Solid Waste Routing – Civil Engineering

An overview of the rules and strategies used for improving efficiency in solid waste collection.

Bob Roberts

In today’s struggling economy we are all forced to look at ways to reduce expenses. This applies to private and public operations equally. For the private operation, priorities are placed on maintaining profits—a difficult task in a competitive industry. Raising rates is typically met with resistance from customers, as well as opens a door for competitors to move in. For the public operation, staying within the dwindling budget is the priority. Now, it is quite difficult to get approval for a rate increase and even more difficult to get an increase in budget. Basic business rules state that to increase profit margin, one must either increase revenue or decrease expenses.

Many strategies and techniques exist for improving solid waste collection that can cut expenses and improve efficiency. These strategies can range from simple operational changes to more extreme collection day changes. Many of these strategies stem from common sense and can be used for most types of routing. Advancements in technologies now enable many options to choose from for computerized routing. Because collection costs make up between 40 and 60 percent of the total solid waste management system costs, this area is generally where the biggest savings can occur. This article will be broken down into two separate areas for improving efficiency: route optimization and operational changes.

Analyzing Current Operations

It is safe to assume that if you are reading this then you may already believe you have room for improvement in your collection operations. There are a couple of ways to test the efficiency of solid waste routes. If there is a route that seems to be troublesome, try putting one of your better drivers on that route for a couple of weeks. If the better driver takes just as long as the regular driver then chances are the problem is the route and not the driver. Bear in mind though that your “better” driver will most likely always get done faster; that is why they are the better driver.

There are some industry “thumb rule” counts for stops per route (some will not pertain to every area). For example, very rural areas will require more driving and thus collect less stops. For automated collection, the maximum stops per route is 1,000 stops for eight-hour day and 1,200 and for semi-automated (with one helper) it is 800 stops for eight-hour day and 1,000 for 10-hour day. So, if you are in a dense city area and you have automated routes that are only collecting 600 stops in an eight-hour day, there is room for improvement.

Route Optimization Strategies

Regardless of whether you are a private or public organization, many of the following techniques or strategies can assist to improve efficiency with your solid waste collection.

Heuristic Routing

“Heuristic is defined as a logical, commonsense thought process learned through experience that helps organize ideas, concepts, and information into a useful form or solution.”¹In 1974, EPA released publication SW-113 entitled Heuristic Routing for Solid Waste Collection Vehicles. For many years, this was the how-to manual to solid waste routing. Today, the majority of the rules still apply. Heuristic routing defined macro-routing and micro-routing. Macro-routing is defined as “determines the assignment of daily collection routes to existing processing and disposal sites.”

Micro-routing is defined as “looks in detail at each daily collection service area to determine the path that the collection vehicle should follow as it collects from each service on its route. The objective is to minimize the driving time on the collection route through minimizing the dead (head) distance…” What we are interested in is the micro-routing aspect. Rules for Heuristic micro-routing include:

Routes should not be fragmented or overlapping. Each route should be compact, consisting of street segments clustered in the same geographical area.
The collection route should start as close to the garage or motor pool as possible, taking into account heavily travelled and one-way streets (see rules 3 and 4).
Collection from heavily travelled streets should not be carried out during rush hours.
In the case of one-way streets, it is best to start the route near the upstream end of the street, working down it through the looping process.
Services on dead-end streets can be considered as services on the street segment that they intersect since they can only be collected by passing down that street segment. To keep left turns to a minimum, collect the dead-end streets when they are to the right of the truck. Collections from dead-end streets must be made by walking down, backing down or making a U-turn at the dead-end.
When practical, solid waste on a steep hill should be collected on both sides of the street while the vehicle is moving downhill. This facilitates safety, ease and speed of collection. It also lessens wear of the vehicle and conserves gas and oil.
Higher elevations should be at the start of the route.
For collection from one side of the street at a time, it is generally best to route with many clockwise turns around blocks. Note: Heuristic rules 8 and 9 emphasize the development of a series of clockwise loops in order to minimize right turns, which generally are more difficult and time-consuming than left turns. Particularly for right-hand-drive vehicles, right turns are safer.
For collection from both sides of the street at the same time, it is generally best to route with long, straight paths across the street before looping clockwise.
For certain block configurations within the route, specific routing patterns should be applied that best fit the layout.

As you can see, with the changes since 1974, there are a couple of the Heuristic rules that are out-dated but they still today make up the general rules of routing.

Right Turns

It is a common concept in solid waste collection to minimize left turns and maximize right turns. Interestingly enough, these days it is done more for safety than efficiency by eliminating or minimizing the dangerous left hand turns causing the solid waste collection vehicle to have to turn in front of traffic. Businessweek had an article on March 5, 2007 entitled “How Technology Delivers for UPS.” This excerpt says it all: “Not so long ago, UPS drivers worked off maps, 3×5 note cards, and their own memory to figure out the best way to run their routes. That changed in 2005 when UPS began to implement a $600 million route optimization system—think MapQuest on steroids—that each evening maps out the next day’s schedule for the majority of its 56,000 drivers. So sophisticated is the software that it designs each route to minimize the number of left turns, thus reducing the time and gas that drivers waste idling at stoplights.

UPS’ innovation is an example of how technology can help companies capture institutional knowledge about their customers. Before, when a truck loader or driver walked out the door, the package-loading techniques or route tips they’d developed over the years usually walked out with them. Now, that knowledge is accessible in a central system. That eases the burden on substitute drivers and shortens the training time for new ones, lessening the chances of a lapse in customer service. There’s no question that the new system has enabled UPS to run its routes more efficiently. In November alone, the company’s drivers logged 3 million fewer miles than they did the year before.”

The television show “Mythbusters” tested the theory of right hand turns on one of their “MiniMyths” and confirmed that with even more miles driven (as was the case in their test) making right hand turns resulted in using less fuel.

Right turns not only increase efficiency by reducing fuel consumption, but they also increase safety for the driver and other vehicles on the road, given that the driver no longer has to face oncoming traffic.

On-board Computers

As modern technology meets solid waste collection, numerous items have been implemented in everyday collection practices. One of these valuable pieces of equipment is the on-board computer. Picture it as a GPS device on steroids. Not only can the driver follow his route on the system, but the driver can also communicate with the office notifying them of obstacles in the way or customers that do not have trash out. Benefits that increase driver efficiency are:

· Track routes in real-time

Provides accountability by being able to see where the collection vehicle is at all times
Eliminates wondering if the driver is doing his job efficiently

· Eliminate going back to pick up “Not Outs”

Provides GPS time and date stamp in addition to message from driver that customer did not have trash out
Depending on contract/requirements may be enough to not have to go back and collect a customer that indeed didn’t have the trash out when the collection vehicle was there

· Turn-by-turn shows driver how to run the route properly

If you have spent the time creating the sequence for a route, then it would be smart to have the driver run it that way

· Relief driver can run route without any prior knowledge of it

Simply follow the GPS directions

· Integration with Billing Systems

With the drivers’ ability to communicate with billing software, you can automatically charge the customer for extra bags or extra collection thus not missing additional revenue

Optimize Dump Trips

Most drivers only head to the landfill to dump when they are completely full. This is generally not the most efficient way to handle the dump trips. Route optimization software has a function to optimize the dump trips. If the route requires two dumps, then these dumps should be scheduled when the vehicle is closest to the transfer station/landfill. By optimizing the dump trips you can generally eliminate a trip or two per week for most routes.

Automated Collection

According to the Arizona Central newspaper, the first automated garbage truck, aptly named “Godzilla”, was created in Scottsdale, AZ and debuted on August 1, 1969. “Godzilla” was the idea of Marc Stragier who soon became known as the “father of automation.” Interestingly enough, this was more than 40 years ago and many cities and companies are just now transitioning to automated collection. There is a reason for this. There are many requirements that go along with automated collection in addition to many pros and cons.

Pros

· Decrease in collection vehicles needed

Generally two automated trucks can do the work of three semi-automated trucks.

· Reduction of labor

Automated trucks typically operated with one driver, thus decreasing crew size

· Reduce risk of injuries

As there is no heavy lifting and no hands on of the trash, there is a much lower risk of injuries.

· Increased driver morale

Less physical labor and better working conditions increase the drivers’ morale.

Cons

· Collection area must be suitable for automation. Some factors include:

Automation requires curbside collection. Rural neighborhoods without sidewalks or with ditches prevent the cart being placed close enough for servicing.
Narrow streets, streets with curbside parking, one-way streets, overhead branches and dead-end/cul-de-sacs are difficult to service with an automated collection vehicle.

· Carts required

1. One high expense with automated collection is that all customers need to have a trash cart.

2. If all of your customers currently have carts this is a non-issue.

3. If not the cost of a trash cart for every customer is quite high.

· City ordinances

1. Ordinances or customer requirements need to be in place for the automation to be successful.

2. Require all trash to be in cart and do not allow bags to be set out so that the driver doesn’t need to exit the collection vehicle. Failure to have this in place will result in an inefficient automated route.

· Equipment costs

1. Automated collection vehicles typically cost quite more than a semi-automated vehicle.

· Maintenance

Generally higher for automated vehicles.

Optimize Customers

In some areas, mostly rural, it can cost more to service customers than you make in revenue. If the customers are spread out with a lot of driving miles and labor hours, you may be paying to service them. If you feel that you have customers that may fall into this category, look at the expense for labor hours and fuel, and compare this to the revenue that these customers provide. If you have customers that are costing you money, there are a couple of options:

· Increase rates

If not restricted by contract or rate increases are permitted, raise the rate for these customers to a point where you are no longer losing money servicing them.
Some customers may cancel service if rates are raised, but that is OK as they were costing you money anyhow.

· Sub-Contract

If available, use a sub-contractor for these low revenue areas.

· Cancel service

If no other options work and you are not restricted by contract, cancel the customers that are costing you too much to service.

Routing Software

Again, with modern technology entering into the solid waste collection world, there are now a few different companies that offer route optimization solutions. These software programs use many of the aforementioned strategies and rules. Typically, there are two types of routing software.

High-Density Routing

High-Density routing typically uses arc routing or side of street routing to route residential collection. Many route optimization software use GIS (Geographic Information System) software for mapping and routing. The high-density is for many stops on a street in which the side of the street being serviced is also taken into account. This allows the software to route automated collection with two passes on a street segment and semi-automated to service both sides of a street segment at the same time.

Many of the high-density routing software available can be purchased for in-house routing or the software company can be hired for a service bureau in which you define the parameters and what you want to be done, and they do the routing and provide the final new routes.

Point-to-Point Routing

Point-to-Point routing can use many various platforms. They can be found as desktop applications and, recently, more web-based applications are available. With point-to-point, the side of street collected is typically not taken into account. In solid waste collection, point-to-point routing can be used to create commercial routes in addition to being used for routing call in services such as cart or bin delivery. Point-to-Point routing software is typically less expensive than High-Density solutions and is normally offered as a purchase.

Operational Strategies

Operational strategies are typically harder to get approval for or to implement. The following strategies can successfully be used to improve operations and reduce costs:

· Collection frequency: Changes in how often collections are made can reduce expenses.

· Collection days: Four day per week collection vs. five day per week collection

· Transfer station vs. landfill: Building a transfer station to avoid driving a long way to the landfill

Collection Frequency

There are many areas that are still servicing residential customers twice per week. There is not any reason for doing this. Reasons for twice per week collection include hot weather or animals in the trash. The only viable reason for collecting residential trash more than once per week is because that is what the customer wants. This is highly inefficient. Studies show that in a twice per week residential collection, 60 percent of the customers set out the first collection day and only 40 percent the second collection day. This equates to 60 percent of the time on the second collection day the collection vehicle is just driving around.

If you are providing twice per week collection you are wasting money. Changing from twice per week collection to once per week will be met with a lot of opposition. Customers will feel that they are getting half of the service for the same price. A good way to appease the opposition is to provide customers with larger cart or an additional cart. Regardless of the cost for the new carts, it will be cheaper than the twice per week collection.

Collection Days

The most optimum and efficient residential solid waste collection is a four 10-hour day schedule. This is due to holidays, bad weather days and less costs involved. If you are currently collecting five days per week you may want to look at the benefits of working four 10-hour shifts:

· Holiday schedules

A week with holidays in which collection cannot take place requires rescheduling of the trash collection.
With four day per week collection there is no need to run double routes or the require routes to be run on the weekend.

· Vehicle maintenance

Four day per week collection allows vehicle maintenance to occur on a weekday thus not requiring your mechanics to work the weekend.

· Reduction in non-productive time

Federal law dictates that your employees are required to perform a pre- and post-trip inspection daily. These inspections typically take 15 minutes or 30 minutes per day. Switching from a five to four day per week collection will save you 30 minutes per route.
You are also required to give your driver a lunch break (typically 30 minutes) and possibly additional breaks throughout the day. Switching from five to four days per week collection will save you the 30 minutess per route.

· Less dump trips

Typically, your routes can pack out better on a four-day per week collection as opposed to having the drivers dump partial load on a shorter day.

Transfer Station vs. Landfill

If your drivers have to drive a long distance to the landfill to dump more than once per day due to the volume of trash being collected, you may want to look into the option of building a transfer station. With the higher capacity semi-trailers it may be more cost efficient to build a transfer station to allow the residential drivers to dump there and then haul the waste out to the landfill using the semi-trailers. There are many solid waste engineering and consulting firms that may assist you with calculating the cost comparison.

Evaluating Your Collection Routes

I am often asked how often residential collection routes should be evaluated or updated. Depending on the growth of the service area and annexations, it is good to review your routes every one to two years. In most cases you will know when your routes have changed enough to no longer be efficient. Periodically check your driver’s hours to see if they are taking longer to complete their routes. The use of on-board computers has made life easy for managers to check on route times and verify that the times are longer due to service and not drivers taking too many breaks.

Another benefit of on-board computers is that many can be integrated with sensors on the tipper or the automated arm. This will give you a count of customers on a route based on the number of carts serviced. Remember, in residential collection 100 percent set out never occurs so these counts will tend to be ~ 10 percent less than the actual total customers for each route.

There are additional areas that can be addressed for improving efficiency and saving money. This paper is just a guideline for “self-help” ideas. Solid waste consulting firms can provide more detail in addition to performing an analysis of your existing collection practices. The fact that you are reading this paper suggests that you are already aware that your operation is not efficient or that there is room for improvement. Hopefully, you can take something away from this and move towards more efficiency and increase profitability.

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