Bike Lane Design Calculator
Determine recommended bike lane type, width, and buffer from traffic speed, volume, and roadway conditions using NACTO and AASHTO guidelines.
About this calculator
Choosing the right bike facility for a street is fundamentally a risk-matching exercise: the faster and busier the adjacent motor vehicle traffic, the more physical separation a cyclist needs to feel (and be) safe riding alongside it. This calculator applies that logic in tiers loosely modeled on NACTO and AASHTO bikeway-selection guidance: at low posted speeds and traffic volumes, simple shared-lane markings ("sharrows") may be enough; as speed or volume climbs, the recommendation steps up through a conventional painted bike lane, then a buffered bike lane with a painted no-travel strip, and finally a fully separated protected bike lane at the highest-stress combinations.
On-street parking adds a dedicated "door zone" buffer to keep cyclists clear of suddenly opened car doors, and heavy truck traffic (over 10%) adds a small width allowance for larger vehicle overhang. The calculator also reports a Level of Traffic Stress (LTS) rating from 1 (comfortable for cyclists of all ages and abilities) to 4 (only "strong and fearless" riders will use it) — the same 1-4 scale defined by Mekuria, Furth, and Nixon's 2012 Mineta Transportation Institute research (the basis for NACTO's own LTS guidance), where LTS 1 is calibrated to what "most children" can tolerate and LTS 4 to what only "strong and fearless" cyclists will ride — and checks whether the recommended facility actually fits within your roadway's available curb-to-curb width once minimum travel lanes and any parking lanes are subtracted.
Inputs
Results
Recommended Facility
Buffered Bike Lane
How to Use This Calculator
- Enter Posted Speed, Average Daily Traffic, and Roadway Width.
- Set On-Street Parking to Yes or No depending on whether parked cars line the corridor.
- Adjust Daily Bike Volume, Truck Traffic as needed.
- Review the Recommended Facility result.
- Use Lane Width (ft) and Buffer Width (ft) to inform your decision.
What each input means
- Posted Speed
- Posted speed limit on the roadway. Higher speeds require more bicycle protection.
- Average Daily Traffic
- Average daily traffic volume on the street in both directions.
- Roadway Width
- Total curb-to-curb pavement width available.
- On-Street Parking
- Whether on-street parking exists adjacent to the bike lane (adds door zone buffer).
- Daily Bike Volume
- Estimated daily bicycle volume on the corridor.
- Truck Traffic
- Percentage of heavy vehicles. Higher truck traffic may require wider lanes.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersPosted Speed = 35, Average Daily Traffic = 5000, Roadway Width = 44, On-Street Parking = 0 = 6 input(s) provided
- Calculate Recommended FacilityBuffered Bike Lane = Buffered Bike Lane
- Calculate Lane Width6 = 6
- Calculate Buffer Width2 = 2
Figures and sources
- Level of Traffic Stress (LTS) 1-4 classification framework (2012) — Mekuria, M.C., Furth, P.G., & Nixon, H. (2012). Low-Stress Bicycling and Network Connectivity. Mineta Transportation Institute, Report 11-19: "Level of traffic stress 1 (LTS 1) is meant to be a level that most children... can tolerate," while LTS 4 is "a level tolerated only by those characterized as 'strong and fearless,'" typically riding in mixed traffic with no separation from higher-speed vehicle traffic — the origin of the 1-4 scale NACTO's bikeway-selection guidance and this calculator both use.
Engine last updated . Checked against 4 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
How does posted speed change which bike facility is recommended?
Posted speed is the single strongest driver of the recommendation in this calculator -- as it rises through roughly 25, 35, and 45 mph, the suggested facility steps up from shared-lane markings, to a conventional bike lane, to a buffered lane, and finally to a fully protected/separated bike lane. Higher speeds mean a crash is more severe for a cyclist, so the guidance calls for progressively more physical separation from traffic.
Does high traffic volume alone trigger a protected bike lane, even at a lower speed?
Yes -- traffic volume (average daily traffic, or ADT) can push the recommendation up independently of speed. A high-volume street can warrant a protected or buffered facility even at a moderate posted speed, because sheer traffic frequency, not just speed, raises the number of close encounters between cars and cyclists over a given day.
Why does on-street parking make the recommended bike lane wider?
On-street parking adds a "door zone" buffer -- extra width so a cyclist isn't riding directly in the path of a car door swinging open from a parked vehicle. This buffer is added on top of whatever lane and separation width the speed/volume tier already calls for, so the same roadway needs more total width when parking is present than when it isn't.
Does the calculator account for how many cyclists actually use the corridor?
No -- Daily Bike Volume is not used anywhere in the facility-type, width, buffer, or Level of Traffic Stress calculations. The recommendation is driven entirely by the MOTOR vehicle environment (speed, volume, parking, truck share); actual bicycle usage would inform whether a facility is worth building, but this calculator only sizes it.
Where does the 1-4 Level of Traffic Stress scale come from?
It comes from a 2012 Mineta Transportation Institute study by Mekuria, Furth, and Nixon ("Low-Stress Bicycling and Network Connectivity"), which defined LTS 1 as a level "most children" can tolerate and LTS 4 as tolerated only by cyclists characterized as "strong and fearless" -- typically meaning they're riding directly in mixed traffic with no separation from higher-speed vehicles. NACTO's own bikeway-selection guidance builds on this same framework, which is why this calculator's facility-type tiers and its LTS rating move together: a Protected Bike Lane recommendation always reports LTS 1, while Shared Lane Markings always report LTS 4.
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