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Travel times were modeled using ESRI ArcGIS Pro version 2.1. Fire stations were identified on Geographic Information System (GIS) maps as starting points with vehicles traveling at posted road speeds. When generating the maps, a number of assumptions needed to be addressed prior to drawing conclusions from the analysis. These assumptions are as follows: • Modeled travel speeds are based on reasonable prudent historical traffic speeds occurring on Wednesdays at 5:00 PM.1 Actual response speeds may be slower, and the associated travel times greater, with any unpredictable impedances including, but not limited to: o Traffic Incidents: Collisions and vehicle breakdowns causing lane blockages and driver distractions. o Work Zones: Construction and maintenance activity that can cause added travel time in locations and times where congestion is not normally present. o Weather: Reduced visibility--road surface problems and uncertain waiting conditions result in extra travel time and altered trip patterns. o Special Events: Demand may change due to identifiable and predictable causes. o Traffic Control Devices: Poorly timed or inoperable traffic signals, railroad grade crossings, speed control systems, and traveler information signs contribute to irregularities in travel time. o Inadequate Road or Transit Capacity: The interaction of capacity problems with the aforementioned sources causes travel time to expand much faster than demand.2 • Larger emergency vehicles are generally more cumbersome and require greater skill to maneuver. Therefore, response by these vehicles may be more negatively affected by weight, size, and in some cases, inability to travel narrow surface streets. • Computer modeling only considers travel time of apparatus. Decision makers should understand that once apparatus and personnel arrive on the incident scene there are other essential tasks that must be completed which require additional time before access, rescue, and suppression can take place. Tasks such as establishing a water supply, forcible entry (access), and deployment of an attack line are not considered in the computer modeling. • The reliability of a community's hydrant system to supply water to fire apparatus. • Weather conditions Historical traffic data as contained in ERSI's StreetMap Premium,Version 17.2. 2 David Shrank and Tim Lomax, The 2003 Urban Mobility Report,(Illinois Transportation Institute,Illinois A&M University: September 2003). 4