When You Exit the Right Lane of a Controlled Access Highway to the Right Lane of Another Controlled Access Highway

Last Edited: November 11, 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 in one direction on your originating highway through a pinch point to the start (or inlet) of your originating highway’s right-hand loop exit ramp.

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 that you will be exiting 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 to the destination highway, we will call the ramp at its start (or inlet) an exit ramp (1 to 2).

The ramp could also be called an entrance ramp (1 to 2) at its end (or outlet) at the destination highway.  But in this discussion we focus on what you do approaching the ramp and at its start, not at its outlet.  On a full cloverleaf interchange, there are two such exit 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.

A ramp carrying vehicles from the destination highway to your originating highway will be called an entrance ramp (2 to 1).  Such a ramp could be called an exit ramp (2 to 1) from the destination highway’s base of reference (point of view).  But from your originating highway’s point of view, the ramp at its end (or outlet) should be designated an entrance ramp (2 to 1) because at that end its vehicles are about to enter the right lane of your originating highway.  On a full cloverleaf interchange, there are two ramps (2 to 1) entering the right lane of your originating highway in your direction of travel, one from each direction of travel on the destination highway, one on the near side of the destination highway and one on the far side from your originating highway’s point of view.

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 exit ramp (1 to 2).  The start (or inlet) of this first exit 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.  Exiting your originating highway resembles a single exit to a minor highway or street, the difference being a one-directional merge into the right lane of the destination highway at the outlet of the ramp (1 to 2).

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 exit ramp (1 to 2).  This second exit ramp (1 to 2) starts on the far side of the destination highway.  It is a right-hand loop taking vehicles from the right lane of your originating highway to the right lane of the destination highway in the left travel direction from your originating highway’s point of view.

On the way to it, you will pass your first exit ramp (1 to 2) running from the right lane of your originating highway to the right lane of the destination highway in the right direction of travel from your originating highway’s point of view.  Then you will pass the outlet of the destination highway’s second entrance ramp (2 to 1) on the near side of the destination highway.  This ramp (2 to 1) is a right-hand loop taking vehicles exiting from the destination highway’s right direction of travel from your originating highway’s point of view to the right lane of your originating highway in the left direction of travel from the destination highway’s point of view.

Put more simply, the destination highway’s second entrance ramp (2 to 1) takes vehicles from the destination highway’s right lane to your originating highway’s right lane in your direction of travel.  You will have to interweave with these vehicles in order to reach the start (or inlet) of your second exit ramp (1 to 2).  Your second exit ramp (1 to 2) starts shortly beyond the outlet of this second entrance ramp (2 to 1), on the far side of the destination highway.  This is the pinch point we are focusing on in this tip.

(NOTE:  Once you have entered your second exit ramp (1 to 2), wound around its right-hand loop and emerged from its outlet onto the destination highway, you will have to contend with vehicles exiting the right lane to reach the start of their second exit 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 them in order to merge into the destination highway’s right lane.  This is the second pinch point you will maneuver through to complete your entrance onto the destination highway.  For more details on entering the destination highway, see the When You Enter the Right Lane of a Controlled Access Highway from the Right Lane of Another Controlled Access Highway tip.)

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 your originating highway.  The apron starts at the outlet of the destination highway’s second entrance ramp (2 to 1), runs under or over the destination highway and ends at the start of your originating highway’s second exit ramp (1 to 2).  (Some aprons run past your originating highway’s second exit ramp (1 to 2) to provide a longer acceleration lane for vehicles emerging from the destination highway’s second entrance ramp (2 to 1.)  To get to your second exit ramp (1 to 2), you have to move right into the apron as vehicles emerging from the destination highway’s second entrance ramp (2 to 1) move left out of the apron into the right lane of your originating highway.

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 exiting from one controlled access highway to another via a cloverleaf interchange.  You have vehicles on your right moving to their left as you move past them to your right.  You are at a visibility disadvantage compared to their drivers because their vehicles are on your right (“blind side”) while your vehicle is on their left (“sight side”).

A complicating factor is the curve sharpness of some destination highway second entrance ramps (2 to 1) as they join the aprons or right lanes of your originating highways.  Truck drivers emerging from these entrance ramps (2 to 1) 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 your originating highways.  You can give the truck drivers swing room by crowding to the left in the right lane as you pass by on your way to your exit ramp (1 to 2).

You can usually swing into the apron in front of slower vehicles that are just entering it and merge behind vehicles that have already entered in front of your vehicle.  If my truck emerges from the destination highway’s second entrance ramp (2 to 1) alongside your vehicle, I will allow you to move in front, unless you brake for me.  If you don’t brake for me, pull briskly ahead and be aware that you will be passing through risk zones on the left side of my truck and then in front of it (see the Risk Zone:  Close in Front of My Truck and in the Left Lane Next to Mine and the Risk Zone:  Close and Directly in Front of My Truck 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 your originating highways can be significantly greater than those of vehicles emerging from the destination highways.  This is because the former vehicles are traveling at highway speeds until they brake shortly before and during their exits (1 to 2), while the latter are accelerating from much slower speeds out of the destination highway’s right-hand loop second entrance ramps (2 to 1).

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 your originating highways and vehicles emerging from the destination highways’ second entrance ramps (2 to 1) is smaller.  Cooperative interweaving should be easier.

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

Interchanges without Aprons

Some cloverleaf interchanges, most of which connect minor highways, have no aprons.   These interchanges require drivers emerging from the destination highways’ second entrance ramps (2 to 1) to hesitate, or even stop and wait for a traffic opening before moving into the right lane of your originating 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 my way to your originating highway’s second exit ramp (1 to 2) on the far side of the destination highway, I may be able to help a truck driver who is waiting to enter your originating highway.  If possible I will slow down and blink my lights to let the driver move in front of me.  Other truck drivers often help me, and I or another driver may even help you enter your originating highway.  You may be able to do the same for me or another truck driver on your way to your originating highway’s second exit 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 exit 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 exit 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 exit 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 exit 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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