title: The impact of precipitation on land interfacility transport times.
abstract: BACKGROUND
  Timely transfer of patients among facilities within a regionalized critical-care system remains a large obstacle to effective patient care. For medical transport systems where dispatchers are responsible for planning these interfacility transfers, accurate estimates of interfacility transfer times play a large role in planning and resource-allocation decisions. However, the impact of adverse weather conditions on transfer times is not well understood.
  
  
  OBJECTIVE
  Precipitation negatively impacts driving conditions and can decrease free-flow speeds and increase travel times. The objective of this research was to quantify and model the effects of different precipitation types on land travel times for interfacility patient transfers. It was hypothesized that the effects of precipitation would accumulate as the distance of the transfer increased, and they would differ based on the type of precipitation.
  
  
  METHODS
  Urgent and emergent interfacility transfers carried out by the medical transport system in Ontario from 2005 through 2011 were linked to Environment Canada's (Gatineau, Quebec, Canada) climate data. Two linear models were built to estimate travel times based on precipitation type and driving distance: one for transfers between cities (intercity) and another for transfers within a city (intracity).
  
  
  RESULTS
  Precipitation affected both transfer types. For intercity transfers, the magnitude of the delays increased as driving distance increased. For median-distance intercity transfers (48 km), snow produced delays of approximately 9.1% (3.1 minutes), while rain produced delays of 8.4% (2.9 minutes). For intracity transfers, the magnitude of delays attributed to precipitation did not depend on distance driven. Transfers in rain were 8.6% longer (1.7 minutes) compared to no precipitation, whereas only statistically marginal effects were observed for snow.
  
  
  CONCLUSIONS
  Precipitation increases the duration of interfacility land ambulance travel times by eight percent to ten percent. For transfers between cities, snow is associated with the longest delays (versus rain), but for transfers within a single city, rain is associated with the longest delays.
authors.forename: Wayne C W
authors.initials: WC
authors.lastname: Giang
authors.forename: Birsen
authors.initials: B
authors.lastname: Donmez
authors.forename: Mahvareh
authors.initials: M
authors.lastname: Ahghari
authors.forename: Russell D
authors.initials: RD
authors.lastname: MacDonald
mesh_terms: D000552:Ambulances; D001334:Automobile Driving; D006801:Humans; D009864:Ontario; D011891:Rain; D012914:Snow; D013997:Time Factors; D014187:Transportation of Patients