Ladder_SOW_for_FedBizOp.docx

NIOSH Ladder Climbing Simulator (Procurement to Support a Study on Firefighter Aerial Ladder Design Optimization)

Table of Contents I .Object of Contract Document II. Background and Need III. Current and Historical Market Items IV. Scope of Work Task 1. Ladder Climbing Simulator

1.1 Ladder Requirements

1.2 Non-Instrumented Rung Requirements

1.3 Control Requirements

1.4 Safety Requirements

Task 2. Force Measurement System

2.1 Instrumented Rung Requirements

2.2 Data Acquisition Requirements

V. Reference

I. Object of Contract Document The Division of Safety Research (DSR), NIOSH, is seeking to procure the development of a “ladder climbing simulator”, i.e., experimental laboratory model of a telescopic firefighter aerial ladder with various configurations. The ladder climbing simulator will allow evaluation of the ergonomic compatibility of fire truck aerial ladder to firefighters through lab testing of a number of experimental conditions, including a range of ladder rung spacing, telescopic ladder angles, simulated climbing distances, and telescopic ladder side-rail heights. To address the complexity of the development effort for the proposed equipment, the contract includes the following two tasks: Task 1 – Ladder climbing simulator including standard (non-instrumented) rungs; Task 2 – Force measurement system with instrumented rungs and data acquisition system to read and transfer the data.

II. Background and Need Accessing and using the aerial apparatus has been identified by the firefighter community as a significant source of risk of falls (Dunn 1992). NIOSH along with fire apparatus stakeholders and firefighter community are seeking for scientific data to update the current NFPA 1901 standards (ladder configuration and rung spacing) for aerial fire apparatus design.

The current NFPA standards for fire apparatus design (NFPA 1901, Chapter 19) specify that aerial ladder rungs shall be uniformly spaced between 11.75 and 14 inches (300 ~ 350 mm). Most of the existing fire truck aerial ladders are made with rungs spaced at the upper limit, i.e., 14 inches. This is in contrast to the current standard requirements for extension and straight portable ladders used in the general industry (ANSI A14), in which the rung distance is fixed at 12 inches. Several firefighter groups have expressed their concern with the difficulty in climbing the telescopic ladder at various ladder angle settings, and scientific data are absent on optimal rung distance for the telescopic ladder.

Using real fire apparatus aerial ladders for the study can be problematic, since they are between 50 and 135 feet long (NFPA 1901) and only available with a 14” rung spacing. Fall hazards, outdoor environmental variability, and instrumentation challenges (for physiological, motion, and force measurements) make such an experimental setting impractical. The idea of a “ladder climbing simulator” is therefore proposed. The firefighter participants will traverse and climb the “ladder climbing simulator” with full firefighting gear (protective clothing, boots, breathing apparatus, and firefighting tools) in a controlled laboratory environment, including conditions (with elevated temperatures) simulating active firefighting.

III. Current and Historical Market Items Ladder climbing simulators have been developed and used in the past both as research equipment and for exercise or training activities. Among the references and conceptual products can be found in the literature:

Popular Science June 1936 pp.43 Endless Ladder -- http://books.google.com/books?id=eSYDAAAAMBAJ&pg=PA3&lpg=PA3&dq=popular+science+june+1936+endless+ladder&source=bl&ots=qEuPGjOdLc&sig=GvMVlSqmGYmSP5PbRoXZn-KqlAg&hl=en&sa=X&ei=s85ZUZiPLpHk9gTn6oC4CA&ved=0CEwQ6AEwBA#v=onepage&q=popular%20science%20june%201936%20endless%20ladder&f=false Jacobs Ladder -- http://jacobsladderexercise.com/ -- the Unit has a US patent.

“Laddermill and Ergometry: A Comparative Summary”, ELIEZER KAMON, Department of Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh , Pennsylvania; HUMAN FACTORS, 1973, 15(1), 75-90 - This study was supported in part by the National Institutes of Health, Grant 8-RO1-ON40308, and by the Office of Naval Research, Contract N00014-67-A-0402-0009 http://hfs.sagepub.com/content/15/1/75.short HP/COSMOS Discovery -- http://www.h-p-cosmos.com/en/products/discovery/index.htm Draeger Safety - http://www.draeger.com/media/10/00/99/10009909/endless_ladder_br_en.pdf

IV. Scope of Work

1. Task 1 – Ladder Climbing Simulator (with Standard Non-Instrumented Rungs) The technical characteristics for the proposed “ladder climbing simulator” will generally follow the requirements of the technical standard (NFPA 1901) for the telescopic firefighter aerial ladder (the modeled equipment), with exceptions for the characteristic related to the study variables and any integrated data collection instrumentation. Some of the major standard requirements and the specific requirements related to the study variables and the data collection instrumentation are provided below.

1.1 NIOSH will accept separate bids for either or both of the following two options 1.1.a A single unit capable of automatically switching rung distance between at least 3 equally spaced rung distances which must include 10”, 12”, and 14”. Rung distance is defined as the straight distance from the center of one rung to the center of the next. Unit must be capable of running for 24 hours without a misplaced rung. Rungs must be placed within 0.1”. (In this type of unit NIOSH would also be interested in 11” and 13” if possible.)

1.1.b Three (3) units each with a separate equally spaced fixed rung distances of 10”, 12” and 14”. Each unit must be physically and operationally exact with respect to climbing except for the rung distances.

1.2 Common specifications for apparatus 1.1a or apparatuses 1.1b

1.2.1 External Size

1.2.1.1 Operational Size Limitations: Height is limited to 120”.

1.2.1.2 Transport Requirements in an Elevator : Unit must fit in Box 83” high x 64” wide by 92” deep

1.2.1.3 Other Transport Requirements: Unit must be max 47” wide and 81” high in other transport mode.

1.2.2 Usable Climbing Range: The usable active climbing range length must allow safe climbing for the tallest individuals, the flat usable length of the ladder should be 8’ minimum.

1.2.3 Variable Angle

1.2.3.1 The unit or units must be capable of easily changing the climbing angle to be within 0.5 degrees (accuracy/precision) for at least a selection of 30, 45, 60 and 75 degrees from horizontal (Figure 1), although it is desirable to have adjustability between 0-90 degrees.

1.2.3.2 The ladder must indicate the angle at which it is positioned by means of a readout (not necessarily digital). Readout should indicate in 5 degree increments within 0.5 degree accuracy.

1.2.3.3 The ladder angle position needs to be adjustable under its own weight by a single person but not necessarily adjustable at the same time a firefighter is on the ladder. The force exerted by the single person adjusting the angle of the ladder shall be no more than 30 lbs. No single method is required but means to accomplish this might be for example using a balance mechanism (i.e., gas spring) or motorized mechanism.

Figure 1 : Unit should be safely usable in a variety of positions between and including 30, 45, 60 and 75 degrees

1.2.4 Load Limits

Unit or Units must be capable of supporting 500 lbs as a minimum operating (no yield) load and 1000 lbs as a failure load. When considering the effect of load transfer from the rung to the ladder, loads shall be considered distributed over a 3 ½ “ (89mm) wide area at the center of the length of the rung with the rung oriented in its weakest position. Design loads shall also be considered distributed at other points on the unit as required by best practices for design. (NFPA 1901-19.2.4)

1.2.5 Side Rails

Units will have side holds to approximate the rails available on a telescopic firefighter aerial ladder according to the requirements of NFPA 1901 (NFPA 1901-19.2.8 Top rails shall have a minimum width of 1 in (25mm), and shall be at a minimum height of 12 in. (300mm) above the centerline of the rungs). Furthermore, the side holds should be replaceable or have variable height, and capable of supporting body weight of 500 lbs without failure.

1.2.6 Rungs Mounting

Rungs shall have a quality feel free of excess play in the unit while being climbed on. Any play shall be minimal as to not be noticeable by the individual climbing. The rungs shall have a maximum amount of play of 1/32”.

1.2.7 Speed Control

1.2.7.1 Speed Modes: The ladder speed shall be controllable by two Speed-Mode mechanisms. Speed-Mode-1: Settable, fixed speed, with a safety/stopping method if the firefighter cannot keep up. Speed-Mode-2: Variable, self-paced speed, controlled by the movement of the firefighter. A supplemental speed control mechanism may be needed for Speed-Mode-2 to determine if the firefighter is going faster or slower than the ladder and readjust the speed accordingly. This feedback control mechanism could be electrical (camera based, string pot, rung force/pressure) or mechanical. Reliability and safety are to be design considerations.

1.2.7.2 Speed Range: The device must have a maximum ladder speed of 150 feet per minute or greater. There must be a digital readout of the speed so it may be set in increments of 0.5 feet per minute with an accuracy of 0.5 feet per minute.

1.3 Safety Requirements and Guarding

1.3.1 The ladder must be designed for and constructed to be safe as defined by industry standards. The contractor must perform a risk assessment and determine how each hazard will be addressed; a sample of a Risk Assessment is available from NIOSH. The contractor shall use current machine standards, exercise standards, electrical, and functional safety standards to address these hazards if needed. The standards listed below serve as an example of what might be considered applicable as industry best practices: Safety of Machinery (ANSI B11.0; B11.TR6; B11.19), Robotic Safety (ANSI RIA 15.06 and ISO 10218), Risk Assessment (ISO 12100), Functional Safety (ISO 13849; ANSI B11.19 and B11-TR3), Treadmill Design (ASTM F2115-12 and ASTM F2106-12), General Military (MIL-STD 882 - for risk assessment), National Electrical Code (NFPA 70), Electrical Standard for Industrial Machinery (NFPA 79).

The risk assessment shall address how hazards are being protected. It shall indicate the reliability of the hazard reduction method if necessary and all hazards leading to a significant injury shall be addressed or designed out. A suggested risk assessment format could include the following topics: Task/Activity, Hazard, Severity of potential injury, Likelihood of incident, and Expected Mitigation. A cheap and reliable method of dealing with the hazards should be acceptable. Designing out the hazards would be preferable.

It is not planned for the ladder to be used outside a research environment without trained personnel. Research participants will be wearing a harness attached to a short-fall arrest device.

Residual risks are those risks which cannot be addressed or are deemed acceptably low risk in general because of low-severity, extremely-low probability or some level of practicality. NIOSH recognizes that there is always some level of residual risk and some risks are deemed acceptable. Residual risk must be minimal and NIOSH reserves the right to approve and determine these risks acceptable prior to acceptance of deliverables.

It is required that the contractor delivers a risk assessment at the design stage for NIOSH comment and as part of the documentation delivered for final approval.

1.3.2 Specific protection requirements

1.3.2.1 There shall be an inner guard to protect feet from pinch hazard of rungs rotating on the other side. A slip from a rung shall not create a leg injury; this shall be evaluated at high and low angles. There must be some method to stop the motion when a foot slips to prevent a serious leg injury. This guard may be interlocked to the motion shutdown circuit. There may be a light curtain to detect a foot slip from the rung interlocked to the motion shutdown circuit. There shall be a minimum of 9” depth to this interlocked light sheet or pan which will not trigger a fault. (NFPA 1901-19.2.7.1 requires a minimum of 7 in (180mm) clearance between the centerline of a rung and an obstruction.)

1.3.2.2 The ladder must be locked in angular position while there is a person on it. The lock must be interlocked to prevent motion when lock is not in place.

1.3.2.3 The firefighter shall be able to get on and off without unaddressed pinch/crush hazards.

1.3.2.4 Safety shall be evaluated at all critical/adjustable angles throughout the ladder angular positioning range (at least at each 10 degree position).

1.3.2.5 The ladder shall be free of electrical hazards. It shall be well grounded and issues such as current leakage (GFCI) or static buildup shall be addressed.

1.3.2.6 There shall be an emergency stop button or rail designed to NFPA 79 and B11.19 or other acceptable industry standards: 1. Reachable by the participant, 2. Reachable by the researcher. This could be a cable pull toward the outside of the ladder on either side.

1.3.2.7 Ladder shall be free of pinch hazards while climbing or operating

1.3.2.8 Ladder shall be free of cut hazards due to sharp edges

1.3.2.9 Ladder shall not restart without reset, when power is lost. (This is generally done with a contactor relay setup.)

1.3.2.10 The device shall be stable. The device shall be stable enough to: 1. Not fall over if a firefighter of 500 lbs was to slip; 2. Given a sideways force of 200lbs; 3. During usage at speeds between 150-200 fpm; 4. For situations involving foreseeable misuse. Means to accomplish this can be to attach to a base which widens the unit or to control the center of gravity/weight of the unit. The unit shall be built with tabs to secure to a floor or base if needed. Securing the unit directly to the floor cannot be a basis for supplying stability.

1.4 Non-Instrumented Rung Specifications

1.4.1 The standard (non-instrumented) rungs must be removable and changeable, to allow for an easy replacement with instrumented rungs.

1.4.2 There must be a method to mount the data acquisition system for instrumented rungs. This system must be planned for in Task 1 and is either part of the rung or part of the ladder.

1.4.3 Rung mounting must be conducive to the use of metal and multiple changes of rungs, and the rung shall be aluminum or steel.

1.4.4 Rungs must be supplied in 1 ¼” or greater diameter with a non-slip surface as required by NFPA 1901 (NFPA 1901-19.2.2).

1.4.5 The climbing portion of the rung must be 18 inches in width as required by NFPA 1901 (NFPA 1901-19.2.6).

1.4.6 Rungs must be capable of supporting 500 lbs minimum on each rung without failure and fail at no less than 1000 lbs. Firefighters will be using it with and without gear. Loads shall be distributed over a 3 ½ ” (89mm) wide area at the center of the length of the rung with the rung oriented in its weakest position. (NFPA 1901-19.2.4)

2. Task 2 – Force Measurement System (Instrumented Rungs and Data Acquisition) Three instrumented rungs and associated data acquisition system(s) are needed for each ladder.

2.1 Instrumented Rung Design

2.1.1 Physical rung requirements are the exact same as the non-instrumented rungs in Contract Task-1 section 1.4.

2.1.2 Contractor must make the Instrumented Rung interchangeable with the rungs supplied under Task 1.

2.1.3 Each instrumented rung shall have capability to measure at least the following forces and moments: Fy each side, Fz each side, Mx overall (Figure 2). If more channels are needed to deal with contributive effects of multiple forces (physical cross-talk) then a six-axis cell may need to be supplied. The instrumented rungs shall have a method of checking calibration. A calibration matrix must be supplied with the rungs.

Figure 2: Instrumented Rung coordinate system and description of forces and moments

2.1.3.1 They shall be accurate to 5 lbs ( 0.5% on 1000 lbs ) minimum increments. Physical crosstalk between load-cell measurements should be in the 2-5% range. Each rung axis shall have minimum load range(s) as specified on Figure 2.

2.1.3.2 They shall have NIST traceable calibrations supplied with them.

2.1.3.3 Connectors shall be a low-noise instrumentation connector.

2.1.4 Power requirements for the supplied instrumentation are expected to be that necessary for strain gage instrumentation. Selected power supply requirements must be conducive to supplying power to a rotating unit and are expected to be battery based but others will be considered.

2.2 Data Acquisition System

2.2.1 Data Acquisition: Data acquisition system(s) shall be supplied to read data from a single or multiple rungs and be integrated with the ladder(s) as provided under Task 1 (1.4.2). Each supplied ladder shall have an independent system.

2.2.1.1 Batteries, if used, shall not be susceptible to fire hazards due to vibration. Battery packs shall have a charging system and internal temperature monitoring if standard for safe charging by industry standard (i.e. lithium rechargeable)

2.2.1.2 Data acquisition must be interfaceable to a PC with no effort and text based data files with pre-scaled and zeroed engineering units must be available.

2.2.1.3 System shall be capable of handling all channels of one rung (or of all 3 rungs)

2.2.1.4 The preferred method of data acquisition is wireless with local logging of data.

2.2.1.5 Data must be time synchronized and recorded using simultaneous data acquisition as needed by multi-axis force measurement. Possible methods of data acquisition are wireless, brush based, inductive pickup, and capacitive pickup. The preferred method should allow continuous feedback as to which rung is transmitting data and to output data during any contact cycle. There must be a method to synchronize data between rungs if they use separate data loggers. A synchronization pulse rotating on the ladder may be a possible method to synch to data on external PC. Synchronization must be less than 0.001 seconds.

2.2.1.7 There should be a method to check the load cell for shunt or other self-test that might be on rung.

2.2.1.8 They shall be precise and accurate to a minimum 0.5 lb (.1% on 1000 lbs) minimum increments given a 2mv/V excitation signal. System shall be capable of supplying an excitation signal required for accuracy. It is understood that there may be a loss of accuracy below 1% of full scale reading.

2.2.1.9 All connectors must be supplied.

2.2.2 Reporting and Delivery Schedule:

2.2.2.1 Task 1 - “Ladder Climbing Simulator” Delivery Date: September 30, 2014 Deliverables: Completed “ladder climbing simulator” unit(s) with non-instrumented rungs as specified in 1.1.a or 1.1.b. If multiple units are supplied there must be enough rungs for each unit to run at the same time. Documentation and labels to be delivered are at a minimum: Maintenance and Usage Documentation; Parts List; Safety Assessment; and, Required Safety Signs and Labels.

2.2.2.2 Task 2 – “Force Measurement System” Delivery Date: September 30, 2014 Deliverables – Rungs: Three rungs along with documentation and labels to be delivered: Maintenance and Usage Documentation; Parts List; Safety Assessment; and, Required Safety Signs and Labels; NIST traceable calibrations certificates; details of any calculations needed to read or interpret data.

Deliverables – Data Acquisition: Data Acquisition units (to support all instrumented rungs) along with ancillary support equipment, cables or software needed to read data from the system locally or wirelessly to a PC including anything expected to be supplied or required on the PC. Documentation and labels to be delivered are at a minimum: Maintenance and Usage Documentation; Drawings and Schematics; NIST traceable calibrations certificates; details of any calculations needed to read or interpret data.

V. References NFPA 1901. (2009) Standard for Automotive Fire Apparatus.

Karter and Molis (2011). US Firefighter injuries – 2010. National Fire Protection Association, Fire Analysis and Research Division. Quincy, MA.

Karter and Stein (2011). U.S. Fire Department Profile Through 2010. National Fire Protection Association (NFPA), Fire Analysis and Research Division. Quincy, MA.

Dunn V. (1992). Safety and survival on the fireground. Pennwell Corp., Tulsa, OK.

Hammer and Schmaltz (1992). Human behavior when climbing ladders with various inclinations. Safety Science 15, 21-38.

Hirth and Khalil. (2004). Ergonomic Design Problems in the Entry/Exit Systems of Elevated Vehicles. Proceedings of the IIE Annual Conference and Exhibition.

Hsiao H, Long D, Snyder K. (2002). Anthropometric differences among occupational groups, Ergonomics 45:136-152.

image1.emf image10.emf image2.png