The Array of Roadways
When considering the topic of speed limits on different types of roadways in the United States, it is important to know the characteristics that make up each type of roadway. Some types of roadways, like local roads, are designed for a relatively low rate of speed for the traffic that travels on them. Other types of roads, especially interstates, are designed for motorists to drive at relatively high rates of speed. Each of these types of roads have characteristics that influence the speed limits.
Let’s first begin with local roads. Local roads would be your average city or rural street. According to the U.S. Department of Transportation in their article “Road Function Classifications,” these local roads “provide limited mobility and are the primary access to residential areas, businesses, farms, and other local areas” and are the majority of roads in the United States. These types of roads are not built to go fast on, because a high rate of speed would put the drivers and pedestrians on and around these type of roads in danger. Also according to the U.S. Department of Transportation in their article “Road Function Classifications,” the fatality rate, at 2.13 fatalities per 100 M VMT (100 million vehicle miles travelled), of these types of roadways from speeding and non-speeding accidents is one of the highest of any type of roadway. It would seem to be pretty illogical to increase the speed limit on this category of roads, as an increase in speed limit would more than likely increase the number of driver and pedestrian fatalities.
The next category of roads is called collectors. According to the U.S. Department of Transportation in their article “Road Function Classifications,” collectors are major and minor roads that connect local roads with arterials such as highways and freeways. These roads have on average a slightly higher speed limit than local roads. These roads have proven to be dangerous, as the U.S. Department of Transportation states that they have the highest overall fatality rate of any type of road, at 2.17 per 100 M VMT. The danger of this type of roadway makes it clear that the speed limit on these types of roads does not need to be increased. An increase in the speed limit on these roads would more than likely result in a spike of the fatality rate.
These first two categories of roads seem to fit into one big category; roads that the speed limit should never be increased on. These types of roads generally include multiple intersections. According to the National Department of Transportation’s Federal Highway Administration, approximately 40% of all accidents in the year 2007 were intersection or intersection-related crashes. This high percentage makes it clear that roads with many intersections should not have the speed limit increased as all it would do is lead to more red lights and stop signs ran, and less vigilance in the intersections. This carelessness would lead to a higher number of accidents.
The next category of roads is arterial roads such as highways and freeways. According to the U.S. Department of Transportation in their article “Road Function Classifications,” these roads connect major cities and industrial areas at a higher rate of speed than local roads and connectors. These are your average four to eight-lane highways that go through one state, such as New Jersey’s Route 55, connecting route 42 to Philadelphia to route 47 in Maurice River Township. These roads are designed to be traveled on at a higher rate of speed to help drivers get from one major area to another as quickly as possible. The 1999 study in the U.S. D.O.T.’s article “Road Function Classifications,” shows that the fatality rate of arterials has the second-lowest fatality rate of any type of road at 1.48 fatalities per 100 M VMT. Increasing the speed limit on a road like this with an already high rate of speed and a lower fatality rate seems much more reasonable than on the local and connector roads.
The final category of roads is interstates. Interstates are large arterial roads that connect two or more states. An example of an interstate is I-95, stretching from northern Maine to southern Florida. According to the U.S. Departement of Transportation in their article “Road Function Classifications,” an interstate has the “highest level of mobility and the highest speeds over the longest uninterrupted distance”. These highways are generally travelled by people who are going between two or more states. The high level of mobility makes interstates the safest type of roads compared to all other types of roads and allows them to travel at much faster speeds than local roads or collectors. According to the U.S. Department of Transportation in their article “Road Function Classifications,” the fatality rate on interstates is 0.87 fatalities per 100 M VMT. This number is lower than half the rate of collector and local roads. Raising the speed limit on interstate highways also seems pretty reasonable when considering the fatality statistics.
The last two roads discussed also seem to fit into another category, roads that someday could have the speed limit increased on. Highways and interstates generally do not have many intersections and sometimes do not have any at all. This lack of intersections makes travelling at higher speeds safer. Also, arterial roads, especially interstates, have long stretches of straight road. Increasing the speed limit in these areas would more than likely help the traffic to move quicker and more seamlessly.
The main topic to focus on when considering raising speed limits is if it would be safe to do so. On local and collector roads, the high fatality rate makes it clear that it would not be safe to do so. A few characteristics of these roads such as low mobility and multiple intersections differentiate them from arterials. Unlike local and collector roads, arterials have high mobility and very few to no intersections. On arterial roads, the relatively low fatality rate makes raising the speed limit seem more reasonable.
Intersection Safety Issue Briefs. (2009, November). Retrieved October 09, 2020, from https://safety.fhwa.dot.gov/intersection/other_topics/fhwasa10005/brief_2.cfm
U.S Department of Transportation. (2000, November). Road Function Classifications. Retrieved October 9, 2020, from https://safety.fhwa.dot.gov/speedmgt/data_facts/docs/rd_func_class_1_42.pdf