Towns Looking for Affordable GIS
(from Maine Townsman, February 2009)
By Lee Burnett, Freelance Writer
Like many small towns in Maine, North Berwick is trying to find an affordable way to implement a Geographic Information System (GIS) to improve town government decision-making.
GIS is a way of storing information in digital maps to make the maps more useful, and also enabling you to answer such questions as: Which roads should be resurfaced next? Which location for a new transfer station would be convenient to most residents? What residents on oxygen-support should be visited in the event of a power outage?
To date, North Berwick has adopted the simplest version of GIS. It has collected a free set of aerial photographs from the state and combined it with digital maps of various zoning districts, and natural resource inventories generated through its own comprehensive planning process; stored all the data on the town’s website server and made it accessible to town employees with free software from TatukGIS. One of the system’s helpful features is allowing the town’s code enforcement officer to determine quite quickly all the restrictions that might apply to building on a particular site.
“We have some semblance of GIS,” explains Town Manager Dwayne Morin. “We’re putting together a small GIS system.” Morin would love to acquire the powerful features available with a higher-end GIS system, but hasn’t figured out how to justify the cost. “I think it would be very useful. We’d expand upon it and use it for water, sewer, storm drains,” said Morin. “Right now, it’s cost prohibitive.”
As North Berwick figures out how to acquire a higher functioning system, it is confronting the same questions as other communities grappling with the potential of GIS. Should GIS be adopted incrementally or wholesale? Should town officials avail themselves of free software and train themselves or rely on a consultant? What are the trade-offs and costs?
Coming to you
GIS is already part of our daily lives. MapQuest, dashboard GPS devices, and Google Earth are all making people comfortable manipulating spatial information. GIS at the municipal level is becoming more available with free aerial photography, free maps of wetlands, wildlife habitat, soils, forest types, and other natural resources, and free software. “What has changed over time .. is it used to be you’d have to make the leap up to GIS, where it’s almost now that GIS is making the leap down to you,” explains Jamie Oman-Saltmarsh, senior planner at Southern Maine Regional Planning Commission.
A leap up is still necessary to make GIS truly usable at the municipal level. The leap involves converting to digital information all the town’s tax maps and property record cards. This includes the shape and dimension of individual lots, which have traditionally been drawn on large sheets of paper and stored in well-thumbed books in the tax assessors’ office. It also includes the property owner’s name and address, description of buildings and other improvements, the property’s assessed value and its ownership history, information that has traditionally been stored on individual property record cards, also in the assessors’ office. Once converted, the tax maps become an interconnected web of property lines that can be superimposed on an aerial photograph; the property record cards are then keyed to individual properties by tax map and lot number.Together, this information is called the parcel layer.
“The parcel map is the key,” said Oman-Saltmarsh. “The parcel map is the foundation of local government. It’s that important.”
Creating a parcel layer costs $6 to $10 per parcel, although it can be done less expensively depending on in-house expertise. North Berwick, which has 3,500 parcels, estimates it would cost $21,000 to $28,000 for a parcel layer. “Right now, we’re going to sit on it, especially with the economy the way it is. Possibly in future years, we’ll look at it,” said Morin.
Once the parcel layer is created, all kinds of useful things are possible. Embedded data is searchable, so, for example, a town hall staffer could generate a list of abutters for notification purposes whenever a development proposal or proposed zoning change calls for it. Planning boards appreciate GIS because layering maps on top of the parcel layer helps them visualize the impact of zoning changes. A popular use of GIS is to generate “build-out” scenarios to project existing development patterns and how they would be modified by various zoning restrictions. With GIS, queries from developers can be handled in minutes instead of hours, explains Gretchen Heldmann, the GIS coordinator for Hampden. “Let’s say a big-box developer or a small business wants to know how many parcels there are of five acres or more, on town sewer and water, and within two miles of the [Interstate] interchange. I can do it in five minutes,” she said. In the event of a flood forecast, public safety officials can turn on the GIS flood plain map and determine which houses should be evacuated and what evacuation routes to use. GIS is also a valuable tool in search and rescue missions. Using the last known siting and location of a missing person and the elapsed time, a perimeter can be established to systematize the search. GIS becomes more valuable as new layers are created. Using GPS devices, public infrastructure – such as roads, sewers, storm drains, and water systems – can be mapped and then tied to a conditions assessment inventory and maintenance plan, which aid in management decisions.
“If your data isn’t digitized ... it isn’t accessible, you don’t have information,” explains Tom Burns, a GIS consultant in Portland. “It can’t do anything for you if it’s on paper or in some foreman’s head.”
Tax assessors are among the biggest fans of GIS. Color-coded maps of tax assessment ranges in a particular neighborhood can be generated, which makes variations to the norm “pop out” and alert the assessor to take a closer look at that property to verify the legitimacy of the assessment, explains Aaron Shields of the James W. Sewall mapping company in Old Town. “You wouldn’t have picked it up unless you happen to thumb through assessed values,” he said. GIS ensures all property cards are represented on the tax map and vice versa, he said. It is not unusual, in converting to GIS, to discover the existence of untaxed property that no one knew existed, he said. The power of GIS to illustrate patterns of taxation may help defend a particular tax assessment and, on occasion, it can reveal an inequity, which helps resolve taxpayers’ questions and complaints. Online GIS information can also dramatically reduce routine telephone inquiries from lawyers, real estate agents and appraisers.
“We used to spend 40-50 percent of our time answering questions ... It [GIS]has reduced our phone calls to five percent of our time,” said Anne Gregory, tax assessor for Falmouth, which has put all its GIS maps and tools online.
GIS has also saved Gregory time in the field. If a taxpayer complains that a rocky ledge makes his or her backyard unsafe or too small for kids to play in compared to a similar house next door, Gregory can zoom in on the aerial photography and see the ledge for herself and determine if a reduction is warranted. “I don’t have time to walk the lot, but I can make a judgment call by looking at the map,” she said.
GIS allows Gregory to make assessment adjustments in “five minutes” that would have taken hours or days to make in the past. Without leaving her desk, Gregory can verify whether someone’s water view is blocked by a neighbor’s house or whether their waterfront is a deep-water anchorage or a mudflat.
Gregory said she used GIS to analyze unexplained discrepancies in waterfront home-sale prices and discovered many private piers that had gone untaxed. She used aerial photographs and GIS tools to measure the dimensions of the pier. “I picked up at least $2 million in new valuation by assessing piers for the first time,” she said.
Overall, Gregory estimates the increased productivity in her office has meant not having to increase her staff in a dozen years and has afforded her enough time to complete a full revaluation of property tax assessments every three or four years. “We would not have been able to do it without the technical capability and the time [afforded by GIS],” she said.
Refining maps, photos
Once you become comfortable with GIS and discover its many useful features, you will probably also become a critic. A common problem noticeable to even the casual observer is that the man-made boundaries on the parcel layer – the lot lines, road rights of way and utility corridors – often don’t line up with the visible features on the aerial photograph. It’s not uncommon for lot lines to be off by 30 feet. Instead of a lot line lining up with the edge of the road, it falls across the middle of a roof.
To understand why this happens, it helps to understand the complexities involved. Superimposing a web of thousands of lot lines on a photograph covering tens of square miles involves meshing two kinds of maps, each of which is an approximation of reality. The aerial photograph of a town is actually a series of photographs digitally stitched together to look seamless. But it’s not seamless because the map is a two-dimensional representation of a three-D world. There’s some stretching and pinching to make it all fit. Now, superimpose on that photograph a web of lot lines taken from tax maps. Some of those lot lines may have been drawn by a surveyor, others may have been constructed from ancient deed descriptions that contain references to trees, and other landmarks long gone.
Even more than the photographs, stitching together tax maps involves nipping and tucking, or “rubber-sheeting,” the preferred GIS term for making things fit. It may look like it fits until it’s superimposed on a photograph. Needless to say, it’s very disconcerting to see lot lines falling across roof tops after you’ve spent thousands of dollars or tens of thousands of dollars for a supposedly more useful set of GIS map layers. The bottom line is that paying extra money up front for a high-quality parcel layer may save you the cost of fixing lines later, said Burns, the GIS consultant in Portland.
“The more certainty you have, the better off you will be,” said Burns. “You can get an inexpensive parcel layer done, but what betrays it is high resolution aerial photography. You’ll have parcel lines going over the roofs of buildings and cultural features like stone walls,” he said. His advice: “Spend as much money as you can to get it as good as you can. That way you won’t have to redo it.”
There are four levels of precision in digitizing tax maps, according to Jim Thomas, a GIS consultant in Cumberland, who explains them in laymen’s terms. Level One is where town boundaries, lot lines, road rights of ways and intersections are “pretty close.” Level Two is where all road intersections are anchored to known survey points. Level Three adds rights of way and front-lot lines to fixed surveys. Level Four adds the back-lot lines and corners of all lots are fixed to surveys.
Thomas said Level Four is a level of precision that is beyond necessary. “If you’re a small town with 2,000 lots, it might cost $300,000 or more and you’d never need that level of accuracy,” Thomas explains. Thomas said Level Two is a good balance of precision and cost, though he favors Level Three.
Spending additional money for higher resolution maps is also something that many towns have found worthwhile. A “flyover” can cost $20,000 to $200,000, but the costs don’t vary much whether a single town or a dozen towns are being photographed, which creates incentive to collaborate with other towns on aerial photography, according to Dan Walters of the U.S. Geological Survey in Augusta. Some towns have acquired high-resolution aerial photography for less than $5,000. A high-resolution photograph makes it possible to use desktop measuring tools to calculate areas quite accurately, which saves field engineering costs for road projects, Walters said. “It saves a lot of money in engineering as opposed to having an engineer in the field,” said Walters.
Many towns are keen to use high-resolution aerial photography to refine the boundaries of wetlands because the National Wetlands Inventory maps are very approximate and shoreland zoning has such a major impact on development. Shoreland zoning is the state-mandated buffer strip (ranging from 75 feet to 250 feet depending on the water body) around lakes, streams, rivers and wetlands, where construction is restricted to protect these water bodies from erosion and storm water pollution.
“The impact can range from major to minor, but you will be subject to some governance within the shoreland zone – the number of trees you can cut, whether you can have an in-ground pool, whether you can add to your deck,” said Burns. Using GIS to refine the boundaries of shoreland zoning is a valuable exercise because it can reduce legal challenges and increase the credibility of government decision-making, said Burns.
“You want something that will hold up in court, something that people will believe in and will be bought into by the citizenry,” he said.
Maintaining a GIS system does take some expertise, which either means hiring a consultant or paying for someone at town hall to take training. The parcel layer – just like old-fashioned tax maps – must be updated on an annual basis to reflect newly created subdivisions or lot splits. Adding new data, such as the coordinates for fire hydrants, light poles, manhole covers and other municipal infrastructure also takes expertise.
“Unless you want to maintain your GIS and take the training, don’t make the big leap into GIS because you’re wasting your money,” said SMRPC’s Oman-Saltmarsh. “You have to know how to use it if you’re actually going to create information, edit it and maintain it.”
Many towns have designated a staff person to acquire the training. Arundel Town Planner Aaron Shields, for example, learned AutoCad drawing while in college, which gives him the expertise to revise parcel lines without hiring a consultant. For a fee, vendors provide training in their own software and there are free discussion groups online. Hampden has a paid GIS coordinator. Saco and Scarborough share a GIS staff person. Hampden’s GIS coordinator said a paid staff person can generate maps “on the fly” and can train others. Many towns resort to a consultant because acquiring training is “too many hats to wear” for most town employees, said Oman-Saltmarsh
Two good resources are the Maine Office of GIS and the GeoLibrary Board, a consortium of private and public officials that is looking for more ways to make GIS available to all communities.
“For small municipalities just getting into it, there are some really good tools out there,” said Mike Smith, manager of Maine’s Office of GIS and a member of the GeoLibrary Board.
Quantum GIS and Map Window are two software programs that are “completely free and compatible with Maine Office of GIS,” he said. Smith’s advice: “Set up something small. That allows you to step into it as you go. Then you have a reason to go back to the town and say we need $20,000 to improve it. I think that’s the way to go.”
Gretchen Heldmann, the GIS coordinator in Hampden, agrees on developing a system incrementally. “I think both [free maps and more expensive data] are of value. You can get a lot of free maps from the state to get you started then you can refine them,” she said.
There are ways to save money. Arundel has acquired a decent parcel layer by building off known boundaries and rights of way, explains Planner Aaron Shields. He said he’s borrowing copies of field surveys conducted by Central Maine Power, the State Department of Transportation, Maine Turnpike, the Kennebunk-Kennebunkport-Wells Water District, and communities with shared borders. He’s even borrowed the survey that a property owner commissioned on 3,000 acres of private land.
“We only spent $5,000 to $6,000 when a lot of other communities spend five or six times that much,” said Shields. “They (communities) stop when they hear that $20,000 number, when they don’t realize there is a more economical way.”
Another way to save money in developing or improving a parcel layer is to acquire survey data from subdivision developers. In fact, many towns have written into their ordinances a requirement that survey data from a subdivision be provided as part of the review process.
Burns is a proponent of spending whatever you can afford to acquire the highest quality data available. Free maps – wetlands and federal flood zones – are notoriously imprecise, he said. The state had a grant program of up to $10,000 to pay for digitizing tax maps into a parcel layer, but, according to Burns, what that would buy was often of insufficient quality. “You might have to redo every line,” he said.