“Gurobi has consistently brought major performance improvements (often 10-20%) with each new release, which has been of enormous benefit to us.”Roman Berner
Optimization Specialist, Swissport
Keeping airplanes in the air takes a full crew on the ground, too. Swissport International Ltd. has a team of 43,000 employees that provide airport ground services and cargo handling for 850 aviation customers across 274 airports in 44 countries.
Airport ground handling includes a broad range of passenger and ramp services, all of which can be a challenge to run smoothly. At Zurich airport alone, Swissport employs 2,000 people who do check-in and gate tasks, baggage management, aircraft loading, push-back movements, and much more. And all these people have different work skills, contract types, and shift duties. So, putting together a work schedule for even a single month is complex. It comprises the following key steps:
Before, the Swissport planning teams created schedules manually, sometimes spending weeks sketching out a plan for the coming month. And it was an ongoing challenge to coordinate continually changing labor requirements with individual work contracts and duty preferences. They started looking for a better solution, but none of the available commercial software for staff scheduling could meet their needs.
So, they set out to build their own.
Swissport teamed up with a research team at nearby Zurich University of Applied Sciences ZHAW. Their goal? Develop scheduling software that is powerful enough to handle Swissport’s complex operational planning puzzles. The tool also needed to be general and flexible enough for industries beyond aviation.
They called it Auto-Roster. Unlike most commercial rostering tools, Auto-Roster uses Mixed Integer Linear Programming (MIP), combined with other optimization techniques, including decomposition and relaxation, pre-and post-processing, and a variety of heuristic procedures.
At first, it wasn’t clear that Auto-Roster could make it off the ground. Its optimization engine has over 60,000 lines of code, with more than 1 million integer variables and 500,000 constraints. With so many things to account for, one of the biggest challenges was to solve the problems in a reasonable time—because MIP models are often too slow to be useful.
“Approaching large-scale, real-world rostering problems with MIP techniques is innovative and challenging, since computation times are typically far beyond any acceptable limits,” said Prof. Andreas Klinkert, Technical Project Leader at ZHAW. “Several times, the project was close to failing due to intractable MIP models.”
During the project, the research team had several mathematical breakthroughs and was finally able to establish computationally tractable MIP model formulations. They also brought in Gurobi Optimization to help speed things up even more. With the Gurobi Optimizer, the Auto-Roster team can now run complex models with millions of variables—all within 20-70 hours.
“For a long time, Gurobi was by far the only MIP solver that could solve our models in a reasonable time, and we suspect that this is still the case now,” said Dr. Peter Fusek, Lead Mathematical Modeling at ZHAW.
Now, Swissport is using Auto-Roster to plan work schedules across all three international airports in Switzerland—Zurich, Geneva, and Basel—with more rollouts in progress at other airports in Europe.
Already, it’s making a big difference. The Swissport planning team takes about half the time to set shift schedules. They can plan more efficient shifts, with less wasted time and a better match between supply and demand. Their rosters are also more robust, fair, and—above all— flexible. Employees are happy that their scheduling preferences are fulfilled 95-100% of the time.
All told, better planning is saving Swissport more than $1 million a year.
Choose the evaluation license that fits you best, and start working with our Expert Team for technical guidance and support.
Request free trial hours, so you can see how quickly and easily a model can be solved on the cloud.
|_biz_flagsA||1 year||A Cloudflare cookie set to record users’ settings as well as for authentication and analytics.|
|_biz_pendingA||1 year||A Cloudflare cookie set to record users’ settings as well as for authentication and analytics.|
|_biz_sid||30 minutes||This cookie is set by Bizible, to store the user's session id.|
|ARRAffinity||session||ARRAffinity cookie is set by Azure app service, and allows the service to choose the right instance established by a user to deliver subsequent requests made by that user.|
|ARRAffinitySameSite||session||This cookie is set by Windows Azure cloud, and is used for load balancing to make sure the visitor page requests are routed to the same server in any browsing session.|
|cookielawinfo-checkbox-advertisement||1 year||Set by the GDPR Cookie Consent plugin, this cookie is used to record the user consent for the cookies in the "Advertisement" category .|
|cookielawinfo-checkbox-analytics||11 months||This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics".|
|cookielawinfo-checkbox-functional||11 months||The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional".|
|cookielawinfo-checkbox-necessary||11 months||This cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary".|
|cookielawinfo-checkbox-others||11 months||This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.|
|cookielawinfo-checkbox-performance||11 months||This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".|
|CookieLawInfoConsent||1 year||Records the default button state of the corresponding category & the status of CCPA. It works only in coordination with the primary cookie.|
|elementor||never||This cookie is used by the website's WordPress theme. It allows the website owner to implement or change the website's content in real-time.|
|JSESSIONID||session||New Relic uses this cookie to store a session identifier so that New Relic can monitor session counts for an application.|
|__cf_bm||30 minutes||This cookie, set by Cloudflare, is used to support Cloudflare Bot Management.|
|_biz_nA||1 year||Bizible sets this cookie to remember users’ settings as well as for authentication and analytics.|
|_biz_uid||1 year||This cookie is set by Bizible, to store user id on the current domain.|
|_hjAbsoluteSessionInProgress||30 minutes||Hotjar sets this cookie to detect a user's first pageview session, which is a True/False flag set by the cookie.|
|_mkto_trk||2 years||This cookie is set by Marketo. This allows a website to track visitor behavior on the sites on which the cookie is installed and to link a visitor to the recipient of an email marketing campaign, to measure campaign effectiveness. Tracking is performed anonymously until a user self-identifies by submitting a form.|
|bcookie||1 year||LinkedIn sets this cookie from LinkedIn share buttons and ad tags to recognize browser ID.|
|bscookie||1 year||LinkedIn sets this cookie to store performed actions on the website.|
|doc_langsBB||1 year||Documentation system cookie|
|doc_version||1 year||Documentation system cookie|
|lang||session||LinkedIn sets this cookie to remember a user's language setting.|
|lidc||1 day||LinkedIn sets the lidc cookie to facilitate data center selection.|
|UserMatchHistory||1 month||LinkedIn sets this cookie for LinkedIn Ads ID syncing.|
|whova_client_id||10 years||Event agenda system cookie|
|_gat_UA-5909815-1||1 minute||A variation of the _gat cookie set by Google Analytics and Google Tag Manager to allow website owners to track visitor behaviour and measure site performance. The pattern element in the name contains the unique identity number of the account or website it relates to.|
|_an_uid||7 days||6Sense Cookie|
|_BUID||1 year||This cookie, set by Bizible, is a universal user id to identify the same user across multiple clients’ domains.|
|_ga||2 years||The _ga cookie, installed by Google Analytics, calculates visitor, session and campaign data and also keeps track of site usage for the site's analytics report. The cookie stores information anonymously and assigns a randomly generated number to recognize unique visitors.|
|_ga_*||1 year 1 month 4 days||Google Analytics sets this cookie to store and count page views.|
|_gat_UA-*||1 minute||Google Analytics sets this cookie for user behaviour tracking.|
|_gcl_au||3 months||Provided by Google Tag Manager to experiment advertisement efficiency of websites using their services.|
|_gd_session||4 hours||This cookie is used for collecting information on users visit to the website. It collects data such as total number of visits, average time spent on the website and the pages loaded.|
|_gd_visitor||2 years||This cookie is used for collecting information on the users visit such as number of visits, average time spent on the website and the pages loaded for displaying targeted ads.|
|_gid||1 day||Installed by Google Analytics, _gid cookie stores information on how visitors use a website, while also creating an analytics report of the website's performance. Some of the data that are collected include the number of visitors, their source, and the pages they visit anonymously.|
|_hjFirstSeen||30 minutes||Hotjar sets this cookie to identify a new user’s first session. It stores the true/false value, indicating whether it was the first time Hotjar saw this user.|
|_hjIncludedInSessionSample_*||2 minutes||Hotjar cookie that is set to determine if a user is included in the data sampling defined by a site's daily session limit.|
|_hjRecordingEnabled||never||Hotjar sets this cookie when a Recording starts and is read when the recording module is initialized, to see if the user is already in a recording in a particular session.|
|_hjRecordingLastActivity||never||Hotjar sets this cookie when a user recording starts and when data is sent through the WebSocket.|
|_hjSession_*||30 minutes||Hotjar cookie that is set when a user first lands on a page with the Hotjar script. It is used to persist the Hotjar User ID, unique to that site on the browser. This ensures that behavior in subsequent visits to the same site will be attributed to the same user ID.|
|_hjSessionUser_*||1 year||Hotjar cookie that is set when a user first lands on a page with the Hotjar script. It is used to persist the Hotjar User ID, unique to that site on the browser. This ensures that behavior in subsequent visits to the same site will be attributed to the same user ID.|
|_hjTLDTest||session||To determine the most generic cookie path that has to be used instead of the page hostname, Hotjar sets the _hjTLDTest cookie to store different URL substring alternatives until it fails.|
|6suuid||2 years||6Sense Cookie|
|AnalyticsSyncHistory||1 month||LinkedIn cookie|
|BE_CLA3||1 year 1 month 4 days||BrightEdge sets this cookie to enable data aggregation, analysis and report creation to assess marketing effectiveness and provide solutions for SEO, SEM and website performance.|
|CONSENT||2 years||YouTube sets this cookie via embedded youtube-videos and registers anonymous statistical data.|
|dj||10 years||DemandJump cookie|
|djaimid.a28e||2 years||DemandJump cookiean|
|djaimses.a28e||30 minutes||DemandJump cookie|
|li_gc||5 months 27 days||LinkedIn Cookie|
|ln_or||1 day||LinkedIn Cookie|
|vuid||2 years||Vimeo installs this cookie to collect tracking information by setting a unique ID to embed videos to the website.|
|__adroll||1 year 1 month||This cookie is set by AdRoll to identify users across visits and devices. It is used by real-time bidding for advertisers to display relevant advertisements.|
|__adroll_fpc||1 year||AdRoll sets this cookie to target users with advertisements based on their browsing behaviour.|
|__adroll_shared||1 year 1 month||Adroll sets this cookie to collect information on users across different websites for relevant advertising.|
|__ar_v4||1 year||This cookie is set under the domain DoubleClick, to place ads that point to the website in Google search results and to track conversion rates for these ads.|
|_fbp||3 months||This cookie is set by Facebook to display advertisements when either on Facebook or on a digital platform powered by Facebook advertising, after visiting the website.|
|fr||3 months||Facebook sets this cookie to show relevant advertisements to users by tracking user behaviour across the web, on sites that have Facebook pixel or Facebook social plugin.|
|IDE||1 year 24 days||Google DoubleClick IDE cookies are used to store information about how the user uses the website to present them with relevant ads and according to the user profile.|
|li_sugr||3 months||LinkedIn sets this cookie to collect user behaviour data to optimise the website and make advertisements on the website more relevant.|
|test_cookie||15 minutes||The test_cookie is set by doubleclick.net and is used to determine if the user's browser supports cookies.|
|VISITOR_INFO1_LIVE||5 months 27 days||A cookie set by YouTube to measure bandwidth that determines whether the user gets the new or old player interface.|
|YSC||session||YSC cookie is set by Youtube and is used to track the views of embedded videos on Youtube pages.|
|yt-remote-connected-devices||never||YouTube sets this cookie to store the video preferences of the user using embedded YouTube video.|
|yt-remote-device-id||never||YouTube sets this cookie to store the video preferences of the user using embedded YouTube video.|
|yt.innertube::nextId||never||This cookie, set by YouTube, registers a unique ID to store data on what videos from YouTube the user has seen.|
|yt.innertube::requests||never||This cookie, set by YouTube, registers a unique ID to store data on what videos from YouTube the user has seen.|