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Table 19. Data sources.
| Data Item | Baltimore, MD | Charlotte, NC | El Cajon, CA | Howard County, MD |
|---|---|---|---|---|
| Crash data | Maryland CODES data from National Study Center for Trauma and MSUniversity of Maryland-Baltimore | Charlotte Department of Transportation (DOT) | California Highway Patrol Crash Database (SWITRS) | Maryland CODES data from National Study Center for Trauma and MSUniversity of Maryland-Baltimore |
| Intersection traffic counts | From Baltimore Traffic Management Centers (TMCs), Maryland State Highway Administration counts, MPO (BMC) counts, and vendor loop data | Database of total intersection entering volumes, hardcopied TMCs, midblock counts, and approach volumes on signal plans | El Cajon turning movement counts and permanent station countsLink volumes from the area MPO (SANDAG) | Howard County TMCs and midblock ADTsMaryland State Highway Administration (MDSHA) TMCs and midblock ADTs |
| Number of approach lanes, medians, turn lanes | Aerial photos from Baltimore GIS data | Signalized: Most are from detailed signal plans, a few from aerial photographsUnsignalized: Estimated from aerial photos | Signalized: Signal plansUnsignalized: Aerial photos, signal warranting study reports, and drawings of adjacent intersections | Signalized: Howard County and MDSHA signal plans, aerial photos |
| Intersection "change" data | Baltimore historical timing sheets | No signal timing change data available. | El Cajon historical signal timing sheets | From historical signal plans and log maintained by Howard County staff |
| Traffic signal phasing data | Baltimore printouts of current signal timing | Charlotte signal timing system | El Cajon printouts of current signal timing | Howard County and MDSHA signal plans |
| LEDs and backplates | No data available | From signal drawings | Used by El Cajon, but no formal installation dates were available | From log maintained by Howard County staff |
| RLC installation date | City of Baltimore Traffic Engineering Division | Charlotte DOT | El Cajon Traffic Engineering Division and Police | Howard County staff |
| RLC signing | City of Baltimore policy | Charlotte DOT policy | El Cajon Traffic Engineering Division policy | Howard County policy |
| RLC ticket protocol | City of Baltimore Traffic Engineering Division | Charlotte DOT | El Cajon Traffic Engineering Division | Howard County staff |
Table 19. Data sources. Continued.
| Data item | Montgomery County, MD | San Diego, CA | San Francisco, CA |
|---|---|---|---|
| Crash data | Maryland CODES data from National Study Center for Trauma and MSUniversity of Maryland-Baltimore | California Highway Patrol Crash Database (SWITRS) | California Highway Patrol Crash Database (SWITRS) |
| Intersection traffic counts | Montgomery County ADTs and TMCs | San Diego machine counts and turning movement counts | San Francisco ADT files, hardcopied turning movement counts and approach countsState-maintained ADTs |
| Number of approach lanes, median presence, presence of turn lanes | Signalized: Signal plans supplemented with aerial photosUnsignalized: Intersection drawings on TMCs | Signalized: Signal plans (outdated), aerial photographs, non-scale drawings from reportUnsignalized: Work-order requests, sketches on turning movement counts, and coders assumptions based on volume | Signal plans, pavement marking drawings, and aerial photographs |
| Intersection "change" data | Montgomery County historical signal timing files | San Diego historical timing files | San Francisco historical timing cards |
| Traffic signal phasing data | Montgomery County signal timing files | San Diego signal timing files | San Francisco signal timing files |
| LEDs and backplates | These data are not maintained | Requested but never received from City of San Diego maintenance staff | Although the city uses LEDs, it was not able to provide installation dates |
| RLC installation date | Montgomery County Department of Public Works (DPW) | City of San Diego Traffic Engineering Division | San Francisco Department of Parking and Traffic (DPT) |
| RLC signing | Montgomery County DPW provided general information | City of San Diego Traffic Engineering Division policy | San Francisco signing database |
| RLC ticket protocol | Montgomery County DPW | City of San Diego Traffic Engineering Division | San Francisco DPT |
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FHWA-HRT-05-048
