Which roads and intersections are under Mercer County jurisdiction?

Roads in Mercer County operated and maintained by state, county or local government. The New Jersey Department of Transportation (NJDOT) maintains major routes, such as U.S. Route 1, U.S. Route 130, and N.J. Route 33. NJDOT also maintains interstate routes, such as I-295, I-95 and I-195. County routes are typically assigned a three-digit route number, beginning with numerals 5 or 6. Click here for a full list of county routes and their limits. Nearly all other roadways are maintained by the local municipality in which the roadway is located or by a private entity.

In the case of intersections, typically, the "higher" government entity is responsible. For example, if the location were the intersection of a county road and a local road, the intersection would fall under the county jurisdiction. If the two roadways are formed by a county road and state highway, the NJDOT has jurisdiction. Where both streets are maintained by a single entity, for example County Route 535 (Old Trenton Road) and County Route 571 (Princeton - Hightstown Road) that entity (in this case, Mercer County) would have responsibility for the location. Where the location consists of roadways maintained by two different municipalities, you would need to contact each to find out who has legal responsibility.

For quick reference, visit our County Routes and Roadways webpage to review the extents of County-maintained roadway for each of our 12 municipalities.

For a complete list of Mercer County Routes and Roadways, please view or download the following spreadsheet:
Mercer County Routes and Roadways - By Route

What is the process for installing a traffic signal at an intersection under county control?

Under New Jersey State Law, installation of traffic signals, even locations under county jurisdiction, require approval from the New Jersey Department of Transportation (NJDOT). The NJDOT submittal package includes a crash summary report, traffic count data as well as certification from a licensed Professional Engineer that the intersection meets the criteria for installation of a traffic signal as specified in the Manual on Uniform Traffic Control Devices (MUTCD).

Unfortunately, installation of a traffic signal is often seen as the cure-all for making intersections safer and more efficient. In fact, installation of a traffic signal can have the opposite effect, increasing other types of accidents causing congestion, and having adverse environmental impacts. Motorists on the side street often face longer travel delays as they wait for the green signal. The constant stopping and starting of vehicles as compared to the non-signalized free flow conditions on the main street also increases noise levels and degrades air quality. Finally, traffic signals may divert motorists, who normally use the main street, to narrower, less suitable streets to avoid the traffic signal.

What is the process for getting the speed limit reduced on a County roadway?

While it is certainly reasonable to conclude that lowering the speed limit, posting new signs and increasing enforcement will cause drivers to travel at the posted speed limit, studies have shown drivers are more influenced by the appearance of roads and the prevailing traffic conditions than by speed limit signs. Research studies have also found that if posted speed limit is lower than the prevailing travel speed, many drivers will simply ignore the signs while others will operate their vehicle near the posted speed. This increases conflicts between faster and slower vehicles, reduces the number of gaps in traffic through which pedestrian and vehicle crossings could be made safely, and increases the ability for pedestrians to judge the speed of approaching vehicles. Exiting driveways also becomes more difficult.

New Jersey State Law requires that speeds limits, even on county roadways, be approved by the New Jersey Department of Transportation. The first step in having a speed limit reduced requires that a speed survey be conducted to identify the prevailing travel speeds of motorists using the roadway. This information is then be submitted to the New Jersey Department of Transportation (NJDOT) for concurrence and approval of the recommended speed limit. Since the local police department is responsible for enforcement of new speed limits, we would obtain their concurrence prior to submitting a request to NJDOT for a speed limit reduction.

What is the process for establishing a school zone speed limit on a County road?

The establishment of school zone speed limits requires adoption of an ordinance and approval from the New Jersey Department of Transportation. In general, speed reductions of 10 MPH below the existing posted speed limit would be permitted where children walk or ride a bicycle to school or where school ingress and egress activity would warrant reduction of the posted speed limit. Furthermore, the school speed limit would only be in effect along the roadway section abutting the school property. Where approval is granted for a establishing a school zone speed limit, the county would install appropriate signage to this effect. However, if additional measures were requested, such as flashing lights, the local municipality or school would be responsible for construction and electrical service costs.

What is the process for getting a crosswalk installed on a County road?

By New Jersey State Law, motorists are required to yield to pedestrians at intersections. Therefore, crosswalks in effect, exist at all public street intersections and do not require specific approval by NJDOT. Due to the extensive number of intersections throughout Mercer County, installation of crosswalk lines at all of these locations is simply not feasible. Therefore, we limit installation of crosswalk lines to locations of known pedestrian activity.

Installation of crosswalk lines at locations that are between public streets or at private driveways are considered midblock crosswalks and must be legally established by ordinance and approved by the New Jersey Department of Transportation. In general, midblock crosswalks are not permitted within 300 feet of a public street intersection, must be at a location where there is adequate visibility and must have a demonstrate use by pedestrians. State approved signs must be provided at and in advance of the location.