Loop Naming Rules

A complete loop designation consists of a cabinet name (7 characters) and a loop name (7 characters), separated by a colon.

Consider: ES-504R:MME___2

ES-504R is the cabinet name, and the loop name is MME___2.
The underscores are characters and are required. (This example has three underscores.)

• A loop name is found by selecting one item from each column in the table below (Roadway, Direction, Lane Type, Lane Number).
  These items are then concatenated into a loop name. The correct item is found by following the conventions in the list of rules below.
• Loops used as speed loops are identified by an uppercase 'S' in column 6.
  
• A 'station' is an aggregation of all the lanes on a particular road, and is shown in the last four characters, spanning the lane type and lane number columns.
• Loops used as speed loops will also have a corresponding speed trap designation, with a 'T' in column 6. (Loop data for the sensor will be labeled with an S, speed trap data with a T.)

Roadway	Direction	Lane Type	Lane Number
_M -mainline	S -southbound	_X -exit	_1
_C -collector/distributor	N -northbound	_O -on ramp	_2
_R -reversible	E -eastbound	RA -right advanced q	_3
AM -auxiliary mainline	W -westbound	LA -left advanced q	_4
AC -auxil. coll./dist.		_Q -queue	_5
AR -auxil. reversible		_I -inter q	_6
MM -metered mainline		_D -demand	_7
MC -metered coll./dist.		_P -passage	_8
MR -metered reversible		HX -HOV exit	_9
		HO -HOV on	S1 -speed
		HD -HOV demand	S2 -speed
		HP -HOV passage	S3 -speed
		H_ -HOV mainline	S4 -speed
		__ -mainline	S5 -speed
			S6 -speed
			S7 -speed
			S8 -speed
			S9 -speed
		_Stn -station (all lanes)
		HStn -HOV station (all lanes)

Roadway Naming Rules

1. Each cabinet is assigned a principal roadway. If a cabinet on I-5 (principal roadway) has loops on I-90, then the I-90 loops are considered auxiliary and an "A" is added to the roadway name (column 1). In the case of on-ramps and exits, the principal name will prevail. If a loop could be called an exit from I-90 and an on-ramp to I-5, then it would be called an on-ramp.
2. Loops that are to become a part of a ramp metering station will have a roadway type beginning with an "M". Speed loops and HOV lanes DO NOT have the roadway type beginning with an "M".
3. All loops must have a roadway type. On-ramps and exits will assume the roadway type of the roadway that the ramp enters or leaves.

Direction Rules

1. All loops will have a direction code: N- northbound, S -southbound, E -eastbound, W -westbound.
2. Reversible roadways will use the direction of increasing milepost. The I-5 express lanes are considered as Northbound.

Lane Naming Rules

1. All loops will have one lane type.
2. Each metered lane can have two advanced queue loops, one left movement and one right: "LA" and "RA". If no movement is associated with the advanced queue loop, then use "RA".
3. Depending on the ramp length, each metered lane can have up to 2 queue loops: one intermediate queue loop "_I" and one queue loop "_Q". The queue loop and the intermediate queue loop will be evenly spaced, 200 to 500 feet apart, depending on the ramp length. The intermediate queue loop will be placed between the queue loop and the advanced queue loops.
4. Use "_X" for exit ramps and "_O" for on-ramps that are not metered.
5. HOV loops are specified by an "H" as the first lane type letter.
6. Use "__" or "H_" for mainline loops.

Numbering Rules

1. All loops of similar type are numbered from upstream to downstream.
2. All multi-lane roadways will be numbered from right to left while looking downstream (in the direction of traffic flow). If one or more lanes are HOV, they will be numbered as if they are general purpose lanes.
3. Each HOV lane bypass will have the same lane number as the ramp lane that it bypasses.
4. Speed loops will have an "S" before the lane number (column 6).
5. Ramp meter lanes will be numbered from right to left and upstream to downstream. All existing (installed before 1992) ramp meter lanes are numbered "2".

Station Naming Rules

1. All station names will contain a roadway and direction type followed by either "_Stn" or "HStn".
2. This naming scheme will only work for mainline, collector/distributor, and HOV lanes on these roadway types.