1. (a) Overview.

   1. (1) Purpose. This subchapter provides the information and procedures necessary for establishing speed zones and advisory speeds on the state highway system.
   2. (2) Applicability. This subchapter is intended for use by entities with authority to set speed zones. These procedures shall be followed by the Texas Department of Transportation (TxDOT), cities, and commanding officers of the U.S. military reservations when establishing speed zones on the state highway system. The Texas Turnpike Authority division of the Texas Department of Transportation, and regional tollway authorities shall follow these procedures when establishing speed zones on off-system turnpike highways.

   3. (3) Responsibilities.

      1. (A) The Traffic Operations Division will:

         1. (i) prepare procedures for establishing speed zones and advisory speeds;
         2. (ii) assist districts as necessary with speed zone studies; and
         3. (iii) review and approve district recommendations for speed zoning and prepare minute orders for commission action.

      2. (B) TxDOT districts will:

         1. (i) conduct engineering and traffic studies associated with the establishment of speed zones and advisory speeds;
         2. (ii) submit recommendations for speed zoning, along with results of studies to the Traffic Operations Division;
         3. (iii) request cities to pass ordinances or resolutions establishing speed zones when necessary; and
         4. (iv) erect and maintain necessary speed limit and advisory speed signs and notify local enforcement authorities upon installation of the signs.

      3. (C) Cities will:

         1. (i) request that the district conduct engineering and traffic studies associated with the establishment of speed zones on the state highway system within the city limits or conduct the studies themselves; and
         2. (ii) upon approval by the Traffic Operations Division, prepare and pass city ordinances or resolutions establishing speed zones.
      4. (D) A commissioners court of a county by resolution may request, through the local TxDOT district office, that the commission determine and declare a reasonable and safe prima facie speed limit lower than that established by Transportation Code, §545.352, on any part of a farm-to-market or a ranch-to-market road that is without improved shoulders located in that county.

2. (b) Background.

   1. (1) Basic speed law. Transportation Code, Chapter 545, Subchapter H, "Speed Restrictions," contains the following sections, which collectively are referred to as the "basic speed law," governing speeds in the state:

      1. (A) Section 545.351, Maximum Speed Requirements;
      2. (B) Section 545.352, Prima Facie Speed Limits (see also Transportation Code, §623.101, Speed Limit, relating to manufactured house or house trailer being towed);
      3. (C) Section 545.353, Authority of Texas Transportation Commission to Alter Speed Limits;
      4. (D) Section 545.3535, Authority of Texas Transportation Commission to Alter Speed Limits on Certain Roads;
      5. (E) Section 545.354, Authority of Texas Turnpike Authority or Regional Tollway Authorities to Alter Speed Limits on Turnpike Projects;
      6. (F) Section 545.355, Authority of County Commissioners Court to Alter Speed Limits (see also Transportation Code, §251.154, Maximum Reasonable and Prudent Speeds on County Roads);
      7. (G) Section 545.356, Authority of Municipality to Alter Speed Limits;
      8. (H) Section 545.357, Public Hearing to Consider Speed Limits where Certain Schools Are Located;
      9. (I) Section 545.358, Authority of Commanding Officer of United States Military Reservation to Alter Speed Limits;
      10. (J) Section 545.359, Conflicting Designated Speed Limits;
      11. (K) Section 545.360, Duty of Texas Transportation Commission and State Board of Education to Provide Information and Assistance;
      12. (L) Section 545.361, Special Speed Limitations;
      13. (M) Section 545.362, Temporary Speed Limits;
      14. (N) Section 545.3625, Confidentiality of Violation Information: Fuel Conservation Speed Limit;
      15. (O) Section 545.363, Minimum Speed Regulations;
      16. (P) Section 545.364, Speed Limits on Beaches; and
      17. (Q) Section 545.365, Speed Limit Exception for Emergencies; Municipal Regulation.
   2. (2) Basis. The basic speed law is founded on the belief that the majority of motorists are willing to modify their driving behavior properly, as long as they are aware of the conditions around them. Speed zone regulations are based on Transportation Code, §545.351, which states in part: "An operator may not drive at a speed greater than is reasonable or prudent under the circumstances then existing."
   3. (3) Prima facie concept. In Texas, all speed limits are considered "prima facie" limits. Prima facie limits are those limits which on the face of it, are reasonable and prudent under normal conditions. To exceed a prima facie speed limit does not automatically constitute an infraction of the law, as reasonable and prudent driving behavior is, at times, possible at speeds in excess of the posted limit. However, the burden of proof of reasonable and prudent conduct under the existing conditions rests with the driver. To afford a driver this opportunity to exceed a prima facie speed limit recognizes the fact that any posted speed limit cannot adequately reflect the many different road conditions confronting the driver on the same highways at different times.

   4. (4) Authority to set speed zones.

      1. (A) Transportation Code, §545.353, authorizes the commission to alter maximum speed limits on highway routes both within and outside of cities, provided the Procedures for Establishing Speed Zones are followed.
      2. (B) The altering of the general statewide maximum speed limits to fit existing traffic and physical conditions of the highway constitutes the basic principle of speed zoning.
      3. (C) Transportation Code, §§545.355 and 545.356 give counties and cities the same authority within their respective jurisdictions. The law also provides that any speed zone on highway routes in cities established by commission minute order will supersede any conflicting zone set by city ordinance or resolution.
      4. (D) Except in very unusual circumstances, the zoning on state highway routes within cities should only be set by city ordinance or resolution based upon the recommendations of TxDOT. The usual practice, even for speed zones established by city ordinance or resolution, is for TxDOT to make the necessary speed studies and recommend the most appropriate zoning to the city. Cities that have a traffic engineering staff may also make speed studies on state-maintained highways and recommend proper zoning. The procedure is permissible so long as TxDOT is afforded an opportunity to review and approve the recommended city zoning.
      5. (E) County commissioner courts and governing bodies of incorporated cities and villages may alter maximum prima facie speed limits on roadways under their jurisdiction in accordance with the provisions of Transportation Code, §§545.355 and 545.356 respectively. However, alteration of maximum prima facie speed limits on any designated or marked roadway of the state highway system, even within the corporate limits of a city, typically requires an engineering and traffic investigation in accordance with §25.23 of this title (relating to Speed Zone Studies), and the approval of TxDOT.
      6. (F) A county that increases the prima facie speed limit on a county road or highway is also required to conduct an engineering and traffic investigation. However, for a county road or highway outside the limits of the right of way of an officially designated or marked highway or road on the state highway system, the county commissioners court may declare a lower speed limit of not less than 30 miles per hour, if the commissioners court determines that the prima facie speed limit on the road or highway is unreasonable or unsafe.
      7. (G) County authority does not extend to any segment of the state highway system; however, the commissioners court of a county, by resolution, may request the commission to determine and declare a reasonable and safe prima facie speed limit that is lower than a speed limit established by Transportation Code, §545.352, on any part of a farm-to-market or ranch-to-market road without improved shoulders located in that county.
      8. (H) The commission shall give consideration to local public opinion and may determine and declare a lower speed limit on any part of the road without an engineering and traffic investigation, but the commission must use sound and generally accepted traffic engineering practices in determining and declaring the lower speed limit. Sound and generally accepted engineering practices for these FM and RM roadways without improved shoulders are described in §25.23(d) of this title.
      9. (I) This is different from the authority of cities, who may exercise concurrent authority subject only to commission override. In exercising their authority, cities must base any speed zones on engineering and traffic investigations, notwithstanding the type of road or street and whether the state highway system is involved.
      10. (J) The authority of the Texas Turnpike Authority, regional tollway authorities, and Commanding Officer of a United States Military Reservation to alter the speed limits are addressed in Texas Transportation Code, §§545.354 and 545.358. These decision making authorities are required to follow the speed zone procedures as adopted by the department when altering speed limits on off-system turnpikes or on-system highways within the confines of a military reservation.

   5. (5) Value of speed zoning.

      1. (A) Although comparative "before-and-after" studies indicate that speed limit signs actually have very little influence on the driver's choice of speed, speed zoning is necessary and does serve a worthwhile purpose. Realistic speed zoning will serve to protect the public and to regulate the unreasonable behavior of an individual. Having recognized that normally careful and competent actions of a reasonable person should be considered legal, the Texas Legislature has passed legislation concerning speed zoning in order to assure this protection. If a speed zone is determined by the actions of the majority of drivers on a highway, then it is hoped that speed zoning will facilitate the orderly movement of traffic by increasing driver awareness of a reasonable and prudent speed.

      2. (B) Properly applied speed zoning can:

         1. (i) help drivers adjust their speed to the conditions;
         2. (ii) make enforcement easier by furnishing police officers with a reasonable indication of what is excessive speed;
         3. (iii) result in more motorists driving within the same speed range at each of the locations along the highway; and
         4. (iv) reduce the frequency and severity of crashes when accompanied by enforcement.

      3. (C) The Michigan Department of Transportation made a study, entitled "Comparison of Speed Zoning Procedures and Their Effectiveness," dated September 1992. The following are some of the study's conclusions.

         1. (i) Posting speed limits within 5 miles per hour of the 85th percentile speed has a beneficial effect, although small, on reducing total crashes, but has a major beneficial effect on providing improved driver compliance. (See §25.23(b) of this title for a discussion on the 85th percentile speed.)
         2. (ii) Posting speed limits more than 5 miles per hour below the 85th percentile speed does not reduce crashes and has an adverse effect on driver compliance.
         3. (iii) Speed zoning should not be used as the only corrective measure at high crash locations in lieu of other safety improvements.
         4. (iv) The use of radar to collect speed data appears to underestimate the 85th percentile speed by approximately 3 miles per hour.

   6. (6) Guidelines for selecting speed limits. All authorized entities using these procedures should observe the following guidelines when setting speed limits.

      1. (A) Speed limits on all roadways should be set based on spot speed studies and the 85th percentile operating speed (see §25.23 of this title). Legal minimum and maximum speeds should establish the boundaries of the speed limits. If an existing roadway section's posted speed limit is to be raised, the roadway's roadside features should be examined to determine if modifications may be necessary to maintain roadside safety.
      2. (B) It is appropriate for posted speed limits to be based on the 85th percentile speed, even for those sections of roadway that have an inferred design speed lower than the 85th percentile speed. Posting a roadway's speed limit based on its 85th percentile speed is considered good and typical engineering practice. This practice remains valid, even where the inferred design speed is lower than the resulting posted speed limit. In such situations, the posted speed limit would not be considered excessive or unsafe.
      3. (C) Arbitrarily setting lower speed limits at point locations due to a perceived shorter than desirable stopping sight distance is neither effective nor good engineering practice.

      4. (D) If a section of roadway has, or is expected to have, a posted speed in excess of the roadway's inferred design speed and a safety concern exists at the location, then appropriate warning or informational signs should be installed to warn or inform drivers of the condition.

         1. (i) Slightly shorter than desirable stopping sight distances do not present an unsafe operating condition because of the conservative assumptions made in establishing desirable stopping sight distances.
         2. (ii) It is important to remember that any sign is a roadside object and that it should be installed only when its need is clearly demonstrated.
      5. (E) New or reconstructed roadways and roadway sections should be designed to accommodate operating speeds consistent with the roadway's highest anticipated posted speed limit based on the roadway's initial or ultimate function.

3. (c) Factors affecting safe speed.

   1. (1) Introduction. This subsection discusses various factors influencing drivers and their perception of the safe speed at which to operate a vehicle. Because so many variables affect the safe operating speed of vehicles, it is not practical to consider each individually. These factors should be considered as a whole and weighed accordingly.

   2. (2) Design and physical factors of the roadway.

      1. (A) The design and physical factors of the roadway place a definite limitation on the safe operating speed of vehicles. These factors include:

         1. (i) horizontal and vertical curves;
         2. (ii) hidden driveways and other roadside developments;
         3. (iii) high driveway density;
         4. (iv) rural residential or developed areas; and
         5. (v) lack of striped, improved shoulders.
      2. (B) Speed restrictions, if any, imposed by some curves can be calculated easily and checked by the use of the ball bank indicator, described in §25.25(b) of this title (relating to Curves and Turns). Likewise, the restriction imposed by obstructions to sight distance can be calculated.
      3. (C) The effects of such factors as lane width, condition of surface, type and width of shoulders, frequency of intersections, and roadside development are not so easily measured. As a general rule, especially on tangents, these factors will be measured on the basis of prevailing speeds as determined by speed checks.

   3. (3) The vehicle.

      1. (A) The mechanical condition of vehicles and their characteristics for accelerating, decelerating, stopping, and turning definitely affect safe speeds.
      2. (B) The body roll angle of different makes of cars and year models of the same make also affects the safe operating speed on curves.
      3. (C) Braking capabilities of different vehicles, such as passenger cars, buses, and various truck-trailer combinations, are obviously different, and it would generally not be practical to post safe speeds for each group.
      4. (D) Normally, the posted speed will be that for the passenger car.

   4. (4) The driver.

      1. (A) The ability of different drivers varies from skillful to those who would not be able to pass an examination for an operator's license if required to take one. It would not be wise to post safe speeds for drivers at either of the two extremes of abilities, so the selection of speeds to be posted will be aimed at the ability and performance of the average driver.
      2. (B) Average driver ability, of course, is considered in the form of perception--reaction time in the calculation of critical approach speeds to intersections, crosswalks, and locations with limited sight distance and in determining the posting distance for signs.

   5. (5) Traffic.

      1. (A) The presence of other vehicles on the highway, including those which may be entering, crossing, turning off, or parked definitely affects operating speeds.
      2. (B) The frequency of pedestrians is likewise an important factor. This is especially true at intersections with limited sight distance and at approaches to crosswalks.
      3. (C) The speeds shall be posted for off-peak hour traffic on an average weekday for the purpose of the procedures outlined in this subchapter. This will require drivers to adjust their speeds to lower values at times of peak hour traffic at some locations.

   6. (6) Weather and visibility.

      1. (A) Speeds will normally be selected and posted for good weather conditions and dry pavement. Texas law, however, also provides for the posting of speeds for wet weather conditions.
      2. (B) Except in cases where the statewide maximum legal limits are posted, speeds will normally be posted on the basis of daylight speed values determined under good weather conditions. It is permissible, however, for different day and night speeds to be posted for speed zones where it can be shown to be necessary by nighttime speed surveys.

      3. (C) When it can be shown that it is required during wet or inclement weather, a wet weather speed zone may be established by commission minute order.

         1. (i) The wet weather speed limit should be posted in addition to the regular posted speed zone.
         2. (ii) When appropriately signed, this wet weather speed limit will be effective during wet weather at any time during hours of daylight and darkness.

Source Note:The provisions of this §25.21 adopted to be effective February 17, 2000, 25 TexReg 1151.