4. Self Quiz on Example Scenarios
Note: for the purposes of this self-quiz, assume all plans are to be implemented on or after June 30, 2024.
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A local municipality is hearing complaints about speeds on an arterial with many retail shops and restaurants. The road currently has a speed limit of 25 mph. Can the speed limit be lowered?
Answer: If the road can be established as a business activity district, the prima facie speed can be set at 20 mph in accordance with AB 43.
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A local police department is deciding how to allocate resources for speed enforcement and are considering enforcement on a collector road that does not have a prima facie speed limit. The E&TS survey that was used to establish the current speed limit on the road was conducted 12 years ago and was evaluated by a registered engineer. Should the police department assign officers to perform radar speed enforcement on this road?
Answer: Yes, the police may use this road for court-justifiable radar speed enforcement since AB 43 extends the validity of an E&TS required for such efforts from 7 years to 14 years. NOTE: This requires that no significant changes in roadway or traffic conditions have occurred, including changes in adjoining property or land use, roadway width, or traffic volume.
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a) A local jurisdiction is concerned about the current posted speed limit on a roadway. There have been few serious or fatal crashes on this roadway, and there are very few bicyclists or pedestrians present. Utility poles carrying electrical wires run along the roadway and the incline on a certain section of the highway is very severe so that driver sight distance is limited significantly. If the 85th percentile speed turns out to be 37.4 mph, what is the lowest speed limit that can be set?
Answer: The lowest speed limit to set is 30 mph (for a total 7.4 mph reduction). First, round down to 35 mph (the nearest 5 mph increment). Then, reduce by another 5 mph for the unsafe roadside conditions created by severe sight distance limitations in close proximity to the utility poles.
b) A local jurisdiction is concerned about the current posted speed limit on a roadway.There have been few serious or fatal crashes on this roadway, and there are very few bicyclists or pedestrians present. Utility poles carrying electrical wires run along the roadway and the incline on a certain section of the highway is very severe so that driver sight distance is limited significantly. If the 85th percentile speed turns out to be 37.5 mph, what is the lowest speed limit that can be set?
Answer: The lowest speed limit to set is 35 mph (for a total 2.5 mph reduction). Round up to 40 mph, and then reduce by 5 mph for roadside conditions not readily apparent to the driver. OR Round down to the nearest 5 mph increment rather than up.
c) A local jurisdiction is concerned about the current posted speed limit on a roadway. They have noted a high number of serious injury crashes on the roadway and a few fatalities. Additionally, utility poles carrying electrical wires run along the roadway and the incline on a certain section of the highway is very severe so that driver sight distance is limited significantly. If the 85th percentile speed turns out to be 37.4 mph, what is the lowest speed limit that can be set?
Answer: The lowest speed limit to set is 25 mph (for a total 12.4 mph reduction). First, round down to 35 mph (the nearest 5 mph increment). Then, reduce by another 5 mph for the unsafe roadside conditions created by severe sight distance limitations in close proximity to the utility poles. THEN, Reduce by another 5 mph for a Safety Corridor (with documentation provided).
d) A local jurisdiction is concerned about the current posted speed limit on a roadway. They have noted a high number of serious injury crashes on the roadway and a few fatalities. Additionally, utility poles carrying electrical wires run along the roadway and the incline on a certain section of the highway is very severe so that driver sight distance is limited significantly. If the 85th percentile speed turns out to be 37.5 mph, what is the lowest speed limit that can be set?
Answer: The lowest speed limit to set is 30 mph (for a total 7.5 mph reduction). Round up to 40 mph, and then reduce by 5 mph for the unsafe roadside conditions created by severe sight distance limitations in close proximity to the utility poles. OR Round down to the nearest 5 mph increment rather than up. THEN, Reduce by another 5 mph for a Safety Corridor (with documentation provided).
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A local roadway has experienced a significant number of serious motor-vehicle crashes involving bicycles over the years. A recent engineering and traffic survey identified the 85th percentile speed on this road to be 49.9 mph. To best protect vulnerable road users, what is the lowest speed limit that can be set by the municipality?
Answer: The lowest speed limit to set is 40 mph (for a total 9.9 mph reduction). First, elect to round down to 45 mph rather than up to 50 mph. Then, take another 5 mph reduction if the road is designated as a Safety Corridor (with documentation provided).
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A 4-lane local road in a downtown business district has a current speed limit of 35 mph. This road carries very high levels of pedestrian and bicycle activity and has experienced a significant number of serious motor-vehicle-related crashes over the past 3 years. What speed limit should be established on this road if the road is classified as a business activity district per AB 43 (including a maximum 30 mph speed limit on both approaches)?
Answer: Could choose between 20 or 25 mph per AB 43. NOTE: Probably would want to strongly consider 20 mph given the high incidence of crashes and high concentrations of vulnerable users.
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a) A 4-lane local road has a currently posted speed limit of 35 mph. The previous posted speed limit was 30 mph but had to be changed when the 85th percentile from the last E&TS was measured at 32.8 mph. The city engineer performs a new E&TS because their old one is expiring and finds a new 85th percentile speed of 37.5 mph, which would round up to 40 mph, which seems concerningly high. What is the lowest speed limit that can be established on this roadway?
Answer: The lowest speed limit to set is 30 mph. This is allowable because this is the immediately prior speed limit. NOTE: This can only be done if no general purpose lanes have been added. ALSO NOTE: The speed limit could be set at 35 mph, retaining the current limit
b) A 4-lane local road has a currently posted speed limit of 35 mph. The previous posted speed limit was 25 mph by had to be changed when the 85th percentile from the last E&TS was measured at 32.8 mph. The city engineer performs a new E&TS because their old one is expiring and finds a new 85th percentile speed of 37.5 mph, which would round up to 40 mph, which seems concerningly high. What is the lowest speed limit that can be established on this roadway?
Answer: Still, the lowest speed limit to set is 30 mph. The immediately prior speed limit of 25mph is over 5 mph below the currently posted limit of 35 mph, but only 5 mph maxiumum can be deducted. NOTE: This can only be done if no general purpose lanes have been added. ALSO NOTE: The speed limit could be set at 35 mph, retaining the current limit.