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Access Management Manual - Appendix D - Auxiliary Lane Graphs
Access Management Manual
Effective: April 30, 2006
Appendix D
AUXILIARY LANE GRAPHS
D1.1 - General
The auxiliary lane graphs provided in this Appendix are used to determine when a separate turn lane is needed for proposed access connections.
D1.2 - Left Turn Lane Warrants: Two-Lane Roadways
Two graphs are provided for left turn warrants on two-lane roadways: one for high-speed conditions (>40 MPH posted speed) and one for low-speed conditions (<40 MPH posted speed). The plotted curve indicates the left turn percentage. Actual left turn percentage for the case being analyzed should be interpolated using the plotted curves as a guide. Any points that lie beyond the provided curves should likewise be extrapolated to determine if a left turn lane is warranted. Note that for 2-lane roadways, the advancing traffic volume includes the left-turn volume.
2-Lane Highway Left Turn Lane Warrant =<40 mph or 70 kph Posted Speed (PDF, 103KB)
2-Lane Highway Left Turn Lane Warrant >40 mph or 70 kph Posted Speed (PDF, 167KB)
D1.3 - Left Turn Lane Warrants: Four-lane Roadways
Two graphs are provided for divided and undivided four-lane roadways. Warrants for left turn lanes are based solely on left turning vehicle volume and the opposing traffic volume. A roadway is considered divided as long as the median width is adequate to store at least one left-turning vehicle without impeding the progress of vehicles in the adjacent through lane.
4-Lane Highway Left Turn Lane Warrant (PDF, 88KB)
D1.4 - Right Turn Lane Warrants
Separate graphs are provided for right turns for two-lane and four lane roadways for both high-speed (>40 MPH posted speed) and low-speed (<40 MPH posted speed) conditions. The plotted curve indicates the right turn percentage. Actual right turn percentage for the case being analyzed should be interpolated using the plotted curves as a guide. Any points that lie beyond the provided curves should likewise be extrapolated to determine if the turn lane is warranted.
2-Lane Highway Right Turn Lane Warrant >40 mph or 70 kph Posted Speed (PDF, 85KB)
2-Lane Highway Right Turn Lane Warrant =<40 mph or 70 kph Posted Speed (PDF, 88KB)
4-Lane Highway Right Turn Lane Warrant =<40 mph or 70 kph Posted Speed (PDF, 90KB)
4-Lane Highway Right Turn Lane Warrant >40 mph or 70 kph Posted Speed (PDF, 90KB)