6.0 PROCUREMENT CONSIDERATIONS
An outline for a statement of work (SOW) is provided in Appendix C. However, note that specific project needs can significantly alter the SOW.
The procurement of mobile LIDAR services will introduce a new technology into transportation agencies that was probably not considered when the current procurement systems were implemented. Some traditional surveying and mapping tasks are often based on the collection of one point at a time using a level, total station, or GNSS receiver and an experienced survey crew. Mobile LIDAR systems are capable of collecting in excess of one million points per second, plus still and video imagery with at most one skilled technician and a driver. Similar to photogrammetric mapping, which can also produce large datasets, MLS requires much more time in data processing than acquisition.
Traditional survey methods require that substantial time be spent in the field with a survey crew, followed by generally an equal or lesser amount of time in the office to process the data. In the case of mobile LIDAR the amount of time spent collecting data in the field may only represent 10% of the overall number of hours required to produce a final deliverable, but the cost of providing and operating the mobile LIDAR vehicle per hour can be 5 to 10 times that of a traditional survey crew. While there is a significant reduction in field time, it is important to realize that acquiring scan data is more than just driving a vehicle and requires skilled planning and operation.
The actual “surveying,” that is the process of deciding which points to use from a mobile LIDAR survey is made virtually in the office. It is important to also note that the data from a mobile LIDAR survey is so dense that it can be used to create 3D models of the objects and surfaces in the scene. Converting the 3D points into CAD objects is a time consuming, manual process that requires an experienced technician.
With the leading CAD and GIS software systems slowly beginning to support the use of point clouds as a data type for certain applications, it may be possible to work directly from the point cloud. One of the key advantages of using mobile LIDAR is the concept of “collect once – use many.” This is where the value in using mobile LIDAR can be derived. The more groups that can use the data collected the greater the return on investment.
Recommendation: Coordinate with other divisions/agencies prior to procuring mobile LIDAR services.
The procurement procedures for airborne photogrammetry and LIDAR data collection and processing would have similarities to mobile LIDAR. These could possibly represent a reasonable starting point for the development of mobile LIDAR data procurement procedures, although the processing of mobile LIDAR is not currently as automated as airborne imagery and/or LIDAR.
Some agencies, such as the Government Services Administration (GSA) found it advantageous to pre-qualify bidders and put in place Indefinite Delivery Indefinite Quantity (IDIQ) contracts with laser scanning service providers. This may be worth investigating in order to streamline the procurement process and insure that the service providers are qualified to do the work.
The procurement group needs to work closely with subject matter experts to insure that all aspects of the Guidelines are being incorporated into the contracting process. The transition from traditional survey to 3D mobile LIDAR and laser scanning will require close cooperation between all departments in order to realize the potential cost savings and overall benefits of this technology.
6.1 Decision process
In the following Decision Flow Chart (Figure 4) our intent is to provide assistance with the basic decision of whether or not to use mobile LIDAR for a geospatial data collection project. As you can see and infer, there are a number of variables and related reasons why it often makes sense to use mobile LIDAR, but perhaps the most important is whether your application can benefit from the knowledge of 3D geospatial location and relationships. This may not be immediately essential to your project, but it does make the use of other traditional survey technologies much less attractive when this is required.
We have identified safety, schedule, type of project and cost as the major factors to consider. The challenge is in deciding the relative importance of each of these, and of the subfactors. Empirical evidence is still being gathered on this topic and in the final analysis we believe that each agency will need to develop the criterion that works best for them.
Section 3.1 discusses additional considerations for benefit cost analyses for the applicability of MLS.
Figure 4: Decision Flowchart to determine when mobile LIDAR use is appropriate for a project.
6.2 Generic cost considerations
Many factors influence the actual cost of a MLS project, particularly since it is evolving technology. Hence, it is difficult to estimate the cost of one project based on the cost of another. Generally, accuracy requirements (particularly network accuracy) are the key driver of cost, especially in complex environments (e.g., urban environments, tunnels). Improved point density can be obtained through either slower speeds or additional passes. This differs from airborne LIDAR where acquisition costs are typically the most significant portion. Table 3 provides examples of factors and their relative influence on project cost.
Recommendation: Perform a benefit cost analysis and determine return on investment rather than focusing solely on the single project cost.
As discussed in Section 4, the steps in a MLS workflow will depend on the application. For each project, an agency will need to decide how much of the work to contract out versus how much will be completed in-house. For work performed in-house staff will need to be fully trained and have sufficient hardware and software resources to efficiently complete the work. Table 4 provides guidance on relative costs for performing these tasks since each agency will have different capabilities and preferences. The procedures that the agency wants to complete internally versus what the data provider will do should be clearly communicated to the data provider. Some tasks, such as data mining, could be completed in stages as long as the point cloud is properly managed.
Recommendation: Should an agency choose to contract out parts of the workflow and perform others in house, be sure that it will be properly coordinated with the data provider to minimize data transfer.
Recommendation: Always request a copy of the point cloud (at the highest level of processing completed) so that it is available for future data mining.
Table 3: Example of costs for a MLS project. Notes: This table is meant for guidance purposes only and is not comprehensive. Circumstances may significantly vary depending on project scope and requirements. (Modified from Saylam, 2009).
Table 4: “Menu” of relative costs (additive) and considerations for primary deliverable workflow stages of mobile LIDAR.
6.3 System ownership
Transportation agencies have options to deploy mobile laser scanning on projects or programmatically. The most comprehensive document at this time is “LIDAR for Data Efficiency: by Kin S. Yen, Bahram Ravani, and Ty A. Lasky performed for the AHMCT Research Center in 2011. We have identified some general considerations for these Guidelines, but it is not meant to be comprehensive documentation of all the factors a transportation agency might consider. A transportation agency can purchase a mobile laser scanner and become the owner and operator. A transportation agency may also procure professional consultant services. A third alternative would be an equipment rental option; however, at this time rentals are not widely available or used. A transportation agency can consider some combination of all of these. For example, own a basic system and contract out for more advanced data acquisitions. Below are considerations for ownership and contracting professional services.
Ownership of a mobile laser scanner has many benefits and drawbacks to consider, depending on the mission and capabilities of the transportation agency.
- Initial Equipment Purchase: Mobile laser scanners available on the market have varying levels of accuracy capabilities, which normally drive the cost of the equipment. An owner needs to consider what type of data collection they will routinely need, before they purchase a system. The cost of systems can range from a few hundred thousand to over a million dollars depending on the system design.
- Routine and Annual maintenance: Mobile laser scanners have multiple components and they all need to be calibrated and checked regularly. In addition, most mobile laser scanners have annual maintenance agreements, which are additional cost items.
- Additional Software: Mobile laser scanners will come with basic processing software, but there are many software packages on the market that are well suited for more advanced processing such as to extract line work, create DTMs, or generate 3D models. An owner needs to consider the costs of software and training staff to complete these tasks.
- Equipment obsolescence: Mobile laser scanning technology is advancing at a very fast rate. In 2-3 years, the hardware and software advancements make significant gains in the marketplace. The ability and costs of keeping up with advancements in technology can be challenging.
- Staffing: The amount of training and dedicated staff to operate, process, and extract quality data from a mobile laser scanning system is ongoing. The recommended staffing model is to have a dedicated team of operators, processors, and data extractors whose primary focus is mobile laser scanning.
- Learning Curve: The effective operation of a mobile laser scanner is just one portion of how to successfully complete a project. The owner will need to setup protocols for safety, workflows, and documentation. The owner needs to accept that the first few projects might not be successful and understand the learning curve for this equipment is different than traditional surveying equipment such as static laser scanners and GNSS equipment.
- Equipment Access: Owning a mobile laser scanner will provide a transportation agency with easier access to the equipment for emergency projects. In addition, a transportation agency may be able to dedicate the resources needed to keep a long term maintenance program going.
6.3.2 Professional Consultant Services
- Equipment/Software/Maintenance: The costs of mobile laser scanning equipment, software and maintenance are all taken care of by the consultant. A transportation agency has limited risk for equipment failure as the consultant will be responsible for these items.
- Equipment obsolescence: A transportation agency will always have access to the most reliable and advanced technologies when using consultants. A transportation agency should make sure that the consultants are qualified and have demonstrated experience for the type of services required.
- Staffing: A consultant provides a transportation agency with additional staffing and skills which a transportation agency may not possess in-house. The tools to extract LIDAR data also advance quickly and a consultant will be able to stay current with these tools and provide an efficient delivery. A transportation agency must understand what data formats and standards they expect from the consultants.
- Equipment Access: A consultant may not be able to respond to emergency projects as timely, unless a contractual arrangement has been setup by the transportation agency.