Speed Limits in Frederick County Discussion Paper Revised May 1997

What Agency is Responsible for Posting Speed Limits?
State-maintained roads usually have a number (MD 550, US 15, I-70, etc.) and are under the jurisdiction of The Maryland State Highway Administration, District-7 office, (301) 624-8100.

County-maintained roads are under the jurisdiction of The Division of Public Works. Call (301) 600-1687 to discuss County-road speed limits.

City/Municipal-maintained streets are under those jurisdictions.

Basic Speed Law
The Maryland Vehicle Law provisions on speed limits are based on the premise that the behavior of most drivers is reasonable. The speed laws are written to single out the unreasonable behavior of a minority of our drivers. The basic speed law states:

"A person may not drive a vehicle on a highway at a speed that, with regard to the actual and potential dangers existing, is more than that which is reasonable and prudent under the conditions. "

Reasonable drivers want to travel about as quickly and safely as possible. Consequently, they will select speeds with which they are comfortable, neither too fast nor too slow. It will be based on an instinctive consideration of the conditions that they encounter, such as traffic volume, weather, and road geometry. The posted speed has little effect on the speed that they choose. Regulatory speed limits (black-on-white signs) are posted to inform the motorists of the speed which is considered reasonable by a majority of drivers on the road. Only these signs can be enforced. Advisory speeds (black-on-yellow supplemental signs below curve warnings, etc.) are intended to warn a driver of a situation ahead, like a sharp curve, intersection, or stop ahead.

Setting Speed Limits
Years of experience and research have led engineers to the conclusion that the 85th percentile speed is a reasonable speed. This is the speed at, or below, which 85 of 100 drivers will travel the road. It is an acknowledgement that 15% of drivers drive unreasonably for the given conditions. Many speed studies conducted over the past several decades have found that the likelihood of an accident is lowest when the majority of motorists are moving at the same rate. The 85th percentile speed is the safest rate for all ranges; safer even than the 50th percentile (half travel faster, half travel slower) or the average speed (sum of all speeds divided by the number of vehicles) for the simple reason that the speed differential is least for this group. Measurements of the 85th percentile are made under free-flowing and ideal traffic conditions. Finally, the engineers will consider other factors such as number of driveways, the volume of traffic, the proximity of schools and playgrounds, and the like; however, the basic speed limit through a zone remains premised on the 85th percentile. There are other appropriate signs (curve warnings, intersection-ahead signs, school signs, etc.) that are intended to complement the overall signing scheme.

Maximum Limits
Section 21-801.1 in The Maryland Vehicle Law (MVL) lists the maximum speed limits for certain roads. In summary the limits are as follows. Please reference the MVL for the complete language and definitions.

• 30 mph on all highways in a business district
• 30 mph on undivided highways in a residential district
• 35 mph on divided highways in a residential district
• 50 mph on undivided highways in other locations
• 55 mph on divided highways in other locations

[In 1996 the State began raising some Freeway and Interstate limits to 60 or 65 mph.]

The MVL allows that the above maximum limits can be changed by the duly authorized jurisdiction.

It is unreasonable to expect all streets and roads, especially in subdivisions, to be posted in both directions between each block. The police can write tickets on unsigned roads in subdivisions but they prefer to have the signs up, for the obvious reason that they will have more standing in court. They might also cite "reckless driving" instead of speeding, thereby avoiding the posted-versus-not posted dispute. The Department of Highways and Transportation will only undertake a priority signing review and sign erection in subdivisions following notice directly from the Sheriff's office that they are planning an enforcement campaign on those streets. Otherwise, we will respond to requests for signs on a first come, first served basis, with respect to our own prioritization schedule for County-wide sign maintenance and safety reviews.

Common Misconceptions
“Lower speed zones reduce speeds and reduce accidents."
Setting an arbitrarily low speed limit is not proven to cause nominal speeds to drop. Before and after studies consistently determine that speeds remain very nearly the same regardless of the number on the sign. Unrealistically low speeds promote a general disregard for all speed limits. Frustrated drivers may speed up (to make up lost time) or pass illegally to get around slower traffic. Enforcement personnel must not only deal with the 15% minority of unreasonable speeders, but now must bear the brunt of the dissatisfaction when ticketing reasonable drivers who "violate" the low number when conditions clearly support higher speeds.

"My street is different because kids play on or near the street."
We respectfully respond that children can be found just about everywhere. Drivers know which days are school days, and on which streets kids can typically be found (i.e., in subdivisions, etc.) but they are still responsible to obey the tenets of The Maryland Vehicle Law and drive for the given conditions for all roads. The majority of drivers on your street are frequent users of that street; maybe not everyday users, but often enough users to know the nominal conditions.

"Raising the speed limit by 5 or 10 mph will raise the speeds by 5 or 10 mph. It is a mandate to promote speeding!"
Most all speed increases are the result of speed studies that have determined that the posted limit is sufficiently below the measured 85th percentile. Given this presumption, the new limit will not cause drivers to go 5 or 10 mph faster, but rather is a correction to bring the posted speed in line with what the given conditions already support. Also, it is now easier for enforcement personnel to target the 15% minority of unreasonable drivers who are truly speeding. The Office of Transportation Engineering will always endeavor to do before and after studies to confirm this premise.