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Roads
and Highways in America
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Interstate
Highway System
Known officially as the Dwight
D Eisenhower System of Interstate and Defense Highways, this
massive federal road-building project began in the late 1930s.
But it wasn't until 1952 that Congress authorized spending
and construction began. In 1956, uniform construction standards
were adopted, governing such things as access, speeds, number
of lanes, width of lanes and width of shoulders.
Standards for numbering
the routes
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North-south highways
are numbered Odd in increasing order as you go from west
(I-5 in California) to east ( I-97 in Maryland)
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East-west highways are
numbered Even in increasing order as you go from south
(I-4 in Florida) to north ( I-96 in Michigan)
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One other rule is that
roads divisible by 5 (E.g I-5, I-10, I-55, I-80, etc.)
tend to be the major roads that cross most, if not all,
of the country.
Three highways run from coast
to coast: I-10, I-80, and I-90.
Seven highways run from border
to border: I-5, I-15, I-35, I-55, I-65, I-75, and I-95.
What about 3 digit
Interstates?
Most Interstates have children
when they reach major cities.
If the baby Interstate goes
through the city or all the way around the city, then it will
start with an even number. 3-digit Interstates starting with
2, 4, 6, and 8 typically start and end at an interstate. Beltways,
like I-495 around Washington D.C, also start with even numbers.
When an interstate hits a major urban area, beltways around
the city carry a three-digit number. These routes are designated
with the number of the main route and an even-numbered prefix.
To prevent duplication within a state, prefixes go up. For
example, if I-80 runs through three cities in a state, routes
around those cities would be I-280, I-480 and I-680. This
system is not carried across state lines, so several cities
in different states can have a beltway called I-280.
If the baby Interstate stops
somewhere in the city, then it gets an odd third digit. They
are spur routes (as in spur into a city), that is, a 3-digit
Interstates starting with an odd-numbered typically has a
dangling end.
Everything Illustrated
In this map of Washington D.C
vicinity, you can notice the following:
I-70 is a
major (divisible by 5) East-west highway (runs from Baltimore,
MD to Cove Ft, UT total 2175 miles)
I-66 is a
not so major (not divisible by 5) East-west highway (runs
from Washington DC to Middletown, VA, total 77 miles )
I-95 is a
major (divisible by 5) North-south highway (runs from Houlton,
ME at the Canadian border to Miami, FL, total 1907 miles)
I-495 is the
famous Beltway. That is, I-95 instead of passing through Washington
D.C, forms a Beltway. Note the three digit numbering and even
digit ‘4’
I-270 is a
three-digit-loop baby interstate. Note the prefix digit ‘2’
even – because it has Interstate highways on both its ends
(I-70 and I-495)
I-395 is a
three digit-spur baby interstate. Note the prefix digit ‘3’
odd – because it is a spur into Washington D.C downtown and
doesn’t have an Interstate in that end.
System for numbering
interstate interchanges, also known as exits
States do this numbering and
can choose between two methods:
1. The consecutive numbering
system starts at the most western or southern point on each
Interstate route, and interchanges are numbered consecutively
(so the first one is Exit #1).
2. The milepost system numbers
the interchange according to the miles counted, starting at
the most western or southern point. An interchange occurring
between mileposts 47 and 48 would be designated Exit #47.
Toll
Roads and E-Z Pass
You never want to be stuck
on a toll road without a pocket full of change. It can be
a bit nerve-racking to dig through the car seats, trying to
find something to give to the toll booth attendant while drivers
behind you honk and yell for you to move on. These are the
kinds of situations that cause delays at toll plazas.
Millions of drivers pass through
toll booths every day. Traditionally, the process is to put
some change in a basket, which tabulates the coins and opens
a gate to allow the driver through. Today, many local and
state traffic agencies have installed or are installing electronic
readers that allow drivers to pass through toll stations without
coming to a complete stop. Thus, most toll roads are equipped
with an electronic toll-collection system, like E-Z Pass that
detects and processes tolls electronically. E-Z Pass is used
by several U.S. states (in east coast), but most other electronic
toll systems (like I-Pass of our Illinois State) are very
similar to E-Z Pass. Basically, E-Z Pass uses a vehicle-mounted
transponder that is activated by an antenna on a toll lane.
Your account information is stored in the transponder. The
antenna identifies your transponder and reads your account
information. The amount of the toll is deducted and you're
allowed through. Electronic toll collection is designed to
make traffic flow faster, as cars don't have to stop to make
a transaction.
Here's how the
system works
1. As a car approaches
a toll plaza, the radio-frequency (RF) field emitted from
the antenna activates the transponder.
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2. The transponder broadcasts
a signal back to the lane antenna with some basic information.
3. That information is
transferred from the lane antenna to the central database.
4. If the account is
in good standing, a toll is deducted from the driver's
prepaid account.
5. If the toll lane has
a gate, the gate opens.
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6. A green light indicates
that the driver can proceed. Some lanes have text messages
that inform drivers of the toll just paid and their account
balance.
The entire process takes a
matter of seconds to complete. The electronic system records
each toll transaction, including the time, date, plaza and
toll charge of each vehicle. Typically, consumers maintain
prepaid accounts. The lanes are monitored using video cameras.
If you try to go through the plaza without a transponder,
the camera records you and takes a snapshot of your license
plate. The vehicle owner then receives a violation notice
in the mail.
HOV
Lanes - Less Pollution
High occupancy
vehicle (HOV) lanes, commonly called carpool lanes, are lanes
reserved for people who share the ride in carpools, vanpools
and/or buses or drive a motorcycle. These lanes are marked
with a diamond symbol and HOV signs. HOV lanes reduce traffic
congestion, protect the environment and save tax money. They
help highways move more people efficiently.
HOV lanes offer
relatively fast, reliable travel, particularly when traffic
is congested. This is an incentive to commuters who are able
to share the ride, which frees up space on unrestricted lanes
for those who can't or don't carpool, vanpool, or take the
bus. High occupancy vehicle lanes carry more people than unrestricted
lanes.
Traffic congestion
increases air pollution. The federal government recommends
adding HOV lanes to help reduce pollutants from cars and trucks.
The major contributor to ozone and carbon monoxide gases in
urban areas is the automobile. HOV lanes help because
they encourage people to switch from single occupant vehicles
to riding in buses, carpools and vanpools. By reducing congestion
and air pollution.
Those of you
residing in the metro areas of big cities like Atlanta, Houston,
SFO, LA, Washington D.C etc., must be knowing about or using HOV
lanes. Generally HOV lanes are inner most lane(s) as these
are the least affected by traffic entering or exiting
the highway. Successful HOV lanes are those that best allow
reliable and uninterrupted travel times. This is typically
the situation in the left lane where HOVs are less affected
by vehicles weaving between lanes. Each state dictates/decides
the HOV restrictions and rules. For example, Virginia has
a special exemption for less polluting vehicles, even if it's
occupied by one person.
Talking of
air-pollution and HOV, Hybrid gas-electric autos such as the
Toyota Prius, the Honda Insight
and the Honda Civic Hybrid are exempt from
Virginia's HOV highway restrictions, provided the owner spends
$10 for "clean fuel" license plates. (The neighboring
state Maryland does not provide this HOV exemption).
This is one way that folks can drive alone in the HOV lanes
during rush hours and not receive a citation. The Prius
(five seats), Civic Hybrid (five seats) and Insight (two seats)
work on a combination of gasoline and electric power from
self-recharging batteries getting as high as 60 miles to a
gallon!!!
Links of Interest:
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