided rural highways are signed at 65 mph, with no minimum speed. Urban minimum speeds are becoming increasingly uncommon in Iowa, however, until the recent reconstruction of Interstate 235 in Des Moines, a 40 mph minimum speed was signed.

Michigan freeways are usually posted with both minimum and maximum speeds. The minimum speed is currently 55 mph.^[67]

Mississippi has a minimum speed of 30 mph on four-lane U.S. highways when no hazard exists. Strangely, there is no law for the minimum speed of the state's growing number of four-lane state highways. The minimum is 40 mph on Interstate highways and on 4 lane U.S. designated highways which have a posted maximum speed limit of 70 mph, but this minimum shall be posted.^[68] In 2004, Mississippi posted minimum speed limits (40 mph) on all rural Interstates, but this minimum speed limit was already state law before the widespread posting.

Missouri and Minnesota interstate highways have minimum speed of 40 mph.^[69]

A small portion of Interstate 95 in New Hampshire has a minimum speed of 45 mph.^{[citation needed]}

North Carolina has blanket minimum speed limits on interstate and primary highways only when signs are posted. The minimum is 40 mph if the maximum is 55 mph. The minimum is 45 mph is the maximum is at least 60 mph. These minimums do not apply to vehicles that are towing other vehicles.^[70]

Oklahoma has minimum speed limits posted on more or less all interstate highways that are 25 MPH below the maximum speed limit. For example, on the turnpikes, which have a maximum speed limit of 75 MPH, they are nearly always accompanied by a sign stating a minimum speed limit of 50 MPH.

The Pennsylvania Turnpike has a minimum speed limit of 15 mph below the posted maximum speed limit. Therefore, the minimum speed is 50 mph when the speed limit is 65 mph, and 40 mph when the speed limit is 55 mph. The Pennsylvania Turnpike Commission also states that vehicles that cannot maintain this speed on a level road may not use the turnpike. This minimum speed is not generally posted.

In Tennessee, a minimum speed limit of 45 mph (70 km/h) is posted in some metropolitan areas where the speed limit is 55 mph (90 km/h) or 65 mph (105 km/h).^{[citation needed]}

In New York State, a minimum speed limit of 40 mph has been set on the entire length of Interstate 787.

In Virginia the Chesapeake Bay Bridge-Tunnel has a minimum speed limit of 40 mph.

In Utah, there is a minimum speed limit of 45 mph on interstate highways, when conditions permit.

[edit] Truck speed limits

Some jurisdictions set lower speed limits applicable only to large commercial vehicles like heavy trucks and buses. While they are called "truck speed limits", they generally do not apply to light trucks.

[edit] Theory

Since trucks are far heavier than other vehicles, they take longer to stop, are less adept at avoiding hazards, and have much greater crash energy. Therefore, it follows from basic physics that limiting truck speeds could reduce the severity and incidence of truck-related crashes.

However, the research record is mixed. A 1987 study finds that crash involvement significantly increases when trucks drive much slower than passenger vehicles^[71], suggesting that the difference in speed between passenger vehicles and slower trucks could cause crashes that otherwise may not happen. Furthermore, in a review of available research, the Transportation Research Board, part of the United States National Research Council, states "[no] conclusive evidence could be found to support or reject the use of differential speed limits for passenger cars and heavy trucks" (page 11) and "a strong case cannot be made on empirical grounds in support of or in opposition to differential speed limits" (page 109) ^[72].

Two thirds of truck/passenger car crashes are the fault of the passenger vehicle^[73].

[edit] Truck speed limit differentials

The following states have different statutory speed limits for cars and trucks.

State	Statutory car speed limit	Statutory truck speed limit
Alabama	70	55 (HAZMAT only)
Arkansas	70	65
California	70	55
Idaho	75	65
Illinois	65	55
Indiana	70	65
Michigan	70	60
Montana	75	65
Ohio	65	65 on Ohio Turnpike, 55 on all other freeways.
Oregon	70* never implemented, 65 or less still in effect^[74]	5 mph differential, effectively 60^[75] although 55 is still posted in most locations
Texas	70-80 mph day/65 mph night	70 day/65 night
Texas (Farm-to-Market roads only)	70 mph day/65 mph night	60 day/55 night
Washington	70	60

[edit] Texas

Texas formerly had a 60 mph (100 km/h) day/55 mph (90 km/h) night truck speed limit. This speed limit did not apply to buses or to trucks transporting United States Postal Service mail.

Whenever the speed limit on a road was above this threshold, separate truck speed limit signs were posted. These signs disappeared when all speed limits were capped at 55 mph (90 km/h) in 1974, but reappeared with the introduction of 65 mph (105 km/h) limits in 1987. Effective September 1, 1999, Texas repealed truck speed limits on all roads except farm to market and ranch to market roads.^[76]

Even after Texas repealed the truck speed limit, the Harris County Toll Road Authority erroneously retained the separate truck speed limits on its Interstate-class toll roads. The separate truck speed limits were removed with the 2002 adoption of the 55 mph environmental speed limit. The signs did not reappear when a 65 mph limit was imposed, but the truck speed limit sign posts are still standing as of January 2006.

2001 and 2003 statutes allowing 75 and 80 mph speed limits in certain areas of west and south Texas only apply to passenger vehicles. Truck speed limits remain 70 mph, so separate truck speed limit signs are slowly reappearing on these roads.

Due to the enormous unpopularity of a 55 mph speed limit cap that was imposed on the greater Houston area in 2002, the Texas Commission on Environmental Quality examined alternatives. Analysis suggested that the vast majority of emissions reductions from a 55 mph limit was from reduced heavy truck emissions. A proposed alternative was to restore passenger vehicle limits but retain a 55 mph truck speed limit. Concerns about safety problems and enforceability of such a large differential (up to 15 mph on many roads) scuttled that proposal, and a compromise plan, described above, was enacted that retained uniform, but still reduced, speed limits.

[edit] Louisiana

In August 2003, Governor Mike Foster announced speed and lane restrictions on trucks on the 18 mile (29 km) stretch of Interstate 10 known as the Atchafalaya Swamp Freeway. The restrictions lower the truck speed limit to 55 mph and restrict them to the right lane for the entire length of the elevated freeway.^[77]

[edit] Utah

In 2007, The Utah State Legislature is considering legislation which would limit trucks to a speed limit of 65 miles per hour. The bill is H.B. 199 Speed Restrictions on Commercial Vehicles- Allen, S. The complete text of the bill is available here: [1]

[edit] Metric speed limits

Though not common in the United States, a speed limit may be defined in kilometers per hour (km/h) as well as miles per hour (mph). The MUTCD states that "speed limits shown shall be in multiples of 10 km/h or 5 mph."^[78] If a speed limit is posted in km/h, the number is circumscribed and "km/h" is written below. Prior to 2003, metric speed limits were designated using the standard speed limit sign, but with yellow supplemental "METRIC" and "km/h" plaques above it and below it, respectively.^[79] Nearby many border crossings, there will be supplemental speed limit signs giving the approximate speed limit in metric units to aid travelers.^[80]

[edit] References

Retrieved from "http://en.wikipedia.org../../../s/p/e/Speed_limits_in_the_United_States_7256.html"

Categories: Articles with unsourced statements since February 2007 | All articles with unsourced statements | Road transport | Traffic law | Transportation in the United States

Speed limits in the United States

From Wikipedia, the free encyclopedia

Contents

[edit] Charts

[edit] Speed limits

[edit] Legend

[edit] Footnotes

[edit] Other speed-related laws

[edit] Definition of speeding

[edit] Prima facie

[edit] Federal speed limit controls (55 mph)

[edit] Noteworthy state distinctions

[edit] Alabama

[edit] California

[edit] Delaware

[edit] Hawaii

[edit] Indiana

[edit] Iowa

[edit] Montana

[edit] New Hampshire

[edit] New York

[edit] Ohio

[edit] Oregon

[edit] Pennsylvania

[edit] South Dakota

[edit] Texas

[edit] 75 mph and 80 mph limits

[edit] 85 mph limits

[edit] Night speed limits

[edit] Texas

[edit] Other states

[edit] Environmental speed limits

[edit] Texas

[edit] Tennessee

[edit] Minimum speed limits

[edit] Truck speed limits

[edit] Theory

[edit] Truck speed limit differentials

[edit] Texas

[edit] Louisiana

[edit] Utah

[edit] Metric speed limits

[edit] References

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