2010-04-14 CC Packet - Laserfiche WebLink

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August 1, 2007 TRAFFIC ENGINEERING MANUAL The District Traffic Engineer shall then make the field investigation and prepare speed limit 10.kil'AtIlandations. These recommendations : should be discussed with the local authority after completion of the investigation. The local authority may be furnished with a copy of the investigation results, if they desire. The District Traffic Engineer shall submit a speed litnit recommendation report to the Assistant State Traf`f'ic Engineer, OTE -ITS, for review and approval. A formal authorization is then prepared by OTE -ITS for the approved speed limits. This authorization shall be limited to speed zoning only, and shall be signed by the Assistant State Traffic Engineer, OTE -ITS. Following receipt of Mir DOT authorization- the local authority shall install the speed limit signs. imp ` g. the authorization- Installation shall cotiforrn to the current. NIN MUTCD- When roadways are turned back, exchanged with other roadways or renumbered, technically the speed limit authorization is still in effect. However.. to prevent confusion and provide for unquestionable documentation in prosecuting speeding offenses, it is highly advised that 6e new road authority request a study of the road in question_ Subsequently.. the new authorization will list all information correctly- 13 -6.03 Principles of Speed Zoning The statutory speed bits are intended to provide uniformity for typical highways, tinder ideal: conditions and no. hazards- Alteration of the statutory speed limits: to fit existing traffic and physical conditions of the highway constitutes the basic principle of speed zoning. The objective of correct speed zoning is to influence as many drivers as possible to operate at or near the same speed, thus reducing conflicts created by wide differentials in speed It is widely recognized by traffic engineers and is a proven fact that wide differences. in speed fiequently to, crashes. The speed zone surely is , to determine the maximum safe speed that should be posted for that location to provide continuity of traffic flow. Correct and realistic speed zoning will serve to protect the public and regulate the unreasonable beh. avWr of an individual- Having recognized that normally careful and competent actions of a , cabtmidble driver should be considered legal, Mn/DOT has a responsibility 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 most efficient and orderly movement of traffic by increasing driver awareness of reasonable and prudent speed The speed limit should aid the motorist in adjusting speed to the conditions and furnish police a4ficers with an indication of what is excessive and unreasonable speed. 13 -6.04 Determination of Speed Limits The posted regulatory speed limits should be for off-peak hour traffic on an average weekday. The speed limit on a hard - surfaced road inust reflect clear, dry and ideal conditions, so that the road may be driven at the highest safe speed. When the weather, or road surface, deteriorates or traffic congestion occurs, it is then the driver's responsibility to reduce speed and drive accordingly.. When physical features at spot locations (such as limitedd sib distance, narrow bridges, blind intersections, etc.) or potential hazards (such- as pedestrians. children in unfenced playgrounds, etc.) occur, the use of warning signs and advisory speeds should be considered. Prevailing speeds, physical features, crash experience and traffic characteristics are the primary factors m determining the appropriate speed limit_. The most important factor is the 95th percentile speed from a spot speed study. The 85th percentile speed reflects a safe speed for existing conditions as perceived by the majority of motorists. Using the 85th percentile speed tends to group the other factors since they are reflected in the driver's choice of speed, which is altered to adjust for those conditions.. It also recognizes the need for considering the majority of drivers to be involved in the decision-making process which is necessary to establish an enforeeable limit. The 85th percentile speed is usually at or near the upper limits of the 10 mile per hour incremental "pace speed ". Posting a speed limit near the 85th percentile speed will result in the highest percentage of drivers being grouped in the pace speed. 13 -23 36