DRIVING IN SINGLE-LINE SITUATIONS

OVERVIEW

In most traffic situations, there is at least one line of traffic in each direction permitted. Therefore, drivers are unprepared when they encounter single-line situations -- there is room for only one line of traffic to pass on a two-way road. What you do depends on which of the following three conditions you encounter:

1. Supervised control of single-line traffic
2. One short single-line section (neck-down, or single stopped vehicle)
3. Long or multiple single-line sections (excessive parking or one-lane bridge)

The key requirement in single-line driving is to not be greedy. Whenever a greedy driver enters a single-line section before it is his turn, he delays not only himself, but all other vehicles on the road, by creating a blockage. It can take a quarter of an hour or more to clear up a single-line blockage, especially if a driver who does not understand single-line driving is present. When in doubt, yield.

Here are the various methods to use when faced with a single-line situation in traffic. Some of them have been resurrected from the horse-and-buggy days, when single-line roadways were more common. Each case is different, so each case has a different set of rules:

1. SUPERVISED CONTROL

   Supervised control is the easiest form of single-line traffic for the motorist to drive through, because traffic control devices are in place. Traffic lights, flagmen, workers with paddles, or pilot vehicles, determine when traffic is permitted to enter the single-line section. The timing of the releases of traffic are determined by the length and number of single line sections, the amount of traffic on the road, and the length of any passing loops between single-line sections. The driver needs to do nothing but obey the traffic controls present. This is the only single-line method that allows cars to group into platoons. It is usually used in construction zones or at one-lane bridges.

   There is one case that needs to be clarified under supervised control. If a driveway exits into the single-line section, and no flagman or signal is present at the driveway, then the driver must follow these rules:

   • Wait until a platoon of cars passes, going in the direction you wish to go. Join that platoon, by turning into a gap in traffic, or by joining the rear end of the platoon.
   • Never enter the single-line section ahead of the pilot vehicle.
   • Never enter the single-line section behind any official vehicle marking the end of the platoon (it should pause for you to enter ahead of it).
   • Obey all signals given to you by workmen.

2. ONE SHORT SECTION

   The main idea here is to alternate traffic direction car-by-car. Here are the rules:

   • Never follow another car into any unsupervised single-line section. Wait until it leaves the section, and also wait for one car coming toward you (if present) to pass through the section.
   • Slow down or stop before entering a single-line section.
   • If two cars reach an empty single-line section sequentially, the one arriving first enters the section first.
   • If two cars reach an empty single-line section simultaneously, the car on the least-obstructed approach goes first.
   • Safety rule: Always watch for drivers who do not notice that single-line operation is occurring.
   • When in doubt, yield.

3. LONG OR MULTIPLE SECTIONS

   Here is absolutely essential that only one vehicle is in this kind of single-line section at any time. Failure to obey these rules will lock up the section, or a passing loop, with vehicles intending to go in both directions blocking each other's paths:

   • PAY ATTENTION: You can easily enter a single-line section of road without realizing it. Then it is too late to avoid a blockage if the section is already occupied.
   • Never follow another car into any unsupervised single-line section. Wait until it leaves the section, and also wait for one car coming toward you (if present) to pass through the section.
   • STOP as far forward in the passing loop as you can without blocking traffic leaving the single-line section or locking your vehicle into a pocket.
   • NEVER enter an already occupied single-line section.
   • If the vehicle occupying the single-line section is moving in your direction of travel, you must wait for it to leave the section, and for a vehicle (if present) to pass through the section in the opposite direction (toward you) before you can proceed.
   • DON'T enter a single-line section until you are sure the passing loop beyond it has available room in it to accept your vehicle.
   • If an inattentive driver starts to enter a single-line section while you are heading toward him in the section, use 4 closely-spaced short honks of the horn to alert him.
   • If an inattentive driver enters a section before he should, blocking himself and another car, then one of the vehicles must back up to a passing loop.
   • If a driver sees such a blocked conflict in a section or passing loop ahead, he must not enter any single-line section until the blockage is cleared. Otherwise, several places may become blocked with too many cars.
   • If a vehicle longer than the next passing loop enters the section, a SAW-BY maneuver (below) must be used.
   • If an inattentive driver follows another driver into a single-line section so that their combined length is longer than the next passing loop, a saw-by is also used.
   • If a passing loop becomes blocked because too many cars tried to enter it, the DOUBLE-SAW maneuver (below) must be used.
   • Safety rule: Always watch for drivers who do not notice that single-line operation is occurring.
   • When in doubt, yield.

The SAW-BY* maneuver

The saw-by* is a maneuver which is used to avoid a blockage in a single-line passing loop. It is much better to avoid locking up a passing loop than using a time-consuming double-saw* to unlock it. The saw-by is simple to perform:

1. Any vehicles waiting to proceed in the opposite direction must wait in their passing loops until the offending vehicles have passed.
2. If any driver gets greedy and does not wait in the passing loop until the offending vehicles have passed, a double-saw will be needed.

The DOUBLE-SAW* maneuver

The double-saw is a maneuver to be avoided, unless a passing loop locks up. It is much better to avoid locking up a passing loop, but if it happens, the double-saw is the only way to unlock it.

1. If any cars can alleviate the situation by temporarily turning into driveways, they must do so.
2. The shorter line of cars occupying a single-line section must back up enough for the longer line to pass forward enough to free the exit of the passing loop. If some of them enter another passing loop in the process, those cars must stay there until the blockage clears, unless the passing loop is too short to hold all of them (step 1 of figure).
3. The entire longer line must move forward until it clears the exit of the passing loop. If some of them enter another passing loop, the entire long line must proceed forward, one at a time, until the blockage clears (step 1 of figure).
4. The cars still in the passing loop are now freed, they must leave, one at a time, until the passing loop is empty (step 1 of figure).
5. The longer line (if it hasn't cleared) must back up until it allows more of the shorter line to enter the passing loop (step 2 of figure).
6. As many of the cars in the shorter line that will fit in the passing loop must move forward and enter it. The remainder (if any) should stay where they are instead of moving forward (step 2 of figure).
7. The longer line (if it still exists) must move forward again until it clears the exit of the passing loop (step 3 of figure). If nothing is blocking their way, they must proceed to the next passing loop.
8. The cars from the short line which are now in the passing loop must proceed forward, one at a time, until the passing loop is empty (step 3 of figure).
9. If the blockage has not cleared, repeat steps 3 through 8 until it clears out.

* These names came from the terms used by railroads for the same maneuvers.

Single-line driving is an unusual situation that can trap the unwary. Be prepared for it, so you don't get trapped.

LINKS:

• UNUSUAL TRAFFIC HAZARDS
• HOME