LEVEL OF SERVICE FOR SIGNALIZED INTERSECTIONS1
| level of Service | Description | Control (Signal) Delay Per Vehicle (Seconds) |
|---|---|---|
| A | Very short delay, good progression; most vehicles do not stop at intersection. | ≤10.0 |
| B | Generally good progression and/or short cycle length; more vehicles stop at intersection than at Level of Service “A.” | >10.0 and ≤20.0 |
| C | Fair progression and/or longer cycle length; significant number of vehicles stop at intersection, though many still pass through without stopping. | >20.0 and ≤35.0 |
| D | Congestion becomes noticeable; longer delays from unfavorable progression, long cycle lengths, or high volume/capacity ratios; many vehicles stop at intersection. | >35.0 and ≤55.0 |
| E | Considered to be the limit of acceptable delay; indicative of poor progression, long cycle lengths, or high volume/capacity ratios; frequent individual cycles failures. | >55.0 and ≤80.0 |
| F | Often an indication of over-saturation (i.e., arrival flow exceeds capacity); also caused by poor progression and long cycles lengths; capacity is not necessarily exceeded under this level of service. | >80.0 |
1 Transportation Research Board, Highway Capacity Manual 2022, National Research Council, Washington, DC, 2022.