What people all over the German-speaking world and in San Francisco call the bus, San Diego calls bus rapid transit.

Cities have learned they can improve public transit, without spending the massive sums to improve their rail systems, by instead improving their bus networks.

The umbrella term for such improvements is bus rapid transit, or BRT, and in San Diego MTS has taken this on with its “Rapid” branded bus lines. But San Diego is also part of another global trend: BRT creep. That’s when a transit agency sells an improvement to the public as BRT, but due to cost considerations or political opposition, it ends up providing something only marginally faster than a regular bus.

Details of BRT systems vary, but in big U.S. cities it’s typically used to complement rail service, running on key urban streets where existing rail lines aren’t.

San Diego’s Rapid consists of five routes. The 215 route is the only route through urban streets, connecting downtown and Mid-City through El Cajon and Park boulevards. The other four routes — the 235, 237, 280 and 290 — are express routes along dedicated freeway lanes using I-15 in the direction of Escondido, with long nonstop segments through the urban core.

In branding, Rapid looks as sleek as the best BRT systems. But on the ground, it falls short of the standards for good bus service.

There is a set of best practices for running buses optimally. Some involve BRT features, others don’t. Every bus stop should have shelter from rain and sun. Stops should not be too close together; in North America the standard is a bus stop every eighth of a mile, but in Europe and East Asia, a bus stop every quarter-mile is more standard, which lets buses run faster. Those are standards independent of BRT. They’re featured on Rapid routes, but are absent through much of San Diego’s bus network.

True BRT also requires a feature known as off-board fare collection. North American bus operators require passengers to board at the front door and pay at a farebox next to the driver. At busy stops, the bus waits several minutes as passengers file on, even if they already have monthly passes. To speed up buses, urban operators all over Europe have instead implemented all-door boarding, with the fare enforced via random inspections, the same system San Diego already uses on its trolley. American bus drivers have expressed support for this as a way of reducing assaults on drivers coming from fare disputes.

Within the United States, San Francisco Muni lets passengers board buses from any door, enforced through random inspections. Since it implemented this policy in 2012, the average time a bus is stopped at a station has declined by one third. Fare evasion in San Francisco has actually gone down since 2012, according to one report. Passengers without monthly passes can still pay at the front, so there is no need for ticket-vending machines at every station, reducing costs.

Yet even within its Rapid brand, San Diego only has off-board fare collection at the stops that are also rail stations. Rapid-only stops don’t meet what most consider a minimally viable BRT standard. MTS did, however, launch this week a mobile ticketing platform that will work on all its buses and trolleys.

Nor is what SANDAG installed on the urban Rapid route, the 215, real BRT. This comes from the distinguishing feature of BRT: a bus with 40 passengers gets 40 times the traffic priority of a car with one driver and no passengers.

In practice, this means the bus gets dedicated lanes, which may be physically separated from regular traffic lanes, to discourage car drivers from infringing on them. It also means that the bus gets signal priority at intersections, to reduce the time it spends at a red light. San Diego’s Rapid routes have signal priority, but besides a short stretch on Park Boulevard, none has a dedicated lane in mixed traffic.

This, in action, is the global problem of BRT creep. All the 215 route has is signal priority, better bus shelter and wider stop spacing.

The separate Rapid brand is a step in the right direction for San Diego’s bus network. However, it combines what are really two separate kinds of service. The limited-stop urban 215 route is not the same as the four freeway routes. In the North American cities with the biggest bus networks, freeway routes with long nonstop segments are usually treated differently from BRT. They get limited ridership, and practically all of their ridership is at rush hour, which raises operating costs since the buses run fewer hours per day and the drivers have to work split shifts. The BRT efforts in the North American cities with the biggest networks, such as New York and Vancouver, Canada, are focused on urban routes, like the 215.

Nationally renowned transportation consultant Jarrett Walker stresses the importance of frequency for transit service: There is a minimum all-day frequency at which passengers find a city bus usable, about 15 minutes. The 215, San Diego’s supped-up Rapid, just meets that standard, with a bus every 15 minutes at midday and every 10 minutes around rush hour.

San Diego’s busiest bus, the 7, runs every 12 minutes in the midday off-peak. For developers considering University Avenue to build the walkable, transit-oriented projects the city’s clamoring for, there simply is no transit to rely on. Instead, developers have to provide underground parking for new tenants at $50,000 per spot, driving up home prices.

San Diego has good light rail bones, owing to investments it made starting in the 1980s, when it built the trolley at relatively low cost. It should use its bus network to complement light rail. Some routes, like the 7 and 215, can fill in the gaps, serving neighborhoods that aren’t on light rail corridors. Other routes should be set up to feed into the trolley.

On the West Coast, the best model is Seattle. Seattle only opened its light-rail network, Link, in 2009, and the system still only has one line, with half the ridership of the trolley. As it extends Link, however, Seattle reconfigures its bus network to feed the trains; in areas close to the neighborhoods served by the train, the best transit connection may involve a bus-train transfer. As a result, Seattle has had burgeoning transit ridership: by 2015 bus ridership surpassed its 2008 peak, with Link providing substantial extra ridership on top of it. San Diego County has similar size to Seattle’s metro area and could learn from its bus-rail network design.

In addition to network design, SANDAG needs to deploy the best industry practices for bus operations systemwide: all-door boarding, dedicated lanes and signal priority on the most congested streets, bus stops with shelter from the elements and bus stop consolidation to one stop per quarter mile. Providing dedicated lanes will require significant political capital, but for an agency lacking actual capital it’s a low-cost alternative to improve transit.

The key routes should have at a minimum a bus every 15 minutes all day, ideally every 10. If SANDAG is interested in shifting people’s travel modes from cars to transit, it should implement these, in order to boost ridership, rather than announcing BRT on select routes and delivering the service quality of what in many cities is an ordinary bus.

Alon Levy is a Paris-based mathematician and public transportation policy writer.

Correction: An earlier version of this story incorrectly stated how often the 7 bus runs during off-peak hours. It runs every 12 minutes.