Volume related information, including traffic volumes on each intersection approach.

Geometry related information, including the number of lanes and lane configuration for each approach.

The default ideal saturation flow rate is 1,900 passenger cars per lane per hour of green. We will use this default value as a starting point in our analysis. But field data should always be collected if possible for the particular site that you are studying. We should revisit this assumption if we find that the intersection's critical v/c ratio is near a threshold in which mitigation is required. In this case, it would be worthwhile to collect additional field data on some of the more critical factors affecting the outcome of the analysis, including flow rates, green splits, peak hour factor, and lane utilization.

Are there a significant number of vehicles that turn right during the red phase? If so, and if a field count of the number of right-turn-on-red vehicles is available, then these vehicles should be excluded from the analysis. The analysis procedure contained in the HCM is based on data collected at a variety of sites, including those where right-turns-on-red regularly occurred, an so a "normal" number of right-turns-on red is already implicitly assumed in the procedure. Therefore, if a field count of the number of right-turns-on-red is not available, then no special adjustment should be made. The data available to this analysis does not include a separate count of right-turns-on-red, and so no additional adjustment will be made.

Are there parking maneuvers within 250 feet of the intersection approaches? Parking is not currently allowed on the intersection approaches for this problem. In situations where parking is allowed, remember that parking and unparking are both counted as separate parking maneuvers.

Do buses stop along the intersection approaches? There are no bus routes that currently serve this area. It is important to clarify that this factor relates to local buses stopping at the intersection and not through buses which are included as part of the heavy vehicle data.

Do bicycles and pedestrians impede vehicular flow? Field observations show that both bicycle and pedestrian traffic is minimal. If this were not the case, then both would need to be included through field observation or estimation.

How will the signal operate and what will be the lost time at the intersection? Lost time is a factor that is commonly misunderstood by users of the HCM signalized intersection procedure. This issue will be discussed in detail in sub-problem 4a.

Do narrow lane widths impede traffic flow? Field studies have shown that the existing lane widths do not have an effect on the final saturation flow rate of this intersection. Each approach was measured in the field as 12 feet wide, which is the standard width and therefore no adjustment to saturation flow rate is necessary.

Do heavy vehicles affect the performance of the intersection? Heavy vehicles are not present in sufficient numbers to affect the saturation flow rate at the intersection.