August 5, 2013
by HKS Research Team

Healthcare settings are often noisy environments that make it difficult for staff to perform tasks without being interrupted or for patients to rest and heal without disruptions. There are a number of issues that elevate the noise in patient units, but one of the greatest culprits is excessive staff and equipment traffic in corridors adjacent to patient rooms.  The majority of units are designed as a race track forcing all traffic, be it staff, visitors, equipment or patients, into the same corridors. Designers often utilize previously proven methods of sound mitigation by treating surfaces to be sound absorbent. These methods can be effective at diminishing noise but do not eliminate the cause of excessive traffic and noise.

A recent study conducted at an ICU at an academic medical center in central Illinois evaluated the ability of a third corridor, dedicated to the movement of staff and equipment, to reduce noise and disruptions. The study used a multi-methods approach of staff surveys, decibel readings, and observations to find that there was a significant decrease in noise and reduction in stress in the staff who worked on the unit.


Healthcare setting are meant to be places to facilitate healing and rest, but all too often they are filled with noise that can impart undue stress to both patients and staff.  Decibel levels in inpatient environments often exceed the levels recommended by the World Health Organization (WHO) and the US Environmental Protection Agency (EPA). Noise has been widely identified as a source of sleep disturbance and deprivation.  Noise from equipment and staff in the corridors permeate throughout units, creating regular distractions and irritations for both patients and staff. Previous research has shown that patient-related outcomes staff performance can be impeded by noise (Baker, 1984; Evans, 1995; Preto, 2009).

 Noise and too much traffic

Patient units are often designed in a racetrack formation with two corridors that run parallel to each other with access to patient rooms and support areas.  This configuration, while an efficient use of space, leads to the two corridors serving as the only way in or out of the unit. This results in congested corridors that become noisy and disruptive as equipment, staff, visitors and patients all share the same corridors. Not only are these corridors noisy and congested, but all of this activity occurs directly outside patient rooms, projecting noise into the spaces that should be the most quiet rooms in the facility. It is not surprising that these noisy and crowded corridors have the potential to produce negative distractions and disturbances for staff that may lead to medical errors and impact bedside care (Joseph & Ulrich, 2007; Mahmoodet al., 2011).

How it has been mitigated in the past

The destructive nature of excess noise in healthcare environments has been studied for many years. However, the methods utilized to mitigate noise continue to evolve.  One method to mitigate noise is to utilize surface treatments such as sound absorbing ceiling tiles, sound attenuating surfaces, or carpeted hallways.  While these types of interventions are effective and should not be neglected, they do not consider the origin of the unwanted noises.  Other, more layout focused changes include designing private patient rooms over multiple-occupancy rooms as a way to reduce noise among other positive outcomes.  Strategies that have been utilized in practice but not verified by research include various shapes of patient units and corridors as well as decentralized nurse stations. Designers and researchers have been working to find effective planning-related and architecture-related solutions.  A recent study evaluates a way to reorganize the flow of goods and services in a way that minimizes the amount of traffic outside of patient rooms.

About this study

This study evaluated the strategy of adding a central dedicated service corridor in addition to the typical racetrack design.  The study’s goal was to provide data and analysis to determine if the dedicated staff corridor in an ICU played a role in noise control and staff performance. The study utilized a quasi pre and post methodology to measure the performance gains of a new cardiac ICU.

The units studied are below:

  • Existing unit (served as the control)
    •  20 bed, 14,895 SF
    • Adult-cardiac ICU (pre move)/ Adult-surgical ICU (post move).
    • New unit
      • 18 bed 29,665 SF
      • Adult-Care Cardiac Unit with a centralized corridor dedicated to staff and material movement.

The same group of nursing staff worked on the unit before and after the move, and was surveyed twice.  The first survey asked the staff to recall their experience in the previous Unit; 72 staff members responded. The second survey asked the same set of questions regarding the new unit; 46 staff members responded. During the study the control unit housed an adult-surgical ICU unit.  While the function of the control unit was slightly different, the built environment remained unchanged from before the move and,  according the ICU managers the daily tasks, patient care requirements and visitor activities were very similar between the adult-cardiac and adult-surgical ICU units at the time of the study.  In addition to surveys, sound measurements were taken and compared throughout both units after the move. On site observations of corridor traffic were also conducted in both the new and control environments. Corridor traffic including number and type of people as well as the number and type of carts and equipment observed  during the observation times was recorded by type, including staff, patient, and visitors.  The study did not take into account the patient perspective.  There were no patient surveys or sound reading from within the patient rooms, leaving the impacts on the patient experience unknown.


The data indicated that overall the new ICU is quieter and less stressful than the control unit.  While the study’s results cannot be attributed entirely to the dedicated staff corridor the strategy seems to provide some benefit to reducing noise. Overall, the nursing staff perceived the new environment to be significantly quieter.  They also reported being significantly less stressed and more energized during the work day in the new ICU. The average sound reading in the new ICU was 53.04 dBA during the day and 51.34 dBA during the evening. The levels in the control environment were 56.1 dBA and 52.53 dBA respectively.  Although the new unit decibel levels are not within the range of the WHO recommendations, they were significantly lower than the control unit. The observers on the units reported that the while much of the cart and staff traffic was within the central corridor, there were some staff who still chose to travel directly to the patient rooms particularly, housekeeping and food delivery. The observers noted that there were fewer carts stored in the corridor in the new unit than in the control and fewer staff congregating around those carts. This shows that there is still room for improvement in the adoption of the new process however, within the first year there were marked improvements with the 3 corridor layout. Data on the patient experience would be valuable as we look to address the impacts of the third corridor on patient relaxation and healing. However, the data from the corridors and staff perspective does provide valuable insight into the potential benefits.





This study provides meaningful data on how we can work toward mitigating noise through layout driven strategies. In the case of this project Dr. Zhe Wang, the author of the article, says “The original idea of a third circulation corridor for services was from the client.” As we know it is difficult to get buy in from all the players involved in the design process when additional cost and space is on the table.  This study provides evidence that begins to justify the additional space required for a third corridor and can be used to illustrate the benefits. The strategies used to mitigate noise could have also have a positive impact of process as well as reduction in staff turnover and errors caused by interruptions.  More research is needed to address the potential benefits to efficiency and the care cost. Given the potential for gains in these areas the third corridor concept could be utilized throughout hospitals in many inpatient unit types. This study is a great first step in making the case for a new and possibly viable solution for reducing noise even beyond the ICU environment.

Full Article:
Wang, Z., Downs, B., Farell, A., Cook, K., Hourihan, P., & McCreery, S. (2013). Role of a service corridor in ICU noise control, staff stress, and staff satisfaction. Health Environments Research & Design Journal 6(3), pp. 80–94.

Tagged acoustics, evidence based design, healing environment, healthcare architecture, HERD, hospital design, Info Byte, noise, Research, sound