New Mexico Administrative Code
Title 18 - TRANSPORTATION AND HIGHWAYS
Chapter 31 - CLASSIFICATION AND DESIGN STANDARDS FOR HIGHWAYS
Part 6 - STATE HIGHWAY ACCESS MANAGEMENT REQUIREMENTS
Section 18.31.6.17 - SPEED-CHANGE LANE REQUIREMENTS
Current through Register Vol. 35, No. 18, September 24, 2024
A. Purpose: This section defines the criteria for determining where speed-change lanes are required along non-access controlled and controlled-access state highways that provide access via at-grade intersections. Application guidelines for speed-change lanes on controlled-access interstate highways and freeways, which provide access exclusively by grade-separated interchanges, are also provided; however, specific criteria for speed-change lanes on grade-separated highway facilities are not explicitly defined (see Subsection C of 18.31.6.17 NMAC).
B. State highways with at-grade intersections: At unsignalized at-grade intersections, four types of speed-change lanes are used including left-turn deceleration lanes, right-turn deceleration lanes, left-turn acceleration lanes, and right-turn acceleration lanes. At signalized at-grade intersections, three types of speed-change lanes are used including exclusive left-turn lanes, exclusive right-turn lanes, and right-turn acceleration lanes.
C. State and interstate highways with grade-separated interchanges: Speed-change lanes are used on controlled-access state and interstate highways at or between grade-separated interchanges. The need for speed-change lanes on grade-separated highway facilities should be determined based on design principles contained in the AASHTO publication a policy on geometric design of highways and streets, and based on detailed traffic operations analyses of the grade-separated facilities according to highway capacity manual methodologies. The need for and function of speed-change lanes should be documented in an interchange access management plan for the interchange (refer to 18.31.6.12 NMAC). Speed-change lanes on grade-separated highway facilities should enable a driver to make the necessary transition between the speed on a ramp and the speed of operation on the mainline highway in a safe and functional manner. Additional guidance is provided in Section 17 of the state access management manual.
Table 17.B-1 Criteria for Deceleration Lanes On Urban Two-lane Highways |
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Turning Volume (vph) |
LEFT-TURN DECELERATION LANE |
RIGHT-TURN DECELERATION LANE |
||||
Minimum Directional Volume in the Through Lane (vphpl) 2 |
Minimum Directional Volume in the Through Lane (vphpl) 2 |
|||||
[] 30 mph |
35 to 40 mph |
45 to 55 mph |
[] 30 mph |
35 to 40 mph |
45 to 55 mph |
|
[] 5 |
Not Required |
Not Required |
Not Required |
Not Required |
Not Required |
Not Required |
5 |
510 |
450 |
330 |
1,080 |
610 |
360 |
10 |
390 |
330 |
210 |
700 |
400 |
240 |
15 |
320 |
250 |
150 |
500 |
280 |
170 |
20 |
270 |
200 |
120 |
380 |
210 |
140 |
25 |
230 |
160 |
100 |
300 |
180 |
120 |
30 |
200 |
130 |
Required |
250 |
160 |
110 |
35 |
170 |
110 |
Required |
220 |
150 |
100 |
40 |
150 |
Required |
Required |
200 |
140 |
Required |
45 |
130 |
Required |
Required |
190 |
Required |
Required |
[] 46 |
Required |
Required |
Required |
Required |
Required |
Required |
Left-turn Deceleration Lanes are required on Urban Two-lane Highways for the following Left-turn Volumes: | Right-turn Deceleration Lanes are required on Urban Two-lane Highways for the following Right-turn Volumes: | |||||
1. [] 30 mph : 46 vph or more 2. 35 to 40 mph : 36 vph or more 3. 45 to 55 mph : 26 vph or more |
4. [] 30 mph : 46 vph or more 5. 35 to 40 mph : 41 vph or more 6. 45 to 55 mph : 36 vph or more |
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Notes: 1. Use linear interpolation for turning volumes between 5 and 45 vph. 2. The directional volume in the through lane includes through vehicles and turning vehicles. |
Table 17.B-2 Criteria for Deceleration Lanes on Urban Multi-lane Highways |
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Turning Volume 1 (vph) |
LEFT-TURN DECELERATION LANE |
RIGHT-TURN DECELERATION LANE |
||||
Minimum Volume in the Adjacent Through Lane (vphpl) 2 |
Minimum Volume in the Adjacent Through Lane (vphpl) 2 |
|||||
[] 30 mph |
35 to 40 mph |
45 to 55 mph |
[] 30 mph |
35 to 40 mph |
45 to 55 mph |
|
[] 5 |
Not Required |
Not Required |
Not Required |
Not Required |
Not Required |
Not Required |
5 |
Not Required |
490 |
420 |
1,200 |
730 |
450 |
10 |
420 |
370 |
300 |
820 |
490 |
320 |
15 |
360 |
290 |
220 |
600 |
350 |
240 |
20 |
310 |
230 |
160 |
460 |
260 |
180 |
25 |
270 |
190 |
130 |
360 |
230 |
150 |
30 |
240 |
160 |
110 |
290 |
200 |
130 |
35 |
210 |
130 |
100 |
260 |
180 |
120 |
40 |
180 |
120 |
Required |
240 |
170 |
110 |
45 |
160 |
110 |
Required |
220 |
160 |
Required |
50 |
140 |
Required |
Required |
200 |
Required |
Required |
55 |
120 |
Required |
Required |
190 |
Required |
Required |
[] 56 |
Required |
Required |
Required |
Required |
Required |
Required |
Left-turn Deceleration Lanes are required on Urban Multi-lane Highways for the following Left-turn Volumes: | Right-turn Deceleration Lanes are required on Urban Multi-lane Highways for the following Right-turn Volumes: | |||||
3. [] 30 mph : 56 vph or more 4. 35 to 40 mph : 46 vph or more 5. 45 to 55 mph : 36 vph or more |
6. [] 30 mph : 56 vph or more 7. 35 to 40 mph : 46 vph or more 8. 45 to 55 mph : 41 vph or more |
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Notes: 1. Use linear interpolation for turning volumes between 5 and 55 vph. 2. The volume in the adjacent through lane includes through vehicles and turning vehicles. |
Table 17.B-3 Criteria for Left-Turn Deceleration Lanes on Rural Two-lane Highways |
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Left-Turn Volume 1 (vph) |
LEFT-TURN DECELERATION LANE |
|||
Minimum Directional Volume in Through Lane (vphpl) 2 |
||||
[] 30 mph |
35 to 40 mph |
45 to 55 mph |
[] 55 mph |
|
[] 5 |
Not Required |
Not Required |
Not Required |
Not Required |
5 |
400 |
220 |
120 |
60 |
10 |
240 |
140 |
80 |
40 |
15 |
160 |
100 |
60 |
Required |
20 |
120 |
80 |
Required |
Required |
25 |
100 |
Required |
Required |
Required |
³ 26 |
Required |
Required |
Required |
Required |
Left-turn Deceleration Lanes are required on Rural Two-lane Highways for the following Left-turn Volumes: | ||||
1. [] 30 mph : 26 vph or more 2. 35 to 40 mph : 21 vph or more 3. 45 to 55 mph : 16 vph or more 4. [] 55 mph : 11 vph or more |
||||
Notes: Use linear interpolation for left-turn volumes between 5 and 25 vph. The directional volume in the through lane includes through vehicles and turning vehicles. |
Table 17.B-4 Criteria for Left-turn Deceleration Lanes on Rural Multi-lane Highways |
||||
Left-Turn Volume 1 (vph) |
LEFT-TURN DECELERATION LANE |
|||
Minimum Volume in Adjacent Through Lane (vphpl) 2 |
||||
[] 30 mph |
35 to 40 mph |
45 to 55 mph |
[] 55 mph |
|
[] 5 |
Not Required |
Not Required |
Not Required |
Not Required |
5 |
450 |
310 |
210 |
130 |
10 |
310 |
220 |
130 |
90 |
15 |
240 |
160 |
100 |
70 |
20 |
190 |
130 |
80 |
Required |
25 |
150 |
110 |
Required |
Required |
30 |
130 |
Required |
Required |
Required |
35 |
110 |
Required |
Required |
Required |
[] 36 |
Required |
Required |
Required |
Required |
Left-turn Deceleration Lanes are required on Rural Multi-lane Highways for the following Left-turn Volumes: | ||||
5. [] 30 mph : 36 vph or more 6. 35 to 40 mph : 26 vph or more 7. 45 to 55 mph : 21 vph or more 8. [] 55 mph : 16 vph or more |
||||
Notes: 1. Use linear interpolation for left-turn volumes between 5 and 35 vph. 2. The volume in the adjacent through lane includes through vehicles and turning vehicles. |
Table 17.B-5 Criteria for Right-Turn Deceleration Lanes on Rural Two-lane Highways |
||||
Right-Turn Volume 1 (vph) |
RIGHT-TURN DECELERATION LANE |
|||
Minimum Directional Volume in Through Lane (vphpl) 2 |
||||
[] 30 mph |
35 to 40 mph |
45 to 55 mph |
[] 55 mph |
|
[] 5 |
Not Required |
Not Required |
Not Required |
Not Required |
5 |
800 |
460 |
270 |
160 |
10 |
430 |
280 |
170 |
110 |
15 |
290 |
180 |
110 |
80 |
20 |
200 |
140 |
90 |
70 |
25 |
170 |
120 |
80 |
Required |
30 |
160 |
110 |
Required |
Required |
[] 31 |
Required |
Required |
Required |
Required |
Right-turn Deceleration Lanes are required on Rural Two-lane Highways for the following Right-turn Volumes: |
||||
3. [] 30 mph : 31 vph or more 4. 35 to 40 mph : 31 vph or more 5. 45 to 55 mph : 26 vph or more 6. [] 55 mph : 21 vph or more |
||||
Notes: 1. Use linear interpolation for left-turn volumes between 5 and 30 vph. 2. The directional volume in the through lane includes through vehicles and turning vehicles. |
Table 17.B-6 Criteria for Right-Turn Deceleration Lanes on Rural Multi-lane Highways |
||||
Right-Turn Volume 1 (vph) |
RIGHT-TURN DECELERATION LANE |
|||
Minimum Volume in Adjacent Through Lane (vphpl) 2 |
||||
[] 30 mph |
35 to 40 mph |
45 to 55 mph |
[] 55 mph |
|
[] 5 |
Not Required |
Not Required |
Not Required |
Not Required |
5 |
910 |
520 |
310 |
180 |
10 |
520 |
330 |
200 |
130 |
15 |
370 |
220 |
140 |
100 |
20 |
270 |
170 |
110 |
90 |
25 |
220 |
140 |
100 |
Required |
30 |
200 |
130 |
90 |
Required |
35 |
180 |
120 |
Required |
Required |
[] 36 |
Required |
Required |
Required |
Required |
Right-turn Deceleration Lanes are required on Rural Multi-lane Highways for the following Right-turn Volumes: |
||||
3. [] 30 mph : 36 vph or more 4. 35 to 40 mph : 36 vph or more 5. 45 to 55 mph : 31 vph or more 6. [] 55 mph : 21 vph or more |
||||
Notes: 1. Use linear interpolation for left-turn volumes between 5 and 35 vph. 2. The volume in the adjacent through lane includes through vehicles and turning vehicles. |