For many trips, the interstate highways are the most efficient way to travel by automobile between two points. Being limited access highways, interstates do not have traffic lights except on rare occasions. They typically have speed limits of 55 miles per hour or more. And they are well maintained and have the latest safety features.
The number that is assigned to an interstate highway has a specific meaning in identifying its purpose:
Even numbered one- and two-digit interstates under 100 transverse the country west to east. Higher numbers are further north and lower numbers are further south. Those ending in 0 are typically longer, transversing nearly the entire country.
Odd numbered one- and two- digit interstates under 100 transverse the country north to south. Higher numbers are further east and lower numbers are further west. Those ending in 5 are typically longer, transversing nearly the entire country.
• Three-digit numbered interstates are generally localized highways that intersect with a one- or two-digit interstate. They share the last two digits with the main highway, and run either near or off of that highway.
Types of signs
Directional signs: Indicate what exits one should take to reach a certain destination. Usually appear in green.
Distance signs: Indicate the distance in miles to various cities, towns, or other points along the highway or other routes off the highway. Usually appear in green.
Service signs: Indicate certain service related businesses, such as food, fuel, and lodging, are coming up at a nearby exit. Usually appear in blue, and display the logos of various chain businesses.
Mile markers: Indicate which mile point one is at from the state line. Sometimes appear every mile, sometimes every tenth of a mile.
Like most other roads, all interstate highways have speed limits. The limits, which are controlled and enforced by the respective states where they are located, can vary, depending on the laws of that state, the volume of traffic, and other factors. Typical speed limits range from 55-75 miles per hour, though there are exceptions both above and below this.
Tolls exist on some interstates. The tolls could be either for the highways themselves or for bridges along the highways.
Some of the tolls on Interstate Highways are (this list is currently incomplete):
Delaware: between exit 1 (DE-896) and exit 109 in Maryland (MD-279), there is a $4 toll in each direction. This toll is described by signs as being for the entire Delaware Turnpike, though it only needs to be paid if traveling between these two exits. The toll can be avoided southbound by taking exit 1 north, turning left on Christiana Parkway (DE-4/896), and left on Elkton Road (DE-2/MD-279), then re-entering I-95, or the reverse while traveling northbound. This takes an addition 10 minutes.