Material Handling
Pages Appendix1 Appendix2 References

Material flow and Logistics


Present Warehouse situation:

Existing and expanding your warehouse, reorganizing or planning a new one, all concepts start with a few basic thoughts:
computer aided design
  • How much space is really required? Note the space requirement of each article to be stored and multiply it by the quantity. 
  • Must all articles be stored in your warehouse? Can some of the dust collectors be stored at your vendors facility? 
  • Are the transport distances in your warehouse optimized? Take under consideration that fast movers should be located with shorter transport distances.
  • Is your warehouse setup to handle multiple load sizes? Take note of the dimensions and weights of your loads and see if a unified common denominator can be utilized economically.

Material flow and Logistics

A "warehouse" by definition states:

"The warehouse is an integral supply chain component, in which its principal purpose is to bridge the gap between a synchronised manufacturing and consumption. Considerable savings can be achieved if the storage system supports the dynamics of the material flow, and the static function of plain STORAGE is avoided."

This means that the warehouse, should never be considered a stand alone individual entity but rather a portion of the entire material flow process.

The analysis of the material flow logistics, emphasizes optimum material flow while on the other hand reducing storage costs by increased productivity and reduced space requirements.


 Pallet Handling System

The Locator System is composed of two parts: mobile terminals called Locator Terminals and a base system called .

The Locator System is designed with the concept that the action takes place on the warehouse floor. The operator is given suggestions about what should be done and where pallets should go. The supervisor can set all parameters within the software to automatically schedule shipping and storage moves. If the operator however decides that he wants to do something else, he can refuse the suggested task or move and enter what actually was done.

Optimize Warehousing with VNA technology
warehousing with narrow aisles and flow racksAs an example Warehousing costs may be distributed in the following manner:
  • 40% - Building
  • 40% - Personnel
  • 10% - Rack Structure
  • 10% - Forklift Vehicles

It follows that space reduction to the absolute minimum requires a more detailed and precise planning.

It is equally important to minimize the traffic aisles and staging areas as well as reducing the storage areas.

The Planning also requires a balance between various related factors to achieve a comprehensive solution. 

  • Building: Height vs. Area - depending on the geographical region - the same building volume with a reduced surface area and higher ceiling height can be less costly to build.
  • Fire Protection: at certain storage heights a sprinkler system may be required
  • Safety: corporate and insurance concerns as well as a general safety awareness drive the safety system requirements - most narrow aisle systems have included a planned safety profile while general traffic contends with rules of the road
  • Vehicles: the forklift truck selection is based on lift height, capacity, throughput capability and aisle requirements all other items being equal

To what depth does the forklift selection have an influence on the overall warehouse design

Better Space Utilization at a set warehouse height
In the following example a warehouse with 138' Long x  95' Wide x 47.5' High yielded the comparative storage found in the table below: high bay turret truck
reach truckconventional counter-balanced forkliftwalkie stacker
Forklift Model
Walkie Stacker
Reach Truck
VNA Turret
Working Aisle width
Number of Aisles
Pallet Levels
Pallets on floor level
Rack Units
Pallets stored
Pallet numbers  %

Rack Structures
turret truck operating in narrow aisle with conventional pallet racksRack Structure and Material Organization:
  • size of the warehouse
  • inbound / outbound pallet movement as well as information on the average storage time of the material
  • floor conditions ( existing, type of floor, condition, capacity, rebar, floor topping)

There are numerous solutions for each possible condition.

In general the following applies:
In order to maximize warehouse capacity and throughput, one must select a suitable rack structure with the appropriate vehicle and logistics system. In other words a comprehensive working system.

The in / outbound load movement and their average storage times directly influence the rack structure requirements.

Guidance Systems

Very Narrow Aisle vehicles operate in aisles with little free space between the vehicle and the rack or the overhanging loads. Travel speeds can only be maintained if the operator is free to concentrate on the hydraulic and travel functions. Steering controls within the aisle are part of the "Guidance System". Rail guidance via the vehicle mounted guide rollers and angle iron mounted within the aisle. Wire Guidance requires vehicle electronics and a floor embedded wire to follow.

In general there are two types of guidance: Rail Guidance and Wire Guidance both have their benefits.


vehicles with rail guidanceRail Guidance

As can be seen in the picture, rail guidance is a method in which the vehicle travels between angle iron rails mounted on both sides of the working aisle. A set of four guide rollers mounted on the vehicle maintain the path. The steer wheel is centered electronically in order to prevent oscillation back and forth between the rails; entry guides assist the operator to enter the aisle and optical sensors provide automatic aisle identification - releasing optional travel and hydraulic functions.

vehicle with wire guidanceWire Guidance

In the middle of the working aisle a small 1/8" wide x 3/8" deep groove is cut. A flexible and durable wire is embedded in the floor and sealed with epoxy. The wire is installed as a loop with a connection to the LDU "Line Driver Unit" which sends a low voltage RF frequency through this loop. Antenna mounted on the vehicle utilize this magnetic field and steer the vehicle along its path.


  • additional floor clearance without guide rollers - beneficial on uneven floors
  • larger systems tend to be more cost effective with wire guidance - NO additional bottom rack level to compensate for the floor guide rails
  • NO mechanical stress on vehicle or floor structures (rails)
  • floor level storage without rail interference or structural compensation (raise floor level or install lower rack shelf level)
  • increased flexibility to change the layout - wire can stay in the floor simply cut new path disconnect area or aisle not to be used
  • reduced overall system installation times
  • adaptable to full automation

Floor System

The following criteria should be utilized with a narrow aisle forklift system:

narrow aisle floor system specificaitons

  1. Floors should meet or exceed a minimum of an F - 50 "FACE floor rating"
  2. The sub floor should be capable of supporting the racks and rolling loads
  3. Floor joints should run parallel to the working aisle under the rack structure. If unavoidable the floor joints should cross the working aisle perpendicular and when possible outside of the working aisle only.


  Tolerance in mm allowed 
between measurement positions
Floor Covering 0,1 m 1 m 4 m 10 m ab 15 m
Floor coverings may be added as self levelling toppings 





  absolute height difference h allowable
between the wheel track in widths shown
  up to 1,0 m over 1,0 m
to 1,5 m
over 1,5 m
to 2,0 m
over 2,0 m
to 2,5m
Lift Height < 6,00 m
2,0 2,5 3,0 3,5
Lift Height > 6,01 m and
Automatic Operation
1,5 2,0 2,5 3,0








  Test Positions as indicated in the table below
as absolute maximum values
1,0m 2,0m 3,0m 4,0m
for all applications 2,0 mm 3,0 mm 4,0 mm 5,0 mm


4.   In warehouse areas in which the vehicles travel with raised loads,
      the following exception table applies to the wheel track.

5.   The floor should not flex or permanently deform under the weight of the operation

6.    Trenches, power conduits, cut off floor anchors etc. should be avoided within the narrow working aisles

7.    The floor should resist absorbing oils and grease as this may have an adverse affect on braking.

8.    Floor grounding should conform with current specifications and not exceed 106 W  - avoid static build up.

9.    The floor should allow sufficient adhesion to brake the vehicle according to the manufacturers specification

10.   Because the vehicles diagonal travel capability, it is advisable to avoid floor deviations when ever              possible.


Safety Systems
A safety distance or border generally accepted between forklift and pedestrian traffic is not obtainable in the very narrow aisle configuration. Therefore pedestrians should only have restricted access to the VNA aisles.

If customer requirements specify pedestrian access to the narrow aisle area, it is recommended to install a personal detection system. The systems are designed to warn both the vehicle operator and pedestrian early enough in case of danger. NOTE ultimately this a customer decision, the best solution remains to avoid pedestrian traffic in operational machine aisles.

Wide Span Shelving
Storage of all types of goods that are not normally stored on pallets and that may require individual pick and storage capability.

A frame work supports of uprights supports a shelf of sheet metal or wood


  • Good space utilization
  • Variable to suit specific loads
  • Can be serviced manually or with vehicles
  • Handles Automated AS/RS - tote boxes

Pallet Racks
high bay pallet racksApplication
Storage for pallets.

Rack Options include:

  • Drum Storage
  • Front to Back support / shelving
  • Load stops prevent pushing pallets to far
  • P&D stands

    These racks vary from shelving in that they are designed with carrying beams to support more weight. 

    Practical applications up to 45 feet to be serviced by Very Narrow Aisle Forklifts.

    Higher rack systems are available and require special attention to rack upright design making them suitable for AS/RS systems.

    The rack configuration may vary depending on load weights and warehouse design. A single rack row may stand on its own or require support from walls / ceiling or over the top of the working aisle with other rack rows (some aisle will have back to back rows). Rack heights, floor conditions, seismic zones, sprinkler requirements, load types, load weight, customer application and servicing vehicle type will influence the rack design.

    Rack designs include structural steel, formed channels, hanging beams, clamped beams, bolted and welded components. Some rack systems are have flexible beam locations and their levels may be altered. Usually the placement of the first beam level has the greatest effect on the overall stability and capacity of the upright supports.


  • Flexible applications suitable for various load types and material flow concepts
  • Ability to add or modify the rack structure after the initial installation

  • pallet rack supports for varying loads or storage of barrels

Drive-In and Drive-Thru Racks
Drive-in and drive-thru rack struturesApplication
  • Storage of larger quantities of the same item
  • Pallets not suitable for block storage

    This Storage system allows maximum cube utilization for like pallets without placing pallets on top of one another (block storage). Rails placed perpendicular to the work aisle allow for multiple deep pallet storage. 

    This configuration will reduce the number of aisles but will also restrict pallet or load selection. 

    The Drive-in Rack works on the principal of "First in-Last out". The Drive-Thru Rack works on the "First in-First out" principal.


  • Maximum Storage and limited selection
  • Limited number of pallet face openings
  • Limited to specific types of forklift equipment

  • Use of drive-in rack structures
    Loads are placed in storage lanes. Vehicles must enter these lanes to store & retreive loads

Moveable Racks
moveable rack structureApplication
  • Storage with limited load movement and limited space availability


    Pallet Racks, Shelving and Cantilever Racks can all be utilized. The Racks are installed on moveable platforms. The access aisle is created by moving the rack structure either by hand or automatically.


  • Up to 50% space savings over stationary rack systems
  • Variable configurations available
  • After opening the access aisle, each storage space becomes accessible.

advantages of moveable rack systems

Space Comparison between a stationary and mobile rack system 

Flow Racks
flow racksApplication
Pallet picking / large scale distribution

Racks are based on standard rack component uprights with engineered load support beams that to provide a specific angles to the flow lane. The loads are placed on the inbound (higher) side and flow (gravity) to the outbound (lower) side. Loads are slowed via brakes located in the lanes. Some flow racks are manual in nature, others have controlled lanes. Each lane is FIFO - first in - first out - only.


  • Compact Storage
  • FIFO
  • Segregation of shipping / storage / and inbound load
  • Shorten transportation distances for load distribution

flow rack application

Application as distribution rack 

Cantilever Rack
cantilever rack structureApplication
Storage of long loads such as bar stock, pipes, lumber etc.

Cantilever Racks are specially constructed storage racks for long loads, either single sided or double sided. The design may incorporate fixed arms (welded construction) or moveable arms (bolted or clamped).


  • Versatile in configuration and storage capability
  • Self supporting, the heavy duty construction also lends itsself to outdoor applications

cantilever rack application

Cantilever Rack shown in single and double sided construction

Personnel Detection

Personnel Detection Laser-Scanner-System. The complete system is integrated on the vehicle. The Laser Scanners face both travel directions forward / reverse, the units are mounted under the rear cover and on top of the front axle.

Advantages of the Laser Scanner System:

  • NO faulty error conditions caused by environmental conditions (light, temperature)
  • Individual zones can be configured to meet the exact in customers requirements
  • the system is designed as a collision avoidance
  • not only pedestrians are detected, also objects are recognized within the detection zone

Functional Description of the Laser Scanner
The Laser scanner is a light sensor, that measures light distance in time. A short laser pulse is emitted. A rotating mirror reflects the light around a 180 degree half circle. At the same time an electronic stop watch is started. If the light hits an obstruction, the difused light is returned to the receiver and the timer stopped.

The distance measurement is calculated by subtracting the time between the sent pulse and the received light. Together with the detection angle and the distance the exact position of the object can be determined. If the position falls within the predetermined safety zone "warning" the automatic speed reduction is initiated. If the position falls within the safety zone "danger" an e-stop is initiated to bring the vehicle to a complete halt.. 

functional description of pedestrian laser safety system

When entering the working aisle in the forward direction the front scanner becomes active when the vehicle enters the aisle (eg. guide rail detection - wire guidance detection - magnetic codes at the beginning of the aisle). The laser scanner detecting reverse travel direction, even though active will only be evaluated once its travel direction is selected within the aisle. 

The control aspect assures for redundant detection in a fail safe manner. The switching of the active scanning device ensures authentic obstacle detection avoiding as an example pedestrian and traffic in the intersecting aisle when the vehicle is heading away from this zone. The working aisle detecting scanner always remains active until the absolute end of the aisle has been obtained. 

overview of pedestrian laser scanner operation in narrow aisles




Top of page
Site Policy Contact Us Disclosure Policy Suggested Operating Environment