When You Enter the Right Lane of a Controlled Access Highway from the Right Lane of Another Controlled Access Highway

Last Edited: November 13, 2016 // by TruckerScape, Inc.

Cloverleaf Interchange Basics

Risks in interchanges connecting one interstate or major highway with another may be underappreciated by some drivers.  Exits and entrances are more complicated and require more attention and care than those of minor highways and surface streets.  Many interchanges are “cloverleafs,” with ramps connecting the right lanes of one highway with the right lanes of the other highway, so all entries onto both highways are merges from the right in the direction of travel.  A “full” or complete cloverleaf interchange between two highways has eight ramps.  For each highway, there are two exit (off) and two entrance (on) ramps connecting to it in each of its two travel directions.

Looking at the two exit ramps for one highway (the “originating” highway) as viewed from one of its travel directions, the first ramp exits the originating highway on the near side of the second (“destination” highway), i.e., before the originating highway crosses over or under the destination highway.  This ramp runs from the right lane of the originating highway to the right lane of the destination highway in a relatively direct line.  From the originating highway’s point of view, the ramp takes traffic onto the destination highway in a direction of travel to the right.

The second exit ramp exits the originating highway on the far side of the destination highway, i.e., after the originating highway has crossed over or under the destination highway.  This ramp runs from the right lane of the originating highway in a right-hand loop onto the right lane of the destination highway.  From the originating highway’s point of view, the ramp takes traffic onto the destination highway in a direction of travel to the left.

In a full interchange the two highways, in each of their two directions of travel, are both an originating and a destination highway.  Four right-hand loop ramps are required to take traffic onto their right lanes in the “left” direction of travel.  Thus when viewed from overhead, the interchange layout resembles a cloverleaf.

We are going into detail about cloverleaf interchanges to point out potential contention between exiting and entering vehicles at certain “pinch points” on them.  Pinch points pose a degree of risk, especially those in which some vehicles slowing down from highway speeds are mixing with others accelerating from much lower speeds.  In the following discussion, we will follow your travel from the end (or outlet) of your originating highway’s right-hand loop exit ramp, through a pinch point, and onto the destination highway.

NOTE:  The potential problems we are describing here generally do not exist on cloverleaf interchanges between a highway and a surface street or between major surface streets.  This is because traffic flow at street ramp exits and entries is controlled by stop lights or stop or yield signs.

Labeling Cloverleaf Interchange Ramps

All ramps running between one controlled access highway and another start from their originating highway and terminate on their destination highway.  To describe these ramps, we will refer to the highway whose exit ramp end (or outlet) you are emerging from as “your originating highway.”  We will focus on one direction of travel on your originating highway and use it as our primary base of reference (or point of view) and assign it the number 1.  The destination highway from the point of view on your originating highway will be assigned the number 2.  When you take a ramp from your originating highway, we will call the ramp at its outlet at the destination highway an entrance ramp (1 to 2).

The ramp could also be called an exit ramp (1 to 2) at its start (or inlet) from your originating highway.  But in this discussion we focus on what you do at the ramp’s outlet, not at its start. On a full cloverleaf interchange, there are two such entrance ramps (1 to 2) from your originating highway, the first joining the destination highway in its right direction of travel (from your originating highway’s point of view), and the second joining the destination highway in its left direction of travel.

Reaching the Destination Highway in the Direction of Travel to Your Right

If you’re making what is in effect a right turn from the right lane of your originating highway to the right lane of the destination highway, you will take your originating highway’s first entrance ramp (1 to 2).  The start (or inlet) of this first entrance ramp (1 to 2) is on the near side of the destination highway, before you reach an entrance ramp (2 to 1) from the destination highway.  You will avoid contention with traffic emerging from the destination highway’s entrance ramp (2 to 1), as well as a crossover or cross under of the destination highway.  Merging from the end (or outlet) of your ramp (1 to 2) into the right lane of the destination highway is relatively straightforward.  But as discussed in other tips, you still need to be careful around other vehicles in your vicinity.

Reaching the Destination Highway in the Direction of Travel to Your Left

If you’re making what is in effect a left turn from the right lane of your originating highway to the right lane of the destination highway, you will take your originating highway’s second entrance ramp (1 to 2).  To reach the start (or inlet) of this second entrance ramp (1 to 2), you first have to navigate through a pinch point on your originating highway.  This is because in a cloverleaf interchange, your second entrance ramp (1 to 2) departs your originating highway on the far side of the destination highway.

As you approach your originating highway’s second entrance ramp (1 to 2), you will have to contend with vehicles emerging from the destination highway’s second entrance ramp (2 to 1).  (These vehicles have been traveling in the right direction from your originating highway’s point of view.)  You will have to interweave with them as you cross over or under the destination highway to get to your second entrance ramp (1 to 2).  For more details see the When You Exit the Right Lane of a Controlled Access Highway to the Right Lane of Another Controlled Access Highway tip.

Once you have entered your second entrance ramp (1 to 2), wound around its right-hand loop and reached its outlet onto the destination highway, you will have to contend with vehicles exiting the right lane to reach the start of their second entrance ramp (2 to 1).  (In contrast to the vehicles emerging from the second entrance ramp (2 to 1) that you just maneuvered through, these vehicles are traveling in the opposite (left) direction from your originating highway’s point of view.)  You will have to interweave with these vehicles in order to merge into the destination highway’s right lane.

You may be able to help yourself and other drivers from your vantage point on the ramp loop as it guides you away from your originating highway, then points you towards oncoming traffic on the destination highway before turning further to align with the destination highway.  By observing oncoming entrance traffic, you may be able to anticipate or “time” which vehicles you will be able to emerge in front of and which, especially trucks, you will have to let in front of you.

Once in the right lane of the destination highway, you will be driving in the left direction of travel from your originating highway’s point of view.

The Apron for Right-Hand Loop Entrances and Exits

There is often a short merge lane or “apron,” to the right of the right lane on the destination highway.  The apron starts at the outlet of your second entrance ramp (1 to 2), runs under or over the destination highway and ends at the destination highway’s second entrance ramp (2 to 1).  (Some aprons run past the destination highway’s second entrance ramp (2 to 1) to provide a longer acceleration lane for you and other drivers emerging from your second entrance ramp (1 to 2).  To get to the destination highway’s right lane, you have to move left out of the apron as vehicles exiting the destination highway move right into the apron to reach their second entrance ramp (2 to 1).  Their ramp (2 to 1) takes them onto the right lane of your originating highway in the direction of travel opposite yours.  Put another way, their ramp (2 to 1) takes them onto your originating highway in the left direction of travel from the destination highway’s point of view.

The Pinch Point

The highway interchange “pinch point” is where drivers moving from one highway to the other should be particularly careful of others making the opposite switch.  Drivers should cooperate by merging in alternating fashion to change lanes, with extra attention paid to trucks alongside them.  Navigating through this pinch point mix (or “churn) is the riskiest step in entering one controlled access highway from another via a cloverleaf interchange.  You have vehicles on your left moving to their right as you move past them to your left.  You have a visibility advantage over their drivers because their vehicles are on your left (“sight side”) while your vehicle is on their right (“blind side”).

A complicating factor is the curve sharpness of some of your originating highway second entrance ramps (1 to 2) as they join the aprons or right lanes of the destination highways.  Truck drivers emerging from these ramps (1 to 2) may have to swing so wide left to get their trailer tails past guard rails on their right side that they crowd the left edge of the aprons or right lanes on the destination highways.  Drivers exiting a destination highway can give truck drivers swing room by crowding to the left in the right lane as they pass by on their way to their second entrance ramp (2 to 1).

Exiting drivers can usually swing into the apron in front of you as you emerge from your originating highway’s second entrance ramp (1 to 2).  Once you have progressed into the apron and begun accelerating, exiting vehicles should have braked enough to merge behind you.  If an exiting truck pulls alongside you, you should allow it to merge ahead of you unless the driver brakes for you.  If the driver slows down for you, pull briskly ahead and be aware that you will be passing through risk zones on the right side of the truck and then in front of it (see the Risk Zone:  Close in Front of My Truck and in the Right Lane Next to Mine and the Risk Zone:  Close and Directly in Front of My Truck tips).

It is important to note that to complete your merge into the destination highway’s right lane, you may have to contend with vehicles that are traveling in that lane but are not exiting.  This can be a challenge, since they may be travelling at or near highway speeds, while you are still accelerating.  Hopefully, truck drivers and at least some personal vehicle drivers will have moved left for you (see the When You Enter the Right Lane of a Controlled Access Highway and When You Enter the Right Lane of a Controlled Access Highway on the Open Road tips).

Open Road Interchanges versus Congested Interchanges

On the open road (typically on interstates or major highways with two or more lanes in each direction, in sparse traffic, usually in rural areas), there are two factors, one facilitating the pinch point mix and one complicating it.  On the plus side, open road interchange traffic is lighter, making it easier for drivers to interweave.  On the negative side, speeds of vehicles, especially personal vehicles exiting the destination highways can be significantly greater than those of vehicles emerging from your originating highways.  This is because the former vehicles are traveling at highway speeds until they brake shortly before and during their exits (2 to 1), while you and other drivers are accelerating from much slower speeds out of your originating highways’ right-hand loop second entrance ramps (1 to 2).

NOTE: On approaches to open road exits, I and most other truck drivers slow down earlier and to lower speeds than personal vehicle drivers because of our trucks’ slowing/stopping and other maneuverability limitations.  This factor, along with trucks’ slower acceleration out of entrance ramps, can cause uneven traffic flow and complicate navigation through cloverleaf interchange pinch points.  My concern is that some drivers take this churn casually and don’t pay close enough attention to other vehicles, particularly trucks exiting the destination highways.

On more congested interchanges of city freeways and other major highways, the speed differential between vehicles exiting the destination highways and vehicles emerging from your originating highways’ second entrance ramps (1 to 2) is smaller.  Cooperative interweaving should be easier.

You and other drivers on your originating highways’ second entrance ramps (1 to 2) can help in both open road and congested conditions.  You can look to the left for drivers signaling their intent to exit the destination highways and anticipate how to interweave with them.  In particular you can prepare to let exiting trucks swing in front of you.

Interchanges without Aprons

Some cloverleaf interchanges, most of which connect minor highways, have no aprons.  These interchanges require drivers from your originating highways’ second entrance ramps (1 to 2) to wait for a traffic opening before moving into the right lane of the destination highways.  Fortunately speeds on many of the highways are relatively slow.  Personal vehicle drivers obviously have an easier time accelerating into the right lane than truck drivers.

On the way to the destination highway’s second entrance ramp (2 to 1) on the far side of your originating highway, a truck driver may be able to help another truck driver who is waiting to enter the destination highway.  The exiting driver will slow down and blink his lights to signal the entering driver to move in front of him.  An exiting truck driver may even help you enter the destination highway.  You may be able to do the same for me or another truck driver on your way to the destination highway’s second entrance ramp (2 to 1), when it is practical, safe and lawful for you to do so.

Final Note

The first entrance ramp (2 to 1) from the destination highway in its left direction of travel from your originating highway’s point of view intersects your originating highway on the far side of the start (or inlet) of your originating highway’s second entrance ramp (1 to 2).  This first entrance ramp (2 to 1) from the destination highway in its left direction of travel forms the fourth and final connection with your originating highway in your originating highway’s direction of travel.  The end (or outlet) of the destination highway’s first entrance ramp (2 to 1) is thus on the opposite side of the destination highway from the start (or inlet) of your originating highway’s first entrance ramp (1 to 2).  Traffic on the destination highway’s first entrance ramp (2 to 1) makes what is in effect a right turn from the right lane of the destination highway to the right lane of your originating highway.

The second entrance ramp (2 to 1) from the destination highway takes vehicles from its right lane in the left direction of travel from your originating highway’s point of view to your originating highway’s right lane in the left direction of travel from the destination highway’s point of view.  Put more simply, this second entrance ramp (2 to 1) takes vehicles from the destination highway’s right lane to your originating highway’s right lane in the direction of travel opposite yours.  The start of this ramp (2 to 1) is located on the far side of your originating highway from the destination highway’s point of view.  From your originating highway’s point of view, this entrance ramp (2 to 1) is located on the far side of the destination highway and the left side of your originating highway.

Takeaways

On your way to your originating highway’s entrance ramp (1 to 2) on the far side of the destination highway on a cloverleaf interchange, allow swing room for trucks emerging from the destination highway’s near side entrance ramp (2 to 1).

On your way to your originating highway’s entrance ramp (1 to 2) on the far side of the destination highway on a cloverleaf interchange without an apron, consider yielding to a truck waiting to emerge from the destination highway’s near side entrance ramp (2 to 1).

In cloverleaf interchange “pinch points,” carefully merge in alternating fashion to change lanes, but yield to trucks alongside your vehicle unless they slow down for you.

When driving straight through an open road cloverleaf interchange (not changing highways), move to a left lane away from the pinch point mix when it is practical, safe and lawful for you to do so.

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